Striving To Be Near Normal

Soldiers returning from the battlefields whether from Iraq, Afghanistan, or some other distant place are confronted with a myriad of emotional and physical issues as they slowly attempt to adjust to civilian life again. It’s difficult enough for those who luckily were not physically injured, but for those who lost an arm or leg or worse, the road to some sense of normalcy truly can be very long and hard indeed. These individuals have to accept a life much different from what they had before they were injured.

Not surprising, there are some pretty exceptional prostheses coming on the market to help soldiers and civilians alike deal with the loss of a limb. But these new prostheses are much different than yesterday’s artificial hand with its somewhat unnatural finger movements and grasping actions that did not provide any tactile feedback. What they have now has much more capability including the sense of touch.

Sponsored by the Defense Advanced Research Projects Agency (DARPA), led by the Applied Physics Lab at Johns Hopkins University, and supported by Kinea Design, a team of researchers is working on a prosthesis that will have the functionality of a natural hand and arm. As noted in a recent Kinea Design press release, the prosthesis will have more than 80 sensors and allow the hand to move in as many as 13 different axes. Amputees will experience a more natural environment where limb movements are more intuitive because they are driven by electromyography electrodes.

Kinea Design has developed a tactile fingertip sensor that enables amputees to feel the texture of different substances, to sense the temperature of a product, and to ascertain how much pressure to apply for a given situation. The sensor also provides an indication of friction when the finger is moving over a surface, for example.

The company faced a number of challenges in designing a power source for the artificial hand. Two major requirements were the size and weight of the supply since it had to be integrated into the forearm and it had to be extremely energy efficient. The company developed a supply weighing in at under two pounds that, according to the website, “couples artificial tendons actuating 15 hand joints to a single electromagnetic motor via infinitely variable rolling-contact transmissions…. The 15 infinitely variable transmissions draw power as needed for their respective hand joint from a common shaft driven by a single motor. This architecture proved more lightweight and more power efficient than using 15 motors paired to 15 fixed-ratio drivetrains.”

Because of the cowardly tactics of the enemy our soldiers face on a daily basis, more and more are returning home with the loss of a limb or worse. Providing rehabilitation with these highly interactive and intuitive prostheses hopefully will provide them with some degree of normalcy as they return to civilian life.

Paul Milo
Editorial Director
[email protected]