Article

Strategy for capturing of a tumbling space debris

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Abstract

In general space debris objects do not possess much convenient features and are non-cooperative. In such cases, since the conditions for capture are not favorable, tracking errors will lead to loading, and momentum transfer will occur during the capture process.In most cases, detailed mass and inertial characteristics of the target are unknown, either because design details are unavailable or due to changes as a result of damage sustained when failure occurred or gradual degradation over the years, and this makes impedance matching of the capture arm force control system difficult.This led to us to devise a “joint virtual depth control” algorithm for robot arm control, which brakes the rotation of a target with unknown inertia. This paper deals with a removal work strategy and control method for capturing and braking a tumbling, non-cooperative target space debris.We propose a new brush type contactor as end-effecter of a robot arm for reducing the rotational rate of the target debris. As a means for relieving the loads generated during target tapping, in addition to joint compliance control we propose a new control method that controls the arm tip force according to a contact force profile.

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... Nomenclature E n = n × n identity matrix e = angular velocity error, rad/s e max = maximum allowable angular velocity error, rad/s f = control force of child, N f = constant thrust of thruster, N I max = maximum allowable impulse, N ⋅ s I sp = impulse of thrusters, N ⋅ s I 1 ; I 2 = inertia matrices of target and child, kg ⋅ m 2 J 1 ,J 2 = fitness functions in case 1 and case 2 L = angular momentum of combined system, kg ⋅ m 2 ∕s m 1 , m 2 = masses of target and child, kg P = linear momentum of combined system, kg ⋅ m∕s Q, R = weighting matrices of linear quadratic regulator R 1 ; R 2 = rotation matrices of frames Σ 1 and Σ 2 with respect to frame Σ I R 12 = relative rotation matrix of frame Σ 2 with respect to frame Σ 1 r 1 ; r 2 = position vectors of center of mass of target and child, m _ r 1 ; _ r 2 = linear velocities of target and child, m/s t f = terminal time of detumbling mission, s t 0 = moment of impact, s t 2 = end time of detumbling operation in case 2, s x = optimization vector of particle swarm optimization x 1 , x 2 = optimal solutions of x in case 1 and case 2 ρ = position vector from target's center of mass to child's center of mass, m τ = control torque of child, N ⋅ m ϕ 1 ; ϕ 2 = attitude angles of target and child (z − y − x Euler angles), rad ω 1 ; ω 2 = angular velocities of target and child, rad/s 0 m×n = m × n zero matrix j ⋅ j = absolute value of scalar k ⋅ k 1 = 1-norm of vector Superscripts -= motion variable of target or child before impact = motion variable of target or child after impact 0 = vector or matrix expressed in frame Σ 1 0 0 = vector or matrix expressed in frame Σ 2 0 0 0 = vector or matrix expressed in frame Σ 3 ...
... For a tumbling debris target with large inertia, detumbling it before the capture operation can improve mission reliability and avoid damage to the robotic arm. In recent years, some detumbling strategies using specific equipment, such as brush contactor [12], multifinger manipulator [13], electromagnetic coil [14], laser emitter [15], and chemical thruster [16], to exert control force on the target have been proposed. The effectiveness of these detumbling strategies has been preliminarily verified by numerical simulation or ground experiment. ...
... Note that B is not invertible since the singular matrixρ 0 explicitly exists in its two terms [see Eqs. (12) and (14)]. Thus, Eq. (17) cannot be rewritten ...
Article
This paper presents a new detumbling strategy for non-cooperative tumbling targets using a low-thrust device. The device with a harpoon on the front is released from the servicing satellite and embedded in the target. Then, the device’s thrusters are used to reduce the target’s angular velocity. In this paper, an impact model between the target and the device is established based on the conservative principle of linear and angular momentum. The dynamic equation of the combined system after impact is derived based on the principle of virtual power. A detumbling control scheme combining the linear quadratic regulator (LQR), pulse-width pulse-frequency (PWPF) modulation, and particle swarm optimization (PSO) is developed. The continuous optimal control signal obtained by LQR is transformed into a series of pulse signals by a PWPF modulator. To improve the performance of the detumbling controller, the weighting matrices of LQR are optimized by PSO, and two constrained optimization problems are studied. Finally, the effectiveness and robustness of the proposed strategy are verified by numerical simulations.
... Robotic Contact [21][22][23] Electromagnetic [16][17][18][19][20] Space debris mostly contains conductive materials such as aluminum alloys and titanium alloys. Therefore, when the target is in an external magnetic field, eddy currents are internally induced to hinder the relative motion. ...
... Robotic Contact [21][22][23] In this method, the service satellite touches the target intermittently by using the elastic deceleration device attached to the end of the arm. The target rotation is detumbled by the friction. ...
... DELTA.t between adjacent path points can be lengthened as much as possible during planning. From Formulas (21) and (22), the maximum value of ∆t is found: ...
Article
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In order to avoid damage to service satellites and targets during space missions and improve safety and reliability, it is necessary to study how to eliminate or reduce the rotation of targets. This paper focused on a space detumbling robot and studied the space detumbling robot dynamics and robot arm deployment path planning. Firstly, a certain space detumbling robot with a ‘platform + manipulator + end effector’ configuration is proposed. By considering the end effector as a translational joint, the entire space detumbling robot is equivalent to a link system containing six rotating joints and three translational joints, and the detailed derivation process of the kinematic and dynamic model is presented. Then, ADAMS and MATLAB were used to simulate the model, and the MATLAB results were compared with the ADAMS results to verify the correctness of the model. After that, the robot arm deployment problem was analyzed in detail from the aspects of problem description, constraint analysis and algorithm implementation. An algorithm of robot arm deployment path planning based on the Bi-FMT* algorithm is proposed, and the effectiveness of the algorithm is verified by simulation.
... A driving force that will require new methods is the need for a system that can perform fully autonomous rendezvous in several domains (e.g., low Earth orbit, low lunar orbit, etc.) [3]. Several vehicles capable of autonomous docking are either already operational or in development, ranging from large vehicles such as the SpaceX Crew Dragon, Soyuz, and Orion [1,3,4], to smaller robotic vehicles for clearing orbital debris [5][6][7]. ...
... Furthermore, some pulse durations are almost exactly ≈ Δ min s. This shows that the smoothed discrete logic (41d) actively enforces the MIB constraint (5). The constraint (41d) is indispensable for satisfying the minimum impulse-bit, and removing it causes the MIB constraint to be violated. ...
... Example of a control history that is compatible with the impulsive thrust model (4) and the pulse duration constraint(5). ...
Preprint
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This paper presents a computationally efficient optimization algorithm for solving nonconvex optimal control problems that involve discrete logic constraints. Traditional solution methods for these constraints require binary variables and mixed-integer programming, which is prohibitively slow and computationally expensive. This paper targets a fast solution that is capable of real-time implementation onboard spacecraft. To do so, a novel algorithm is developed that blends sequential convex programming and numerical continuation into a single iterative solution process. Inside the algorithm, discrete logic constraints are approximated by smooth functions, and a homotopy parameter governs the accuracy of this approximation. As the algorithm converges, the homotopy parameter is updated such that the smooth approximations enforce the exact discrete logic. The effectiveness of this approach is numerically demonstrated for a realistic rendezvous scenario inspired by the Apollo Transposition and Docking maneuver. In under 15 seconds of cumulative solver time, the algorithm is able to reliably find difficult fuel-optimal trajectories that obey the following discrete logic constraints: thruster minimum impulse-bit, range-triggered approach cone, and range-triggered plume impingement. The optimized trajectory uses significantly less fuel than reported NASA design targets.
