Effect of Robot Driving Mode on Lower Limbs Rehabilitative Training

According to the combination of lower extremity rehabilitative robot(LERR) and trainer, the effects of multi-point driving form and single point driving form on muscle force and joint torque are explored. The musculoskeletal model of lower limbs was established, based on the physiological structure of human lower limbs. And considering the position of the attachment points of each muscle, the mechanical properties of muscles can be obtained under different rehabilitative training strategies by inverse dynamic analysis. Using the wire-driven rehabilitation robot as the driving device of the rehabilitation training, the robot was used to Simulate the motor function of patients’ lower limbs by modifying the parameters of muscle and the parameters which can effect the resistance moment of joint ,then the effects of driving form were analysed. The results show that single point driving form was better than multi-point driving form on muscle force and joint force training. Introduction Ambulation dysfunction is one of main dysfunctions in patients with stroke, and it is the main important index to evaluate the motor function of patients with stroke that the patients can resume security independent walk or not [1]. Conventional treatment is through early trunk control to strengthen the strength of lower extremity and stand balance, and then dynamic gait training will be started. However correct gait needs trunk control stably and Coordinate contraction of lower limbs muscle and other conditions. In the early walking training, the patients can get those conditions difficultly, and therapists also can not take fully consideration on the all lines of force that participate in joint movement in gait cycle, and it will result in easing the feedback of central nerve system error and forming abnormal gait [2]. Gravity balancing orthosis (GBO) was created by the college of Mechanical Engineering and the medical college in University of Delaware which was aimed at reduce or eliminate the effect of lower extremity gravity when walking. The experiment showed that 75% of the joint torque was saved when normal knee statically [3-4]. Reha Technology produced a Plantar-driven gait rehabilitative robot to help patients to practice walking which can drive patients’ lower extremity moving through driving the pedals. Four kinds of patterns (flatland, steps, ramps and obstacles) and active-passive training pattern were Contained in the robot’s walking patterns [5]. The lab in University of Tsukuba created gait rehabilitative robot named Gait Master that could captured patients’ EMG in the training process to inform the current status of patients and switch training patterns automatically, and completely passive training pattern was overcome[6]. Another gait rehabilitative robot towed by rope, STRING-MAN, was created in German Research Center for Frances Hofer which could achieve the posture control of legs, pelvis and trunk, and meanwhile rope improved the running speed and flexibility of the system because of little Inertia and flexibility[7]. A kind of walking rehabilitation training robot was developed in Shanghai University ,and this robot was equipped a three degrees of freedom leg including hip, knee and ankle joint to help patients to complete lower extremity walking skills training and passive training basing on the theory of loss of weight training. There were two main driving forms in the cooperation of rehabilitation training robot and the trainer . One was that robot was connected to different parts of the limbs of the trainer through multiple points and did regular exercise by multipoint driving; another was that robot was connected to the extremity of limbs of the trainer and the 622 Advances in Engineering Research (AER), volume 105 3rd Annual International Conference on Mechanics and Mechanical Engineering (MME 2016) Copyright © 2017, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). robot drive joints to move. The training effect of these two kinds of driving forms aiming at the same training goal had not been studied. So in the thesis multi-point driving training pattern and single point driving training pattern of the lower extremity rehabilitative robot were studied, and the advantages and disadvantages of two kinds of driving methods on the training of muscle group of thigh and hip joint and knee joint were analysed. Then it is discussed that the patients with different movement disorder should choose appropriate rehabilitation drive form. Musculoskeletal of Lower Extremity Modeling Muscle modeling played a very important role in rehabilitation and medical diagnosis, and relatively complete theoretical system about muscle modeling had been established. The representative theory of muscle contraction was the theory of muscle wire sliding. In this thesis the muscle of lower limbs was modeled according to theory of Hill muscle modelling[8]. The output force of muscle was expressed as follows: