Comparison of myo-electrical control methods: From muscle energy consumption to mechanical speed output

Abstract

In this study, an answer was sought to the question of how the person's muscle energy consumption is related to the prosthesis average speed outputs obtained through a comparison of the three control methods normally used in commercial prosthetics. Data sets for the sEMG (Surface Electromyography) were generated using commercial muscle tester for different contraction levels of wrist extension motion. These signals were then conditioned to get valuable information for moving the motor using comparable control methods. A customized experimental setup was established for the comparison of these control methods.For comparison purposes, the desired response from the prosthetic hand was considered as the ability to vary the speed constantly and uniformly from a minimum (zero) to a maximum value. Each sEMG signal was applied to the controllers, and the controller outputs were applied to the prosthetic hand. Measured prosthetic hand speeds were compared to the desired motion. To do this, parameters such as the error from the desired speed, total energy transferred to the motor of the prosthesis, and average speed were compared.The results indicate that the three control methods map the same sEMG energies to a different range of control signal energies and consequently, to different speed ranges. It has been shown that no control method alone can cover the all-speed range. This study suggests that new control methods (such as hybrid control methods) should be developed that better cover all speed ranges.