Index — Manipulators

Auto-extracted reference table: authors · year · title · DOI/locator, taken verbatim from the notes below. Nothing invented; — = field not given in the source. Where an entry is filed under a year header that differs from its citation, the Year column follows the citation text. Sorted in your four batches, by year.

Very Early works: year ≤ 2000

Early works: 2000 < year ≤ 2010

Semi-Early works: 2010 < year ≤ 2020

Recent works: year > 2020

Original notes

Very Early works: year <= 2000 1987 • R. Longman, R. Lindererg, M. Zedd. Satellite-mounted robot manipulators—new kinematics and reaction moment compensation. Int J Robot Res, 6 (1987) • Umetani & Yoshida. Continuous path control of space manipulators mounted on OMV (orbital maneuvering vehicles) (1987) • Theoretical analysis on the formulation of kinematics for the manipulator mounted on a satellite is presented. Firstly, to solve the inverse kinematics, the authors define a new generalized Jacobian matrix, and utilizing this generalized matrix, the problem can be treated analytically. Secondly, the authors verify the method proposed here in the simulation study. Thirdly, they also discuss on the several points which are indispensable for further investigations. 1989 • Y. Umetani and K. Yoshida, “Resolved motion rate control of space manipulators with generalized Jacobian matrix”(1989) • control method for space manipulators taking dynamical interaction between the manipulator arm and the base satellite into account. The kinematics of free-flying multibody systems is investigated by introducing the momentum conservation law into the formulation and a novel Jacobian matrix in generalized form for space robotic arms is derived. The authors develop a control method for space manipulators based on the resolved motion control concept. The proposed method is widely applicable in solving not only free-flying manipulation problems but also attitude-control problems.

1990 • Vafa & Dubowsky, The Kinematics and Dynamics of Space Manipulators: The Virtual Manipulator Approach 1990 • Virtual manipulator approach • Papadopolous and Dubowsky. On the nature of control algorithms for space manipulators. 1990 • A study of the characteristics of control algorithms that can be applied to the motion control of space manipulators is reported. The results obtained show that nearly any control algorithm that can be applied to conventional terrestrial fixed-base manipulators, with a few additional conditions, can be directly applied to free-floating space manipulators. • Barycenters are used to formulate efficiently the kinematic and dynamic equations of free-floating space manipulators. A control algorithm for a space manipulator system is designed to demonstrate the value of the analysis. 1991 • C. W. De Silva, “Trajectory design for robotic manipulators in space applications”, J. Guid. Control Dyn., vol. 14, no. 3, pp. 670-674, 1991. • utilized the robotic arm redundancy of the space robot for optimal trajectory planning to minimize its impact on the spacecraft base 1992 • Papadopoulous and Dubowsky, Dynamic Singularities in Free-Floating Space Manipulators (1992) • Barycentric vector approach • R. Longman. The kinetics and workspace of a satellite-mounted robot, space robotics: dynamics and control. Springer (1992), pp. 27-44 • author demonstrated that given the history of the robot joint angles as a function of time, the final joint angles can be used as in the standard fixed-base manipulators problem to obtain the robot׳s end-effector position relative to the base spacecraft. • Then, by the principle of angular momentum conservation, it is possible to get the inertial position of the satellite as well as its orientation. • Following such a method, the authors were able to find a feasible inverse kinematics solution that achieves not only the desired end-effector position but also the desired spacecraft attitude. The workspace was also analyzed and found to be a perfect sphere whose radius is a monotonically decreasing function of the manipulator׳s mass • D. Nenchev, Y. Umetani and K. Yoshida, “Analysis of a redundant free-flying spacecraft/manipulator system”, IEEE Trans. Robot. Automat., vol. 8, no. 1, pp. 1-6, Feb. 1992. • used the generalized Jacobian matrix to describe the kinematics model when a single-chain manipulator is attached to the satellite • Although this model cannot solve all the complex configuration satellites, it has been able to accurately describe the satellite body torque and momentum generated by complex satellite attachments • An analysis of the momentum conservation equations of a redundant free-flying spacecraft/manipulator system acting in a zero-gravity environment is presented. • In order to follow a predefined end-effector path, the inverse kinematics at velocity level is considered. • The redundancy is solved alternatively in terms of pseudoinverses and null-space components of the manipulator inertia matrix, the manipulator Jacobian matrix, and the generalized Jacobian matrix. • A general manipulation task is defined as end-effector continuous path tracking with simultaneous attitude control of the spacecraft. • Three subtasks of the general task are considered. The case of manipulator motions that yield no spacecraft attitude disturbance is analyzed in more detail and a special ‘fixed-attitude-restricted’ (FAR) Jacobian is defined. Through singular-value decomposition of this Jacobian, corresponding FAR dexterity measures (FAR manipulability and FAR condition number) are derived. 1993 • Papadopoulous. Nonholonomic Behavior in Free-floating Space Manipulators and its Utilization. 1993 • (Not in library) ○ Free-floating mode, not free-flying mode ○ Appendix on Barycentric vectors • Joint space path planning techniques that take into advantage the nonholonomic behavior of free-floating systems, like the Self Correcting Planning technique, and Lyapunov-based techniques, are reviewed. Potential problems in using these techniques are identified. Finally, a Cartesian space path-planning technique is presented. This technique avoids dynamically singular configurations, and hence permits the effective use of the full reachable workspace of a free-floating system • if singularities of J* can be avoided, nearly any control algorithm applied to fixed-based systems can be used in free-floating systems. • A workspace point can induce a singularity or not, depending on the path taken to reach it. Trouble-free Path Independent Workspaces were defined. Two planning techniques that use nonholonomy to control a spacecraft’s orientation by manipulator joint motions were reviewed. It was shown that in some system configurations, joint manipulator motions cannot affect a spacecraft’s orientation. • Finally, a planning method was presented that permits the effective use of a system’s reachable workspace by planning paths which avoid dynamically singular configurations. • Dubowsky & Papadopolous, The Kinematics, Dynamics, and Control of Free-Flying and Free-Floating Space Robotic Systems, 1993 • • Virtual manipulator approach • The principle of this method is to modify the kinematics of the fixed base to make it conform to the kinematics of the floating base, and to improve the modeling method of the kinematics and dynamics of the space robot. • However, the VM method does not describe the angular momentum of the system, and the attitude motion of the satellite base must be considered in other ways. 1996 • Saha, S. K. (1996). Inverse Dynamics Algorithm for Space Robots. Journal of Dynamic Systems, Measurement, and Control, 118(3), 625–629. https://doi.org/10.1115/1.2801191 • An efficient algorithm for the inverse dynamics of free-flying space robots, consisting of a serial manipulator mounted on a free-base, e.g., a spacecraft, is presented. The kinematic and dynamic models are based on the concepts of the Primary Body (PB) and the Natural Orthogonal Complement, respectively, reported elsewhere. In this paper, besides the efficiency, the usefulness of the PB in deriving different kinematic models and selecting an efficient one is pointed out. Moreover, it is shown that a recursive algorithm for the inverse dynamics of the space robot at hand can be developed even without the consideration of the momenta conservation principle. • 1998 • Liang et al. Mapping a space manipulator to a dynamically equivalent manipulator (1998) • The DEM concept not only allows us to model a free-floating space manipulator system with simple, well-understood methods, but also to build a conventional manipulator system to experimentally study the dynamic performance and task execution of a space manipulator system, without having to resort to complicated experimental set-ups to simulate the space environment. This paper presents the theoretical development of the DEM concept, demonstrates the dynamic and kinematic equivalence • theoretically proved equivalent to the suspension problem as a fixed base. 1999 • Legnani et al. A contribution to the dynamics of free-flying space manipulators (1999) • https://www-sciencedirect-com.ezproxy.lib.torontomu.ca/science/article/pii/S0094114X98000561?via%3Dihub • In this paper we study some properties of the disturbance maps showing how a proper robot design introduces some dynamic singularities, using which, a robot can perform many tasks preserving the base orientation at no cost whatsoever. Although this subject can be discussed for any robot, for sake of clarity our examples deal with simple 2 degree of freedom (d.o.f.) planar robots.

