Inexpensive and Portable System for Dexterous High-Density Myoelectric Control of Multiarticulate Prostheses
Multiarticulate bionic arms are now capable of mimicking the endogenous movements of the human hand. 3D-printing has reduced the cost of prosthetic hands themselves, but there is currently no low-cost alternative to dexterous electromyographic (EMG) control systems. To address this need, we developed an inexpensive (~675) and portable EMG control system by integrating low-cost microcontrollers with a six-channel surface EMG (sEMG) acquisition device. Using this low-cost control system, we quantify, in a pilot study, the performance of a common EMG-based control algorithm-the modified Kalman filter (MKF)-when computational resources and electrode count are limited. We also demonstrate the ability to provide proportional and independent control of various six-degree-of-freedom prosthetic hands in real-time using the MKF. We found no significant differences in the signal-to-noise ratio (SNR) of the low-cost control system and that of a high-end research-grade system (paired t-tests). We also found no significant difference in the Root Mean Squared Errors (RMSEs) of predicted hand movements for the low-cost control system and that of the research-grade system when using only six sEMG electrodes. We then demonstrate that the SNR of the low-cost control system is statistically no worse than 44% of the SNR of the research-grade system (equivalence tests). Likewise, we demonstrate that RMSEs were typically a few percent better than, and statistically not more than 6% worse than, RMSEs of a research-grade system. This held true even when controlling up to six degrees of freedom on a prosthetic hand. Despite minimal computational resources and only six sEMG electrodes, the system performs satisfactorily and highlights the practicality and efficiency of the modified Kalman filter for dexterous EMG-based control. Successful deployment of this low-cost control system constitutes an important step towards the commercialization and wide-spread availability of dexterous bionic hands.