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76
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731
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Citations since 2017
Introduction
Liang Sun currently serves as an Assistant Professor in the Department of Mechanical and Aerospace Engineering at New Mexico State University. His research interests include dynamic task allocation with uncertainty, cooperation control of mobile robots in GPS-denied environments, distributed stochastic optimization, and bio-inspired sound-source localization.
Additional affiliations
August 2015 - present
August 2015 - present
April 2013 - August 2014
Education
September 2007 - December 2012
September 2004 - May 2007
September 2000 - August 2004
Publications
Publications (76)
This paper presents a three-dimensional (3D) localization and attitude estimation system to track a Unmanned Aerial Vehicle (UAV) using a single camera without prior knowledge of the environment. The hardware system consists of a Dynamic Vision Sensing (DVS) camera, a circle-shaped blinking marker made by Light-Emitting Diodes (LEDs), and a base st...
View Video Presentation: https://doi.org/10.2514/6.2022-2500.vid In this work, we investigated the efficacy of two data-driven approaches towards wind estimation for a multicopter that follows a circular orbit rather than in a hover flight. The position and attitude of the multicopter were collected from flight simulations for a vareity of wind spe...
View Video Presentation: https://doi.org/10.2514/6.2022-2238.vid This paper addresses the task allocation problem for a drone package delivery scenario, where a number of warehouses delivery packages to a number of locations using drones. A novel algorithm, namely, Duplicate Agent Hungarian Based Algorithm (DAHBA), is proposed. DAHBA adopts cloned...
View Video Presentation: https://doi.org/10.2514/6.2022-2237.vid In this paper, we consider a formation control problem for leader-follower unmanned aerial vehicles (UAVs) in a GPS-denied environment. The distance and the azimuth and elevation angles, defined in a local spherical coordinate frame, are used to describe the relative motion between tw...
This paper considers the self-localization of a tethered drone without using a cable-tension force sensor in GPS-denied environments. The original problem is converted to a state-estimation problem, where the cable-tension force and the three-dimensional position of the drone with respect to a ground platform are estimated using an extended Kalman...
While vision-based localization techniques have been widely studied for small autonomous unmanned vehicles (SAUVs), sound-source localization capabilities have not been fully enabled for SAUVs. This paper presents two novel approaches for SAUVs to perform three-dimensional (3D) multi-sound-sources localization (MSSL) using only the inter-channel ti...
This paper reports a novel optical localization method, including both the hardware design and algorithm design, to track mobile Unmanned Aerial Vehicles (UAVs). The method relies on a circle-shaped blinking LED marker installed on the UAV and uses a single Dynamic Vision Sensing (DVS) camera to sense the temporal difference of the video streams. A...
This paper addresses task-allocation problems with uncertainty in situational awareness for distributed autonomous robots (DARs). The uncertainty propagation over a task-allocation process is done by using the Unscented transform that uses the Sigma-Point sampling mechanism. It has great potential to be employed for generic task-allocation schemes,...
In this paper, we present a novel distributed task-allocation algorithm, namely the Sequential Task Addition Distributed Assignment Algorithm (STADAA), for autonomous multi-robot systems. The proposed STADAA can implemented in applications such as search and rescue, mobile-target tracking, and Intelligence, Surveillance, and Reconnaissance (ISR) mi...
In this paper, we consider the problem of identifying the global communication network topology of a distributed multi-agent system using only local data of each individual agent. A tree-based machine learning technique is developed for each individual agent to create and update their local knowledge of the network topology graph. The proposed tech...
In this paper, we propose a novel approach to trajectory optimization of electric vertical takeoff and landing (eVTOL) vehicles for urban air mobility (UAM) missions such as passenger transportation and cargo delivery. Our particular interest is to develop efficient algorithms that facilitate fast generation of optimal cruise, descent, and landing...
In this paper, we present a nonlinear trajectory-tracking controller for a multicopter to deliver a pressurized fluid through an attached hose system. The three-dimensional (3D) dynamic model of the entire system is derived that incorporates multicopter dynamics, the reaction force from the release of the fluid, and the force applied by the weight...
