Research On High Efficient Dynamics Of On-orbit Space Robots Mulitbody System

At present, with the development of the space science and technology, the space robots are becoming imperative to understand their distinctive dynamics. Flexible space robots, as well as large flexible space structures in general, have unveiled a new and challenging field of dynamics and control. The dynamics model of the space flexible robots is very complex. So the high O(n) recursive dynamic method and real time simulation to solve large space robots system become very important. The parameter identification is necessary for precise control because the payload changes the kinematics of the system together with the dynamics. Two methods are proposed under the condition that the robot is free to translate and rotate. The kinematics, recursive dynamics, real time simulation and parameter identification of space robot system have been discussed in this thesis.Based on the mathematical basic theory of the multibody system dynamics, the topological structure, screw theory and Spatial Operator Algebra were discussed. The dynamics equation of space robots multibody system was derived based on Lagrange equation. The model of the flexible body was discrete used finite element method, and the mass matrix and stiffness matrix were gained. The dynamic equation of flexible multibody system was gained.The recursive dynamics of the general multibody system, which contain rigid body and flexible body, was discussed. The topology of the general multibody system was described used Huston's Lower-body-array theory, then recursive dynamics was researched according to the feature (flexible or rigid) based on SOA theory.The hybrid recursive dynamics base on the spatial operator algebra theory and real time simulation of the generalized flexible multibody was presented in this paper. the generalized flexible multibody was described in according to the type of the joint (active or passive); then the generalized articulated inertia-matrix, the residual forces and the generalized acceleration and torque were computed through twice tip-to-base recursive and once base-to-tip recursive; at last the O(n) hybrid dynamic was gained. Next the real time solver for the large differential-algebra equation was studied based on the linear multi-step method in this paper. Simulations results show that the dynamic modeling and fast integration techniques proposed in this paper are very useful.With the parameter identification methods for inertial parameters of the base and unknown object handled by manipulators on a free-floating space robot was concerned in this paper. Firstly, kinematic model of robots based on spatial operator algebra theory was gained. Next, parameter identification of the base was studied based on the conservation principle of linear and angular momentum, then parameter identification of the unknown object handled by manipulators is considered based on the parameter of base. Al last the effect of the parameter of robots to parameter identification was considered.Numerical integration method based linear muti-step numerical method was researched. Various numerical methods for dynamics of multibody systems are discussed. A new method for solving the differential-algebra equation and differential equation are discussed. This method was proposed by professor Zhai-Wanming based on Newmark-βmethod. The correct value of the dynamics equation was gained by translates the differential-algebra equation or differential equation to algebra equation by constraint stabilization.This chapter has laid the foundation for software module programming. It has studied the multibody system mark dynamics programming. It uses the Mathematica software platform. And it is a visualization contact surface, so the user can easily describe the topology, the restraint information, and information acquisition of the multibody systems which is for simulation analysis. And it also gives the result like simulation run time, the SOA operator, the movement, the stress and so on with the form of the curve and the animation formal expression and so on.At last, engineering problems were simulated on computer according to the above theories.The feasibility of the parameter identification methods is demonstrated by a hardware experiment on the ground as well as numerical simulation.