Parameter Identification and Control of a Ball Balancing Robot

The ballbot is a dynamically stabilizable mobile robot that can balance on a ball, which is suited to maneuver and interact in narrow and crowded environments. The ballbot system is a nonlinear unstable system with five degrees of freedom; moreover, it forms an underactuated system with nonholonomic dynamic constraints, thus, it is a rich and challenging control problem. In this paper, we consider a ballbot robot we have recently designed and fabricated. To increase modularity and to provide smooth behavior of the robot, the closed-loop system consists of two level controllers. A high-level controller computes the required commands to balance the robot, which are in the form of reference speeds of a low-level controller for the actuators. To obtain a realistic dynamical model for designing the high-level controller, a practical procedure for parameter identification is proposed. The proposed control approach is implemented on the hardware, where, several experiments are conducted to demonstrate its robustness and to validate the quality of the identified model.