T. Walley Williams and the Evolution of Prostheses

T. Walley Williams stopped by M5 this past Friday, giving a talk on the Boston Digital Arm and its role in the evolution of prostheses. Williams, who is currently the Director of Product Development at Liberating Technologies, Inc., began working on the Boston Digital Arm in 1974 while at Liberty Mutual. He proved to be an engaging and animated speaker, encouraging thoughtful discussion with an audience of 40 M5 community members.

Williams explained that prostheses are constantly being innovated to be lighter, while also striving for the highest level of natural and intuitive control possible. Through the case study of the first patient fitted with the Boston Digital Arm, he illustrated the intense amount of medical, scientific, and engineering innovation needed to perfect the product not only in general, but also for each individual patient. After the patient underwent intensive occupational therapy, his pectoral muscle was separated into three bands. Then, targeted muscle reinnervation was performed; nerves from the amputated body part were integrated into the pectoral muscle. Contraction of the individual muscle bands then represented muscle commands of the missing limb, allowing control of a prosthesis using myoelectric pickups attached to a servo motor.

The journey of developing such innovative technology was not an easy one. Countless revisions were made on the product before it was ready to be fitted on an amputee patient. Williams explained that a lot of the development happened in his basement, and he even used bungee cords in some designs.

Williams also covered overlapping innovations and issues within the prosthetic community. Osseointegration, the attachment of a prosthesis directly to a bone, is an emerging technology with much promise. The concept is currently seen in wide application in dentistry. He also touched on the “interlocking community” of signal processing. With the technology available today, only one myoelectric signal is able to be processed at a time. The community hopes to reach the possibility for two or more signals to be processed at a time. With that, a higher level of intuitiveness is possible, allowing for actions like the simultaneous raising of an arm and gripping of a hand.

Williams provided ample demonstration of his product and others. The audience was quite captivated by the ability of the Digital Arm, especially given Williams demonstration of a more primitive example. He also passed around an example of a bebionic hand, a prosthetic hand with a high level of dexterity. Following the talk, Williams encouraged questions, even sticking around for a more intimate discussion with a few people.

He provided some practical advice for the young engineer. He explains that his “Eight Fold Method,” providing eight solutions to a given problem, has served him well; he has 29 ways to attach the Boston Digital Arm’s elbow. Williams hopes to continue his work into his 90s, arguing “Why would I do anything else if they pay me to have fun?”

Video from the event


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