DSP technology may let amputees regain mobility and more control over their lives by using electronic limbs created at Liberating Technologies (Holliston, MA). The company has developed hardware and signal-processing software that produce realistic and useful movements in multi-axis electro-mechanical prostheses. In a video demonstration at the Texas Instruments Developer Conference in Dallas, TX, T. Walley Williams, Director, Product Development at Liberating Technologies, showed the range of motions available to amputees in a prototype prosthesis that employs from five to seven motors and weighs about three pounds.
The company’s Boston Digital Arm System harnesses myoelectric signals sent to muscles that remain after amputation, but that no longer control arm motions. These electrical signals provide control inputs to circuits based on a Texas Instruments DSP chip. Control algorithms within the chip control motions customized to the amputee’s needs. According to Liberating Technologies’ Williams, during customization of a patient’s prosthesis, much information goes back and forth between the DSP chip and a host PC used to fine-tune the algorithms. Williams also noted the prosthesis can accommodate people who have more or fewer available nerves for limb control. That type of customization requires only clicking on menus and cut-and-paste operations to change the Texas Instruments DSP code. “The tools make me many times more productive that I used to be,” said Williams. Mechanical-arm testing has taken place at the Rehabilitation Institute of Chicago and DARPA has provided research funds.