Early works: 2000 < year <= 2010 2001 • Yoshida et al. Zero reaction maneuver: flight validation with ETS-VII space robot and extension to kinematically redundant arm (2001) • https://ieeexplore-ieee-org.ezproxy.lib.torontomu.ca/document/932590 • reaction null-space based reactionless manipulation, or zero reaction maneuver (ZRM). The concept has been developed with an insight into the motion dynamics of free-flying multibody systems and its practical availability is clearly demonstrated with ETS-VII, a Japanese space robot. • The ZRM is proven particularly useful for removing the velocity limit of manipulation due to the reaction constraint and the time loss due to waiting for the attitude recovery. The existence of the ZRM is very limited for a 6 DOF manipulator arm mounted on a free-flying base, but it is discussed how more operational freedom is obtained with a kinematically redundant arm. 2002 • Li, Q.Z.; Gu, W.K.; Ye, X.Q.; Xiang, Z.Y. Research on intelligent pre-scanning control method for path tracking of mobile robots. Robot; 2002; pp. 252-255. [DOI: https://dx.doi.org/10.13973/j.cnki.robot.2002.03.013] • obstacles in motion with respect to the space base, which includes moving parts on the service satellites and target satellites, and space debris 2003 • Lampariello R, Agrawal S, Hirzinger G. Optimal motion planning for free-flying robots. In: IEEE international conference on robotics and automation, vol. 3, Taipei, Taiwan; 2003. p. 3029–35. • merge the first two categories (fully actuated and partially actuated) into the free-flying case • In order to find the minimum time for spacecraft actuation while satisfying kinematic and dynamic constraints at the same time, combined nonlinear optimization and look-up table methods to propose a cost function representing the total mechanical energy of the manipulators for the local and global motion of the space robot, respectively. • However, this planning scheme still relies on actuators with strong servo capabilities on large free-flying space robots, which is difficult to achieve on micronano space robots that are easier to achieve saturation torque. 2004 Ellery. An engineering approach to the dynamic control of space robotic on-orbit servicers (2004) • Files: An_engineering_approach .. • The problem of control is directly related to the fact that manipulator motions exert reaction effects on the mounting spacecraft. A solution to this problem is outlined-one in which no fuel is expended and that demands no excessive computational resources that would otherwise preclude real-time performance. • formulates dynamics for free flying robots. • Bai, W.D.; Zhou, Z.P.; Zhang, S.B.; Wu, J.Y. A study on inter-object collision detection in VRML. Comput. Appl. Res.; 2004; 6, pp. 128–130+133. • VRML (Virtual Reality Modeling Language) is a file format and language for creating interactive 3D virtual worlds and scenes, • The FDH (fixed direction hull) encloses the original object more tightly than other enclosing bodies and creates a hierarchical tree with fewer nodes, which reduces more redundant computations when intersection detection is performed, but the intersection operations are more complex with each other 2005 • Belousov et al. Motion planning for the large space manipulators with complicated dynamics (2005) • motion planning algorithms for the large space robot manipulators with complicated dynamic behavior. • We propose two “two-stage” iterative algorithms, which provide collision-free robot motion taking into account robot’s dynamics. The approach is based on new efficient methods for robot manipulator dynamics simulation and probabilistic methods for motion planning in highly cluttered environments. • algorithms are applicable for the robot manipulators of general class with arbitrary kinematics and dynamics parameters. We have demonstrated the approach for a particular task of servicing the satellite by a large space manipulator. This task is one of the most challenging since large space manipulators have extremely complicated dynamic behavior caused by elasticity of their structure, huge payloads they work with and zero-gravity conditions. Experiments involving a 15.5 meters long manipulator carrying a satellite inside a space shuttle with clearance less than 3 cm are presented. • Luo, F. Fast Collision Detection and Intersection Calculation for 3D Mesh Models. Master’s Thesis; Zhejiang University: Zhejiang, China, 2005 • many feasible collision detection algorithms have been formed, among which the widely used one is the hierarchical wraparound box algorithm 2006 • Papadopoulos, E.; Tortopidis, I.; Nanos, K. Smooth Planning for Free-floating Space Robots Using Polynomials. Proceedings of the IEEE International Conference on Robotics & Automation; Barcelona, Spain, 18–22 April 2006. • used smooth continuous functions, such as polynomials, to drive the system to the desired configuration in a finite and prescribed time. Limitations on reaching arbitrary final configurations were discussed and examples were presented. 2007 Moosavian and Papadopolous. Free-flying Robots in Space: an Overview of Dynamics Modeling, Planning and Control. (2007) • brief review of different approaches to control fixed-base manipulators is introduced. • specific problems related to application of such systems in space and a microgravity environment will be addressed. Fundamental issues on the kinematics and dynamics modeling of such systems, trajectory planning and control strategies, and cooperation of multiple arm space free-flying robots will be discussed. Finally, experimental studies and technological aspects of such systems with their specific limitations will be shortly reviewed. • Free-floating systems exhibit nonholonomic behavior that can be used to control not only manipulator joints, but also the attitude of the system base. This is achieved by small cyclical motions in the joint (V&D) or Cartesian space of the manipulator. (P) The drawback of these techniques is that they are time consuming. • A fast and computationally inexpensive method developed for terrestrial mobile manipulator systems has been further improved to be of potential use in space free-flyers. (P et al) The developed method uses smooth and continuous functions such as polynomials to construct trajectory inputs that drive both the manipulator and its platform to a final configuration without violating the constraints. The idea employed is to construct a transformation that maps the nonholonomic constraint associated with a given platform point from the Cartesian space to a space where it can be satisfied trivially. The proposed transformation is obtained through a systematic methodology that can also be applied directly to other more complex systems. Since the mapping is smooth and planning in this new space is achieved using polynomial trajectories, the resulting Cartesian paths and trajectories are also smooth.

