Controller Design Of Series Elastic Actuator

With the increasing development of science and technology,there are more and more applications related to robots.Traditional industrial robots can no longer meet various application scenarios with flexible loads.Instead,collaborative robots become more attractive,for which Series Elastic Actuators(SEA)play a key role as a new generation of flexible drives.Due to the existence of elastic elements,SEA control is more complicated than traditional robot joints.Currently,the study on SEA control still at infancy stage.The hardware has a higher cost with much larger volume and mass.This thesis combines the application of SEA,and the deficiencies of existing SEA research,to study the driving and control problems of highly integrated SEA.It's purpose is to improve the torque density and control accuracy of SEA under hardware constraints,so that SEA can be popularized and applied.The research content and contributions of this thesis include the following parts:1.Research on motor winding temperature protection strategy based on winding temperature estimation and multi-stage temperature cut-off curve:Research on motor winding temperature protection strategy based on winding temperature estimation and multi-stage temperature cut-off curve.Due to the limited internal space of the SEA joint used in this article,it is necessary to use the winding temperature estimation method to replace the temperature sensor.This article also studies the temperature protection strategy,considers the output limit problem,and makes the peak torque of the SEA joint improved.2.Design of voltage source SEA torque controller based on radial basis function(RBF)neural network and environment decoupling: A torque control algorithm based on motor voltage input is designed.It combines the ease of use property of feedback control and the rapidity and accuracy of RBF torque feedforward.And by adding motor speed compensation to reduce the impact of environmental coupling.The dependence of the controller on the hardware is reduced and the control performance of the torque controller is improved.3.Design of active disturbance rejection cascade SEA position controller based on polynomial transition and feedforward:This thesis uses the advantages of the active disturbance rejection control not relying on the model,and uses the torque controller as the inner loop controller.The structure of the SEA dynamics model divides the system disturbance into known and unknown.The known disturbance are fed forward by the order information of each order generated by polynomial programming.The unknown disturbance are estimated and compensated by the extended state observer.It improves the performance of the position controller without increasing the observer gain and bandwidth.