Tweelie: Tactile Wheel-Shaped Sensor for Force Reconstruction and Localization Over Curved Spherical Surface

This letter introduces Tweelie: a tactile wheel-shaped sensor with soft elastomer skin based on barometric pressure transducers. Tweelie enables high impact force reconstruction and localization over a curved spherical surface. Multiple contacts occurring simultaneously can be detected and inferred over a 6457 $\text{mm}^{2}$ surface. Based on the spatial distribution of 48 micro-electromechanical system (MEMS) sensors along a cylindrical surface, a graph is constructed to infer the contact state. The 3-D force localization is done by mapping the pressure readings onto an appropriate pressure distribution based on the shape of the Tweelie sensor; the 3-D force is obtained by integrating this distribution. Results show a localization error of 2$^{\circ }$ and regression error of less than 1 N for a single contact on rigid surface, enabling direct force localization and reconstruction for locomotion and other tactile applications.