Vibration Control Of Space Flexible Manipulator Based On Magneto Rheological Principle

Current space task usually is of expensive cost and high risk, malfunction of spacecraft will lead to huge loss. On-orbit service technologies have a promising application prospect and research value because on-orbit service will ensure normal operation of spacecraft and reduce loss caused by malfunction. On-orbit service technologies involve contact between manipulator and non-corporate target. Non-corporate target to be captured usually rotates in a high speed. The moment manipulator reaches target, instantaneous impact force of target may seriously influence manipulator, cause vibration and lead to task failure. In this thesis, a multi-DOF space flexible manipulator with magneto rheological dampers (MRD) in all the joints is proposed to solve this vibration control problem. Kane method is adopted to establish general dynamics model of multi-DOF space flexible manipulator with distributed controllable dampers, and manipulator’s vibration control method based on Particle Swarm Optimization (PSO) is discussed. This paper is supported by NSFC [51305039], Fundamental Research Funds for the Central Universities [2014PTB-00-01]. Specific work is as follows:Firstly, dynamics model of a N-joint6N-DOF space flexible manipulator with controllable damping units is established. To achieve vibration control, controllable damping unit consisting of magneto rheological damper and buffer is installed in each joint of manipulator, taking floating base as an extending link, and whole space manipulator is discretized into multi-rigid segment connected by springs and dampers, adopting Kane method to establish dynamics equations. Simulate manipulator dynamics both in Adams and Matlab, and analyze results to verify the established dynamics model.Secondly, based on magneto rheological principle, this thesis discusses magneto rheological damper’s (MRD) modeling and controlling method. Since MRD’s nonlinear and hysteresis characteristics, neural network is used to derive MRD’s forward and inverse model. Connect inverse and forward model in sequence to achieve MRD’s accurate control.At last, based on control goal, vibration control method of floating space flexible manipulator with distributed controllable dampers by using Particle Swarm Optimization (PSO) algorithm is designed. With the goal of all joints’ minimum vibrations, this thesis employs multi-objective optimization method to determine the objective function, selects PSO evolution algorithm and designs detailed process of control method. In the meanwhile, PID controller is adopted to realize manipulator vibration control. Dynamical simulations are carried out for a three joints manipulator space capture with twelve controllable dampers under PSO、 PID、Un-control condition for comparison. Results show that vibration control method based on PSO algorithm can significantly reduce vibration.