Today, often ankle’s active prosthesis is used for transtibial amputated people’s walking, because these prostheses have some advantages such as increasing power and decreasing metabolism. In most of active prosthesis in order to create a movement or increase the force at the push-off, electrical actuators are used like a motor. In cases where a higher-power motor is necessary, the capacity, weight and using electricity in motor become increased, which causes problem for people with an amputation. This research is conducted to optimize ankle prosthesis with use of an active alignment which is made by experts. In this prosthesis to reduce the motor power, a passive element of spring is used in order to save energy while walking and release it in push-off. After setting spring position in the prosthesis, the dynamic and kinematic analysis are done and eventually the amount of used force in both modes of spring and non-spring would be compared. The results show that the presence of spring in the selected mechanism would cause motor to perform force increase and power reduction to mechanism at the push-off phase. پرونده مقاله

In this article a new and an accurate method for kinematic and dynamic analysis of a parallel robot 3PRS and a hybrid robot (parallel and serial) 3PRS-RRP are presented, which is based on the Denavit-Hartenberg transformation matrix algebra. First, basic properties of various kinds of robots are compared, and then the Denavit-Hartenberg parameters and their table are introduced. Next, the methods of forward and inverse kinematic are explained and system dynamic equations are obtained by Lagrange method. Finally for defined sizes and with imagination of a rotational movement for the center point of the moving plate of parallel robot and two input kinematic for serial robot, a few kinematic and dynamic results for parallel and serial robot by Newton and Lagrange methods are presented for singularity consideration. Generally, the forward kinematic solution of parallel robots and inverse kinematic solution of serial robots are difficult. For these hybrid robots, it would be better to use parallel robots, which have linear movement on the moving plate in the forward mode to increase the space and strength, or the two robots be time independent. پرونده مقاله