| In view of the constant volume control method commonly used in negative pressure servo systems,there are insufficient vacuum pumping capacity and dynamic characteristics of pipelines in the low negative pressure simulation range,this paper proposes a variable volume control method and designs a negative pressure servo system based on the vacuum cylinder.Also,both the robust control strategy and the adaptive robust control strategy of the negative pressure servo system based on the vacuum cylinder is developed.The work carried out in this paper is as follows:Firstly,a vacuum cylinder with a symmetrical structure is designed,and a state-space model of the vacuum cylinder is established.The natural frequency of the vacuum cylinder is obtained by two methods of FFT and formula calculation.According to the relationship between the natural frequency and the structural parameters,a DE algorithm is proposed for the optimization of the structural parameters of the vacuum cylinder.This section has reference significance for the optimal design of the components in the negative pressure servo system.Secondly,using the optimized design vacuum cylinder as the controlled object of the negative pressure servo system,a negative pressure servo system scheme based on the vacuum cylinder is proposed.An experimental platform of the negative pressure servo system is built for the system feasibility verification simulation and experimental research of sine signals under the pressure range of 1～6k Pa,tracking amplitude of 0.2k Pa,tracking frequency of 2Hz.According to the simulation and experiment results,the negative pressure servo system based on a vacuum cylinder is feasible,but the pressure control performance needs to be further improved,and other control strategies need to be introduced based on the feedforward PID control research.This section verifies the feasibility of the negative pressure servo system based on a vacuum cylinder and expands the control structure of the negative pressure servo system.Finally,the influence of interference factors such as friction,leakage,initial pressure offset,and initial position offset of the negative pressure servo system on the pressure response is analyzed.The influence is added to different state-space variables,and a robust controller is designed based on the feedback linearization of the system.This method overcomes the problem that the interference factors such as friction and leakage are of uncertainty and difficult to accurately model,and avoids the complicated process of decoupling the interference of different variables.Furthermore,an adaptive robust controller is developed to realize continuous control of 1～10k Pa negative pressure.According to the results of the robust control and the adaptive robust simulation,compared to feedforward PID control strategy,the robust control strategy overcomes the problem of the system being greatly affected by interference,improves the pressure control performance of the negative pressure servo system,and the adaptive robust control achieves the consistency control performance of high precision and high dynamic in the low pressure range of 1～10k Pa.This section can provide a reference for the control strategy research of the negative pressure servo system.This paper designs a negative pressure servo system based on a vacuum cylinder,which has certain theoretical and engineering application value for optimizing negative pressure servo system,expanding control structure,and achieving low negative pressure continuous control. |
