Modeling and control system design of a ball segway

Abstract

In this research, ball Segway, a robot with three omnidirectional wheels balancing on a ball, is introduced. Translation while balancing is achieved by coordinating relative motions of the three omni-driving modules where each of them is composed of an omnidirectional wheel, a gear box and a smart motor. Kinematics and dynamics of the composed motion of the three omni-driving modules and the ball is decoupled into two orthogonal 2D motions and modeled with Lagrange equation. An embedded PC-based controller gets posture information of the ball segway with an AHRS sensor and gives commands to motion controllers of the three omni-driving modules based on the decoupled dynamics. Additional balancing control is provided with two sets of control moment gyro (CMG) pair where each pair gives recovering torques in frontal and sagittal directions, respectively. An Arduino mega board, four servo controllers and four motion controllers compose control system for the CMG modules.