Coordinated Control For Trajectory Tracking Of Lunar Rover

China has carried out its first plan of lunar exploration Chang E Project since March 1st ,2003.This project is carried out through three stages. Nowadays the importance of exploring lunar is greater than that in Apollo Age, and the exploring has great significance in the scientific, economic, political and military fields.The research of Lunar rover is in the need of the development of lunar exploration. As the tool to explore the Moon , Lunar rover is an important component of the project. Lunar rover is a robot combined with remote control and autonomous navigation. As a pioneer landing on the Moon, it can proceed long-term practical exploration in place of the astronaut and can bring back experimental samples that can be analyzed by researchers. The deve1opment of Lunar rover is a com1p1ex systematic project involving many techniques, such as Machine design, computer science, electronics, communication, material, automatic control and so on. The driving system, as an important constituent of Lunar rover's design, has some different patterns in the world, such as wheeled rover, legged rover, wheeled-legged rover and pedrail rover, and the wheeled Lunar rover is the most popular one.firstly; In the process of rover moving , it needs the fusion of environmental information which is obtained by kinds of sensors equipped on the rover to plan a reasonable path autonomously, and then tracks the path. The path also can be given through operator on the Earth. Lunar rover controller must be designed in any case.The paper is organized as follows:1. Kinematics model of lunar rover, identification the model of the drive machine system model building.2. Kinematic analysis of lunar rover and control method simulation3. Design of the optimal tracking controller for mobile robot.4. Test the optimal control by experiment and simulation.First part, we build a simple kinematics model according to the lunar rover's structure features and relation between the lunar rover and the path. Static feature and dynamic feature of driving system is analyzed. Choose adverse M sequence as system identification'input signals through analyzing the static state characteristic of vehicle's steering system. The choice principle, including the biggest operating frequency, clock period, sequence signal period, and signal peak-to-peak value, is expounded. It is show that adverse M sequence is better than M sequence by theoretical analysis and experiment test. Then the vehicles steering system mathematical model is obtained by using least squares method and system identification. The simulation experiment contrast result indicates that the mathematical model can reflect the steering system performance well, which makes the better foundation for controller design of lunar rover. Finally, the dynamic equation for the vehicle steering system by system identification experiment is obtained.The suspension is the important component of the lunar rover locomotion system. it has the direct and indirect influences to smoothness and stability of the locomotion system. The design and analysis of the lunar rover locomotion system is extremely important. It is useful to improve the lunar rover locomotion system. At present, the analysis on the lunar rover is only about kinematics, statics and dynamics, and the mechanism analysis on the lunar rover is little. This article establishes the statics equations and moving simulates of lunar rover with any circumstances on the horizon. using optimal controller for trajectory tracking control by analysing the result of simulationIn the optimal controller design, state space model of the system is founded using lunar rover's kinematics model and driving system transfer function obtained before. The analysis has been done to controllability, observability and stability of system. Analysis results show that the system open cycle is not steady. Yet the system is controllable and observable, so it may become closed loop steady by means of the pole configuration. Because it is the linear time invariant system ( LTI ),the paper choose the linear quadratic form optimal controller design scheme in the contemporary control theory by applying the modern optimal control theory. By means of analysis to step response diagram and poles diagram of the closed loop system, the matrixes Q and R that represent the weight of control process and control expense are fixed reasonable. And then obtain the optimal state feedback array K, and finish design of optimal controller of Lunar rover. Simulation and experimental results show that the designed controller can realize accurate and stable navigation control and it has the well steady-state characteristic and adaptability to the changes of speed. At the same time, it also validates the above mathematical model of the control system.