In this paper, we present two bioinspired approaches to localize and track a sound source that moves in a three-dimensional (3D) space. Both the approach mimics humans and uses only two microphones rotating at a fixed angular velocity. The motion of the sound source along with the rotation of the bi-microphone array results in a sinusoidal inter-ch...
This paper presents the concept of teaming up snake-robots, as unmanned ground vehicles (UGVs), and unmanned aerial vehicles (UAVs) for autonomous navigation and obstacle avoidance. Snake robots navigate in cluttered environments based on visual servoing of a co-robot UAV. It is assumed that snake-robots do not have any means to map the surrounding...
In this paper, we present three approaches to localizing and tracking a sound source moving in a three-dimensional (3D) space using a bi-microphone array rotating at a fixed angular velocity. The motion of the sound source along with the rotation of the bi-microphone array results in a sinusoidal inter-channel time difference (ICTD) signal with tim...
This work presents a novel technique that performs both orientation and distance localization of a sound source in a three-dimensional (3D) space using only the interaural time difference (ITD) cue, generated by a newly-developed self-rotational bi-microphone robotic platform. The system dynamics is established in the spherical coordinate frame usi...
![Fig. 2: The EKF recursive process loop algorithm [21].](profile/Amer-Al-Radaideh/publication/335197297/figure/fig2/AS:837364410761239@1576654641866/The-EKF-recursive-process-loop-algorithm-21_Q320.jpg)
This paper presents a novel dynamic progressivelyspiral-out (PSO) formation for a team of unmanned aerial vehicles (UAVs) to perform an exhaustive search of mobile ground targets. Two novel procedures are designed for a UAV to be inserted to and removed from an established PSO formation without discontinuing the confidence area. A comparison study...
This paper presents a novel three-dimensional (3D) sound source localization (SSL) technique based on only Interaural Time Difference (ITD) signals, acquired by a self-rotational two-microphone array on an Unmanned Ground Vehicle. Both the azimuth and elevation angles of a stationary sound source are identified using the phase angle and amplitude o...
While vision-based localization techniques have been widely studied for small autonomous unmanned vehicles (SAUVs), sound-source localization capability has not been fully enabled for SAUVs. This paper presents two novel approaches for SAUVs to perform multi-sound-sources localization (MSSL) using only the interaural time difference (ITD) signal ge...
While vision-based localization techniques have been widely studied for small autonomous unmanned vehicles (SAUVs), sound-source localization capabilities have not been fully enabled for SAUVs. This paper presents two novel approaches for SAUVs to perform three-dimensional (3D) multi-sound-sources localization (MSSL) using only the inter-channel ti...
![Fig. 3. Influence of τ on the state convergence: τ ∈ [−0.4, 0.4] − {0}...](profile/Liang-Sun-37/publication/319501398/figure/fig3/AS:614328331948080@1523478696918/Influence-of-t-on-the-state-convergence-t-04-04-0-for-the-initial-condition_Q320.jpg)
In this paper, we present a novel decentralized controller to drive multiple unmanned aerial vehicles (UAVs) into a symmetric formation of regular polygon shape surrounding a mobile target. The proposed controller works for time-varying information exchange topologies among agents and preserves a network connectivity while steering UAVs into a form...
In this brief, we present a novel decentralized controller for multiple unmanned aerial vehicles (UAVs) to fly in a symmetric formation surrounding a hostile mobile target while maintaining and controlling the network connectivity. The multi-UAV information exchange topology is considered as a time-varying function of interagent distances. We inves...
In this paper, we present a decentralized multi-target tracking system for cooperative Unmanned Aerial Vehicles (UAVs) with limited sensing resources. The proposed system distributively incorporates a clustering algorithm, an optimal sensor manager, and an optimal path planner. A set
of Extended Kalman Filters (EKFs) is used by each UAV to estimate...
This paper presents a novel approach to estimate the relative position of an aerial vehicle that is connected to a fixed location on the ground through a taut tether of varying length. The onboard commercial-of-the-shelf (COTS) inertial sensors are the only source of sensory data used for the proposed approach. A three-dimensional (3D) dynamics mod...
