Model-Based Design of a Soft 3-D Haptic Shape Display

Haptic shape displays provide compelling touch interactions by allowing users to freely explore a rendered surface. However, these displays are currently limited to 2.5-D surfaces due to the space requirements of their actuation. Building on previous work in haptic jamming, we developed a novel, soft 3-D shape display. A fully 3-D display that a user can grasp and hold allows for improved interactions for applications such as medical palpation training and virtual reality experiences. The shape display is implemented as an inflatable silicone membrane with embedded particle jamming cells that change stiffness and soft pneumatic actuators that control the distance between points on the surface. The device was modeled as a mass-spring system, and this model is used to develop a control sequence for a device to match a target shape. Due to constraints in actuation imposed by the 3-D geometry of the device, we developed an automatic design algorithm for the display, so that a display can be custom-designed to reach a set of target shapes using a relatively small number of actuators.