Abstract:

To improve the course stability of underactuated surface vessel (USV), a fractional order PIλDμ （proportion integration differentiation, PID）controller is applied to ship autopilot, which is more flexible, robust and has stronger disturbance rejection ability with the integralorder λ and differential order μ. However， difficulties for optimization also increase. A new method of designing PIλDμ controller based on the improved particle swarm optimization (IPSO) algorithm is proposed, which solves the problems of the particles falling into local optimum and the design complexity in fractional order PIλDμ controller design. The fractional order PIλDμ controller based on IPSO is compared with the traditional PSO PID controller under the same conditions. The simulation results show that，the controller can optimize the adaptive parameters well and automatically, and has a high tracking speed, small overshoot and strong immunity.