In this paper, we present a novel bi-directional cooperative obstacle avoidance system of heterogeneous unmanned vehicles, consisting of an unmanned ground vehicle (UGV) and a micro-aerial vehicle (MAV), equipped with cameras, operating in an indoor environment without Global Positioning System (GPS) signals. The system demonstrates the synergistic...
Heterogeneous Bi-Directional Cooperative Unmanned Vehicles for Obstacle Avoidance Presentation
This paper addresses a three-dimensional (3D) leader-follower formation control problem where an event-triggered transmission scheme is developed to schedule the information exchange between the leader and follower unmanned aerial vehicles (UAVs). A novel 3D model based on a local level spherical frame is developed to characterize the relative dyna...
Sound source localization serves as a significant capability of autonomous robots that conduct missions such as search and rescue, and target tracking in challenging environments. However, localization of multiple sound sources and static sound source tracking in self-motion are both challenging tasks, especially when the number of sound source or...
Implementing a control law on an Unmanned Aerial Vehicle can be problematic when the existing autopilot system is incompatible with the controller structure. This paper extends the control strategy that incorporates a pre-existing autopilot system in a closed-loop control law design [1]. In [1], the control scheme explicitly involves the autopilot...
In this paper, we present a decentralized cooperative multiple target tracking method for multiple Unmanned Aerial Vehicles (UAVs). The decentralized cooperative multi-target tracking algorithm incorporates an optimal sensor management scheme and a cooperative path planner. To localize and track targets, a set of Extended Kalman Filters (EKFs) is u...
In real life, human listeners rarely experience cone of confusion errors in localization of sound sources due to the limitation of interaural time difference
(ITD) as a spatial
hearing cue. Previous work on robotics suggested that the confusion is disambiguated as successive observation of ITD is made over time, when self-motion of the microphone s...
When an array of two acoustic sensors is used to localize sound sources based on time differences alone, possible solutions form a cone of confusion. This study, together with a similar one for human listeners, demonstrates that azimuth/vertical planes localization of a sound source using only time difference information is feasible when self-motio...
This paper presents a strategy for optimal estimation of parameters for towed cable systems using moving horizon estimation (MHE). The main contributions of the work include a novel formulation of MHE using a dead-band that explicitly rejects measurement noise, real-time implementation results, and the investigation of time-varying stochastic distu...
![Fig. 6. Trajectories of Re(λ i ), m h 1 ∈[1.65,2.00].](profile/Liang-Sun-37/publication/276880168/figure/fig4/AS:667599323009036@1536179490553/Trajectories-of-Rel-i-m-h-1-165-200_Q320.jpg)
Applying the selective harmonic elimination (SHE) technique to grid connected cascaded modular multilevel inverters has been widely discussed in literature. However, due to the difficulties of solving high-order non-linear transcendental equations, the SHE technique cannot be implemented in real time so its applications are limited. This paper pres...
As technologies in digital computation, sensing, wireless and wired communications, embedded systems, and micro-electro-mechanical systems continue to advance in the coming years, it is certain that we will see a variety of distributed sensor networks (DSNs) being deployed in an increasing number of systems such as power distribution systems, engin...
In this paper, we present an optimal sensor manager and a path planner for an Unmanned Aerial Vehicle (UAV) to geo-localize multiple mobile ground targets. A gimbaled camera with a limited field of view (FOV) and a limited range is used to capture targets, whose states are estimated using a set of Extended Kalman Filters (EKFs). The sensor manageme...
In this paper, we present a cooperative target-centric formation control strategy that maintains the dynamic graph connectivity for a system of unmanned aerial vehicles. The connectivity of a graph plays a critical role in dynamic networks of multiple agents since it represents a level of information sharing capability of a system. The connectivity...
A method for aerial rendezvous of small unmanned aircraft systems is proposed. The system includes placing a passively towed drogue into an orbit that is suitable for a small unmanned aircraft systems to follow, and a seeker guidance method for use with a monocular camera mounted on the centerline of the unmanned aircraft systems. The principle con...
