Conference Paper

A study of cooperative control of self-assembling robots in space with experimental validation

DOI: 10.1109/ROBOT.2009.5152788 Conference: Robotics and Automation, 2009. ICRA '09. IEEE International Conference on
Source: IEEE Xplore


Modular self-assembling on-orbit robotic and satellite systems can be more reliable, have lower launch costs, and be more easily repaired and refueled. However, when individual modules assemble, many challenges and opportunities make the control of the assembled system complex. These issues include changes in inertial properties, and redundancy of actuators and sensors. Optimal control methods may be used to coordinate the control of the modules after assembly, insure good performance, and best utilize the combined resources of the assembly of modules. Simulation and experimental results compare this Cooperative algorithm's performance to that of an approach in which the control of the individual modules is not coordinated. Cooperative optimal control methods prove well-suited for controlling redundant, modular space systems.

Download full-text


Available from: Chiara Toglia, Sep 11, 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a case-study on the performance achieved by the me-chanical interactions of self-assembling mobile robots. This study is based on the hand-bot robot, designed to operate within heterogeneous swarms of robots. The hand-bot is specialized in object manipulation and can improve its performance by exploiting physical collaborations by self-assembling with other hand-bots or with foot-bots (ground robots). The paper analyzes the achieved performance and demon-strates the highly super-linear properties of the accessible volume in respect to the number of robots. These extremely interesting performances are strongly linked to the self-assembling mechanisms and the physical nature of the interaction, and do not scale to a large number of robots. Finally, this study suggests that such interest-ing properties are more accessible for heterogeneous systems or devices achieving complex tasks.
    Preview · Article · Jan 2013 · Springer Tracts in Advanced Robotics
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This work introduces a novel approach and its experimental verification for propellant sub-optimal multiple spacecraft assembly via a Linear Quadratic Regulator (LQR). The attitude dynamics of the spacecraft are linearized at each time step, about the current state vector, and the relative dynamics between two spacecraft are assumed as a double integrator. This allows for implementation in real-time of a LQR that computes the optimal gain matrix depending on the current phase of the spacecraft's mission. As a result, both the attitude and position are sub-optimally controlled. The presented logic compensates for the structural evolution related to an incremental assembly by updating the system's dynamics matrices. The actuators' reallocation and command of the assembled structure is dealt with through inter-robot wireless ad-hoc communication. Each spacecraft runs symmetric algorithms, differing only in the number of docking ports that each possesses for the mission, which are related to the number of assembling spacecraft and the final structure's desired shape. Once the spacecraft are assembled, one acts as master by performing the required navigation and control of the new structure through real-time wireless commanding of the other spacecraft's actuators. The improved third generation (3G-i) of spacecraft simulators developed at the Spacecraft Robotics Laboratory SRL of the Naval Postgraduate School (NPS) is presented to demonstrate experimental verification of the proposed methodology. Features of the (3G-i) robots include an unique customized construction of rapid prototyped thermoplastic (polycarbonate) that incorporates a lightweight modular design with a small footprint, thus maximizing the entire surface of the SRL robotic testbed.
    Full-text · Article · Aug 2009
  • [Show abstract] [Hide abstract]
    ABSTRACT: This work introduces a novel control algorithm for close proximity multiple spacecraft autonomous maneuvers, based on hybrid linear quadratic regulator/artificial potential function (LQR/APF), for applications including autonomous docking, on-orbit assembly and spacecraft servicing. Both theoretical developments and experimental validation of the proposed approach are presented. Fuel consumption is sub-optimized in real-time through re-computation of the LQR at each sample time, while performing collision avoidance through the APF and a high level decisional logic. The underlying LQR/APF controller is integrated with a customized wall-following technique and a decisional logic, overcoming problems such as local minima. The algorithm is experimentally tested on a four spacecraft simulators test bed at the Spacecraft Robotics Laboratory of the Naval Postgraduate School. The metrics to evaluate the control algorithm are: autonomy of the system in making decisions, successful completion of the maneuver, required time, and propellant consumption.
    No preview · Article · Apr 2011 · Acta Astronautica
Show more