• A motion control technique has been developed based on the general three-dimensional equations of motion of an n link manipulator mounted on a spacecraft. 90 Instead of performing a single inverse kinematic calculation at the beginning of a movement in order to determine the required joint setpoints, multiple inverse kinematic updates based on an optimal algorithm have been done throughout a movement. The derived motion control technique incorporates the base motion without base motion control.
• Employing the generalized Jacobian matrix approach, the kinematics of space manipulators has been described not by positions or angles but by their motion rates.91 Consequently, the inverse kinematics problem is solved analytically, and a resolved motion rate control is developed to compensate for spacecraft motion.

• Tortopidis, I.; Papadopoulos, E. On point-to-point motion planning for underactuated space manipulator systems. Robot. Auton. Syst.; 2007; 55, pp. 122-131. [DOI: https://dx.doi.org/10.1016/j.robot.2006.07.003] • studied the incomplete behavior of a spatial manipulator actuator in free-floating mode. They used higher-order polynomials as parameters of the cosine function to specify the desired path directly in the joint space. The accessibility of the configuration was extended. • Huang, P.; Xu, Y. PSO-Based Time-Optimal Trajectory Planning for Space Robot with Dynamic Constraints. Proceedings of the IEEE International Conference on Robotics & Biomimetics; Kunming, China, 17–20 December 2007. • used the PSO algorithm to search the global time-optimal trajectory of a spatial manipulator. The time-optimal trajectory planning method based on the particle swarm algorithm is verified by examples to have good performance and practical engineering significance. 2008 • Friend R. B., “Orbital Express Program Summary and Mission Overview,” Sensors and Systems for Space Applications II, Vol. 6958, edited by Howard R. T. and Motaghedi P., International Soc. for Optics and Photonics, SPIE, Orlando, FL, 2008, • The Orbital Express program was created to prove that the technical obstacles to satellite servicing were surmountable- to “take the technical excuse off the table” as it were. This mission demonstrated short range and long range autonomous rendezvous, capture and berthing, on-orbit electronics upgrades, on-orbit refueling, and autonomous fly-around visual inspection using a demonstration client satellite. The Orbital Express spacecraft were launched March 8, 2007 and completed their mission on July 22, 2007. 100% of mission success criteria and objectives were achieved. This paper describes, at a high level, the program goals and objectives, key milestones & events, accomplishments, and some of the obstacles that were overcome during the mission.

• K. Seweryn, M. Banaszkiewicz. Optimization of the trajectory of a general free-flying manipulator during the rendezvous maneuver, AIAA Guidance, Navigation and Control Conference and Exhibit (2008) • proposed a new motion planning method of the space robot by substituting the calculated momentum changes into the system motion equations, namely, the equation modification approach, and there is no need to design additional controllers to counteract the changes in the system due to momentum changes • the momentum of the servicing satellite is not conserved since the system is subjected to predefined forces and torques exerted by thrusters, and the equation modification approach was used to analyze the optimal trajectory of the manipulator during the rendezvous and docking maneuvers.

• Semi-Early works: 2010 < year <= 2020 2011 • Xu et al. Practical approaches to handle the singularities of a wrist-partitioned space manipulator (2011) • presented the singularity separation plus damped reciprocal (SSPDR) method, which separates the singularity parameters from the inverse of the Jacobian, and replaces their reciprocals using the damped reciprocals. • For another control strategy, i.e. inertially referenced end-point motion control, including spacecraft attitude-controlled mode and free-floating mode, the linear momentum equation is used to eliminate three independent variables. With modifying some expressions, the SSPDR method is utilized to solve the singularities of spacecraft attitude-controlled space robot. When the space robot is free-floating, the singularities, i.e. the so-called dynamic singularities, cannot be predicted according to its kinematic structure. Combining with the measured angular velocity of the base, the dynamic singularity handling problem is transformed into real-time kinematic singularity avoiding problem, which can be solved by the SSPDR method. Since the SVD decomposition, the estimation of the minimum singularity value, and the calculation of the generalized Jacobian matrix are not required, the algorithm has lower computation load. Another advantage is that, only the accuracy of part velocity components is reduced by adding the damped coefficients. • E. G. Kaigom, T. J. G. Jung and J. Roßmann, “Optimal motion planning of a space robot with base disturbance minimization”, Proc. 11th Symp. Adv. Space Technol. Robot. Automat., pp. 1-6, 2011. • particle swarm optimization (PSO) and genetic algorithm (GA) are commonly used optimal planning and control tools 2012 • Legnani et al. Attitude dynamic singularities in 3D free-flying manipulators for improved path planning (2012) • https://link-springer-com.ezproxy.lib.torontomu.ca/content/pdf/10.1007/s11012-012-9608-4 • Their idea is that each robot may profit by certain joint movements which do not influence the spacecraft attitude. In other words, when a robotic arm moves along certain trajectories (called zero-disturbance trajectories, ZDTs) the attitude is exactly maintained. There is an infinite number of such trajectories and they completely fill the whole working space of a robot. The motion between two configurations lying on the same trajectory can be performed without disturbing the attitude of the spacecraft. However, it has to be noted that usually these trajectories do not intersect each other. When a robotic arm moves from an initial configuration I to a final configuration F , it might be bound to follow a path intersecting several ZDTs (Fig. 1), thus causing a dynamic disturbance to its base attitude. The disturbances map helps determining a new path, along two or more ZDTs, which, thanks to the above mentioned characteristic of these trajectories, minimizes disturbances and, thereby, the energy spent to counter balance disturbance effects. • Wang, Y.; Jia, Y.H.; Xu, S.J. Collision-free trajectory planning algorithm for redundant space robotic arm coarse capture segment. Chin. Space Sci. Technol.; 2012; 32, pp. 49-56 • replace the convex obstacle with a convex polyhedral envelope and non-convex obstacles with multiple convex polyhedral envelopes. The robotic arm is then discretized, and a sufficient number of detection points are selected, which in turn detects whether each point is within the obstacle envelope. A point is selected on each face of the convex polyhedron, and then the inner product of the vector pointing from the point to be detected and the outer normal vector of that face of the convex polyhedron is calculated. If such inner product is positive for all faces of the convex polyhedron, the point to be detected is inside the convex polyhedron. As long as there exists a point to be detected that is inside one of the convex polyhedra, the point to be detected is considered to be inside the obstacle. • Komendera, E., Scheeres, D., & Bradley, E. (2012). Intelligent Computation of Reachability Sets for Space Missions. • This paper introduces a new technique for intelligently exploring the reachability set of a spacecraft: the set of trajectories from a given initial condition that are possible under a specified range of control actions. The high dimension of this problem and the nonlinear nature of gravitational interactions make the geometry of these sets complicated, hard to compute, and all but impossible to visualize. • Currently, exploration of a problem’s state space is done heuristically, based on previously identified solutions. This potentially misses out on improved mission design solutions that are not close to previous approaches. The goal of the work described here is to map out reachability sets automatically. • This would not only aid human mission planners, but also allow a spacecraft to determine its own course without input from Earth-based controllers. Brute-force approaches to this are computationally prohibitive, so one must focus the effort on regions that are of interest: where neighboring trajectories diverge quickly, for instance, or come close to a body that the spacecraft is orbiting. • In this paper, we focus on the first of those two criteria; the goal is to identify regions in the system’s state space where small changes have large effects— or vice versa—and concentrate the computational mesh accordingly.

