Research On Motion Control For Four-wheel Independently Drive Planetary Rover

Motion control is the key for lunar rover to accomplish deep space exploration task also is the reliable assurance for stable operation and reach the target point. We design a unique structure lunar rover to adapt rugged roads and establish kinematic model to simulate the movement performance. In order to have a good motion control performance in unknown terrain environment, combined fuzzy control and behavior control to research on autonomous behavior control. The main contents are as follows:Firstly, design a four-wheeled lunar rover and all wheels can driving and steering.The lunar rover using the rocker bogie structure, so the lunar rover has strong ground adaptability and driving capability. Build a distributed motor control system based on Vx Works System and CAN bus to improve information transmission real-time and reliable. Each motor as a node mount on the bus and all nodes independently to each other. The control system has good real-time performance and stable information transmission characteristics, which provides the basis for movement control and behavior control.Secondly, modeling analysis for the four-wheeled lunar rover. This kinematics model can deduces position and orientation of lunar rover, also can deduces in rugged terrains velocity relationship between rover body and wheels. The modeling analysis provide the basis for the research of traction control and behavior control. Using Solidworks and Open Inventor software complete the lunar rover kinematics simulation system realize fused the kinematic model with three-dimensional model. In order to realize tracking control of desired velocity and angular velocity, a forward velocity coordinated control which is based on the inverse kinematics has been proposed to control the speed and direction of each wheel. The proposed method is tested on the simulation platform and experimental results indicated the feasibility and efficiency of this method.Then, a fuzzy behavior system is proposed to control the motion of the system by combined fuzzy control and behavior control in order to improve the stability in unknown environment and ensure lunar rover safely run to the target point. Obstacle avoidance behavior and goal approaching behavior are analyzed and designed.Besides designed a behavior weight coefficient distributor to distribution child behaviors weight coefficient, which can effectively fuse the two basic behaviors in order to improve the stability of the operation. Experimental results indicated the feasibility and efficiency of this method.Lastly, the behavior-based obstacle avoidance strategy for lunar rover is transplanted. The experiments in unknown terrain environment achieved the desiredresults, proved the effectiveness of the algorithm further.