... For the latter, Nishida and Kawamoto [16] used a flexible brush as a tool to contact the tumbling debris and found that the interaction forces generated by the elastics deformation brush reduced the tumbling velocity of the debris. Similarly, in our previous work [17,18], we employed a flexible bar to slow down the tumbling target. ...
... To prove that the relationships given in (16) and (19) are valid, three simulations are performed, in which x(0) = 0.001, ẋ(0) = 0, C = 1 × 10 5 , and the other parameters are the same as the simulations made in Sect. 3.1. ...
... As seen, the change speed of curve (13) is slower than that of curve (15), and the change speed of curve (15) is slower than that of curve (18). Those results demonstrate that the relationships in (16) and (19) are valid. Now, we will prove that lim t→∞ x(t) of (18) > 0. According to the collision theory, x(0) = b > 0 and ẋ(0) = 0 at the beginning of the recovery phase. ...
Article
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Using a space robot to capture a non-cooperative spacecraft with high-speed rotation is significantly challenging since any collision generated during capturing will have great impact on both. To reduce the risk in capturing operations, it is crucial to slow down the rotation velocity of the target before capturing. Hence, this paper studies a collision control strategy for using a robotic arm to detumble a non-cooperative spacecraft. The goal of this strategy is to maintain contact between the robot and the target and to apply continuous detumbling force on the target to slow down its rotational motion. To achieve that, first the mechanism analysis of the two balls for a central collision scenario is performed. Then an overdamping control method is proposed to avoid the separation of the balls after the central collision based on the overdamping property of the mass-spring-damper system, the effectiveness of which is validated theoretically. Finally, to use this overdamping control method in the detumbling missions of space robots, a position-based overdamping control strategy is introduced. In this strategy, the relative dynamic behavior between the robotic arm tip and the contact surface of the target during detumbling is approximated to that of a mass-spring-damper system. Owing to the proposed overdamping control method, the contact between the robot and the target can be maintained, and the space robot can apply continuous control torque to slow down the rotational velocity of the target. Numerical simulations are performed to demonstrate the validity of the proposed control strategy.
... Collisions of the space debris with spacecraft and other debris, however, can significantly increase the number of small debris around the Earth [the Kessler syndrome (Kessler and Cour-Palais, 1978;Kessler et al., 2010)]. There is a large number of papers focused on this problem (Pelton, 2015;Anselmo and Pardini, 2016;Aslanov, 2017;Benvenuto et al., 2015;Nishida and This study focuses on rendezvous and soft docking space debris with a space tug. The rendezvous is carried out by retraction of the tether. ...
... Kawamoto, 2011;Lee et al., 2012, Lee andSchaub, 2014;Sabatini et al., 2016;Wen et al., 2016;Pang et al., 2015;Aslanov, 2016; Yudintsev, 2015, 2014;Aslanov and Ledkov, 2014;Huang et al., 2016;Aslanov and Pikalov, 2017;Trushlyakov et al., 2018;De Luca et al., 2013;Park et al., 2016). Various approaches have been offered to remove defunct satellites and old upper stages (Pelton, 2015;Benvenuto et al., 2015;Nishida and Kawamoto, 2011;Lee et al., 2012;Sabatini et al., 2016). ...
... . Various approaches have been offered to remove defunct satellites and old upper stages (Pelton, 2015;Benvenuto et al., 2015;Nishida and Kawamoto, 2011;Lee et al., 2012;Sabatini et al., 2016). These approaches include the use of tether systems (Pelton, 2015;Aslanov, 2017). ...
... Non-contact detumbling methods [9][10][11], such as thruster plume impingement, electrostatic force, and eddy current, have characteristics of small torque, less impact and long-term operation. Compared to it, contact detumbling methods [12][13][14] provide larger torque in a shorter term, which include Tethered Space Robot, mechanical impulse and brush contactor. Consequently, studies on the impact reduction method using mechanical impulse with flexible end-effector were developed for the ground detumbling experiment [15], which are aimed at keeping efficiency of detumbling and capturing mission. ...
... The removal of out-of-area pressure data regarded as noise contributes greatly to the impact pressure distribution. As for the 8th row, the pressure values in these 9 columns (j = 1, 2, 3,4,12,13,14,15,16) are out-of-area data, so they are set to zero. The unspaced pressure distribution includes 16 raw values (F i,j ) and 15 supplementary values (S i,j ). ...
Article
Full-text available
During the contact between the detumbling end-effector and large non-cooperative target, the recognition of impact pressure distribution is important for estimating the success rate of detumbling mission. To figure out the pressure trends, the ground experiments before the real space mission are necessary. However, due to the drawbacks of the pressure array-like sensor, dynamic characteristics of impact, and unavoidable noise, the accurate dynamic pressure distribution is hard to obtain. In this letter, we propose a recognition method, Impact Pressure Distribution Recognition. The proposed method can quickly generate dynamic impact pressure distribution without limitation on sensor accuracy through pressure data supplement and area correction based on contact model. The analysis results show that our method can efficiently recognize multiple distributed pressure and rebuild the more accurate impact pressure distribution.
... This allows the procurement of an adequate amount of information especially related to the integrity of the target and its rotational motion [21]. Detumbling actions can be applied before or after the capture or physical contact between the chaser and the target, ranging from plume impingement [22] or magnetic torque generation [23,24], to the use of a kinematically redundant robotic arm [25,26] or a brush-type contractor [27]. Those actions are necessary if the rotational velocities of the target exceed servicing capabilities and, therefore, prohibit a safe approach for the attachment and capture [28]. ...
... More recently, the beneficial features of the pomelo's peel have been recognized by the science community and articles have been published studying and modelling the foam-like structure [80,81]. Therefore, it is hypothesized that a bio-inspired material is equally able to dampen the impact between the arm and the target as well as reduce the impact of the preliminary connection onto the target's trajectory [27]. ...
Article
Full-text available
The ever-increasing number of man-made space debris creates the need for new technologies to mitigate it. Therefore, within the ESA-funded project BIOINSPACED, biologically inspired solutions for active debris removal were investigated, conceptualized and integrated to innovative and comprehensive scenarios. In the following, the collection process of existing and new biomimetic concepts as well as the evaluation of ten concepts based on a feasibility analysis will be presented. Out of the ten, the three most promising scenarios, were chosen for further investigation and further elaborated in detail specifying the biological models incorporated as well as how the scenario could be implemented in a simple demonstrator. The first scenario (A) is a gecko kit canon and describes a system that fires deorbiting kits towards the target from a safe distance. The second scenario (B) involves a robotic arm with a gecko-adhesive end-effector and a bee-inspired harpoon to achieve a preliminary and subsequent rigid connection to the target. The last scenario (C) is mimicking a Venus Flytrap and its bi-stale mechanism to capture its prey. One of these scenarios will be manufactured and built into a demonstrator to showcase biology's potential for the development, optimization and improvement of technologies, especially within the space industry.
... All these factors make it difficult to capture such debris [6,13]. Space objects that tumble at a rate below 3 • /s can be captured easily; a tumbling rate above 30 • /s is not regarded as a target; an object tumbling between 3 • /s and 30 • /s can be detumbled in advance [14]. Thus, if the object is tumbling rapidly, a fly-around and grasping by a robot arm seem infeasible. ...
