Control Technique Research On Power-assistance Exoskeleton’s Lower Extremity

An exoskeleton is a kind of external structure that supports and protects an animal’s body. However, today the word "exoskeleton" has taken a new meaning, which refers to an equipment facilitating the integration of man and machine. This dissertation focuses on the control of exoskeleton’s lower extremity, and the main contents of it are as follows:In chapter 1, the background of the exoskeleton’s research is described. Some state-of-the-art exoskeleton projects are presented, and their advantages and disadvantages are analyzed. The related techniques used in exoskeleton are introduced. At the end of this chapter, the research contents of this thesis are introduced.Beginning with review of the anatomical terminology, the human walking gait cycle and the biomechanics of walking are analyzed in chapter 2. This chapter lays the foundation for the research of exoskeleton.In chapter 3, on the basis of chapter 2, the kinematic model of exoskeleton during single support phase and double support phase are built respectively. At the end of this chapter, the morbidity of the Jacobian matrix near kinematic singularities is studied. Based on the simulation, the drawbacks of the most used Damped Least Squares (DLS) method are pointed out, and an alternate method is proposed to overcome the drawbacks of the DLS method.In chapter 4, the experiment platform of the exoskeleton is introduced. At first the hardware system of the exoskeleton is introduced, then the control scheme for single leg is analyzed. At the end, the debugging interface is described.In chapter 5, a sliding mode controller based on the nonlinear model of the electro-hydraulic system is designed and obtain good position tracking performance. Human-machine control strategy based on multi-axis force sensor is studied at the end of this chapter. Based on multi-axis force sensor, a human-machine control strategy is proposed and realize human-machine collaboration.Chapter 6 summarizes the main work and preliminary results obtained, and points out the shortcomings and the scope of improvement. At the end of this chapter, future direction of work is proposed.