Real-Time Hybrid Test Control Research Based on Improved Electro-Hydraulic Servo Displacement Algorithm

Abstract

Real-time hybrid testing (RTH) is a test method for dynamic loading performance evaluation of structures, which is divided into digital simulation and physical testing, but the integration of the two may lead to problems such as time lag, large errors, and slow response time. The electro-hydraulic servo displacement system, as the transmission system of the physical test structure, directly affects the operational performance of RTH. Improving the performance of the electro-hydraulic servo displacement control system has become the key to solving the problem of RTH. In this paper, the FF-PSO-PID algorithm is proposed to control the electro-hydraulic servo system in real-time hybrid testing (RTH), which uses the PSO algorithm to operate the optimized PID parameters and the feed-forward compensation algorithm to compensate the displacement. First, the mathematical model of the electro-hydraulic displacement servo system in RTH is presented and the actual parameters are determined. Then, the objective evaluation function of the PSO algorithm is proposed to optimize the PID parameters in the context of RTH operation, and a displacement feed-forward compensation algorithm is added for theoretical study. To verify the effectiveness of the method, joint simulations were performed in Matlab/Simulink to compare and test FF-PSO-PID, PSO-PID, and conventional PID (PID) under different input signals. The results show that the proposed FF-PSO-PID algorithm effectively improves the accuracy and response speed of the electro-hydraulic servo displacement system and solves the problems of RTH time lag, large error, and slow response.

Keywords: FF-PSO-PID; PSO algorithm; composite control; electro-hydraulic servo; real-time hybrid test.

Figure 1

Real-time hybrid test system.

Figure 2

Hydraulic cylinder model.

Figure 3

Electro-hydraulic servo system PID control.

Figure 4

Feed-forward displacement compensation system.

Figure 5

FF-PSO-PID algorithm control system.

Figure 6

Adaptive degree value of the PSO algorithm.

Figure 7

Simulation diagram of PID and PSO-PID.

Figure 8

(a) Step input signal; (b) Conventional PID and PSO-PID response curves under step signal.

Figure 9

Error response curve under step signal.

Figure 10

Simulation of conventional PID, PSO-PID, and FF-PSO-PID with sinusoidal and random signals.

Figure 11

(a) Sine input signal; (b) Random input signal.

Figure 12

Response curves under sinusoidal and random signals. (a) local enlargement of sine signal; (b) local enlargement of random signal; (c) enlargement of starting position of sine signal; (d) enlargement of starting position of random signal; (e) enlargement of wave crest of sine signal; (f) enlargement of wave crest of random signal.

Figure 13

Response curves under different signals. (a) local enlargement of the ramp signal; (b) local enlargement of the ramp sine synthesis signal; (c) local enlargement of the triangular wave signal; (d) enlargement of the start position of the triangular wave ramp synthesis signal.