Design of a closed loop controller for a two wheeled balancing transporter

This paper discusses the design of the control algorithm used to control a two-wheeled balancing transporter. The device is a drive and steer by wire device using closed loop feedback to provide both fore-aft stability as well as directional control. The controller consists of two parts, a closed loop pitch controller that maintains balance and governs the morion of the device forward and backward and a yaw or steering controller that governs the turn rate via differential wheel speed. The transporter is unique in that it is much smaller than the operator and it couples to motions of the entire body, rather than an arm or leg independently. An impedance model was adopted to account for the human in the loop, there by making the design problem tractable and relatively straightforward to implement.