Disturbance Analysis and Control for an Omnidirectional Wheeled Mobile Robot

The mobile robot with an orthogonal-wheel assembly has omnidirectional motion ability and simple kinematic model for controller design. However, two sliced spheres that switch upon movement are likely to cause disturbances that act on the wheeled motor robot (WMR)'s body. The purpose of the traditional control for a WMR is high joint control stiffness using odometry, which might worsen the trajectory tracking performance of the WMR with orthogonal-wheel assemblies. This is because the robot's vibration might cause wheel slippage. Thus, the real-time motion states of the WMR body must be obtained to enable the robot controller to suppress such vibration. This paper provides a method with which to estimate the velocities of the WMR using inner sensors. In our proposed method, the real-time velocities of the WMR are estimated using accelerometers and position-measurement sensors. The fused signal is fed into the WMR controller instead of into the odometry feedback signal. The experimental results demonstrate that the proposed method is effective.