Proximity and Contact Sensor by Combining Multiple ToF Sensors and Self-Capacitive Sensor

Abstract

Collaborative robots, which work in the same places with humans, have recently been attracting a lot of attention. Proximity and tactile sensors are among the vital devices for collaborative robots to work safely. In this study, we proposed a proximity and contact sensor for a collaborative robot by combining a multiple time-of-flight (ToF) sensor and a self-capacitive sensor. ToF sensors can detect distance at a non-contact range, and they have a long measurement range with respect to the sensor vertical direction (Z-axis). However, the detection accuracy and X-Y axis detection range of ToF sensors are reduced at close ranges. Self-capacitive sensors can detect objects before and on contact, and they have high sensitivity at close ranges. However, the detection range of their Z-axis is small, and it is difficult for them to detect distance. In this study, we aimed at expanding the measurement range and reducing the blind spot area of collaborative robot sensors using multiple ToF sensors with the larger electrodes of self-capacitive sensors. Using the prototype sensor, it was possible to obtain efficient distance measurements with a range of 0-400 mm. The prototype sensors were placed on a robot arm, and they were able to detect object positions at a proximity range in addition to human contact. Additionally, the robot arm was controlled using measurement data. We believe that the proposed sensor can be used as a proximity and contact sensor for collaborative robots.