Modeling And Motion Control Of A 4-Wheel Independently Driven Mobile Robot

With the development of science and technology,wheel mobile robots are more and more widely used in industrial manufacturing,medical&services,field work,space exploration and other fields.The four-wheel skid-steered mobile robot has been paid more attention due to its simple structure,economy and applicability.As a result of the mechanical structure,such robots are steered with different wheel speeds and skiding during steering.In fact,the wheels are inevitably skiding because of environmental factors.Therefore,the study of wheel slip/non-slip and the friction is of great significance.Due to dif-ferences in structure and power,there are many differences in the kinematics and dy-namics modeling and control strategy of different robots.Firstly,based on a four-wheel independently industrial inspection robot,a three-dimensional(3D)kinematic and 3D dynamic model was established,and the corresponding parameter identification was carried out.In dynamic modeling,consid-ering the longitudinal/lateral slip/non-slip states of the four wheels,the system was modeled by Newtonian mechanics and Lagrangian equations respectively.The ad-vantage of the former is that it can analyze both the motion state and the force state of the system.The advantage of the latter is that it can analyze the motion state more simply without the internal forces.Secondly,based on the Newtonian dynamics model,force and motion state of the robot under the plane condition of wheel slip/non-slip were analyzed via Matlab/Simulink.The results explained the effect of parameters,torque,friction and ground environment on the system.These provided theoretical guidance for the practical ap-plication.Based on the Lagrangian model and Dugoff friction model,the motion state of the robot were simulated and compared with the former.Finally,designed PID control algorithm for the robot.The control experiments showed that,the traditional four-wheel independently control strategy could result in some problems such as shaking and internal loss.The improved unified control strat-egy could effectively improve the stability and reduce the energy loss.