Abstract:
In the heading control of a high-speed unmanned surface vessel(USV), there are time delay elements in both the forward channel and the feedback loop. Moreover, it has a large delay/dynamic time ratio, significantly reducing the performance of heading control. Conventional Smith predictors can only effectively compensate for time delays in the forward channel and are ineffective against time delays in the feedback loop. In this paper, the time delay in the feedback loop was incorporated into the design of the Smith predictor, constructing a predictive model that incorporated time delays in both directions. This approach allowed for simultaneous compensation of time delays in both the forward channel and feedback loop, thereby significantly reducing the erosion of the system’s phase margin caused by bidirectional time delays. Furthermore, a hybrid mean center opposition-based learning particle swarm optimization(HCOPSO) algorithm was introduced for the parameter tuning of the proportional-integral-derivative(PID) controller. This algorithm employed a mean center opposition-based reverse learning strategy in the early stages of iteration to expand the search range and utilized an adaptive compression factor in the later stages for fine-tuning. Therefore, it combined the advantages of both global exploration and local exploitation, effectively solving the problem of local optimal solutions in the optimization process. Simulation tests were conducted based on the USV heading model. The results demonstrate that the improved Smith predictor-based PID controller shows significant improvements in system overshoot and settling time compared to conventional PID controllers and traditional Smith predictor-based PID controllers, with a steady-state error of less than 0.1°. When the compensation model of the improved Smith predictor contains parameter deviations, the system can still maintain good dynamic stability and steady-state accuracy. Meanwhile, for the Smith predictor-based PID controller, the navigation control performance of the HCOPSO algorithm was further compared and analyzed with that of the particle swarm optimization(PSO) algorithm, genetic algorithm(GA), and whale optimization algorithm(WOA). The results show that the integral of time-weighted absolute error(ITAE) index obtained by the HCOPSO algorithm is 55.38%, 22.47%, and 24.63% lower than that of the PSO algorithm, GA, and WOA, and it demonstrates strong disturbance suppression ability and heading stability ability, verifying its effectiveness.