Development of an Optical Sensor Capable of Measuring Distance, Tilt, and Contact Force

Depth, proximity, and tactile sensors are often used in robotic object manipulation. The three types of sensors are combined to address each sensor limitation: Depth use is limited by blind spots and measurable range, proximity sensor is limited to millimetric distances, and the tactile sensor requires direct contact with the object. Here we present a novel sensor that can simultaneously measure millimetric distance and surface tilt, as well as contact force. We demonstrated the advantage of this novel sensor during a contact task. There, we implemented an admittance control and succeeded in achieving smooth transition from zero- to infinite-impedance contact condition and vice-versa. This novel sensor affords the realization of advanced interactions between robot and objects and contrary to previous approaches—limited by distance, blind spots, and impact force during initial contact—demonstrated good performance at all times with smooth and continuous measurements during contact.