Compliant Ultrasound Proximity Sensor for the Safe Operation of Human Friendly Robots Integrated with Tactile Sensing Capability

The robot proximity and tactile sensors can be categorized into two groups: grip sensors and safety sensors. They have different performance requirements. The safety sensor should have long proximity range and fast response in order to secure enough response time before colliding with ambient objects. As for the tactile sensing function, the safety sensor need to be fast and compliant to mitigate the impact from a collision. In order to meet these requirements, we proposed and demonstrated a compliant integrated safety sensor suitable to human-friendly robots. An ultrasonic proximity sensor and a piezoelectric tactile sensor made of PVDF films have been integrated in a compliant PDMS structure. The implemented sensor demonstrated the maximum proximity range of 35 cm. The directional tolerance for 30 cm detection range was about +/- 15 degrees from the normal axis. The integrated PVDF tactile sensor was able to detect various impacts of up to 20 N in a controlled experimental setup.