SqueezeBlock: Using Virtual Springs in Mobile Devices for Eyes-free Interaction

Sidhant Gupta, Tim Campbell, Jeffrey R. Hightower, Shwetak Patel


Haptic feedback provides an additional interaction channel when auditory and visual feedback may not be appropriate. We present a novel haptic feedback system that changes its elasticity to convey information for eyes-free interaction. SqueezeBlock is an electro-mechanical system that can realize a virtual spring having a programmatically controlled spring constant. It also allows for additional haptic modalities by altering the Hooke's Law linear-elastic force- displacement equation, such as non-linear springs, size changes, and spring length (range of motion) variations. This ability to program arbitrarily spring constants also allows for "click" and button-like feedback. We present several potential applications along with results from a study showing how well participants can distinguish between several levels of stiffness, size, and range of motion. We conclude with implications for interaction design.