Modeling and Velocity Control for a Novel Narrow Vehicle Based on Mobile Wheeled Inverted Pendulum

Traffic problems such as pollution and congestion are becoming more and more serious in urban areas. A potential solution to these problems is to develop narrow vehicles that occupy less space and have lower emissions. There has been increasing interest in underactuated mechanical systems, i.e., mobile wheeled inverted pendulum (MWIP) models, which are widely used in the field of autonomous robotics and intelligent narrow vehicles. A novel narrow vehicle based on an MWIP and a movable seat, called UW-Car, is investigated in this paper. The dynamic model of the underactuated vehicle system running on flat ground is derived by Lagrange's equation of motion. Based on the dynamic model and terminal sliding mode control method, two terminal sliding mode controllers are designed to control velocity and braking of the UW-Car. The first one is used to control the forward speed to a desired value while keeping the body upright and the seat on some fixed position. The second one is a switching sliding mode controller, composed of three terminal sliding mode controllers that quickly brakes the system according to an optimal braking scheme. All the control algorithms are tested in both Matlab simulation and a UW-Car experiment. The simulation and experimental results demonstrate the efficiency of the model and controllers.