Trajectory Optimizing And Experiment Study Of Space Robot For Target Capturing

With the development of space exploration, space robotic systems are expected to play an increasingly important role in the future. One of the key technologies for application of space robot is the capturing technology. Because of the dynamic coupling between the robot and the spacecraft base, the motion of robot results in disturbance to the spacecraft base when capturing targets, results in communication failure between the spacecraft and ground. According to this problem, path optimizing for targets capturing of space robot is studied in this paper, different optimizing objectives and methods are proposed to suit the different base conditions of space robot, contrastive simulations and ground experiments are implemented combined with samples.Firstly, kinematics and dynamics math models of space robot are established, according to whether the base attitude is under controlling, the direct kinematics equations of both free-floating and free-flying space robot, the differential inverse kinematical equations based on generalized Jacobian matrix of free-floating space robot and the inverse dynamical equations of free-flying space robot are derived. The object studied in this paper is introduced, and according to the kinematical and dynamical parameters of the 6-dofs space robot, characteristics of space robot are analyzed.Secondly, the path optimizing is studied in this paper. Parameterized trajectory equations of space robot in joint and Cartesian space are proposed, different optimizing objectives according to the base conditions are proposed as: the attitude optimizing for free-floating space robot and moment optimizing for free-flying space robot. Genetic algorithm is chosen to obtain the optimized parameters, and methods of optimizing in joint space and Cartesian space are designed. Singularity flag is used in optimizing method in Cartesian space to make sure no singularity included in the optimized trajectory.Finally, a simulation program is established, combined with specific samples, simulation of attitude adjusting optimizing in joint space and non-disturbance to attitude optimizing in Cartesian space for free-floating space robot and simulation of moment disturbance optimizing both in joint space and Cartesian space for free-flying space robot are implemented, the results of simulation are analyzed by compare. Ground experiment system for free-floating space robot is established based on theory of relative movement, on which attitude optimizing for 3-dof space robot is implemented, the moment disturbance to the base of free-flying space robot is proved to be nearly equal to which of ground robot in this paper, according to this theory, ground experiment system of moment for free-flying space robot is established, on which moment disturbance experiments are implemented.By applying the methods introduced in this paper, for free-floating space robot, the optimized trajectory in joint space make it feasible to control both the joint angles and base attitudes to desired value, and the optimized trajectory in Cartesian space makes no attitude disturbance to the base while ends moving to desired position. For free-flying space robot, the optimized trajectory reduce the pressure on controlling he attitude of the spacecraft base.