Isfahan University of Medical Sciences

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Design and Fabrication of a Passive Upper Limb Rehabilitation Robot With Adjustable Automatic Balance Based on Variable Mass of End-Effector Publisher



Eslami M1 ; Mokhtarian A1 ; Pirmoradian M1 ; Seifzadeh A2 ; Rafiaei M3
Authors
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Authors Affiliations
  1. 1. Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr, Isfahan, Iran
  2. 2. Department of Biomedical Engineering, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr, Isfahan, Iran
  3. 3. School of Rehabilitation, Isfahan University of Medical Sciences, Isfahan, Iran

Source: Journal of the Brazilian Society of Mechanical Sciences and Engineering Published:2020


Abstract

The purpose of this work is to design and fabricate a balanced passive robotic arm with the capability of applying variable mass to the end-effector in order to upper limb rehabilitation. To achieve this purpose, the first step is associated with establishing a robot structural design in the CAD environment. The next step is focused on developing the kinematic model based on the degrees of freedom and joint range of motion of the lower legs. Thereafter, the potential energy functions are determined for the springs and weight of components applied in the mechanism. The genetic algorithm is employed as a proper optimization program to extract the system design parameters, including the spring stiffness coefficients and their placement positions within the system. A prototype is fabricated for a balanced robot, and the end-effector mass variations are utilized to develop an adjustable balance capability. To create balance in the system, several items are designed, consisting of a control panel, two electric motors, and an electronic processor. This situation provides an equivalent force equal to the weight of selected mass from the end-effector to the user’s hand. (It is done by a reverse process.) The actual mass required for robot balance is compared to the mass defined in the simulation environment. The evaluation results indicate that it is possible to create an optimized balance by using the simulation outputs. © 2020, The Brazilian Society of Mechanical Sciences and Engineering.