... Furthermore, a detumbling method based on a flexible device is considered more efficient and safer than other approaches. Nishida and Kawamoto [14] designed a brush-type contactor as an end-effector of the robot arm to reduce a cylindrical object's rotation. Braking torque is produced by friction. ...
Article
Full-text available
Malfunctioning satellites are generally non-cooperative tumbling objects. Due to their complex tumbling motion, it is essential to stabilize the target within an acceptable rotating range in the pre-capture phase. In contrast to contactless methods, contact methods based on flexible devices are efficient and can generate sufficient operating torque through flexible contact. However, accurate dynamic analysis of the operation is challenging because of two limitations. It is difficult to obtain a high-efficiency description of the large deformation arising from the operating process. Moreover, the contact between a flexible device and a tumbling object is hard to detect efficiently. This paper proposes a method for detumbling a free-floating rotating satellite; it uses a flexible rod to contact the solar array of the target. The absolute nodal coordinate formulation is first applied to a rod-contact detumbling model in simulation to describe the large deformation of the rod precisely with a low computational burden. Next, a two-step method to detect the contact is employed to pinpoint the contact point and speed up the simulation: coarse detection in the contactless phase and fine detection in the contact phase. Finally, the feasibility of the contact detumbling method is verified. In addition, through further analysis of the contact process, some characteristics of this kind of strategy are studied for the first time.
... All these factors make it difficult to capture such debris [6,13]. Space objects that tumble at a rate below 3 • /s can be captured easily; a tumbling rate above 30 • /s is not regarded as a target; an object tumbling between 3 • /s and 30 • /s can be detumbled in advance [14]. Thus, if the object is tumbling rapidly, a fly-around and grasping by a robot arm seem infeasible. ...
... Furthermore, a detumbling method based on a flexible device is considered more efficient and safer than other approaches. Nishida and Kawamoto [14] designed a brush-type contactor as an end-effector of the robot arm to reduce a cylindrical object's rotation. Braking torque is produced by friction. ...
Preprint
Full-text available
Malfunctioning satellites are generally non-cooperative tumbling objects. Due to their complex tumbling motion, it is essential to stabilize the target within an acceptable rotating range in the pre-capture phase. In contrast to contactless methods, contact methods based on flexible devices are efficient and can generate sufficient operating torque through flexible contact. However, accurate dynamic analysis of the operation is challenging because of two limitations. It is difficult to obtain a high-efficiency description of the large deformation arising from the operating process. Moreover, the contact between a flexible device and a tumbling object is hard to detect efficiently. This paper proposes a method for detumbling a free-floating rotating satellite; it uses a flexible rod to contact the solar array of the target. The absolute nodal coordinate formulation is first applied to a rod-contact detumbling model in simulation to describe the large deformation of the rod precisely with a low computational burden. Next, a two-step method to detect the contact is employed to pinpoint the contact point and speed up the simulation: coarse detection in the contactless phase and fine detection in the contact phase. Finally, the feasibility of the contact detumbling method is verified. In addition, through the further analysis of the contact process, some characteristics of this kind of strategy are studied for the first time.
... It is worth mentioning that in these on-orbit experiments, the target and chaser satellites were launched together and the targets assisted the chasers to complete the capture operation by docking mechanisms and vision markers. However, space debris is usually uncooperative and rolls under the influence of the vibrations of flexible appendages and complex space environment [7,8]. Therefore, the research on the capture and detumbling strategy of uncooperative flexible targets will contribute to the development of ADR technology. ...
... 3.2 is adopted to find the Pareto optimal solutions of the MOOP. After getting the optimal trajectory set of the target, the desired trajectories of the end-effector can be obtained by Eq. (8), that is, ...
Article
Full-text available
The rapid growth of space debris poses a serious threat to space exploration activities. Large space debris, such as malfunctioning satellites, are generally uncooperative tumbling objects with flexible appendages. This paper investigates the detumbling scheme for a flexible target using a flexible-base space robot in post-capture phase. This scheme consists of trajectory planning and coordination control, which can bring the target to rest and stabilize the base attitude of the space robot while suppressing the vibrations of the flexible panels. In this paper, a recursive method based on the Newton–Euler formulation is employed to derive the kinematics and dynamics of the combined system. The trajectory planning of the end-effector is converted to a constrained multiobjective optimization problem, whose Pareto front is obtained by the multiobjective particle swarm optimization (MOPSO) algorithm. A coordination controller is developed to track the planned trajectories of the space robot. The presented numerical simulations verify the effectiveness of the detumbling scheme and its robustness to space targets with parametric uncertainties.
... Responding to the excessive velocities and parameter uncertainties of tumbling targets, JAXA [49,50] first proposed using a flexible brush contactor for target pre-processing. Ma [51] divided the pre-capture into two stages: maintaining the spacecraft at the same rotation and linear velocity as the target and subsequently capturing the target with relative stationery. ...
Article
Full-text available
Space is the driving force of the world's sustainable development, and ensuring the sustainability of human activity in space is also necessary. Robotic arm active debris capture removal (RA-ADCR) is a noteworthy technology for containing the dramatic increase in space debris and maintaining orbital safety. This review divides the RA-ADCR technology progress history into three periods and presents the status of related research. Two major development trends are summarized and subdivided through the analysis and collation of research achievements over the past three years. Taking the treatment of parameter uncertainties as the entry point, researchers would like to improve the discrimination accuracy and scope to reduce uncertainties. On the other hand, researchers accept such uncertainties and would like to offset and avoid the impact of uncertainties by extending the error margins. Subsequently, the challenges of RA-ADCR are analyzed in line with the task execution flow, which mainly focuses on the conflict between on-satellite computing power and the performance of task execution. In addition, feasible solutions for the current phase are discussed. Finally, future outlooks are evaluated and discussed.
... The contact capture method is a simple and feasible way to capture space debris. There are mainly two types of contact capture: rigid capture and flexible capture (Nishida and Kawamoto, 2011;Shan et al., 2016). Like space manipulator and capture claw, the rigid capture methods will inevitably cause collision between the capture target and operation platform. ...
Article
Full-text available
Similar to a space flying net, the capture field of the space netted pocket system is large and it can be applied to capture space non-cooperative targets flexibly. To maintain the stability of the space netted pocket system, eight inflatable rods are used as the supporting structure of the net surface. In this paper, a space netted pocket system is designed and modeled. Based on ANCF (absolute nodal coordinate formulation), a dynamic model of the complex space rope net system is established, and then an accurate model of closing rope considering the variable length is derived by introducing mass flow element. A double closed-loop sliding control method is designed to maintain the stable attitude of the service spacecraft. An extended observer is applied to estimate and compensate for the disturbances due to the uncertainty of the contact and flexibility in the system. Finally, the dynamic model and control method is verified through the simulation of the virtual prototype. Results show that the service spacecraft can maintain the attitude stability during target captured process and can track the desired angle during attitude maneuver. The flexible deformation and collision cause great disturbance to the service spacecraft, and the extended observer can improve the control accuracy from 10−3 to 10−4.
... ADR is a promising technology in which multiple spacecraft operations are required. ADR methods using robotic arms [1,2], nets [3], or electrodynamic tethers [4] have been proposed, which require contact operations. Such contact operations may have potential risks to the collision between a removal satellite and the target. ...
