ForceSight: Non-Contact Force Sensing with Laser Speckle Imaging

Abstract

Force sensing has been a key enabling technology for a wide range of interfaces such as digitally enhanced body and world surfaces for touch interactions. Additionally, force often contains rich contextual information about user activities and can be used to enhance machine perception for improved user and environment awareness. To sense force, conventional approaches rely on contact sensors made of pressure-sensitive materials such as piezo films/discs or force-sensitive resistors. We present ForceSight, a non-contact force sensing approach using laser speckle imaging. Our key observation is that object surfaces deform in the presence of force. This deformation, though very minute, manifests as observable and discernible laser speckle shifts, which we leverage to sense the applied force. This non-contact force-sensing capability opens up new opportunities for rich interactions and can be used to power user-/environment-aware interfaces. We first built and verified the model of laser speckle shift with surface deformations. To investigate the feasibility of our approach, we conducted studies on metal, plastic, wood, along with a wide variety of materials. Additionally, we included supplementary tests to fully tease out the performance of our approach. Finally, we demonstrated the applicability of ForceSight with several demonstrative example applications.