Redundancy resolution in a hyper-redundant space robots is a big challenge due to its extra degrees of freedom. This article presents a methodology to control motion planning of a planar space robot with multiple links, that is, hyper-redundant space robot. For control purpose, first a curve-constrained link trajectory tracking control has been developed. Then, the developed control approach has been extended for a collision-free trajectory tracking. For curve-constrained link trajectory tracking control, the backbone reference set (curve fitting) has been applied to exploit the redundancy of two-dimensional space robot of multiple links. For kinematic control purpose, a limited number of joints are actuated. The hyper-redundant space robot has the advantage that manipulator can be configured differently through actuation of different joints. The concept of a limited number of joint actuation has further been extended for collision-free trajectory tracking in the workspace in the presence of obstacles. Collision avoidance is based on the configuration transformation approach where the joints are made active or fixed joint position to facilitate collision-free tip trajectory. Before configuration transformation, collision detection has been performed based on the pseudo-distance criterion. The bond graph technique has been used for the dynamic model of the system and to formulate system equations. The simulation and the animation results validated the successful execution of the proposed approaches for the curve-constrained collision-free trajectory planning.

Main advantage of redundant space manipulator is that it can be configured differently by actuating various joints. Space manipulators are designed to be deployed in harsh surroundings, which in turn would increase the possibility of manipulator failure. Thus, the enhancement of the capabilities of the robots and the failures thereafter are a major concern. This article presents three aspects of hyper-redundant space robot. First, the control strategies based on minimum power criterion with all healthy joints are proposed. Second, hyper-redundancy is put upon to reconfigure the space robot with the failure of locked joints. Third, the optimization of workplace trajectory of the manipulator is obtained by genetic algorithm and a minimum power criterion has been adopted in all three cases. The bond-graph technique is employed for robot modeling with the use of SYMBOLS Shakti software, which generates system equations in C++ code. This code is subsequently converted into a MATLAB program. The result obtained through simulation shows that 37% of the total power consumption was reduced by the actuators through an optimization approach.

A free-floating space robot is a non-holonomic system due to the conservation of the angular momentum. To control this type of system, it becomes impossible to have a desired trajectory without taking into account the non-holonomy effect of the system. This is further important for close trajectory tracking during the interaction with free-floating object. This article presents trajectory control of the three planar space robots having 2 degrees of freedom each to handle a free-floating object cooperatively. In this article, the work proposes the use of a control strategy (amnesia removal control) to take care of non-holonomy in the system. To demonstrate the efficacy of the proposed scheme, a comparative study of the proportional-integral-derivative-controlled three planar space robot systems with and without using amnesia recovery has been successfully carried out. Bond graph modeling has been used to model the system dynamics and to implement the control strategy.

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