DARPA Leads Revolution in Prosthetics

By Colonel Geoffrey Ling and Kent Pankratz

For Colonel Geoffrey Ling, the DARPA Program Manager who leads the program entering its fifth year, two main tasks remain. The first is for performers to gain regulatory approval to transition the arms for commercial sale. The second is for performers to initiate clinical trials of the implantable micro- electric arrays that will enable brain control of the prostheses. Colonel Ling views the program as keeping a pact – restoration to near-normal function – with the warriors that have made tremendous personal sacrifice for the nation.

DARPA has committed nearly $150 million to improve the entire upper limb prosthetic system, including sockets and control software. Two performing teams have produced two different prosthetic arm systems. DARPA contracted with one team to develop a “strapand- go” system that could be donned and controlled by the user with no additional surgery. The other team is developing implantable micro-electric arrays that will record and translate the user’s brain signals to control the prosthesis.

Both teams created virtual reality environments to assist prosthetists, engineers, and users to collaborate in development of the arm system. Users can visualize completing tasks while clinicians calibrate control software.

The virtual arm images move using the signals sent to the actual limb, allowing engineers to compare intended motions with actual arm movement.

More than 300 engineers, scientists, and medical professionals have contributed to the program, which also serves as a model of interagency collaboration. The Department of Veterans Affairs has conducted an optimization study using 26 volunteer subjects with all levels of upper limb amputation. Feedback from these subjects provided valuable insight into design of the final non-invasively controlled arm. Users performed more than 3,000 hours of daily living tasks, many of which are not possible with the limitations of current split-hook prostheses.

DARPA is expanding the user community for its Revolutionizing Prosthetics program to include patients with spinal cord injuries and victims of stroke and other neural disorders. By addressing the needs of these individuals, the addressable market increases along with the chance of attracting commercial partners. Goals for commercialization are 2011 for the non-invasively controlled arm and 2013 for the brain-controlled system.