Research On Measurement Control System And Creeping Control Of Wheel-step Mobile Robot

As humans continue to explore the planet,various complex terrains such as sand dunes and craters will also become important detection targets,which poses a huge challenge to the mobile performance of planet detection robots.Wheel-step mobile robots generally adopt active suspension or multi-degree-of-freedom wheel-leg compound mechanical structure,which can achieve large-angle climbing and collapse through creeping.Therefore,It has strong multi-terrain adaptability and mobility,and is widely used in planetary exploration.However,the special structure of the wheel-step robot and the more freedom of the joints increase the difficulty of the robot's creeping control.Therefore,the study of motion planning and coordinated control of each joint to achieve the desired creeping motion is of important role and significance.First,the active suspension structure and joint constraints of the wheel-step robot are analyzed,and the rolling slip phenomenon of the wheels during the robot's creeping process is studied.The D-H method is used to establish the robot kinematics relationship considering the rolling slip of the wheels.In order to prevent the velocity and acceleration changes during the robot's creeping process,the quintic polynomial is used to plan the motion trajectory of the suspension main rocker arm in the robot joint space.In order to improve the trajectory tracking accuracy and robustness of the controller,a sliding mode controller based on linear extended state observer is designed,and the stability of the closed-loop control system is proved by using Lyapunov stability criterion.Then,aiming at the coordination between driving wheel and braking wheel in the process of robot creep,by analyzing the motion state of braking wheel,a wheel coordination control strategy based on fuzzy logic method and braking wheel state is proposed to adjust the slip rate of driving wheel in real time according to the braking wheel state.In order to realize the real-time control of the driving wheel,the driving wheel velocity control algorithm based on the linear velocity constraint of the main rocker arm and the driving wheel slip rate control algorithm based on ADRC are designed for different terrain.The ADAMS-Simulink joint simulation platform is used to verify the effectiveness of the control strategy and algorithm.Finally,from the perspectives of structure,modularity,scalability and interactivity,a hierarchical and distributed control scheme of the robot measurement and control system was designed.A robot motion control and vision processing hardware platform based on Beckhoff industrial computer,GPU embedded industrial computer and Ether CAT bus is built.Combined with the measurement and control system hardware,a modular and expandable software control platform has been developed to realize multi-level and flexible control of the robot.The physical experiment of the robot is carried out to verify the reliability of the robot measurement and control system and the effectiveness of the control algorithm.