Article
Full-text available
An active debris removal method using a laser is a promising technology for its advantage in contactless operations. This paper deals with the attitude control of an uncooperative target by a laser, which is an important phase before deorbiting. The difficulty of attitude control by the laser stems from the torque directional constraint because the laser generates thrust along the normal vector of the irradiated face irrespective of the irradiating direction. Thus, the control torque along the normal vector cannot be generated, which makes the attitude control with the laser torque challenging. To tackle this problem, this paper first designs a reference controller that assumes arbitrary control torques are available. Then, a method for determining the irradiating point is proposed so that the difference between the reference torque and the actual one is minimized. Although the proposed controller does not guarantee theoretical convergence to the desired attitude, the effectiveness of the proposed controller is numerically verified for a box-type object. Furthermore, the robustness to the uncertainties of thrust magnitude and direction is also examined by Monte Carlo simulations.
... More recently, Nishida and Kawamoto [112] examined a capture strategy of a tumbling target with unknown moment of inertia. To this aim, the authors developed a joint virtual depth control algorithm which if applied to a brush-type end-effector is able to reduce the rotational motion of the target while complying with the imposed contact force profile and avoid pushing away the target during the process. ...
Thesis
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This dissertation provides solutions to the active debris removal (ADR) research domain. More specifically it contributes to the initial mission planning as well as to the close-range rendezvous and capture phase of an ADR mission. The first contribution of the thesis consists out of a domain-ontology specifically developed for ADR with an aim to provide a standardized, machine-interpretable knowledge representation framework. This framework is capable not only of efficiently storing complex information but also inferring the most suited ADR capture method(s) for an object from its minimal set of parameters. The second contribution of the thesis is to provide an optimization-based motion planner of a spacecraft equipped with a manipulator, a space robot. The purpose of the planner is to to facilitate an autonomous capture of an uncooperative, rapidly tumbling target by means of a space robot. This is achieved by taking the advantage of the particular dynamics of the space robot and an appropriate partial attitude synchronization strategy. Copyright: CC BY-NC-ND 4.0
... Another key target is ESA's defunct eight-tonne satellite, Envisat, which resides in a densely populated region and is known to be tumbling (Kucharski et al. 2014;Pittet et al. 2018). Studies have explored the challenges of approaching and capturing a tumbling, uncooperative target (Nishida & Kawamoto 2011;Chu et al. 2018), alongside those associated with the removal of multiple targets per mission (Braun et al. 2013;Shen et al. 2018). ...
Article
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October 1957, and the successful launch of Sputnik 1 into Earth orbit, marked the dawn of the Space Age. The first of the 'fellow travellers' - humanity's first artificial satellite - orbited for a mere three months before re-entering the Earth's atmosphere, though its mission paved the way for an era of exploration that has endured to the present day. For many, a world without satellites would be a difficult one to imagine. As a society, we have become reliant on them for a vast array of services and applications. With a divine view of large swathes of the Earth's surface, and the ability to relay signals around its curvature, satellites have enabled the fast transfer of data on a global scale, bypassing the challenges associated with ground-based broadcasting, long-distance wiring, and so on. Positioning, Navigation and Timing (PNT) satellites have revolutionised transportation by land, air, and sea, while weather satellites enable scientists to monitor and warn of large-scale phenomena as they develop in near real-time. Satellites have extended the frontiers of observation: looking outwards, astronomers are able to circumvent the Earth's atmosphere to look deeper into the cosmos than ever before; looking inwards, patterns and processes that feed into general circulation models can be monitored on a range of timescales, improving our understanding of climate change. Satellites, and the services they provide, are not going to disappear any time soon. That said, threats to satellite safety do exist, and it is important that they be addressed as soon as possible to avoid long-lasting damage to operations in the space domain. Nearly sixty-five years on from the advent of human activity in space, I chart the evolution of the orbital debris environment and review latest efforts to make space operations more sustainable.
... However, detumbling depends on distance and will cause higher fuel and time consumption. The contact type can reduce the detumbling time, including brush type contactor (Nishida and Kawamoto, 2011), cushion-type damper (Matunaga et al., 2001), flexible rod (Liu et al., 2019a;Liu et al., 2019b), and rigid end-effector (Wu et al., 2018), which utilize friction to reduce the target angular velocity. However, these will not reduce it to zero. ...
Article
Full-text available
This paper focuses on the control strategy of a dual-arm space robot to capture and detumble a non-cooperative satellite without a specific gripping point. First, an elastic hemispherical claw was designed to reduce the collision impacts and adjust the capture position, and its contact dynamics and capture ability were verified by ground experiments. Analysis of the position constraints led to the proposal of a compliant control scheme to achieve stable capture without a contact-force sensor. Subsequently, a modified adaptive sliding mode based prescribed trajectory tracking control (PTTC) and null space intersection approach was proposed to achieve target detumbling under the actuator constraints. The control system stability was analyzed via the Lyapunov method. Finally, numerical simulations were employed to validate the effectiveness and correctness of the strategy. Results showed that, a large inertia target could be steadily captured and detumbled within 80 s.
... 7 However, high tumble rates 8,9 of retired satellites in GEO complicate these two approaches, as the relative rotation of the debris must either be matched by the servicer (at the cost of additional fuel), or the robotic arms must be capable of capturing a rotating object. 10 The common theme of all aforementioned Active Debris Removal (ADR) methods is that they rely on physical contact. The Electrostatic Tractor (ET) has been proposed to touchlessly relocate retired satellites from GEO using electrostatic forces, 11,12 as illustrated in Fig. 1. ...
Conference Paper
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The electrostatic tractor concept is an active debris removal method that has been proposed to remove retired satellites from Geostationary Earth Orbit without physical contact, using electrostatic forces. These forces are generated by charging the servicing satellite and the debris with an electron gun that is attached to the ser-vicer. Prior work investigated the effects of debris attitude on performance factors such as reorbit time and control effort. Uncertainty in the electric potential of the debris was also considered. This work extends the analysis of the electrostatic tractor performance by considering additional sources of uncertainty, such as uncertainty in mass properties, charge model errors, and electric potential uncertainty of the servicing satellite. The results suggest that errors in the estimated electric potential have the most significant impact on the reorbit performance.
... Liu et al. [21] and Yu et al. [22] conducted a series of studies on the dynamics and control of capturing a floating rigid body by a rigid space robot. Nishida et al. [23][24][25][26] studied the dynamics of capturing space debris by a rigid space robot, and some research results about capturing strategy were achieved. Liu et al. [27], Liu et al. [28,29], and Stolfi et al. [30,31] studied the control problem of the capture of a larger tumbling object by multi rigid robot arms. ...
Article
Full-text available
Capturing space targets by space robots is significant for on-orbit service and is a challenging research topic nowadays. This paper focuses on the dynamics and control of capturing a non-cooperative space target by a space robot with a long flexible manipulator. Firstly, the dynamic equation of the flexible space robot is given. The Hertz contact model is used to describe the contact force between the robot and the target. Secondly, an active compliance controller is designed to reduce the capture impact on the robot. Finally, the capture impact on the whole system is analyzed in detail in four scenarios: the combination of two kinds of movement forms and two kinds of relative positions of the robot and the target before capturing. Simulation results indicate that the capturing operation may cause complicated dynamic behaviors such as the vibration of elastic links and the continuous collision of the target. Moreover, the results show that the control method effectively offsets the capture impact on the space robot system. In general, this work lays a theoretical foundation for further study of the dynamic phenomena of the capture process.
