The programme charts the lows of Gravell's struggle to get to grips with walking on a temporary false leg, to his joy when he manages to master enough control over the artificiallimb to resume driving and regain his independence.
So even when their eyes are closed they can get a sense of whether an artificial arm is extended, or if there is resistance to a grasping motion, making the limb feel less detached and unnatural than an EMG device.