The Design And Analysis Of Moving Simulator For Space Robotic Arm's Capture Experiment

The capture of visiting spacecraft is one of the important on-orbit tasks of the space robotic arm.In order to ensure that the robotic arm can complete these missions normally after launch and to test the capture capability of it,we should do a large number of experiments on the ground.As an important tool for spacecraft simulation,the air-bearing suspension simulator can simulate the hovering spacecraft's movement state.To complete the capture experiments cooperating with space robotic arm on the ground,we designed and developed a spacecraft simulation system with three degree of freedom based on air-bearing suspension.The movement of the simulator is controlled by the jet method.Considering the interference is complicated,the fuzzy adaptive PID control strategy is designed based on traditional PID.To verify the working performance of the simulation system and to test the effectiveness of the control strategy,a lot of ground experiments were done.The specific research content is as follows:The working principle and hardware design of the moving simulation system is introduced in first part.The three major parts of the hardware are presented in detail,and the composition and function of each part are described.Among them,the moving simulator is the key part for simulating the movement of spacecraft.It uses a monolithic granite air floating plate as a support mechanism,and uses an external gas source to provide zero-gravity simulation on the ground;servo motors and jet thrust devices are implemented as Mechanism for controlling the rotation of the adapter and driving the simulator movement.As a control center,the integrated control platform is the key part of connecting external measurement system and simulator.It generates control instructions by accepting the data of external measurement system,and uses network communications to exchange data with simulator.The external measurement system consists of a high-speed measurement camera array,and it can track the position and attitude information of the simulator with high accuracy.Next,a mathematical model related to simulator movement was established.By defining the coordinate system,the position and attitude of the simulator is described.On this basis,the dynamic model of the simulator is deduced.At the same time,various disturbances in the simulator motion control are analyzed.In order to improve the anti-jamming capability of the simulator,a fuzzy adaptive PID control strategy was designed and then designed the controller.On this basis,the simulation was performed by using MATLAB.By comparison with the traditional PID's simulation result,verified that the control strategy has stronger dynamic characteristics and anti-jamming capability.Based on the theoretical design and analysis,a moving simulation system was developed to carry out capture experiments.And under a variety of operating conditions,the traditional PID and fuzzy adaptive PID were used to control the movement of the simulator.Through the comparison and analysis of the experiment results,the effectiveness of the control strategy was further verified,and the performance of the system is evaluated.In addition,through the further analysis of the control error,the main factors which affecting the accuracy of the experiments are summarized,which will provide direction for subsequent improvement.