Design And Control Research Of Rotary Series Elastic Actuator

Since the safety of interaction cannot be guaranteed,the workspace of traditional rigid robots is separated from humans,and its fields of work have been greatly restricted.By introducing elastic element,Series Elastic Actuator ensures its ability to safely interact with humans,which makes scholars considering it as the next-generation actuator mechanism.Series Elastic Actuator has been initially applied in many fields such as rehabilitation robots,service robots,assembly robots nowadays.In this paper,a rotary Series Elastic Actuator(SEA)was designed and its control methods were studied.First of all,the overall design of this Series Elastic Actuator was carried out,including design of mechanical structure and design of control system.In the design of mechanical structure,technical indexes were set up based on the possible workplace of this Series Elastic Actuator.The preliminary configuration of the Series Elastic Actuator was designed,and after that the selection and design of each part were introduced.The parts were assembled and the overall assembly drawing of the Series Elastic Actuator was established.A new type of elastic element was designed,and by adding a circular structure to the flexible beam,the length of the flexible beam was greatly extended.In design of control system,a control structure consists of a IGH master station and two slave stations was established.Due to the limitation of interface on the driver,a signal acquisition board was designed for the absolute encoder at the output.Secondly,the dynamic model of the Series Elastic Actuator was established and the characteristic of it was analyzed.The Series Elastic Actuator was unitized from the mechanical structure.By analyzing the dynamic model of each unit and the relationship between these units,the overall dynamic model of the Series Elastic Actuator was established.Based on the dynamic model,the transfer function of the torque control system was obtained by combining the proportional controller and unit negative feedback.Stability,bandwidth of the closed-loop system and the output impedance were studied using analysis methods of frequency domain.Next,the position control and impedance control of the Series Elastic Actuator were researched.In terms of position control,the singular perturbation method was derived and the singular perturbation controller was designed.Aiming at the problem of complicated adjustment of parameters in the slow subsystem of the singular perturbation controller,fuzzy singular perturbation controller was designed by introducing fuzzy control.For impedance control,the control method of inner position loop and outer torque loop was used.The fuzzy singular perturbation controller was used in the inner position loop,and the impedance controller was used in the outer torque loop.In terms of simulation,a simplified model of the Series Elastic Actuator was built in ADAMS.Block diagrams of position control and impedance control were built in Simulink.The co-simulation of ADAMS and Simulink verified the good position tracking ability of the position controller,and it also showed that the impedance controller had a certain protection ability.Finally,the experimental platform of this rotary Series Elastic Actuator was built,and the various components of this experimental platform were introduced.A preliminary test of the control environment of the IGH main station was carried out,and encoder data was read,doing spadework for the experiment of stiffness calibration.Aiming at the errors existing in the machining process of the elastic element,experiment of stiffness calibration was carried out.The influence factors of the experiment were analyzed,and the design of this new elastic element was proved to be reasonable.