Design And Control Method The Rotary SEA Of A Lower Limb Exoskeleton Robot

Nowadays,due to the rapid development of science and technology and the complexity of work tasks,the traditional rigid joint robot can no longer meet more and more interactions with the outside environment.In order to make the lower limb exoskeleton robot have the flexibility characteristics of bionic joints,this paper designs a series elastic actuator(SEA),which adds flexible control,Finally,it is applied to the lower limb exoskeleton robot for experimental verification.First,according to the working environment of the lower limb exoskeleton,set the technical indicators,carry out the overall scheme design of SEA,and carry out the structural design and selection of each component.For elastic elements,this paper models,analyzes and optimizes five kinds of elastic elements,proposes a comprehensive index combining three parameters of specific energy,mass and manufacturing cost,compares the performance of five topological structures,and finally selects the zigzag elastic element and analyzes its constant stiffness and variable stiffness.The results show that the elastic element meets the design requirements.Secondly,the common dynamic model of SEA is analyzed,and the dynamic model is optimized by introducing three factors: electrical damping,equivalent moment of inertia of transmission mechanism and damping of elastic elements.Finally,the dynamic model of SEA designed in this paper is derived.The frequency domain analysis method is used to analyze the dynamic model under the control of the force source in the frequency domain.The results show that the system is stable,which indicates that the SEA designed this time is relatively reasonable and conforms to the basic characteristics of SEA.Thirdly,SEA flexible control is studied.In position control,PID control,singular perturbation controller and fuzzy singular perturbation controller are designed.In impedance control,impedance controller is added on the basis of fuzzy singular perturbation controller.Finally,the position control and impedance control of the SEA are simulated by using ADAMS and SIMULINK joint simulation method,which verifies that the fuzzy singular perturbation controller can achieve good position tracking and can effectively protect the SEA after adding the impedance controller.Finally,an experimental platform of a flexible lower extremity exoskeleton robot is built to verify the feasibility of SEA designed in this paper.The overall scheme of the experimental device is designed.The mechanical structure,control system and plantar perception system of the lower extremity exoskeleton experimental platform are introduced in detail.The absolute value encoder is debugged and calibrated,the subcalibration measurement is completed by using debugging tool,and the data acquisition of hip joint angle is completed by communicating to the upper computer via CAN bus.