Force & torque feedback vs force only feedback

Providing force and torque feedback in every degree of freedom of a haptic device can be complex and costly, often prohibitively so. Consequently, devices that reduce the number of actuators such as SensAble´s PHANTOM Omni, a 6-degree-of-freedom (DOF) positioning, 3-degree-of-freedom force feedback haptic device, have gained popularity. While these devices have been widely accepted, no previous study has examined how performance with force feedback alone differs from performance with force and torque feedback for a 6-DOF positioning device. Results from this user study show that for simple tasks like drawing and tracing, performance with force feedback alone can approximate the performance with force and torque feedback. Similarly, torque feedback alone is sufficient to minimize contact forces, but is disconcerting to users.