Evaluation of Optimal Vibrotactile Feedback for Force-Controlled Upper Limb Myoelectric Prostheses

Abstract

The main goal of this study is to evaluate how to optimally select the best vibrotactile pattern to be used in a closed loop control of upper limb myoelectric prostheses as a feedback of the exerted force. To that end, we assessed both the selection of actuation patterns and the effects of the selection of frequency and amplitude parameters to discriminate between different feedback levels. A single vibrotactile actuator has been used to deliver the vibrations to subjects participating in the experiments. The results show no difference between pattern shapes in terms of feedback perception. Similarly, changes in amplitude level do not reflect significant improvement compared to changes in frequency. However, decreasing the number of feedback levels increases the accuracy of feedback perception and subject-specific variations are high for particular participants, showing that a fine-tuning of the parameters is necessary in a real-time application to upper limb prosthetics. In future works, the effects of training, location, and number of actuators will be assessed. This optimized selection will be tested in a real-time proportional myocontrol of a prosthetic hand.

The Effects of vibrotactile stimulation of the upper extremity on sensation and perception

“…Our study focuses on the effects of changing the voltage parameter of ERM motors when the stimulation is applied on the shoulder, upper arm, lower arm, and index finger. Other studies have focused on understanding the effect of the stimulation pattern on controlling an upper limb prosthetic [6]. They have found that the stimulation pattern had no significant effect on sensation intensity.…”

Assistance Robotics and Biosensors 2019

“…Other issues that affect classification accuracy are evaluated in [2,3]. An adaptive classification model based on directional forgetting is proposed in [2].…”

“…Another key factor in myoelectric control is the introduction of an adequate force feedback for the prosthesis. In [3], vibrotactile actuators are used to assess the optimal force feedback patterns delivered to the user. This study reflects that changes in amplitude and frequency level do not show significant differences in the discrimination of vibration patterns.…”

Preliminary Evaluation of the Effect of Mechanotactile Feedback Location on Myoelectric Prosthesis Performance Using a Sensorized Prosthetic Hand

“…The measured grip force can be transferred to a prosthesis user’s residual limb, closing the loop during grasp control. Many different surface-mounted methods to translate the measured grip force back to the user have been investigated, including mechanotactile, vibrotactile, and electrotactile [ 8 , 9 , 10 , 11 ]. Researchers have observed promising results indicating improved prosthesis performance and embodiment when using these non-invasive feedback methods [ 12 ].…”