Control of a Six Degree of Freedom Prosthetic Arm After Targeted Muscle Reinnervation Surgery

On subject's left side: (A) The 3-DOF prosthesis consisting of nonpowered locking shoulder, passive humeral rotator, powered elbow, powered wrist rotator, and powered hook terminal device; (B) The 6-DOF prosthesis consisting of powered shoulder, humeral rotator, elbow, wrist rotator, wrist flexor, and hand.

Marker configuration used in motion analysis. A total of 14 markers were used: 3 infrared reflective markers were placed on each rigid segment of the 6-function prosthesis: at the socket, the prosthetic upper-limb, the forearm, and the hand, and 2 additional markers were placed on the tip of thumb and index finger of the prosthetic hand for calculating the hand open and close motion.

Timed tasks: (A) cubbies, (B) cups, (C) Box and Blocks, and (D) clothespin relocation task.

Images of the subject reaching to his head to put on or take off a baseball cap.

Four plots indicating the simultaneous control of elbow flexion/extension and hand open and close. (A) Task: elbow flexion + hand opening, (B) Task: elbow extension + hand close, (C) Task: elbow flexion + hand close, (D) Task: elbow extension + hand opening. Both joints were controlled by electromyographic control signal activity over targeted muscle reinnervation muscles.

Frontal view of endpoint trajectory while the subject was performing circle drawing task. To remove any artifact from body movement impacting the graph, the point of reference is marker located on the shoulder (which was not actuated by the subject in this test).

Joint phase plot between elbow flexion/extension angle and shoulder flexion/extension angle while the subject was performing (A) arm reaching up task and then (B) arm retracting. Zero in the vertical axis for elbow flexion and extension denotes full elbow extension. Horizontal and vertical lines indicate a single DOF moving, whereas slope areas are the phases of coactivation or joint synergy (ie, 2 joints moving together). The red stars indicate the initial joint position.