Kinematic Modeling and Optimum Design of a Rehabilitation Mechanism for Leg Motion of People with Disabilities

Today, with advances in medical, using robotic rehabilitation systems for treating incapability movements have been taken into consideration so much. One of the most important means of rehabilitation systems are used for auxiliary lower leg motion systems that the main factor in design and construction of these systems is moving leg according to the correct walking pattern. In this paper, design of an active device with one degree of freedom is provided for rehabilitating the weak leg of disable people. The proposed model is based on the structure of a four-bar mechanism. Its design and construction parameters with use of genetic optimization algorithm are selected in such a way that leg motions have the least difference with the pattern of walking. After the extraction of the kinematic equations of the closed-loop system and solving them, optimization with focusing on each joint of hip and knee is done separately with appropriate difference with weighting coefficients of objective function (W1, W2). Due to the defined optimization objective function, with increasing W1 respect to W2, the ability of system will increase in approximating the angle of hip joint to the optimal time function and by increasing W2 respect to W1, the ability of device will increase in approximating the angle of knee joint to the corresponding time function. The results indicated that the device ability for empowerment of leg motion of the disable people is in the way to rehabilitate the desired walking movement for them.