A conceptual gait rehabilitation system was developed to generate the coordinated motion of the hip and knee joints according to normal physiological gait pattern with a pair of linkage mechanisms (one for each leg) This article presents the design of a mechanical timing mechanism for the motion control and coordination of the linkage mechanisms in the system The desired motion of the input crank of the linkage mechanism is first obtained for the control purpose To facilitate the implementation of different modes of operation of the gait rehabilitation system, a combination of cam and planetary gears is developed to achieve both timing and coordination through mechanical means Motion simulation of the new timing mechanisms shows that the proper timing of the gait mechanisms, thus the hip and knee joints, is achieved with a constant speed input

Motion control and coordination in the development of a conceptual gait rehabilitation system

This paper presents the optimal synthesis of disk cam mechanisms with a roller follower considering cam size minimization and rotational balancing. With the aid of parametric vector equations of the cam profile, geometric properties of the disk cam are derived. The concept of a disk cam with an inner arc-slot hole and a pair of added circular counterweights is then proposed to practice rotational balancing for the cam shaft. Optimization models to find the minimized cam size and to achieve rotational balancing of the cam shaft with a minimized polar moment of area are established. Two case studies for the optimal synthesis of disk cams with either an offset translating roller follower or an oscillating roller follower are demonstrated. For each case, both the optimized cam size and polar moment of area can be considerably reduced. Hence, this study provides a feasible methodology to synthesize disk cam mechanisms with a roller follower.

Optimal Synthesis of Disk Cam Mechanisms with a Roller Follower Considering Cam Size Minimization and Rotational Balancing

MOTION COORDINATION AND CONTROL IN THE DEVELOPMENT OF A GAIT REHABILITATION SYSTEM by Yazan Ahmad Manna While most take their ability to walk for granted, some are unable to walk due to any number of pathologies, such as traumatic brain injury (TBI), spinal cord injury (SCI), and Parkinson's disease. Decreased activity has been shown to be associated with rapidly deconditioning. Rehabilitation techniques that afford patients the ability to begin reconditioning through walking sooner may ultimately enhance their return to a better quality of life. To assist the functional recovery of such patients, an appropriate afferent input to the spinal cord will help in the therapy of the patient. Manual training is labor intensive, costly, and ergonomically unfavorable and tiring to the trainer, which will make training sessions short. Task-specific exercises delivered by robotic devices have registered success in reducing impairment and increasing motor power. Advantages of using robotic devices over the manual training include: reproducibility of the movement in a physiological manner, prolongation of the training sessions. However, several shortcomings exist in the existing devices. The reliability of the hardware and software is critical for their safe operation. These devices are expensive and only available in some large rehabilitation research institutions, which limit many disabled people to get the therapy they require. A gait pattern generation system was developed, which uses close-chain linkage mechanisms to guide the legs with coordinated movement of the leg joints to follow normal physiological gait pattern. The natural kinematics constraints of the mechanisms produce trajectories that limit the joints' range of motion (ROM) thus improving the gait training safety. The movement of the input links of gait generation mechanisms must be controlled to provide proper timing of both stance and swing phases during a training session. This research describes the development of two methods for the motion control and coordination of the linkage mechanisms. First, the desired motion profile of the input crank of the linkage mechanism is obtained in the form of continuous function of time. The first method controls the input crank of the linkage mechanism directly with a servomotor based on the derived continuous motion profile. The coordination of the mechanisms for the two legs is carried out in the motion control software. The second method proposes to achieve both timing and coordination through mechanical means so that the system works under a simple speed control. A combination of cam and planetary gear mechanisms is synthesized for this approach. The procedures for obtaining the gears ratio of the planetary mechanism, the follower motion profile and the cam profile of the cam mechanism are discussed. Computer simulation is used to demonstrate the correct timing of the ankle movements on the closed path with the two methods. It also shows that the corresponding hip and knee joints follow normal physiological gait pattern. MOTION COORDINATION AND CO NTROL IN THE DEVELOPMENT OF A GAIT REHABI LITATION SYSTEM by Yazan Ahmad Manna A Dissertation Submitted to the Faculty of New Jersey Institute of Technology in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Mechanical Engineering Department of Mechanical and Industrial Engineering January 2010 Copyright © 2010 by Yazan Ahmad Manna ALL RIGHTS RESERVED APPROVAL PAGE MOTION COORDINATION AND CONTROL IN THE DEVELOPMENT OF A GAIT REHABILITATION SYSTEM Yazan Ahmad Manna Dr. Zhiming Ji, Dissertation Advisor Date Associate Professor of Mechanical Engineering, NJIT Dr. Rajpal Sodhi, Committee Member Date Professor of Mechanical Engineering, NJIT Dr. Bernaoplik Committee Member t K , of M chanical Date Professor echanical Engineering, NJIT Dr. Ian Fischer, Committee Member Date Professor of Mechanical Engineering, NJIT Dr. Richard A. Foulds, Committee Member Date Associate Professor of Biomedical Engineering, NJIT

Motion coordination and control in the development of a gait rehabilitation system

Usually, the size optimization by the cam mechanisms is reduced to the cam size only, which is not completely correct because the cam is only one of the two important entities working together. The cam follower optimization is taken into account, but only as distinct part of the cam mechanism. Total size regarded as a minimization criterion is an important problem in cam mechanism synthesis. The paper shows a total size minimization of the cam mechanism, where both parts are equally considered. The mathematical generalization is developed for cam mechanisms with translating roller-follower and flatface follower.

Journal of Engineering Sciences and Innovation

This paper presents a procedure for minimizing the size of roller-follower disc cam mechanisms under the constraint of maximum pressure angle. The pressure angle constraint is realized through establishing the permissible region for the cam centre. The problem of cam-size minimization is reduced to locate the cam centre at the intersection of boundary curves of the permissible region. Its implementation is illustrated through examples.

Y A Manna

Papers

Size minimization of disc cams with roller-followers under pressure angle constraint