Design and Kinematic Analysis of Parallel Robot for Ankle Rehabilitation Muhammad Nazrin Shah Bin Shahrol Aman, and Shafriza Nisha Bin Basah School of Mechatronic Engineering, Universiti Malaysia Perlis (UniMAP), Pauh Putra Campus 02600, Arau, Perlis, Malaysia s101060713@studentmail.unimap.edu.my, shafriza@unimap.edu.my Keywords: Ankle rehabilitation, parallel robot, Pugh method, inverse kinematics Abstract. Ankle injury is one of the most common injuries in sports or domestic related accidents. This injury can usually be treated via a number of rehabilitation exercises. However, currently rehabilitation of ankle injury directly depends of physiotherapy session administered by experts; which is tedious and expensive in nature. In this paper, we proposed a concept based on parallel mechanism to assist patients undergoing ankle rehabilitation procedures. This is due to a number of advantages of parallel mechanism as compared to serial mechanism– higher payload-to-weight ratio, structure rigidity, accuracy and relatively simple solution. We reported our design process; including the concept generation and selection according to a number of relevant design parameters. After which, followed by embodiment design involving kinematic analysis of the proposed mechanism. The findings, in terms of conceptual design and kinematic analysis should be able to provide an insight for ankle rehabilitation based on suitable parallel mechanism. Introduction Generally, ankles injury is one of the most common sports injuries as the ankle joints is one of the most commonly used joints by humans and have tendency of injuries if the athletes are ‘overdo’ the movement [1]. Also in domestic environment there are some cases of ankle injuries such as accidents, crime and etc [2]. Statistically in 2007 ankle injury information obtained from 14 098 patients show 11 847 are ankle sprains related injury and this suggest ankle injury is the most common body site in 24 of 70 included sports [3]. Ankle injuries take a long time to recover depending on the condition of the injuries and if the condition is too severe the ankle would need 4 to 26 weeks to recover [1]. In traditional method of ankle rehabilitation, there are 4 types of ankle rehabilitation exercises which are passive, active, resistive exercises [4]. For these exercises, the patients are using simple tools for ankle recovery to treat ankle impairments such as elastic bonds or wobble boards. Only in recent years, researchers are able to develop more effective way of rehabilitation which is to improve the results of physiotherapy to develop more comfortable way for the patients and for the patients to recover from the injury quicker. There are some machines that already availabe to aid the patients to rehabilitate the injuries. However, the current type of technology is limited by high cost, low portability and complexity to design robotic rehabilitation machines [2]. Also, some of the tools only have single function each which can help ankle joint to rehabilitate in one direction only which is less effective [4]. The design of Rutgers ankle is a Stewart platform type haptic interface rehabilitation robot. This design uses 6 double acting pneumatic cylinders and controlled by on/off solenoid valves to actuate the movement of the parallel robot. It can move and supply forces and torques in 6 degrees of freedom (D.O.F) as required by ankle rehabilitation scenarios by G.Burdea, M.Girone and V.Popescu of Rutgers University [5]. The advantages of using pneumatic actuators are high power-to-weight ratio, cleanliness and ease of maintenance. F. Patane et al have designed an electrically actuated ankle rehabilitation which has 3 degrees of freedom. The robot consists of moving base connected to 3 fixed linear electrical actuators by 3 corresponding fixed length floating arms by means of spherical joint. The limitation of this robot is its inability to relocate its axes of rotation as suggested by Patane et.al so the original scheme of the robot should be redesigned to increase DOF number so that the robot can be more flexible [6]. Applied Mechanics and Materials Vols. 446-447 (2014) pp 1279-1284 Online available since 2013/Nov/08 at www.scientific.net © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.446-447.1279 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 175.140.28.111-15/12/13,00:31:36)