电液伺服试验机力控系统负载刚度自适应控制

摘要

负载刚度的变化会导致电液伺服力控系统的控制特性发生改变,从而降低系统的稳定性与控制精度.本文以电液伺服万能试验机为研究对象,首先建立了考虑负载刚度的力控系统数学模型,分析了负载刚度的变化对控制特性的影响;其次设计了模型参考自适应(MRAC)控制器,并根据试验机力控系统的设计目标提出了一种具有最小拍响应特性且满足严格正实要求的参考模型;然后利用Simulink对最小拍参考模型MRAC控制器及PID控制器进行了仿真,并在自制的实验平台上采用两种不同刚度的试样分别进行了等速力加载实验,仿真及实验结果表明所设计的控制器能有效的抑制试样刚度的差异所引起的控制特性的变化,使电液伺服力控系统的响应具有良好的一致性.%The control accuracy and stability of electro-hydraulic servo force control system will decrease with the change of the control characteristic of system which influenced by different specimen rigidity.First,a mathematical model of force control system considering load rigidity is established, and the influence of the change of load rigidity on the control characteristic is analyzed. Then,a model reference adaptive(MRAC)controller is designed,and a novel reference model which has the characteristics of minimum deadbeat response and strictly positive real has been present.Finally,the performance of minimum deadbeat response MRAC Controller and PID controller have been simulated by Simulink,and constant force speed loading experiments were carried out on the self-made experimental platform by using two specimens with different rigidity.The simulation and experimental results show that the minimum deadbeat response MRAC controller has the advantages of fast response,small overshoot and zero steady-state error,and can effectively restrain the parameter drift of electro-hydraulic servo force control system caused by different specimen rigidity.