Pen-type sensor for surface roughness perception

Surface roughness is one of the most intractable physical properties and its sensing heavily depends on the application and the capability of the sensor. In this paper, a pen-type sensor is proposed for sensing surface roughness. The sensor with a rigid contact probe is able to measure 3D contact forces and the dynamic contact responses along the axial direction of the probe, which facilitate the roughness representation using parameters of roughness profile rather than complex, high level interpretation methods. Strain gauges and a force sensor are used for measuring contact forces and a PVDF sensor is used for the dynamic sensing. The sensor is a self-contained one, and it can transmit sensed data via Bluetooth to the host computer. As preliminary tests, experiments are performed on the measurement of the coefficient of friction and the response to dynamic stimuli of different surface patterns.