... Space robots with manipulators for orbital applications are a growing field of research due to their importance in the space environment. There are many applications for this kind of spacecraft, from satellite maintenance (Beyer et al., 2018) to space debris removal (Reiner et al., 2017;Nishida and Kawamoto, 2011), passing through berthing (Fonseca et al., 2017), dispose malfunctioned satellites (Reintsema et al., 2011), on-orbit refueling operations (Liu et al., 2020), and removal of spent launchers' stages (Felicetti et al., 2016). ...
... In recent years, with the frequent occurrence of space security accidents and the explosion of space debris, active removal methods for abandoned large satellites and space debris have become increasingly important. For various targets and application scenarios, people have proposed various active removal methods with different application scenarios, each with advantages and disadvantages, such as Space robotic arm [1], Tethered Space Robots [2], Tethered Space Net Robot [3], etc. However, the angular velocity range of these methods for capturing non-cooperative targets does not exceed a few degrees per second. ...
Chapter
Due to the increasing risk of space tumbling targets for spacecraft and astronauts, de-tumbling technology of spacecraft become more and more important and various de-tumbling methods have been proposed. This paper mainly studies the fast and safe de-tumbling of space tumbling target. Considering that the required time of de-tumbling via previous methods is too long, this paper first takes the maximum de-tumbling torque as the objective function and solves the optimal trajectory in real time. Then, the MPC algorithm is used to track the trajectory under the constraints of the safe area to ensure a fast and safe de-tumbling. The numerical simulation of large failure satellite verify that the method proposed in this paper is very effective on reducing de-tumbling time. However, it consumes huge control power. The controller will continue to be optimized in the future to reduce the consumption of control power while ensuring rapid de-tumbling.
... According to NASA from the beginning of 2020, at least five large-scale debris targets (e.g., malfunctioning satellite, rocket upper stages, remnants of explosions, etc.) need to be removed each year to maintain the orbit environment. 3,4 Recently, major aerospace countries have begun research into ADR technology and actively carried out key technology testing and verification tasks, such as ETS-VII, 5,6 CSO, 7 RemoveDEBRIS, 8 and AnDROiD. 9 However, these projects mainly focus on cooperative targets, while orbital debris generally does not have a specific docking interface or even tumbling due to their residual angular momentum. ...
Article
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Active debris removal (ADR) technology is an effective approach to remediate the proliferation of space debris, which seriously threatens the operational safety of orbital spacecraft. This study aims to design a controller for a dual-arm space robot to capture tumbling debris, including capture control and detumbling control. Typical space debris is considered as a non-cooperative target, which has no specific capture points and unknown dynamic parameters. Compliant clamping control and the adaptive backstepping-based prescribed trajectory tracking control (PTTC) method are proposed in this paper. First, the differential geometry theory is utilized to establish the constraint equations, the dynamic model of the chaser-target system is obtained by applying the Hamilton variational principle, and the compliance clamping controller is further designed to capture the non-cooperative target without contact force feedback. Next, in the post-capture phase, an adaptive backstepping-based PTTC is proposed to detumble the combined spacecraft in the presence of model uncertainties. Finally, numerical simulations are carried out to validate the feasibility of the proposed capture and detumbling control method. Simulation results indicate that the target detumbling achieved by the PTTC method can reduce propellant consumption by up to 24.11%.
... Although many debris removal measures have been proposed and tested (e.g., Nishida and Kawamoto, 2011;Kibe, 2003), none of them is both technically practicable and economic viable (Hall, 2014). ...
Preprint
Full-text available
In the last few years, countries and commercial firms are increasingly interested in space activities for civil, military, and commercial purposes (Undseth et al., 2020). As it has been shown in NASA report (2019), investment in space program drives to significant economic benefits to the whole society. We propose the first methodological paper to empirically study the efficiency of satellite launches employing the Data Envelopment Analysis input-oriented technique. We show that overall average efficiency is quite low and that it can significantly be improved by studying subsamples of DMUs according to user, purpose, and class of orbit. The most relevant results can be achieved in the communications purpose cluster where the bias corrected efficiency scores tripled with respect to average efficiency level reached by overall estimates. Hence, the scope of satellites seems to affect the mission efficiency and, even more relevant, the future creation of debris.
... An IADC study by Liou et al. [2013] employed six of the leading environmental models, finding that the simulated population of orbital debris would continue to increase by a factor of ∼ 30 % over the next 200 years, even with a 90 % mitigation compliance rate and no future explosions in orbit; of course, these assumptions are incredibly optimistic, and the actual population growth in this period will undoubtedly be worse. Several studies have identified active debris removal (ADR) as a way to reduce the likelihood of a Kessler-like collisional cascade and thus control the orbital debris population [see e.g., Bonnal et al., 2013;White and Lewis, 2014] , and a number of studies have explored the observational and operational challenges of rendezvousing and capturing a spinning, uncooperative target [see e.g., Nishida and Kawamoto, 2011;Kanzler et al., 2015;Gómez and Walker, 2015]. ...
Thesis
Full-text available
The past six decades of space exploration have taken their toll on the safety of satellite operations in near-Earth space. A large population of mission-threatening debris has accumulated in key orbital regions, comprising a mixture of abandoned spacecraft, fragments from collisions or explosions, and mission-related objects that no longer serve a purpose. Of particular concern is the situation in low Earth orbit (LEO), where certain bands are expected to be on the cusp of a "Kessler" cascade, whereby collisional fragments seed further collisions, and so on. Large LEO constellations look set to place an even greater strain on space surveillance systems, with several thousand spacecraft licensed to launch over the coming decade. That said, the problem is by no means limited to the LEO region. Indeed, the population of small debris at geosynchronous (GSO) altitudes remains largely uncharacterised, owing to the limited time available on sufficiently sensitive sensors. A wide variety of solutions have been posed across different sectors, from the drafting of universal debris mitigation guidelines, to the development of in situ technologies for servicing or removing spacecraft. Meanwhile, it is essential that the debris environment continues to be probed by surveillance sensors, in order to better inform future avenues for research into the safe and sustainable use of outer space. This thesis explores a number of ways in which optical imaging can contribute to enhanced levels of space situational awareness, using datasets acquired by a selection of instruments at the Roque de los Muchachos Observatory on La Palma. The 2.54 m Isaac Newton Telescope was used to conduct a blind survey of the GSO region, uncovering debris fragments too faint to be reliably tracked and catalogued by the US Space Surveillance Network. Photometric light curves were extracted from the survey frames, and many of the detected objects were found to exhibit signs of rapid tumbling. Simultaneous observations of the survey fields were acquired using a 36 cm robotic astrograph. A comparative analysis of the resulting datasets was performed to investigate the benefits of pairing a large aperture telescope with a wide-field commercial-off-the-shelf instrument when tasked with surveying the GSO region. In two further surveys, the repurposed SuperWASP-North array and the astrograph were used to carry out targeted observations of catalogued LEO and GSO spacecraft, respectively. Light curves were extracted from early prototype observations, and orbital arcs from the surveys were used as case studies to test a custom orbit refinement algorithm.
