Modelling muscle spindle dynamics for a proprioceptive prosthesis

Muscle spindles are found throughout our skeletal muscle tissue and continuously provide us with a sense of our limbs position and motion (proprioception). This paper advances a model for generating artificial muscle spindle signals for a prosthetic limb, with the aim of one day providing amputees with a sense of feeling in their artificial limb. By utilising the Opensim biomechanical modelling package the relationship between a joints angle and the length of surrounding muscles is estimated for a prosthetic limb. This is then applied to the established Mileusnic model to determine the associated muscle spindle firing pattern. This complete system model is then reduced to allow for a computationally efficient hardware implementation. This reduction is achieved with minimal impact on accuracy by selecting key monoarticular muscles and fitting equations to relate joint angle to muscle length. Parameter values fitting the Mileusnic model to human spindles are then proposed and validated against previously published human neural recordings. Finally, a model for fusimotor signals is also proposed based on data previously recorded from reduced animal experiments

Design and Exploration of Feedforward Haptic Feedback in Anthropomorphically-Driven Prostheses

Here, we present a wearable, anthropomorphically-driven prosthesis with a built-in haptic feedback system. The device was designed and built to accommodate specific design parameters. Two control schemes were proposed and compared in a user study with N=6 able-bodied participants performing the Box and Blocks test. The first control scheme was designed to provide an intuitive, human-like actuation and relaxation of the hand, while the other controller was designed to reduce fatigue from sustaining EMG signals. Participants performed significantly better with lower fatigue levels while using the intuitive controller as opposed to the second controller. In addition, task performance with both controllers was better than reported performance with standard myoelectric prostheses. In addition, a second experiment compared the unilateral manual dexterity of N=3 able-bodied participants under three distinct conditions: vibration haptic feedback, skin stretch haptic feedback, and no haptic feedback. These findings suggest that there is utility in wearable anthropomorphically-driven prostheses, and provide support for future studies aimed at exploring anthropomorphically-driven prostheses