A Reliable Low-Cost Foot Contact Sensor for Legged Robots

Abstract

In an unstructured environment, fast walking legged robots can easily damage itself or the crowd due to slips or missing desired contacts. Therefore, it is important to sense ground contacts for legged robots. This paper presents a low-cost, lightweight, simple and robust foot contact sensor designed for legged robots with point feet. First, the mechanical design of the foot is proposed. The foot detects contact as it presses against the ground through the deformation of a layer of polyurethane rubber, which allows the compressive displacement of the contact foot pad to trigger the enclosed sensor. This sensor is a binary contact sensor using pushbutton switches. The total weight of the foot contact sensor is 82g, and the cost of manufacturing one is less than $10 USD. Next, the effectiveness of the developed foot is confirmed through several experiments. The angle between the center axis of the foot and the ground is referred to as the contact angle in this paper. The foot contact sensor can reliably detect ground contact over contact angles between 30° to 150°. This prototype sensor can also withstand contact forces of over 80N for more than 10,000 steps.