Operability evaluation of manual operation control for force-sensorless cart

In large-scale factories and warehouses, power-assisted carts are effective in transporting cargo to reduce the burden on workers. Herein, we developed a force-sensorless power-assisted cart system that can detect the operating force applied by the operator without using a force sensor and control the power-assisted drive. In this system, the operator directly grasps and operates the body of the cart, and the applied force is estimated from the cart body sway caused by the operation. The transport cart is controlled based on the estimated hand force. In such closed-loop systems formed by humans and machines, mechanical interactions affect the operability of the equipment. In this study, we experimentally verified the power-assisted manual operability of the proposed force-sensorless power-assisted transport cart. We examined the accuracy of the path tracking in manual operation experiments with 20 subjects and analyzed the results of the subjective evaluation. Based on the experimental results, the influence of the control parameters on operability was considered, and design guidelines were presented.