Optimal 3D Kinematic Analysis for Human Lower Limb Rehabilitation Hachmia Faqihi 1 , Maarouf Saad 2 , Khalid Benjelloun 1 , Mohammed Benbrahim 3 and M. Nabil Kabbaj 3 1 LAII, Ecole Mohammadia d’Ingnieurs, Mohammed V University, Rabat, Morocco 2 Ecole de Technologie Suprieure, Montreal, Canada 3 LISTA, Faculty of Sciences, University of Fez, Morocco Keywords: Robotics, Rehabilitation, Inverse Kinematics, Human Leg, Trajectory Generation, Optimization, Minimum Jerk. Abstract: The majority of the kinematics analysis carried out on the human body are usually available only for use in the sagittal plane. Limited studies were interested in this analysis in all three planes (sagittal, transverse, and frontal) where motions of all joints occur. The aim of this paper is to develop a new optimal kinematic analysis of human lower limbs in three- dimensional space for a rehabilitation end. The proposed approach is focused on optimizing the manipulability and the human performance of the human leg, as being a physiologically constrained three-link arm. The ob- tained forward kinematic model leads to define the feasible workspace of the human leg in the considered configuration. Using an effective optimization-based human performance measure that incorporates a new objective function of musculoskeletal discomfort, the optimal inverse kinematic (IK) model is obtained. 1 INTRODUCTION Nowadays several neurologic injuries such as neuro- muscular diseases, spinal cord injury cerebellar dis- orders, stroke, or impaired functions of the member musculature lead to the joint disorders. Indeed, the lower limb is usually including chronic pain, atypical gait patterns, reduced range of motion (ROM), weak strength, and increased joint stiffness, as well as se- vere functional limitations, and thereby reducing pa- tient’s quality of life. To remedy these problems, we use the rehabili- tation process, based on physical therapy to restore patient’s strength, mobility and fitness. Traditionally, limb physical therapy sessions were carried out man- ually with assistance of therapists. However, the poor performances in terms of duration, strength and task orientation of the training, and the inconsistency in therapy sessions from one session to another have been noted, as principles issues, to encouraged many researchers to require the robotic, where a good re- peatability, and a precisely controllable assistance, providing quantitative measures of the subject’s per- formance and reducing the required labor of physi- cal therapists are carried out. Therefore, the use of robotics in this context needs to take into account the different biomedical constraints imposed in the study of this system (H. Faqihi and Kabbaj, 2016). Generally, robotic is largely used in many applica- tions such as medical, physical and industrial, where high accuracy, repeatability, and stability of the op- erations are required. For different robotic studies, the developpement of control laws is commonly exe- cuted in joint space. Howerver, the motion planning is given in the task space, especially when it comes to real applications as rehabilitation, where the desired input is usually the end effector position in task space. Hence the necessity to resorting to the Inverse Kine- matic (IK) task to find a configuration at which the end-effector of the robot reaches a given point in the task space. Several researches have been provided to derive the IK problem, especially for redundant articulated robotic arm, such as a parts of human body, where the complexity is enhanced with the increased Degrees Of Freedom (DOF). Thereby, solving the IK problem is quite a challenging task, where its complexity lies in the robots geometry and nonlinear relation between cartesian and joint space. The most popular IK methods developed in the literature are algebraical, geometrical methods (W. M. Spong and Vidyasagar, 2006), and the analyt- Faqihi, H., Saad, M., Benjelloun, K., Benbrahim, M. and Kabbaj, M. Optimal 3D Kinematic Analysis for Human Lower Limb Rehabilitation. DOI: 10.5220/0006477701770185 In Proceedings of the 14th International Conference on Informatics in Control, Automation and Robotics (ICINCO 2017) - Volume 1, pages 177-185 ISBN: 978-989-758-263-9 Copyright © 2017 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved 177