Design and Analysis of High-Resolution Electrostatic Adhesive Brakes towards Static Refreshable 2.5D Tactile Shape Display

Tactile displays are haptic devices capable of rendering shape and texture information. Unsolved challenges in building tactile shape displays include their traditionally large form factors, low spatial resolution, and high costs. Using electrostatic adhesion to individually brake each pin and a single platform for global actuation, we developed a prototype static refreshable tactile shape display with high spatial resolution (1.7 mm pitch, 0.8 mm pin width; 4 mm pitch, 1.6 mm pin width), high resistance force (76.3 gf static-loading force per pin for 1.6 mm width) and low cost (0.11 USD per pin for raw material). We present an analytical model of our electroadhesive brake mechanism and evaluate its maximum contact force and robustness in various conditions. To demonstrate the mechanism's potential, we built a static tactile shape display prototype with a 4\times 2 array of pins controlled using electroadhesive brakes. To further increase maximsum contact force allowed by our device, we develop and evaluate a global mechanical clutch which can be engaged during user interaction. A user study is carried out to compare our static tactile shape display's performance with printed 2.5D tactile graphics in a shape recognition task, and comparable shape recognition rates and response times are observed.