Understanding the Utility of State-Based Haptic Feedback in Tendon-Driven Anthropomorphic Prostheses

Haptic feedback has demonstrated utility in traditional prosthetic devices, however, it is unclear to what extent haptic feedback improves functionality in an anthropomorphic agonist/antagonist tendon-actuated design. We investigate the impact of state-based haptic feedback in an agonist/antagonist tendon-driven anthropomorphic prosthesis by proportionally mapping haptic sensations of the tension in the tendons during actuation. N =24 participants without limb loss were recruited to perform a grasp and transfer task using a mock prosthesis across three conditions: no haptic feedback, skin stretch feedback, and vibrotactile feedback. We hypothesized that haptic feedback of tendon tension would improve task performance and that skin-stretch feedback would outperform the vibrotactile condition due to the modality-matched similarities of tension and stretch. Results highlight that vibrotactile feedback resulted in significantly more object transfers than skin stretch feedback or no feedback. However, skin stretch feedback had a significantly higher transfer efficiency than vibrotactile feedback, demonstrating that different haptic modalities uniquely affect task performance. This study is the first to demonstrate that feedback of tendon tension in a tendon-driven prosthesis has significant utility and improves task performance establishing a need for further exploration of haptic integration in tendon-actuated systems.