... Capture strategy for non-cooperative targets tumbling at high speed, applying resistance and reducing their angular speed of rotation to make capture less difficult [3]. In terms of contact despinning, Huang et al. [4,5] proposed a method for attitude control of noncooperative targets based on a tether terminal, which stabilizes the attitude of the tumbling target by controlling the tether tension and damping force attached to it; Daneshjou and Alibakhshi [6] proposed a spring damper buffer device which is accomplished by contact collision dur-ing nozzle docking in the despinning process; Nishida and Kawamoto [7] designed a despinning device with a flexible brush as the end-effector, which uses the elastic contact force between the brush and the target for despinning. There are also space debris removal systems such as drag-increasing devices, which accelerate the target deconvolution process by increasing the surface-to-mass ratio of the target, thus increasing the air drag; methods include spraying foam on space debris [8,9] and installing airbags for space debris [10]. ...
Article
Full-text available
A flexible brush mechanism is designed and mounted at the end of a seven-degree-of-freedom robotic arm to despin a tumbling target. The dynamics model of the flexible brush is established using the absolute nodal coordinate method (ANCF), and its contact collision with the solar wing of the tumbling target is analysed. The H ∞ optimal control is proposed for a seven-degree-of-freedom robotic arm during despinning of a tumbling target while ensuring the global robustness and stability. Simulations verify that the despinning strategy can successfully eliminate the rotation speed and is feasible and effective.
... The capture with robotic arms or tentacles requires complicated rendezvous and docking maneuvers. Retired satellites may tumble at rates of 10s of degrees per second [11,12], exceeding the capabilities of certain grappling methods [13]. Thus, touchless ADR techniques provide a great benefit for space debris removal. ...
Article
Full-text available
The electrostatic tractor has been proposed to touchlessly remove space debris from geosynchronous orbit by taking advantage of intercraft Coulomb forces. A controlled spacecraft (tug) emits an electron beam onto an uncooperative or retired satellite (debris). Thus, the tug raises its own electrostatic positive potential to tens of kilovolts, whereas the debris charges negatively. This results in an attractive force called the electrostatic tractor. Prior research investigated the charged relative motion dynamics and control of the electrostatic tractor for two spherical spacecraft and how charge uncertainty affects the relative motion control stability, but attitude effects could not be studied due to the two-sphere model. This work uses the multisphere method to consider general three-dimensional spacecraft shapes, and it investigates how the electric potential uncertainty and debris attitude impact the equilibrium separation distance between the two craft. The results show bounds for safe operations that avoid a collision. State regions are identified where the relative motion is particularly sensitive to potential uncertainty. The relative station-keeping performance using either higher- or lower-fidelity multi-sphere method models are compared to demonstrate that even a lower-fidelity multi-sphere method model can yield good results.
... A UTONOMOUS relative navigation is the key to accomplishing on-orbit servicing and exploration with non-cooperative space targets [1,2], such as space debris [3], dead satellites [4], and small bodies [5]. Non-cooperative space targets have no preset cooperation marks and no communication connection, and there is no prior information about them [6]. ...
Article
The use of monocular sequential images for relative navigation provides an efficient method for estimating the relative state of space non-cooperative targets, where the estimation accuracy is important to the relative navigation mission. A one-step optimal maneuver solution method is proposed that improves the state estimation accuracy. To determine the optimal maneuver and realize high-accuracy relative navigation, the relationship between the entire process of state estimation accuracy and the one-step maneuver is derived as an analytical model through the Fisher information matrix. An optimization problem is constructed and the one-step optimal maneuver is obtained in consideration of fuel constraints, the position constraints, the anticollision conditions and the observability conditions based on the state estimation accuracy analytical model combined with practical engineering requirements. The simulation results indicate that optimal maneuvering can effectively improve the state estimation accuracy, and they illustrate that the fuel constraint is a significant factor. Thus, the fuel constraint can be modified to produce better system state estimation accuracy with a certain range. When the fuel constraint reaches a certain level, the state estimation accuracy attains a stable value.
... Space debris is mostly discarded space scrap, which is out of control and eventually moves freely due to complex nutation. Since these high-speed tumbling targets are very difficult to catch directly, it is necessary to reduce the relative speed between the chaser and the target before the next onorbit capture [5][6][7][8]. us, the final capture of the target can be achieved when the relative speed is slow enough [9,10]. ...
Article
Full-text available
In order to improve the success rate of space debris object capture, how to increase the resistance to interference in the space robot arm has become an issue of interest. In addition, since the space operation time is always limited, finite-time control has become another urgent requirement needed to be addressed. Considering external disturbances, two control methods are proposed in this paper to solve the control problem of space robot arm. Firstly, a linear sliding mode control method is proposed considering the model uncertainties and external disturbances. The robot arm can track the desired trajectory, while a trade-off between optimality and robustness of the solved system can be achieved. Then, in order to reduce conservativeness and relax restrictions on external disturbances, a novel backstepping control method based on a finite-time integral sliding mode disturbance observer is developed, which compensates for the effects of both model uncertainties and infinite energy-based disturbance inputs. Finally, simulation examples are given to illustrate the effectiveness of the proposed control method.
... It is highlighted in [36] that debris within and around the SSO should be the main targets for debris removal missions. Moreover, [38] and [39] reemphasize that the SSO particularly have a greater risk of debris collision (in comparison to other regions in LEO), and thus the Japan Aerospace Exploration Agency (JAXA) is planning a mission to remove rocket upper stage remnants from the SSO. ...
... Most of potential ADR targets, such as intact rocket bodies and non-functional satellites [13], are uncooperative, i.e., not designed to be approached and captured, thus being neither able to actively communicate with the chaser, nor equipped with artificial markers (easily recognizable by the chaser during a rendezvous maneuver) and ad-hoc docking interfaces to facilitate grasping and disposal. Moreover, large debris are non-collaborative, i.e., unable to keep an attitude that facilitates the chaser approach, and may be quickly tumbling [14]. For these reasons, the relative navigation task shall be entrusted to active or passive Electro-Optical (EO) sensors [15,16]. ...
Article
Future Active Debris Removal missions will require an autonomous spacecraft (chaser) to safely monitor at close distance, and then approach and dispose an inactive artificial space object (target). Since these targets are uncooperative, meaning that they cannot provide any hint or help to the chaser navigation system, such operations require the target-chaser relative state and the target inertia parameters to be accurately estimated relying only on measurements from active or passive Electro-Optical sensors. In this framework, this paper proposes an original multi-step architecture for the estimation of the relative motion and inertia parameters of an uncooperative target during a close-range monitoring trajectory. In the first phase, LIDAR-based pose measurements and a smoothing approach are used to retrieve accurate, linearly independent estimates of the target angular velocity. These estimates are then used to compute the target's moment of inertia ratios solving a linear system based on the conservation equation for the angular momentum. Once the inertia parameters are accurately estimated, the LIDAR-based pose measurements are used to feed an Unscented Kalman Filter to determine the full relative state according to a loosely coupled configuration. The architecture foresees autonomous failure detection strategies to avoid divergence in the relative state estimation error caused by unavoidable, unfavorable target observation conditions occurring during the monitoring trajectory. Performance assessment is carried out through numerical simulations realistically reproducing close-range relative motion dynamics and LIDAR sensor operation, and considering targets characterized by highly variable size, shape, and orbital dynamics as test cases.
... Some contact and noncontact de-tumbling methods have already been proposed. Contact methods, including contact with the target using flexible brushes (Nishida and Kawamoto, 2011) and intermittent contact impacts on the target surface (Liu et al., 2019), require a complex close-range operation and high control accuracy of space robotic arm. The risk of collision can be reduced using noncontact de-tumbling methods. ...
