Development of a New Mobility System "Tread-Walk" - Design of a Control Algorithm for Slope Movement-

In Japan, slopes hinder some older persons from moving around freely, particularly in rural areas. Even persons who are able to walk on flat ground might lose their breath or fall when moving up or down a slope. The present authors have developed a new mobility aid, called "Tread-Walk," that makes use of human gait movement for traveling over flat ground. In this paper, the Tread-Walk system is adapted to walk up and down slopes. Slope walking experiments are conducted to obtain the current load of the treadmill motor, which is measured as the kicking/braking force. The relationship between the pitch angle of the vehicle and floor reaction force is defined based on the obtained load current data. An algorithm that uses the pitch angle as a feedback element is then developed. The walking position does not change greatly on the slope, and steady walking was achieved. Furthermore, the system enables the user to walk smoothly up/down a slope ±7(deg) in an outdoor without stopping.