Evaluation of Power-Assisted Cart Based on Inherently Safe Control✶

The power-assisted cart under development by the authors assumes a state in which the load is well-balanced with the restoring force of the coil spring as the basic state. If the basic state is broken, the cart moves by rotating the motor so as to reduce the angular displacement of the spring caused by the human operating force. In the previous report, confirmation of forward and stop operations based on the basic principle was reported in a laboratory experiment with a prototype. However, it turned out that there was a problem with the backward movement. In this paper, modifications were made to solve the problematic behavior, and it was evaluated outdoors. First, improvements such as motor changes were made. Then, the effectiveness of the improved cart is demonstrated by outdoor experiments in forward and backward motions and response to inclination angle change.