Abstract
A tactile sensor for robotic applications has been developed in this study, based on the functionality mechanoreceptors in the glabrous skin of the human hand. Four strain gauges and a single polyvinylidene fluoride (PVDF) film were used to mimic the slow and fast adapting biological receptors respectively. These were embedded in a silicone elastomer with a square protrusion which emulated the role of epidermal ridges on the skin, localizing the applied force onto receptive field of the sensor elements. Strain gauges were orientated to allow the sensor to identify the tri-axial components of an applied force. Multiple linear regression with cross-interaction terms was used to estimate the components of force, with mean errors of less than 15% for each force component in the prototype unit. The PVDF acted as an event detector for determining sensor contact as well as detecting transient changes in applied load. Strain gauge and PVDF experimental data qualitatively matched finite element computer simulation of the unit sensor. A first-generation miniaturised 2 x 2 tactile array was successfully fabricated as a more responsive device, with custom strain gauges exhibiting higher sensitivity compared to the commercial gauges used in the prototype. The sensitivity ranged from 1.1 to 2.9 VN-1 within a load operating range of 0 2.2 N. This biomimetic tactile sensor developed in this study is potentially useful in a range of robotic hand applications, including detection of contact, slippage of handled objects, as well as classifying the texture of handled materials