Simultaneous and Proportional Control of Hand Prostheses with Multiple Degrees of Freedom: A New Method of Improving the Training Process

Kurzfassung

Limb loss heavily affects the quality of daily living. In case of upperlimb loss, activities of daily living (ADLs) become more troublesome, even more when considering fine manipulation. Aid can be provided by prostheses. However, control using muscle signals, e.g. electromyography (EMG), has not yet achieved a level that provides a satisfactorily natural, simultaneous and proportional type of control. By developing a new method called Linearly Enhanced Training (LET) procedure, we seek to advance the current methods of prosthetic hand control towards a more natural way. Over the course of three different experiments, we will first show the potential of the LET procedure, second investigate and compare two models that approximate the composition of the EMG signal of multi-finger motions and eventually perform a validation of one of said models in a goal-based experiment. We found that the parameters of the simpler of the two models show little variance across subjects and motions involving the same number of degrees of freedom (DoFs), here fingers. Based on this model, naive subjects are asked to perform single- and multi-finger motions of the thumb, index and little finger with different levels of intensity. In this goal-based experiment, the subjects achieved on average a 76.1% success rate (SR). In terms of SR, no significant difference between single- and multi-finger motions is evident. We see the lack of difference and the good SR of the LET procedure as a confirmation that the LET procedure is a promising technique to provide simultaneous and proportional control in the area of prosthetics.