The Design And Implementation Of Power Servo Control System

Power assist and servo system is a type of wearable exoskeleton, and its designimitates the human body structure, it takes human as main controlling subject, takesmachine as main motion and power subject. From the mechanical structure point ofview, the exoskeleton can be divided into upper extremity exoskeleton and lowerextremity exoskeleton. From the function point of view, it can be divided into powerassist and servo exoskeleton and medical-rehabilitation exoskeleton. When theexoskeleton technology is mature, it will be extended into more areas and make humanswork and life more convenient. In addition, this system as an integrated technology is agood combination of various disciplines, involving micro-energy technology,micro-driving technology, material technology, control technology and other disciplines.It is a hot and difficult project of the intelligent flexible human-machine system and ishighly concerned by the countries of the world.This study focuses on the research of the control algorithm of the exoskeleton andimplemented of the control algorithms based on embedded platform. Firstly, On theanalysis of the law such as human gait, flexible hydraulic drive model andhuman-machine coupling model, the mathematical model of the position-trackingcontrol system and the hydraulic-position control loop are established, different controlparameters are designed for different modes of motions, and the frequency domaindesign is accomplished by combining PID and feed-forward methods together. Thesimulation results show that, when people walk normally, the control method can followthe human knee joint angular displacement, and the results meet the requirements ofhuman-machine motion coordination. Secondly, a computer is used to realize thecontrol algorithms and outputs control instructions to actuator, at the same time,provides a data acquisition and display platform, when the prototype is working, theplatform can collect important data to analyze the system in real-time. Finally, after thecompletion of the prototype, demonstrating experiments are carried out and overallperformance of the hydraulic system are analyzed in different loads and different motion modes, such as exoskeleton action inaccuracy analysis. The test results showthat lower extremity exoskeleton system uses valve-controlled cylinder to meet theoperation requirements of walking stably on flat ground up and down stairs withcarrying load reaching60kg, and so on.