3-DoF Wearable, Pneumatic Haptic Device to Deliver Normal, Shear, Vibration, and Torsion Feedback

Haptic devices worn on the forearm have the ability to provide communication while freeing the user's hands for manipulation tasks. We introduce a multi-modal haptic device with a rigid rotational housing and three soft fiber-constrained linear pneumatic actuators. Soft pneumatic actuators are used because of their compliance, light weight, and simplicity, while rigid components provide robust and precise control. The soft pneumatic actuators provide linear horizontal and vertical movements, and the rigid housing, affixed to a motor, provides rotational movement of the tactor. The device can produce normal, shear, vibration, and torsion skin deformation cues by combining the movement of the soft pneumatic actuators with the rotational housing. The tactor is able to provide a shear force of up to 0.47 N and a normal force of up to 1.3 N. To elucidate the physical design principle and the actuation strategy, the static force and displacement of the soft tactor are modeled as a function of material, design parameters, and pressure. The models were validated experimentally.