Article
Capturing large space debris with complex rotational motion is extremely challenging. A de-tumbling phase before capturing may be necessary to reduce the risk of collision with debris. This paper proposes a new noncontact de-tumbling method using a two-satellite electromagnetic formation, in which two small electromagnetic satellites, each having a high-temperature superconducting coil, generate control torques to reduce the rotation rate of debris prior to making any physical contact. The electromagnetic interaction of the target-satellite system is analyzed. A relative translational dynamics of the target–satellite system and the attitude dynamics of the target are established. Simulation results show that the proposed method effectively eliminates the rotational motion of the target. It can be safely concluded that the noncontact method for de-tumbling space debris using a two-satellite electromagnetic formation is feasible and potentially applicable to on-orbit capture.
Article
Spacecraft orbit evasion is an effective method to ensure space safety. In the spacecraft's orbital plane, the space non-cooperate target with autonomous approaching to the spacecraft may have a dangerous rendezvous. To deal with this problem, an optimal maneuvering strategy based on the relative navigation observability degree is proposed with angles-only measurements. A maneuver evasion relative navigation model in the spacecraft's orbital plane is constructed and the observability measurement criteria with process noise and measurement noise are defined based on the posterior Cramer-Rao lower bound. Further, the optimal maneuver evasion strategy in spacecraft's orbital plane based on the observability is proposed. The strategy provides a new idea for spacecraft to evade safety threats autonomously. Compared with the spacecraft evasion problem based on the absolute navigation, more accurate evasion results can be obtained. The simulation indicates that this optimal strategy can weaken the system's observability and reduce the state estimation accuracy of the non-cooperative target, making it impossible for the non-cooperative target to accurately approach the spacecraft.
Chapter
In this chapter, symplectic approaches for the finite-dimensional Hamiltonian systems are discussed. Firstly, the foundations of the symplectic method are reviewed, which include the symplectic map, the symplectic matrix, the symplectic structure, and so on. Then, two typical symplectic discretization methods are presented. One is the symplectic Runge–Kutta method and another is the splitting/composition method. With these foundations, some research progresses on the applications of the symplectic approach, including the symplectic precise integration of folding and unfolding processes of undercarriage and the symplectic Runge–Kutta method for aerospace dynamics problems are given.
Chapter
Active contact detumbling method using a brush-type contactor is an effective way for damping the angular momentum of rotating target in order to make it easy to capture. In this paper, we propose a new brush-type detumbling method base on deep deterministic policy gradient (DDPG) for achieving the autonomous detumbling trajectory planning and control strategy of robot arm for the first time. We propose a recommended racemization point as a state space input based on the relative position to avoid the curse of dimensionality. The rewards are designed to associate with the recommended point and continuous damped collisions. Then the agent is trained to learn to find the racemization point and generate smooth trajectory action. The robot arm can track the motion of target panel and automatically select the optimal detumbling point. The proposed method can provide a new control strategy for active contact detumbling application.KeywordsSpace non-cooperative spacecraftReinforcement learningDeep deterministic policy gradientActive robotic detumbling methodFlexible decelerating brush
Chapter
Detumbling space debris is a prerequisite for active space debris removal, especially when the space debris is rotating with large angular velocity. Considering the safety and efficiency, we intend to utilize a soft robotic manipulator for detumbling operation with friction torque. In order to improve the reliability, we design a soft robotic manipulator with ellipse cross section and three chambers to enhance torsional rigidity and realize pitch, yaw and stretch motion. In addition, we analyze the static characteristics and the load-carrying capability of the soft robotic manipulator. Moreover, experiments are conducted to demonstrate the performance of the designed soft robotic manipulator, and we discuss the rationality and validity of adopting the soft robotic manipulator for detumbling space debris.KeywordsSoft robotic manipulatorDetumbling space debrisStatic characteristicsLoad-carrying capability
Article
In this paper, an integrated tracking control approach was developed for a continuum robot in space capture missions. For the configuration of a three-module cable-driven continuum robot, the nonlinear dynamics equations were derived. The uncertain movement of noncooperative debris requires a real-time trajectory planning solution. Therefore, an adaptive controller based on deep reinforcement learning (DRL) is proposed to generate a dynamic controller in continuous action space, where the trajectory planning function is simultaneously integrated into the dynamic solution. To obtain an efficient policy network for the highly nonlinear dynamics model, the rolling optimization method was combined in the DRL method of the deep deterministic policy gradient (DDPG). The DRL controller generated an appropriate control sequence according to the long-term control performance of the robot system and then executed optimal control input according to the rolling optimization. The simulation result shows that the proposed policy network of the improved DDPG controller can reasonably provide the tracking control solution in the noncooperative debris capture mission.
Article
Capturing tumbling target is considered as one of the greatest challenges in on-orbit service missions due to tumbling motion and parameter uncertainty of the space non-cooperative target. The tumbling motion of the target should be attenuated as quickly as poemailssible before grasping to avoid the unexpected collisions and possible damages to the space manipulator or the target, which means the shortest-time detumbling trajectory is neccesary. In many studies about the optimal detumbling trajectory planning the inertial parameters of the target have been assumed to be accurately known, which is usually difficult for a non-cooperative target so that parameter identification is needed before planning a optimal detumbling trajectory. In this paper, a novel strategy for parameter identification and detumbling of a tumbling target by a space manipulator is proposed. The strategy includes two phases. First, unknown inertial parameters of the target are identified in finite-time by a new estimation method with the assumption of interval excitation (IE), which relaxes the strict persistent excitation (PE) condition required in most prior studies. Second, the shortest-time detumbling trajectory of the tumbling target is generated by formulating a time-optimal control problem (OCP) in which the target attitude bounds and the limitations of the contact force as well as the relative velocity between the space manipulator and the target are represented as extended dynamical sub-systems and saturation functions. Then, the Calculus of Variations method is used to solve the OCP to obtain a high accuracy solution. During two phases, the contact force between the space manipulator and the target is utilized to generate external moment for identifying the inertia parameters of the target and detumbling the target. Meanwhile, a unified hybrid impedance control framework is applied to the space robot to track the desired contact force and motion trajectory. The whole strategy is verified by a space manipulator capturing a tumbling target, and numerical simulations demonstrate the effectiveness of the proposed methods.
Article
Force control provided by a small-scaled free-flying space robot on a floating or spinning target will be required for future on-orbit servicing missions, such as detumbling a target, performing an assembly or a maintenance operation. Regarding to different contact geometries for a space robot interacting with a spinning target, this paper addresses the contact model considering its multi-dimensional characteristics. A hybrid motion and force controller is developed to acquire desired contact forces and space robot configuration despite the floating feature of the system. On this basis, the control strategy to implement the operations of three typical phases, namely approaching phase, contact phase and post-contact phase, is proposed. The simulations have been performed to verify the control approaches and visualize the contact scenarios.
Article
A brush type contactor has been proposed to detumble non-cooperative space targets. Current researches mainly focused on the control schemes and their validations, whereas the dynamic modeling is rarely investigated. In this paper, both the analytical formulation and the numerical approach are employed to establish the dynamic model of the detumbling system. An analytical formula is proposed to evaluate the detumbling efficiency from the aspect of energy. The numerical simulation is conducted using flexible multibody dynamics and the contact theory. The analytical results and the numerical results are compared and the influence of various model parameters on dynamic behaviors is studied. It shows that the detumbling efficiency can be significantly affected by several factors, including the stiffness and length of the brush, the end velocity of the contactor, the contact angle, and the contact position. The detachment phenomenon of the brush from the solar panel is investigated. A criterion for the detachment is proposed and verified by numerical simulations.
