Active Disturbance Rejection Control For A Class Of Plant With Non-equlibrium Load

Air visible light camera imaging targets on ground has great civilian and military value and it attracts more attention of many scholars and engineers. In order to ob-tain a larger border images, non-equilibrium load image scanning system uses a cam mechanism for dynamic scanning. CCD scan image in the uniform section, the more stable the cam rotation, the higher quality of the camera imaging and the better photo stitching. However, the gravity of cam and rotating platform which applied to the motor shaft generates periodic disturbance which affecting the cam rotate uniform. Therefore, control methods should be designed to suppress the effect of periodic disturbance in u-niform rotation of the motor, and linear active disturbance rejection controller(LADRC) is used in this paper.Firstly, the system’s mathematical model which based on the non-equilibrium load is established to analyze the basic form of the disturbances. Secondly, we introduce the basic structure of active disturbance rejection controller. Thirdly, this paper designs a n-order LADRC for a n-order controlled object and derives its transfer function. For a second-order LADRC, the influence of the control parameters on its closed-loop sys-tem in the frequency domain is studied and the robustness of LADRC are explored in simulation. Fourthly, for the reason that system output contains measurement noise causing inaccurate parameter identification, a new parameter identification algorithm which is applied to identification the control input gain of LADRC in the case of out-put containing measurement noise is proposed to solve this problem. Finally, for the non-equilibrium load image scanning system, LADRC control which add disturbance information to extended state observer(ESO), PID-LADRC bumpless switching control and reduced order LADRC(RADRC) control is studied.Simulation results show that the ESO which add in more sufficient disturbance information get better the corresponding ADRC control results, bumpless switching control avoid the impact of the peak of ESO on output, and the output transit smoothly when switch different control strategy, in the case of consistent control performance, reduced order ESO in RADRC gets smaller bandwidth and smaller noise effect.