Research And Design On Control System Of An Lower Limp Rehabilitation Robot

In recent years, rehabilitation robotics has been given plenty of attention byresearchers and therapists. How to use robot to help patients get stand up and even walkas usual is the most difficult problem to deal with. It needs not only the knowledge inthe field of robotics, but much more about clinical study and medical science. It is acombination of kinds of subjects together to form a complicated system, consideringbeing stable, smooth, comfortable and adaptive to different conditions in patients, evenin the case when the patient’s circumstance makes a substantial change. As aconsequence, theoretical and experimental researches on control strategies forlower limb rehabilitation robot will be developed in the thesis.In this paper, we focused on developing a robot for rehabilitation of locomotion instroke and hemiplegic individuals. The mechanical structure is a key design for therobot, which can guarantee the steadiness and safety. Pneumatic muscle has been usedfor supplying lightness and energy efficiency. By investigating the dynamics of therobots, we will design intelligent control for the robot.Firstly, the study why those patients in stroke cannot move or walk medically iselaborated, such as how the muscles and knees work when the leg moves, how theycorporate and what makes them stop when a stroke happens to a people. And we willpropose necessary requests for the process of designing, such as mechanical structureand location of sensors to prove that it’s convenient and comfortable when they utilizethe robot.It is a2dof lower limp robot with joints in hip and knee. We will build kinematicmodel and analysis the relationship of motion and forces by using Lagrange Eulerequation. The dynamic equations of motion for a robot are a set of mathematicalequations describing the dynamic behavior. Based at the equations, we test and verifythe correctness and stability of the robot by software tool in Matlab.The robot should have an improved mechanical structure to support a morecomfortable and easier put on function. Therefore, we decided to design two modes:one for patients, who cannot stand at all or in the beginning of rehabilitation, is called Passive Mode; the other one for patients who has a few capabilities to move muscle orstand but cannot walk smoothly, is called Initiative Mode.The core part in the thesis is the design of the control system for the robot. Wewill utilize PID, adaptive control and impedance theories to design different controllerfor the two modes. For the Passive Mode, it is necessary to consider proper gaitplanning for accurate position control, on account of patients cannot provide forces anda direction to walk. For the Servo Mode, how to keep patient and robot consistentlyworking together is the key point. And we add impedance control in it to make sure theforces robot supplies are enough, which is closely connected with the location ofsensors.With simulation results by different control strategies, the feasibility andeffectiveness of lower limb rehabilitation robot have been validated, which provides atheoretical foundation for designing of the prototype in the future.