2013 • Zeng, C. Research on Space Robotic Arm Motion and Mission Planning Methods for On-Orbit Services. Diploma Thesis; Dalian University of Technology: Dalian, China, 2013. • many feasible collision detection algorithms have been formed, among which the widely used one is the hierarchical wraparound box algorithm. The theory of the envelope box technique is to enclose the complex collection of targets with simple geometry and then construct a tree-like geometry structure to achieve the goal. The main focus of this class of methods is the selection of bracketing boxes. The main bracketing boxes are bracketing sphere, axis-aligned bounding box (AABB), oriented bounding box (OBB), and fixed direction hulls (FDH). • Rybus, T et al. Experimental demonstration of singularity avoidance with trajectories based on the Bézier curves for free-floating manipulator. Proceedings of the International Workshop on Robot Motion & Control; Kuslin, Poland, 3–5 July 2013 • explored the idea of using a specific type of parametric curves, the cubic Bézier curves, as trajectories for the free-floating manipulator. These curves can be used to generate trajectories that allow avoidance of system singular configuration. In the considered case of free-floating manipulator dynamic body, Jacobian was used to find dynamically singular configurations (these configurations differ from the kinematically singular configurations obtained for a fixed-base manipulator) • F. Aghili, “Pre-and post-grasping robot motion planning to capture and stabilize a tumbling/drifting free-floater with uncertain dynamics”, Proc. IEEE Int. Conf. Robot. Automat., pp. 5461-5468, 2013. • By minimizing the flight time and distance of objects, Aghili [28] achieved the purpose of using the space robot’s own structure to quickly reduce its momentum when grasping flying objects. • This idea of using its own structural characteristics and optimization algorithms to perform related tasks is of great significance to the realization of multiobjective coordinated orientation of micronano space robots.

2014 • Flores-Abad et al. A review of space robotics technologies for on-orbit servicing (2014) • a literature review of the recently developed technologies related to the kinematics, dynamics, control and verification of space robotic systems for manned and unmanned on-orbit servicing missions. • Pisculli, A.; Felicetti, L.; Gasbarri, P.; Palmerini, G.B.; Sabatini, M. A reaction-null/Jacobian transpose control strategy with gravity gradient compensation for on-orbit space manipulators. Aerosp. Sci. Technol.; 2014; 38, pp. 30-40. [DOI: https://dx.doi.org/10.1016/j.ast.2014.07.012] • proposed a minimal state variable approach to describe the dynamics of a free-floating space manipulator (FFSM) under the action of gravity and gravitational gradient forces. They used a combination of reaction zeros and Jacobi transpose controllers to implement the control and explored the advantages and disadvantages of the method • Qi, R.L.; Zhou, W.J.; Wang, T.J. A genetic algorithm-based trajectory planning method for spatial robotic arm obstacle avoidance. Robotics; 2014; 36, pp. 263-270] • applied the GA to solve the requirement of in-orbit trajectory planning of the space robotic arm. • They established the genetic algorithm fitness rating function about the end trajectory length of the Cartesian space robotic arm, the motion angle of the robotic arm in joint space, the maximum torque of the joint during motion, the total motion time of the robotic arm, and the collision case by the weighted coefficient method. • Finally, the genetic algorithm is applied to plan an ideal trajectory in the joint space with no collision, kinetic characteristics satisfying the margin requirement, and short trajectory length and motion time. • Liu, Y.; Jia, Q.X.; Chen, G. Multi-objective particle swarm optimization algorithm based on load-maximizing trajectory optimization for free-floating space robots. Robotics; 2014; 36, 9. • proposed a multi-objective particle swarm optimization (MOPSO) method. • The method significantly improves the load handling capability of the space robot system by simultaneously optimizing the joint moments, base perturbations, and system energy. • The optimal solution set based on the MOPSO algorithm has good convergence and diversity, and all Pareto optimal solutions can satisfy various constraints, which is easy to implement in engineering. At the same time, the method has a certain universality for solving multi-constrained multi-objective trajectory optimization problems with tandem robotic arms with more degrees of freedom. • Xia, H.W.; Zhai, Y.B.; Ma, G.C.; Deng, Y. Spatial robotic arm trajectory planning algorithm based on chaotic particle swarm optimization algorithm. Chin. J. Inert. Technol.; 2014; 6. • proposed a trajectory optimization strategy based on the chaotic particle swarm algorithm (CPSO) to study the trajectory planning problem of minimizing the base attitude perturbation in the free-floating state. • The CPSO ensures the diversity of particle populations with the advantages of randomness and ergodicity of chaotic motion, improves the ability of particle swarm algorithms to get rid of local extrema, and maintains the advantages of fast convergence of particle swarm optimization algorithms. • 2015 • Wang, M.; Luo, J.; Walter, U. Trajectory planning of free-floating space robot using Particle Swarm Optimization (PSO). Acta Astronaut.; 2015; 112, pp. 77-88. [DOI: https://dx.doi.org/10.1016/j.actaastro.2015.03.008] • Non-holonomic property of free-floating space robot is considered during its trajectory planning. • Joint trajectories are parameterized by the Bézier curves for its simplicity and normalization. • Constrained Particle Swarm Optimization algorithm with adaptive inertia weight is adopted to search for optimal solutions to construct the Bézier curves. • The execution time of the joint motion is determined with respect to the joint velocity and acceleration boundaries. • Multiple objectives optimization can be incorporated into the proposed trajectory planning method.

