The Research Of Global Robust Finite-time Tracking Control Method On Free Floating Space Robot System

Space robot has become an important research branch of outer space exploration technologies,the system is so complicated in a special environment of space.The related research is not perfect enough,and it's still in the phase of accumulation.Considering the structure characteristics of the space robot and gradually establish and improve its dynamic model,and then design control method for a variety of special conditions to achieve good control effect is the main task of research.This paper studied two kinds of free floating space robot's dynamics model including rigid space robot and flexible joint space robot.Combining momentum relationship using Lagrange method to establish rigid space robot dynamics equation.And then,considering momentum conservation relationship to get double coupling dynamic equation of rigid system.For the flexible joints system,simplifing the flexible joints for linear spring and establishing flexible joint space robot double coupling dynamics equation based on Lagrange method.After finishing the modeling work,designing work is start.This paper designed some finite time control method for rigid space robot and flexible joint space robot.The method can make the system state convergence to equilibrium in finite time,and it has a good performance on transient response characteristics,tracking accuracy and robustness.First,designing a global robust finite-time tracking control method for rigid space robot with the effects of model uncertainty and bounded external disturbance in the control condition that the base position is without control and the attitude is on control.And in the control condition that the base position and attitude are both without control,this paper designed the global robust finite-time tracking control method base on augmentation approach.In order to improve the system anti-interference ability and weaken the chattering,then,this paper bring nonlinear disturbance observer into global robust finite-time tracking control method.The nonlinear disturbance observer can give an effectively observation of the system interference so that the system interference can be compensated in output and the control effect will be promoted.And then,this paper go further to design a global robust finite-time tracking control method base on time delay estimation method.The time delay estimation method can estimate the system's dynamic model and the disturbance.It need no complex dynamics operation and can solve the problem of control information delay skillfully.Flexible joint space robot control is required for both the desired trajectory tracking and the suppression of system's elastic vibration.This paper use the singular perturbation theory to decompose the system into a slow subsystem and a fast subsystem.And for the fast subsystem,this paper designed a speed differential feedback controller;for the slow subsystem,this paper designed two finite-time controller including the global robust finite-time tracking control method and the global robust finite-time tracking control method base on time delay estimation method.The fast subsystem controller is using to suppress system's elastic vibration,and the slow subsystem controller is using for the trajectory tracking.Using the finite-time Lyapunov function method to prove the global finite-time stability of all controllers in this paper.The control effects of control methods for Space robots designed in this paper are all verified by means of numerical simulation.