Research And Development Of Intelligent Artificial Leg Controller Based On Differential Evolution Algorithm

Intelligent artificial leg has been an interesting research project in the realm of robotics and bioengineering at present, the different between it and traditional machinery artificial leg lies in their owning the ability to coordinate the speed and gait automatically according to the information recognized from the external environmental, and make the patient obtain the naturally harmonious walking behavior. The intelligent controller installed in the artificial leg is a key factor of accomplishing this task, which can analyse and process the environmental information obtained from the external world, output the corresponding control command, make the servo (cylinder) change its own parameters in order to produce the thrust power and damping needed, and adjust the leg speed and gait of the artificial leg finally.The thesis aims at designing a controller which can realize intelligent of artificial leg, make intelligent artificial leg choose suitable leg speed and gait according to walking environment and make the patient resume relatively harmonious walking behavior. This system is a high-accuracy position servo control system, the variety of the speed of leg is changed by controlling the needle valve in the cylinder to, and the three closed loop control system with electric current loop, speed loop and position loop is designed to get good dynamic performance and stable state performance, corresponding controller is designed to accomplish the task of correcting and regulating each loop, including PI controller, PI controller and an fuzzy PD controller which can adjust on-line parameters by oneself. Among them the current loop and speed loop are for fast performance and strengthening anti-interference performance of the system, the position loop is for getting higher precision of the system.Differential evolution algorithm is a kind of new evolution algorithm which used to optimize the parameters of controller.The differential evolution algorithm is introduced in detail in the article, it is a kind of random search algorithm based on the evolution thought, and it has its unique advantage and application prospect comparing on other similar search algorithm.It is utilized to optimize theparameters of PID controller, and the result indicate that it got good effect. Synchronously the process to design the servo control system with three closed loop is described at length in the article, and the simulated result is provided in this paper.The author has designed and made the hardware circuits of the intelligent controller, and written control software. From the experiment result, it was concluded that the controller of intelligent artificial leg designed in this research has better intelligent behavior, robustness, response speed and accuracy.