2016 • James, F.; Shah, S.V.; Singh, A.K.; Krishna, K.M.; Misra, A.K. Reactionless Maneuvering of a Space Robot in Precapture Phase. J. Guid. Control Dyn.; 2016; 39, pp. 2419-2425. [DOI: https://dx.doi.org/10.2514/1.G001828] • integrated the RRT method and a new time-scale transformation method to obtain the desired joint trajectory, thus reducing the spacecraft attitude perturbations and satisfying the corresponding state constraints. 2017 • Sabatini, M.; Gasbarri, P.; Palmerini, G.B. Coordinated control of a space manipulator tested by means of an air bearing free floating platform. Acta Astronaut.; 2017; 139, pp. 296-305. [DOI: https://dx.doi.org/10.1016/j.actaastro.2017.07.015] • Sabatini et al. [41] performed an experimental campaign using an air-floating table and a free-floating platform to simulate the spatial manipulator used in the pursuer platform. They adjusted the gain mainly by the distance between the target and the tracker. The method is similar to Jacobi pseudo-inverse control but is only used to manipulate the robotic system. • Misra, G.; Bai, X. Optimal Path Planning for Free-Flying Space Manipulators via Sequential Convex Programming. J. Guid. Control Dyn.; 2017; 40, pp. 3019-3026. [DOI: https://dx.doi.org/10.2514/1.G002487] • in the context of the enhanced real-time problem, the authors investigated point-to-point trajectory planning in sequential convex planning (SCP) framework, culminating in an expression for the end-effector positional constraints and their subsequent convex relaxation. • J. Virgili-Llop, C. Zagaris, R. Zappulla Ii, A. Bradstreet, M. Romano Convex optimization for proximity maneuvering of a spacecraft with a robotic manipulator, Proceedings of the 27th AAS/AIAA Spaceflight Mechanics Meeting, San Antonio, TX, Feb. 6-9, vol. 160, Advances in the Astronautical Sciences (2017), pp. 1059-1078 • divided the proximity maneuver into two simultaneous sub-maneuvers, namely a system-wide translation maneuver and an internal re-configuration maneuver, and the optimization problem in each maneuver was solved using a sequential convex optimization method • most studies do not consider the changes of the system momentum directly, but develop control schemes using dynamics-based models, or rely on stage-based strategies to decompose the problem into stages where the condition of the momentum conservation can be applied in a stage-by-stage manner • 2018 • Wilde et al. Equations of Motion of Free-Floating Spacecraft-Manipulator Systems: An Engineer’s Tutorial (2018) • step-by-step tutorial on the Generalized Jacobian Matrix (GJM) approach for modeling and simulation of spacecraft-manipulator systems. • complete analytic derivation of the generalized equations of motion of a free-floating spacecraft-manipulator system. This includes symbolic analytic expressions for all inertia property matrices of the system, including their time derivatives and joint-angle derivatives, as well as an expression for the generalized Jacobian of a generic point on any link of the spacecraft-manipulator system. • The kinematics structure of the spacecraft-manipulator system is described both in terms of direction-cosine matrices and unit quaternions. • An additional important contribution of this paper is to propose a new and more detailed definition for the modes of maneuvering of a spacecraft-manipulator. In particular, the two commonly used categories free-flying and free-floating are expanded by the introduction of five categories, namely floating, rotation-floating, rotation-flying, translation-flying, and flying. A fully-symbolic and a partially-symbolic option for the implementation of a numerical simulation model based on the proposed analytic approach are introduced and exemplary simulation results for a planar four-link spacecraft-manipulator system and a spatial six-link spacecraft manipulator system are presented. • Valverde & Tsiotras. Modeling of Spacecraft-Mounted Robot Dynamics and Control Using Dual Quaternions (2018) • https://ieeexplore-ieee-org.ezproxy.lib.torontomu.ca/document/8431054 • I have been told not to worry about this as it’s too much notation and unnecessary • Zhu, Z.X.; Jing, S.; Zhong, J.F.; Wang, M.M. Spatially redundant robotic arm obstacle avoidance path planning based on collision detection. J. Northwestern Polytech. Univ.; 2020; 38, pp. 183-190. [DOI: https://dx.doi.org/10.1051/jnwpu/20203810183] • transformed the obstacles into joint space. They simplified the occupation relationship between the obstacle and the free-floating space robotic arm based on the idea of a spherical enclosing box and spatial superposition. The simplified approach views the collision detection of the robotic arm with a circle as the intersection detection of a line segment with a circle. The method largely simplifies the computation and improves the planning efficiency. • Han, F.; Wang, Z.; He, L.; Wu, H.; Yang, G.; Duan, G. Trajectory plan for an ultra-short distance on-orbit service based on the Gaussian pseudo-spectral method. IEEE/CAA J. Autom. Sin.; 2018; pp. 1-9. [DOI: https://dx.doi.org/10.1109/JAS.2017.7510892] • designed an innovative “sphere and ellipsoid” model to ensure a safe distance for ultra-short orbital approaches. The exclusion zone and limits were designed according to the satellite sphere envelope to keep the whole spacecraft away from any collision threat. • Stolfi, A.; Gasbarri, P.; Sabatini, M. Spazio. Performance Analysis and Gains Tuning Procedure for a Controlled Space Manipulator Used for Non-Cooperative Target Capture Operations. Aerotec. Missili Spaz.; 2018; 97, pp. 3-12. [DOI: https://dx.doi.org/10.1007/BF03404759] • to absorb the impact energy, described the space manipulator end-effector as a mass-spring-damping system without considering the base reaction force, as shown

