*Rehabilitation Engineering Services, Lothian Primary Care Trust

Efficient prosthesis control is dependant on the user’s ability to control the desired movements of the prosthesis. Observed manifestations of jerk on a complete arm prosthesis can lead to difficulty in performing controlled movements, especially under load on gravity assisted downward movements. The application of so called soft start and soft stop routines for controlling the velocity profile of the prosthesis joint through its rotational movement can go some way to reducing this effect. It is proposed that an adaptive velocity control system can be applied to the same prosthesis under the same test conditions and reduce the discernible jerk considerably. This adaptive system monitors the change is angular velocity thus controlling the second and third derivatives of position. The implication of actively controlled angular velocity lends itself to minimize jerk, combined with reduced power consumption, and an increase in parts life and reliability. This control is applicable to all externally powered prosthetic limbs, regardless of user interface. Introduction to Jer