Dynamic modeling and sliding mode control of a wheeled mobile robot assuming lateral and longitudinal slip of wheels

Abstract

In this article, the dynamic model of a wheeled mobile robot(WMR) is derived by assuming the longitudinal and lateral slip of the wheels. The resulting equations are used to control the robot in the specified trajectory and also between the two specified points. Given that increasing the number of states due to the consideration of longitudinal and lateral slip increases computational volume and complexity of robot control, in this paper, non-holonomic mobile base constraints under wheel slip conditions, without changes in the states of the ideal system is expressed. Due to the uncertainties in the studied system, the sliding mode controller(SMC) with respect to the uncertainty-resistant structure is used to control the robot and the stability of the system is guaranteed by Lyapunov method. To control the robot, defining proper outputs of the system is very important; so by defining appropriate output, the robot is driven in the desired direction. The results show that the sliding mode controller, despite the slip, can track the desired trajectory with 0.05 nm torque increase compared to the non-slip mode. Also, the point-to-point error of the robot is an acceptable value of 2.9 *10−4.