• Gao, X.; Wu, H.; Zhai, L.; Sun, H.; Jia, Q.; Wang, Y.; Wu, L. A rapidly exploring random tree optimization algorithm for space robotic manipulators guided by obstacle avoidance independent potential field. Int. J. Adv. Robot. Syst.; 2018; 15, [DOI: https://dx.doi.org/10.1177/1729881418782240] • proposed a fast exploration random tree optimization algorithm based on obstacle avoidance independent potential field guidance for a space robot robotic arm. Some responding layer factors related to operational cost are used as optimization objectives to improve operational reliability. On this basis, a potential field whose gradient is calculated off-line is established to guide the expansion of rapidly exploring the random trees. The potential field mainly considers indexes about the manipulator itself, such as the minimum singular value of the Jacobian matrix, manipulability, condition number, and joint limits of a manipulator. Thus, it can stay the same for different obstacle avoidance path planning tasks. • The artificial potential field method is considered for obstacle avoidance, the gravitational potential field acts in a larger range. In contrast, the repulsive potential field only acts in a local range, and the region far from the obstacle is not affected by the obstacle repulsive potential field. Therefore, this method is also called the local method, which only solves the local space within the obstacle avoidance. However, it is very widely used due to its ease of mathematical description and its applicability to multi-degree-of-freedom robotic arms. • Wang, M.; Luo, J.; Fang, J.; Yuan, J. Optimal trajectory planning of free-floating space manipulator using differential evolution algorithm. Adv. Space Res.; 2018; 61, pp. 1525-1536. [DOI: https://dx.doi.org/10.1016/j.asr.2018.01.011] • an optimal joint trajectory planning method using forward kinematics equations of free-floating space robots, while joint motion laws were delineated with the application of the concept of reaction null-space. Bézier curves, in conjunction with the null-space column vectors, were applied to describe the joint trajectories. Considering the forward kinematics equations of the free-floating space robot, the trajectory planning issue was consequently transferred to an optimization issue while the control points to construct the Bézier curve are the design variables. A constrained differential evolution (DE) scheme with a premature handling strategy was implemented to find the optimal solution for the design variables while specific objectives and imposed constraints are satisfied • Jie, D.Y.; Lu, H.R.; Wu, H.L.; Ni, F.L. Transporting trajectory optimization method for large space manipulator system. Acta Aeronaut. Et Astronaut. Sin.; 2018; 39, pp. 111-119. • proposed the particle swarm optimization algorithm of “adaptation value correction + natural selection”. • By modifying the adaptation value function, they transformed the attitude perturbation control problem of the floating base into an unconstrained optimization problem in free space and achieved high optimization accuracy. • Rybus, T. (2018). Obstacle avoidance in space robotics: Review of major challenges and proposed solutions. Progress in Aerospace Sciences, 101, 31–48. https://doi.org/10.1016/j.paerosci.2018.07.001 • the problem of obstacle avoidance has been divided into three topics: • (i) collision-free trajectory planning of a space manipulator mounted on a large orbital structure (such as a space station), • (ii) collision-free trajectory planning of a manipulator mounted on a relatively small satellite, and • (iii) collision-free trajectory planning of a space robot moving in proximity to a large orbital structure. • For each topic, major challenges are identified and proposed solutions are reviewed. The presented review shows that the collision-free trajectory planning in space robotics is a very active field of studies, but there are still several open problems that need to be solved before the proposed methods could be applied during on-orbit servicing, active debris removal and on-orbit assembly of large structures. • X. Chu, Q. Hu and J. Zhang, “Path planning and collision avoidance for a multi-arm space maneuverable robot”, IEEE Trans. Aerosp. Electron. Syst., vol. 54, no. 1, pp. 217-232, Feb. 2018. • The displacement of the system center of mass and the change of inertial parameters are another difficult problem in the modeling of micronano space robots • a path planning algorithm for a multi-arm space robot is proposed. The robot is capable of maneuvering on the exterior of a large space station. Based on the maneuver strategy, continuous and smooth trajectories of the manipulator end effectors are first determined via the polynomial interpolation method. Then, the kinematics describing the relation between the end effector and the joint angles as well as the platform are formulated. A Moore-Penrose pseudoinverse solution of the joint trajectories is calculated to describe the motion of the manipulators, particularly, considering the singularity avoidance. In addition, a collision detection algorithm is developed to estimate the security during operation. Constraints are formulated by considering collision avoidance, based on which a collision-free trajectory is optimized through the multiplier-penalty method. • Yost B., Agasid E., Burton R., Carlino R., Defouw G., Perez A. D., Karacalioglu A. D., Klamm B., Rademacher A., Schalkwyck J., Shimmin R., Tilles J. and Weston S., “Small Spacecraft Technology State of the Art,” NASA Ames Research Center NASA/TP—2018–220027, 2018. • The technologies for small spacecraft such as CubeSats are maturing quickly • Bogaerts, B., Sels, S., Vanlanduit, S., & Penne, R. (2018). A Gradient-Based Inspection Path Optimization Approach. IEEE Robotics and Automation Letters, 3(3), 2646–2653. https://doi.org/10.1109/LRA.2018.2827161 • We develop a new gradient-based optimization strategy for robotic inspection planning. The algorithm starts from an initial measurement path and evolves this path to decrease path length while maintaining sensor coverage. The approach is powerful enough to handle inspection tasks of complex objects under articulated manipulator constraints. We show the effectiveness of the algorithm in two complex inspection tasks. 2019 • Rybus, T. Point-to-Point Motion Planning of a Free-Floating Space Manipulator Using the Rapidly-Exploring Random Trees (RRT) Method. Robotica; 2019; 38, pp. 957-982. [DOI: https://dx.doi.org/10.1017/S0263574719001176] • used the RRT algorithm to plan a collision-free manipulator trajectory. The bi-directional approach is used in the construction of the tree in order to plan a trajectory from the given initial state to the specific final state. The feasibility of the proposed method was also demonstrated in a numerical simulation of a chaser satellite equipped with a 2-DOF (degree of freedom) manipulator in the planar case. Their improvements include reducing the number of dimensions of the state space to simplify the tree construction. A new method is used to select control signals during tree construction to obtain better state-space coverage. Numerical simulations performed in a simplified planar case validate the proposed trajectory planning method. • Cui, H. Polynomial interpolation method for motion planning of free-floating space robots. J. Beijing Inf. Sci. Technol. Univ.; 2019; 34, 8. • used 5th and 6th order polynomial interpolation to approximate the trajectory of the joint motion of the free-floating space robot and used sequential quadratic programming to optimally solve the trajectory of the joint hinge motion. The computed trajectories of each joint hinge and control inputs are continuous and smooth by numerical simulation. The planning method has good convergence, high computational efficiency and strong boundary search capability, which are the most outstanding advantages compared with other optimization algorithms. • Xu, W.; Lu, S. Research on path planning of space robotic arm based on Sarsa(λ) reinforcement learning. J. Astronaut.; 2019; 40, pp. 435-443. • used the Sarsa(λ) reinforcement learning method to achieve autonomous trajectory planning for target tracking and obstacle avoidance in an on-orbit operation environment with unknown target characteristics. • Wu, Y.H.; Yu, Z.C.; Li, C.Y.; He, M.J.; Chen, Z.M. Reinforcement learning in dual-arm trajectory planning for a free-floating space robot. Aerosp. Sci. Technol.; 2020; 98, 105657. [DOI: https://dx.doi.org/10.1016/j.ast.2019.105657] • proposed a model-free reinforcement learning strategy, namely the deep deterministic policy gradient (DDPG) algorithm. • The online trajectory planning strategy is trained without modeling the dynamics and kinematics of the spatial robotic arm, enabling the spatial robotic arm to quickly schedule and execute actions. • Davis J. P., Mayberry J. P. and Penn J. P., “On-Orbit Servicing: Inspection, Repair, Refuel, Upgrade, and Assembly of Satellites in Space,” The Aerospace Corp., 2019 • Inspection and mapping of known or unknown space objects in Earth’s orbit is the first essential step toward on-orbit servicing capabilities that include refueling, repairing, assembling, and upgrading of space assets • Banker B. and Askew R., “Seeker 1.0: Prototype Robotic Free Flying Inspector Mission Overview,” 33rd Annual Conference on Small Satellites, SSC19-XI-04, 2019. • State-of-the-art approaches for on-orbit inspection include robotic manipulators with rails for extended work space, single servicing spacecraft, and astronaut intervention. • These approaches have severe limitations: the capability of manipulators are limited due to mechanical constraints • A. Seddaoui and C. M. Saaj, “Collision-free optimal trajectory for a controlled floating space robot”, Proc. Annu. Conf. Towards Auton. Robotic Syst., pp. 248-260, 2019. • used GAs to develop an optimal path planning algorithm for a free-flying spacecraft-manipulator system that exploits the controlled motion of the spacecraft to improve the safety of arm movements. • A novel optimal trajectory generator, capable of avoiding collisions and singularities using a Non-Dominated Sorting Genetic Algorithm II, was presented. The key highlight of the path generator is the possibility to select between two modes of tracking, namely, the direct tracking and the dynamic coupling tracking. The former mode is to be utilised when the effect of the dynamic coupling is undesirable and has to be compensated using active control. The latter favours the fuel conservation by taking advantage of the dynamic coupling effect on the end-effector’s inertial position to help reach the grasping point. The selection of the tracking mode is dependent on the mission. For instance, when handling mirrors during in-orbit telescope assembly, the direct tracking is preferred, where the extra precision is necessary to guarantee a safe and gentle capture at all times. Whereas when the space robot is required to perform multiple tasks in different orbits, fuel conservation becomes a priority and the dynamic coupling tracking can be selected. Additionally, this new algorithm only requires the Cartesian location of the grasping point without a prior knowledge of a desired path or final configuration. The effectiveness of this optimal trajectory generator was verified by operating the space robot in the controlled-floating mode. Although several paths exist, this novel algorithm ensures that the resulting path is optimal, through optimising the configuration trajectories. • Virgili-Llop et al. A convex-programming-based guidance algorithm to capture a tumbling object on orbit using a spacecraft equipped with a robotic manipulator. The International journal of robotics research, 2019-01, 2020 • Lu, X.; Jia, Y. Trajectory Planning of Free-Floating Space Manipulators With Spacecraft Attitude Stabilization and Manipulability Optimization. IEEE Trans. Syst. Man Cybern. Syst.; 2020; 51, pp. 7346-7362. [DOI: https://dx.doi.org/10.1109/TSMC.2020.2966859] • considered end-effector trajectory tracking constraints and joint angle/velocity/acceleration constraints in the trajectory planning problem of the FFSM model. The trajectory planning problem can be further formulated as a constrained convex quadratic programming problem. They avoid the dynamic singularity of the FFSM based on the obtained optimization algorithm.

