Measuring Force Intensity and Direction with a Spatially Resolved Soft Sensor for Biomechanics and Robotic Haptic Capability

Possessing a sense of touch is fundamental for robots to operate outside controlled environments. Nevertheless, pressure and force-sensing technologies are still less mature than vision or proprioception solutions in commercial robots. In this study we present a novel spatially resolved force sensor that allows dynamic measurement of both the intensity and the direction of forces exerted on a custom-shaped surface. Originally designed for biomechanics of arboreal primates, this sensor meets several challenges in engineering robotic skin. Of importance, its ability to measure tangential forces would be instrumental for robotic hands to grasp deformable and unknown objects. Based on optical measurements of deformations, this array sensor presents a soft, biocompatible, weather resistant body, immune to electromagnetic interferences. Central to the cost-effectiveness of this solution is an architecture where a single image sensor handles hundreds of force measurement points simultaneously. We demonstrate the performance of this sensor in reconstructing normal and slantwise forces on a flat prototype adapted to forces under 3 N. Finally, we discuss the broad range of possible customizations and extensions for applications in biomechanics and robotics.