Admittance Control Considering Torque Saturation for Power-assisted Two-wheeled Vehicles

In recent years, population aging in developed countries has become an increasing problem, and labor shortages in the transport industry have become an issue. Human-robot interaction (HRI) is expected to address this problem. Admittance control, an HRI method, is a useful control technique for reducing the burden on humans. However, the vehicle may behave dangerously if the wheels or body collide with an obstacle, or if a sudden large force is applied by a human. This behavior is due to the windup caused by motor torque saturation and reduced tracking performance of the admittance controller. To address this problem, admittance control that considers torque saturation was developed. In this study, a power-assisted control system was constructed using admittance control. The usefulness of the proposed method for tracking performance degradation was demonstrated via numerical simulation. The root mean square errors (RMSE) of the error between the reference and response velocities were compared between the proposed method, the anti-windup method, and standard admittance control. It was confirmed that the RMSE of the proposed power-assisted system was the smallest and that a reduction of approximately 99% could be achieved compared to the standard admittance control-based power-assisted system.