• F.L. Basmadji, K. Seweryn, J.Z. Sasiadek. Space robot motion planning in the presence of nonconserved linear and angular momenta Multibody Syst. Dyn., 50 (2020), • substituting the calculated momentum changes into the system motion equations, namely, the equation modification approach, • considered the change in linear and angular momentums caused by the external forces and torques acting on the manipulator end effector, and used the principle of virtual work to counteract the end effector displacements cause by external forces, the simulation results showed that the manipulator can track the planned trajectory properly in the event of the change in system momentum • This focuses on a dual arm system

Recent works: year > 2020 2021 • Seddaoui et al. Modeling a Controlled-Floating Space Robot for In-Space Services: A Beginner’s Tutorial (2021) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8739970/pdf/frobt-08-725333.pdf • modeling complex space robots operating in the controlled-floating mode and under perturbed conditions. • refined dynamic model of a chaser space robot, derived with respect to the moving target while accounting for the internal perturbations due to constantly changing the center of mass, the inertial matrix, Coriolis, and centrifugal terms of the coupled system; • it also accounts for the external environmental disturbances. • The nonlinear model presented accurately represents the multibody coupled dynamics of a space robot, which is pivotal for precise pose control. • The free-flying approach uses reaction jets to facilitate a stabilized and controlled base for the robot manipulator in motion. • The stable platform is favorable for the manipulator’s motion, however, on the expense of excessive fuel consumption and limited workspace. • Li, Y.C.; Jiang, Q.; Wang, C.H. Adaptive trajectory planning of robotic arms in confined spaces. Electron. Compon. Inf. Technol.; 2021; 5, pp. 53-54. [DOI: https://dx.doi.org/10.19772/j.cnki.2096-4455.2021.10.024] (Not in library) • established the OBB bounding box model for trajectory planning of the robotic arm in the confined environment of the space station experiment box [30]. Figure 4 shows the projection of the mobile manipulator and the obstacles in the experiment. This method is highly efficient in planning routes according to the complexity of the obstacle envelope. • • Huang, Y.S.; Tian, D.; Li, H.J.; Jiao, R.H. A tumbling non-cooperative spacecraft approach and flight avoidance trajectory planning and tracking control method. Space Control Technol. Appl.; 2021; 47, 8. • considered the obstacle avoidance case and combined the constraints such as dynamics and paths for trajectory planning. • Tringali, A.; Cocuzza, S. Finite-Horizon Kinetic Energy Optimization of a Redundant Space Manipulator. Appl. Sci.; 2021; 11, 2346. [DOI: https://dx.doi.org/10.3390/app11052346] • quadratic programming • based on the optimization of the kinetic energy integral over a finite subset of the future end-effector path points so that the manipulator’s joints move towards the minimum kinetic energy. Their proposed method outperforms the pseudo-inverse-based method. • Shrivastava, A.; Dalla, V.K. Engineering. Failure control and energy optimization of multi-axes space manipulator through genetic algorithm approach. J. Braz. Soc. Mech. Sci. Eng.; 2021; 43, pp. 1-17. [DOI: https://dx.doi.org/10.1007/s40430-021-03163-6] • used a genetic algorithm to optimize the trajectory based on the energy conservation criterion. Their proposed method enables the operation of floating bodies in unknown environments with manipulator joint failures. The optimized onboard fuel has a significant impact on the satellite’s lifetime. • R. Jin, P. Rocco and Y. Geng, “Cartesian trajectory planning of space robots using a multi-objective optimization”, Aerosp. Sci. Technol., vol. 108, pp. 106360, 2021. • Chaotic particle swarm optimization was employed to solve the optimization, which could improve the premature phenomenon of PSO in planning of space robot. • However, the PSO algorithm has strict requirements on the hardware computing power of the control system, which makes it difficult for this method to play a role in the real-time control system. • It can only solve the planned path in advance before the task is executed. Fortunately, the PSO algorithm is easy to perform with parallel processing, and multicore CPU or GPU can be used to solve the real-time objective function. • B. Moghaddam Monazzah and R. Chhabra, “On the guidance navigation and control of in-orbit space robotic missions: A survey and prospective vision”, Acta Astronautica, vol. 184, pp. 70-100, 2021. • In a typical nonholonomic constrained system such as micronano space robot, optimal control can solve problems, such as minimizing fuel consumption, shortening control time, minimizing disturbance, or disturbance suppression 2022 • Lei et al. Active object tracking of free floating space manipulators based on deep reinforcement learning (2022) • Free-floating space manipulators(FFSM) are more and more widely used in various space tasks, and active object tracking(AOT) is the basis of many missions in space. AOT of FFSM systems has two main difficulties: modeling and control of FFSM systems and tracking motion planning of space manipulators. • To deal with these problems, the paper proposed an active object tracking proposal of FFSM systems using deep reinforcement learning(DRL) algorithm, Proximal Policy Optimization(PPO). Our approach is completely data-driven, which avoids the complex modeling process of FFSM and does not require motion planning for space manipulators, which is more concise than traditional algorithms. • Dai et al. A Review of Spatial Robotic Arm Trajectory Planning (2022) • spatial robotic arm plays an increasingly important role in space activities. Spatial robotic arms can effectively replace humans to complete in-orbit service tasks. The trajectory planning is the basis of robotic arm motion. Its merit has an essential impact on the quality of the completed operation. The research on spatial robotic arm trajectory planning has not yet formed a broad framework categorization, so it is necessary to analyze and deeply summarize the existing research systematically. This paper introduces the current situation of space obstacle avoidance trajectory planning and motion trajectory planning. • Zhang, C.F.; Chen, M.H.; Hou, Y.Y.; Zhang, W.J. Redundant space robotic arm trial search obstacle avoidance strategy. Aerosp. Shanghai; 2022; 39, pp. 1-7. [DOI: https://dx.doi.org/10.19328/j.cnki.2096-8655.2022.02.001] • used a convex polyhedral vector inner product detection algorithm for redundant spatial robotic arms to perform a trial search for obstacle avoidance. • They use three levels of collision detection problems for robot arm motion, robot arm configuration, and robot arm upper point, respectively. • The method consists of the starting configuration moving continuously toward the target configuration according to a certain pattern. If a collision occurs during the movement, the direction of advance is adjusted until a path is found that does not collide with the obstacle. In this way, instead of solving the entire configuration space, only collision detection is required. • Zhang, W., & Wen, H. (2022). Motion planning of a free-flying space robot system under end effector task constraints. Acta Astronautica, 199, 195–205. https://doi.org/10.1016/j.actaastro.2022.07.005 • This study focuses on the motion planning of a free-flying space robot system with non-conserved linear and angular momentums due to thrusts acting on its base. The system model is established at the kinematic level based on the momentum theorem, which takes into account the change in base mass. In particular, a motion planning strategy is proposed to perform trajectory tracking of the end effector for the free-flying space