Haptic feedback in upper limb prostheses

Development and evaluation of a pneumatic haptic device providing feedback for upper limb prostheses

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Abstract

Background Upper limb prostheses help people with an upper limb deficiency in performing activities of daily living. They can be divided into two categories; body-powered and externally powered prostheses. The advantage of body-powered prostheses is that they provide feedback to the user. The advantage of externally powered prostheses is the low operating force required to control the prosthesis. To reduce rejection rates of upper limb prostheses control, cosmetics and comfort should be improved. To improve control, a design was proposed integrating proprioceptive force feedback into an externally powered upper limb prosthesis with a haptic interface placed on the scapula. However, the cosmetics and comfort are to be improved. The goal of this study is to design a haptic force feedback system that meets the demands regarding comfort and cosmetics. Method Design requirements and mechanical requirements are set. A conceptual design was made using SolidWorks and a prototype was built. The proposed prototype was tested on a test bench to evaluate the overall system. It was analyzed whether the design met the pre-set requirements and the results were compared to other devices. Results The designed haptic device is made out of an anchoring system, pneumatic artificial muscle (PAM), and a distance sensor. The total weight of the system is 41푔 for the anchoring system and PAM, and 29푔 for the distance sensor. The dimensions are 50푥25푥120푚푚. The maximum pressure for the actuator is 3푏푎푟. The output forces reached are 87.41푁, 79.04푁, 100.00푁, 85.38푁, and 104.8푁 for actuators with an initial length of 80푚푚, 90푚푚, 100푚푚, 110푚푚, and 120푚푚 respectively. The designed distance sensor measures a distance up to 58푚푚, with an accuracy of ±1푚푚. Compared to other devices the developed overall system is lighter in weight and smaller in size. Furthermore, it is made out of flexible materials, allowing the device to bend along the curve of the shoulder. Conclusion This study presents a new design for a haptic interface to provide proprioceptive force feedback for an upper limb prosthesis. It is an improvement in cosmetics and comfort, while still meeting the mechanical requirements. Future research should be done with users of an upper limb prosthesis to evaluate the applicability.