Vibrating Slip Feedback for

Smart Prosthetic Hands

 

Advanced prosthetic hands use electrodes to detect muscle flexion to control the movement of the hand. These myoelectric prostheses enable more functionality than traditional prostheses that rely on cables connecting the gripper to the shoulder or other parts of the body, however, there is a lack of touch feedback that makes dextrous manipulation difficult. It is common for prosthesis users to grip objects too hard and break them or to grip too lightly and drop things. It is especially difficult for prosthesis users to manipulate objects while looking away or focusing on anything else.

 

We hypothesized that by applying a vibration to the upper arm that corresponds to object slip, we could enable users to respond more quickly and effectively and adjust grip force to prevent objects from falling. I designed and ran a virtual grasping study in which users interacted with a virtual object on a computer screen using a Phantom haptic device (for force feedback) and received vibrations to their upper arm from a C-2 Tactor.

 

We found that users had a much higher rate of object recovery when slip feedback was provided, especially when visual feedback was not available (the object was not shown slipping on the screen, similar to an actual prosthesis user looking away from their gripper). This study helped us understand the importance of slip feedback for human object manipulation. By including feedback similar to this in actual prosthetic hands, we could enable amputees to complete daily tasks with more ease.