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. 2022 May 21;22(10):3892.
doi: 10.3390/s22103892.

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

Eric D Wells  1 , Ahmed W Shehata  2 , Michael R Dawson  2 , Jason P Carey  1 , Jacqueline S Hebert  2   3
Affiliations

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

Eric D Wells et al. Sensors (Basel). .

Abstract

A commonly cited reason for the high abandonment rate of myoelectric prostheses is a lack of grip force sensory feedback. Researchers have attempted to restore grip force sensory feedback by stimulating the residual limb's skin surface in response to the prosthetic hand's measured grip force. Recent work has focused on restoring natural feedback to the missing digits directly through invasive surgical procedures. However, the functional benefit of utilizing somatotopically matching feedback has not been evaluated. In this paper, we propose an experimental protocol centered on a fragile object grasp and lift task using a sensorized myoelectric prosthesis to evaluate sensory feedback techniques. We formalized a suite of outcome measures related to task success, timing, and strategy. A pilot study (n = 3) evaluating the effect of utilizing a somatotopically accurate feedback stimulation location in able-bodied participants was conducted to evaluate the feasibility of the standardized platform, and to inform future studies on the role of feedback stimulation location in prosthesis use. Large between-participant effect sizes were observed in all outcome measures, indicating that the feedback location likely plays a role in myoelectric prosthesis performance. The success rate decreased, and task timing and task focus metrics increased, when using somatotopically-matched feedback compared to non-somatotopically-matched feedback. These results were used to conduct a power analysis, revealing that a sample size of n = 8 would be sufficient to achieve significance in all outcome measures.

Keywords: capacitive; compliant; feedback; grip force; inexpensive; modality-matched; prosthesis; somatotopical; tactile sensor.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Modular simulated prosthesis adapted from [45].
Figure 2
Figure 2
Summary of MSP grip force sensor accuracy under various loading conditions adapted from [45].
Figure 3
Figure 3
Mechanotactile tactor components (1) servo casing, (2) rack gear mount, (3) M2.5 × 5 mm screws, (4) D47 servo motor, (5) pinion gear, (6) pinion gear mount, (7) rack gear, (8) rack gear plug, (9) washable foam.
Figure 4
Figure 4
(a) Mechanotactile tactors on forearm mounting system. (b) Mechanotactile tactors on fingertip mounting system.
Figure 5
Figure 5
(a) Isometric view of the 3D-printed sensorized prosthetic hand. (b) Cutaway view of linked bar mechanism. (1) Dynamixel MX-64AT, (2) rigid finger brace, (3) hand casing, (4) wrist adapter, (5) linked bar finger rotation point (6) dynamixel rotation point, (7) linked bar mechanism (8) fixed thumb rotation point (9) linked bar thumb rotation point.
Figure 6
Figure 6
Exploded and section views of a finger with a compliant sensor. (1) PLA finger, (2) compliant sensor, (3) SingleTact wire, (4) ADC board, (5) snap-fit lid.
Figure 7
Figure 7
(a) Fragile object. (b) Experimental setup.
Figure 8
Figure 8
Experimental protocol. (a) Block presentation order summary. (b) Block layout summary.
Figure 9
Figure 9
Outcome measure extraction (a) contact point, lift point, and release point (b) adjustments.
Figure 10
Figure 10
Within-participant results for (a) success rate, (b) maximum grasp, (c) completion time, (d) grasp time, (e) adjustments.
See this image and copyright information in PMC

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