This paper presents a strategy of designing a trajectory-tracking control law for unmanned aerial vehicles where an unmodifiable autopilot is incorporated in the closed-loop system. The main contributions of this paper include a novel control structure that enables an explicit design of tracking methods for a system with an unmodifiable autopilot i...
![Fig. 3. l ˇ c [11]](profile/Negar-Farmani/publication/267811460/figure/fig3/AS:295360078598146@1447430738831/l-c-11_Q320.jpg)
In this paper, we present an optimal sensor man-agement technique for an Unmanned Aerial Vehicle (UAV) to autonomously geo-localize multiple mobile ground targets. The target states are continuously estimated using target locations asynchronously captured by a gimbaled camera with a limited field of view and processed with a set of Extended Kalman...
In this paper, we present a reactive, vision based obstacle avoidance technique for Unmanned Ground Vehicles (UGVs) navigating with only visual electro-optic sensors in an indoor environment without Global Positioning System (GPS) signals. The presented work is unique in that, to the best of our knowledge, there was no other bearing angle only obst...
This paper studies the trajectory-tracking strategy for unmanned aerial vehicles where the autopilot is involved in the feedback control. The trajectory-tracking controller is derived based on a generalized design model using Lyapunov based backstepping. The augmentations of the design model and trajectory-tracking controller are conducted to invol...
This paper studies trajectory generation for an aircraft that tows an aerial body using a flexible cable. The major contributions of this paper include model validation for a lumped mass extensible cable using flight test data, and optimal trajectory generation for the towed cable system with tension constraints using model predictive control. The...
In this dissertation, we focus on the strategy that places and stabilizes the path of an aerial drogue, which is towed by a mothership aircraft using a long flexible cable, onto a horizontally flat orbit by maneuvering the mothership in the presence of wind. To achieve this goal, several studies for towed cable systems are conducted, which include...
Many unmanned aircraft systems (UAS) have relatively short endurance and range which limits their usefulness in applications where their home station is a long distance from the area of interest. This paper lays out a method for placing a towed drogue system into an appropriate orbit used by a seeker UAS to track and rendezvous with it. The princip...
This paper presents a method for recovering Micro Air Vehicles (MAVs) in flight using a mothership and towed drogue, in which the mothership executes an orbit that places the drogue in a stable, slower orbit that can be tracked by a MAV. This paper is particularly challenging in the presence of wind. The equations of motion of the cable using an el...
This paper presents a method for recovering Micro Air Vehicles (MAVs) in flight using a mothership and towed drogue. A method for modelling the dynamics of the mothership-cable-drogue system, based
on Gauss’s principle, is presented. The differential flatness property of the system is exploited to calculate mothership trajectories from desired drog...
Aerial recovery of micro air vehicles (MAVs) presents a challenging problem in multi-vehicle dynamics and control. This paper presents a method for recovering MAVs in flight using a mothership and towed drogue, in which the mothership executes an orbit that places the drogue in a stable, slower orbit that can be tracked by a MAV. The differential f...
In this paper, we present two strategies to stabilize the altitude of the towed body (drogue) in the presence of the steady wind. The ight test results are presented to verify the concept of aerial recovery and the mathematical model of the system. By using the parameter conguration and the data collected in the ight test, a matching work is conduc...
This paper presents a new concept for aerial recovery of micro air vehicles (ARMAVs) using a large mothership and a recovery drogue. The mothership drags a drogue attached to a cable and the drogue is controlled to match the flight patten of the MAV. This paper uses Gauss's principle to derive the dynamic model of the cable-drogue systems. A contro...
Projects
Projects (12)
Vehicular Networked Systems are Cyber-Physical Systems (CPS) where the communication, control and information processing technologies are integrated to achieve more safe and effective transport for autonomous vehicles. The goal of this project is to develop interdisciplinary methodologies to ensure safe and efficient VNS under adversarial environments.
This project will localize and track a moving sound source using a rotating bi-microphone array. To improve the performance, it also incorporates an unscented Kalman filter (UKF) which will estimate the states of the non-linear system model.