Article
As one of the potential active debris removal approaches, removal of space debris by a tether tow may be applied to perform the large space debris removal mission. To remedy the omissions of the current references, including effects of the initial state and the considerable elongation of the tether on the evolution of the tumbling angle of the target debris, the dynamic behaviors of the tethered tug–debris system are investigated by using the symplectic Runge-Kutta method in this paper. Introducing the generalized momentum vector for the generalized coordinate vector, the finite-dimensional generalized Hamiltonian function is yielded and the generalized Hamiltonian dual equation describing the coupling dynamic behaviors of the tethered tug–debris system is deduced. To investigate the coupling dynamic behaviors of the tethered tug–debris system, the second-level fourth-order symplectic Runge-Kutta scheme is constructed and the perfect structure-preserving properties of it is verified. The effects of the elastic constant of the tether and the initial Euler angular velocity on the evolution of the tumbling angle are investigated in the numerical experiments in detail. The beat characteristic and the “window” characteristic in the evolution of the tumbling angle with small elastic constants of the tether are reproduced. In addition, the sharp change phenomenon in the evolution of the tumbling angle is found when the elastic constant of the tether is extremely small. The above findings can be used to guide the strategy design of the removal of space debris by a tether tow.
Article
Space debris generally exhibit complex rotating motions, which cause significant challenges when attempting to capture them in orbit. Reducing the rotational speed of the space debris before capturing them with a high rotational energy can reduce the risk of destructive collisions. The electromagnetic de-tumbling method based on eddy currents has the advantages of being non-contact, pollution-free, and exhibiting no orbital height limitations, among other qualities. To improve the efficiency of electromagnetic de-tumbling, distributed high-temperature superconducting (HTS) coils are used in this study. Specifically, a finite element model is established to investigate the induced currents and eddy-current torque, and the optimal configuration of the distributed coils is obtained using numerical optimization. The analysis of the external magnetic field shows that if the distance between the target and the coils exceeds four times the radius of the target, the eddy-current torque and the magnetic field at the center of the target will achieve maximum values in the same configuration, and the external magnetic field can therefore be regarded as a uniform field when calculating the eddy-current torque. Finally, the finite element model and the optimal configuration are verified using simplified ground-based experiments.
Chapter
The aerospace industry continues to progress and develop. The waste left in space by human beings in space activities has lost its attitude adjustment ability and been turned into space junk. This not only causes a waste of orbital resources, but also spacecraft collisions, which could cause the mission to fail. In this paper, the problem of detumbling in the process of capturing noncooperative targets is studied, a set of multi-wheel arm test platform is designed, and a model is built, aiming to complete detumbling for low-speed rotating targets to recycle. Finally, the experimental results show that the performance and function test of the platform have a good effect on the problem of detumbling. This multi-wheel arm test platform is an effective and feasible method for the detumbling of noncooperative targets.
Article
Full-text available
The realization of existing projects of on-orbit servicing and the development of new ones is a steady trend in the development of space technology. In many cases, on-orbit service clients are objects that exhibit an undesired rotary motion, which renders their servicing difficult or impossible. The problem of on-orbit service object motion control determines the topicality of studies aimed not only at the refinement of methods and algorithms of controlling both the translational and the rotary motion of an object, but also at the development and refinement of methods of onboard determination of the object – service spacecraft relative motion parameters. This paper overviews the state of the art of the problem of object motion parameter determination in on-orbit servicing tasks and existing methods of object motion control and angular motion damping and specifies lines of further investigations into the angular motion control of non-cooperative service objects. Based on the analysis of publications on the subject, the applicability of onboard means for object motion parameter determination is characterized. The analysis of the applicability of methods of remote determination of the parameters of an unknown non-cooperative object from a service spacecraft shows that they are at the research stage. The input data for the verification of methods proposed in the literature were simulated or taken from ground experiments or previous missions. Contact and contactless methods of angular motion control of non-cooperative on-orbit service objects are considered. From the state of the art of investigations into the contactless motion control of on-orbit service objects it may be concluded that the most advanced contactless method of motion control of an on-orbit service object is a technology based on the use of an ion beam directed to the object from an electrojet engine onboard a service spacecraft. Lines of further investigations into non-cooperative object motion control are proposed.
Article
In this paper, we investigate the application of Feedback Linearization Model Predictive Control (FLMPC) for the eddy current de-tumbling of space tumbling targets. Based on the Clohessy-Wiltshire (C-W) equation and the Euler rotational equations of motion, the dynamic model of the eddy current de-tumbling process is established, and the error dynamic model is further derived. After that, the safety constraint of the eddy current de-tumbling process is deduced and linearized. On this basis, real-time optimal trajectory is obtained with the optimal equilibrium solver, and FLMPC is proposed to control the system. In order to ensure the simplicity and rapidity of the controller, the feedback linearization input constraint is directly used as the global prediction constraint and the MPC constraint problem is converted into the form of Quadratic Programming (QP) which can be effectively solved. Simulation results show that the proposed algorithm can realize quick and safe de-tumbling of the target with the various constraints ensured and a very small range of steady-state errors.
Article
Using the space robot to rescue the failed spacecraft is one of the manipulations for on-orbit servicing of high-value spacecraft. The primary condition for space servicing is to reduce the angular velocity of the failed spacecraft, i.e. de-tumbling. Unlike other existing studies that mostly support the mode of autonomous de-tumbling, continuous output force/torque, and considering the insufficient intelligence of space robot, a space teleoperation robot system (STRS) is preferable to the simple remote control. This work provides a maneuver of forcedly contact for the de-tumbling process under discontinuous control torque. Concretely speaking, firstly, the capturing strategy is designed based on the failed spacecraft characteristic of quality and nutation. Then, the scheme of the flexible brush-type contact de-tumbling is proposed, in which the flexible brush adheres to the terminal manipulator. Through multiple contacts between the flexible brush and the marked point at the edge of the solar array via teleoperation, the angular velocity of the failed spacecraft is decreased to the desired value. Meanwhile, the system also offers the ability that enables the angular velocity to be decreased when there is an operation force deviation. The effectiveness of the maneuver is validated by simulation results. The results indicate that the angular velocity of failed spacecraft can be reduced to the value, which is a suitable condition for capturing after conducting a de-tumbling operation.
Article
Full-text available
The present electron-collection concept for ionospheric electrodynamic tethers exposes a fraction of the tether length near its anodic end, so that electrons are collected in an orbital-motion-limited regime when a positive bias develops locally relative to the ambient plasma. The tether radius must be small compared with both the thermal gyroradius and the Debye length. Large currents can in this way be drawn with only moderate voltage drops, as is illustrated for the cases of generators and thrusters.
Conference Paper
Space debris objects are generally tumbling in orbit, and so capturing and braking them involves complicated dynamical interactions between the object, the so-called "servicer" spacecraft, and its robot arm, with the possibility of strong loading occurring during the procedure. In this paper, a space debris capture strategy is described which proposes the application of joint virtual depth control to the capture robot arm. We present the results of simulations and experiments that confirm the feasibility of this technique.
R&D of the active removal system for post-mission space systems
  • S Kibe
  • S Kawamoto
  • F Terui
  • S Nishida
  • G Gilardi
S. Kibe, S. Kawamoto, F. Terui, S. Nishida and G. Gilardi, R&D of the active removal system for post-mission space systems, in: Proceed-ings of IAC2003, Bremen, 2003.