robot. The thrusts and torque acting on base satellite are not predefined, but are taken as system control inputs to be optimized, as are joint accelerations. Therefore, the synchronous motion planning of the base satellite and manipulator is formulated as an open-loop optimization problem, which is subject to physical constraints such as thrust and torque saturation, joint motion limitations, and collision avoidance, etc. Finally, the system under different task constraints of end effectors is numerically simulated to demonstrate the effectiveness of the proposed method. • Planning the motion of a space robot at the kinematic level while accounting for non-conserved momentums. • Synchronous motion planning of the base and manipulator is formulated as an optimization problem. • Base thrusts and torque are not predefined, but are system control inputs to be optimized. • The mass change of the base satellite is considered in system model. • Equation Modification strategy • Faghihi, S., Tavana, S., & de Ruiter, A. H. J. (2022). Kinodynamic on-orbit inspection path planning for full-coverage inspection in close proximity of space structures. Acta Astronautica, 198, 354–365. https://doi.org/10.1016/j.actaastro.2022.04.038 • In this paper, a kinodynamic inspection path planner, called Random Kinodynamic Inspection Tree algorithm, is presented to perform in-close proximity full-coverage on-orbit inspection for the space structures, under kinematic/dynamic motion constraints in deep space environments. Inspection, as one of the key elements of proximity operations, would make a significant breakthrough in on-orbit servicing and, therefore, space exploration missions. The presented approach combines a novel coverage planning scheme with a kinodynamic motion planner to quickly and effectively solve the inspection path planning problem while at the same time handling both holonomic and non-holonomic constraints of the environment and the inspector robot. Our planner avoids the previous decoupled two steps method, which usually has been used to solve coverage planning problems, namely the Art Gallery and Traveling salesman problems, which are difficult or infeasible to be applied to a robot with differential constraints working in a high-dimensional environment. By contrast, our planner employs the Rapidly Exploring Random Tree algorithm as an asymptotically-optimal sampling-based technique in cooperation with a Linear Quadratic Minimum Time controller to generate an optimal and smooth inspection trajectory for any space structures, given complete knowledge of the structure and inspector’s dynamics. The algorithm guarantees probabilistic completeness. Simulations are provided as a validation of the achieved inspection performance. •Kinodynamic inspection path planning for space applications is studied.•Three-dimensional kinodynamic coverage path planner is designed.•Full coverage inspection trajectories are developed for three different geometrical shapes.•Our results can be applied to space exploration missions in the future. • propose Random Kinodynamic Inspection Tree path planner designed for close proximity full-coverage on-orbit inspection, which satisfies environmental and actuator constraints.
• Doesn’t consider illumination; manipulator; doesn’t quantify “close proximity” but figures in the paper indicate the mean distance is on the order of 10-30m, which is not close enough for detailed inspection; doesn’t consider occlusion in large structures 2023 • Li et al. Constraint trajectory planning for redundant space robot (2023) • good review of kinematic model for free-floating space robot • normalized m-order Bezier curve is employed in this paper to describe the trajectory of each joint • propose a novel hybrid heuristic algorithm, particle swarm optimization, and whale optimization algorithm (PSO–WOA), to solve a multi-objective optimization problem relating to point-to-point trajectory planning of space robots. • First of all, the kinematics of the space robot is introduced, and the motion of each revolute joint of the manipulator is parameterized by Bézier curve. • Then, contradictory objective functions are proposed, and the trajectory planning problem is transformed into a multi-objective optimization problem. • The pose of the end-effector at the end of motion is set as the primary objective. The base disturbance, execution time, and manipulability of the end-effector are also taken into account. • Furthermore, self-collision avoidance during the motion is also considered. • The trajectory planning problem finally comes down to finding an optimal parameter of the Bézier curve for each joint. We propose a novel hybrid PSO–WOA, which is supposed to take advantages of the best of both methods: the exploration feature of the WOA and exploitation feature of the PSO. In order to enhance the performance of the PSO–WOA, the good point set and lévy flight stochastic steps are employed for the initialization and updating process, respectively. • The proposed method is applied to generate an optimal trajectory for a redundant free-floating space robot. The simulation results demonstrate the effectiveness of the PSO–WOA. • Huang, Z., Chen, G., Shen, Y., Wang, R., Liu, C., & Zhang, L. (2023). An Obstacle-Avoidance Motion Planning Method for Redundant Space Robot via Reinforcement Learning. Actuators, 12(2), 69-. https://doi.org/10.3390/act12020069 • new obstacle-avoidance motion planning method for redundant space robots via reinforcement learning (RL). • First, the motion planning framework, which combines RL with the null-space motion for redundant space robots, is proposed according to the decomposition of joint motion. • Second, the RL model for null-space obstacle avoidance is constructed, where the RL agent’s state and reward function are defined independent of the specific information of obstacles so that it can adapt to dynamic environmental changes. • Finally, a curriculum learning-based training strategy for RL agents is designed to improve sample efficiency, training stability, and obstacle-avoidance performance. • The simulation shows that the proposed method realizes reactive obstacle avoidance while maintaining the end-effector’s predetermined trajectory, as well as the adaptability to unstructured dynamic environments and robustness to the space robot’s dynamic parameters. • Y. Liu, Z. Jin and L. Teng, “PSO-Based Time Optimal Rapid Orientation for Micronano Space Robot,” in IEEE Transactions on Aerospace and Electronic Systems, vol. 59, no. 2, pp. 1921-1934, April 2023 • https://ieeexplore-ieee-org.ezproxy.lib.torontomu.ca/document/9893353 • Simultaneous multidirectional orientation tasks on space robots exhibit strong dynamic coupling between the manipulators and the base-spacecraft, and this phenomenon is more obvious in the micronano space robot. Regarding to the highly coupled dynamic system of micronano space robot and its nonholonomic constraints, a multidirectional rapid orientation method of micronano space robot based on optimization theory is proposed in this article. Dynamic model of satellite-manipulators cooperative operation micronano space robot is established by the combination of virtual manipulator and Newton–Euler method. Then, taking the acceleration continuous cubic polynomial trajectory planning method and the dynamics-based feedback linearization controller as an example, the particle swarm optimization method is used to solve the time and path nodes of the orientation process of the micronano space robot. Finally, three typical spatial orientation problems are simulated to verify the feasibility and rapidity of this orientation method: 1) simultaneous orientation; 2) assisted orientation; and 3) cooperative braking. Furthermore, the article presents the structure of the objective function for optimization in different multicomponent and multiobjective coorientation tasks.