Research of NSMDOB-Based Compound Control for Photoelectric Tracking Platform

Abstract

Disturbance compensation is an important criteria to evaluate the performance of a photoelectric tracking servo control system. In order to effectively compensated disturbance in high frequency, a novel sliding mode disturbance observer (NSMDOB) is proposed in this paper. The dynamic performance of the system is improved by the design of the compound control scheme with the NSMDOB and additive decomposition theory. According to the additive decomposition theory, the photoelectric tracking platform servo system was decomposed into the main system and the auxiliary system. The tracking control and disturbance compensation were considered respectively in two systems. A rapid switching technique of the sliding mode was used to estimate the high frequency disturbance in the NSMDOB and the compensator of the auxiliary system. Finite-time control (FTC) was used to design the sliding mode compensator, which could maintain the state of auxiliary system asymptotically stable. Experiment results prove that the proposed method may offer the fast convergence rate, the high tracking accuracy, and the strong robustness of the control system. INDEX TERMS Novel sliding mode disturbance observer, finite-time control, photoelectric tracking platform, additive decomposition, sliding mode control.

Development of Sliding Mode Controller Based on Internal Model Controller for Higher Precision Electro-Optical Tracking System

“…where α and β are the parameters of the sliding mode surface. The design method of sliding mode controller based on the reaching law was adopted and the exponent reaching law given as follows: σ = −k c σ − ηsgn(σ) (7) where k c is the exponential convergence rate (k c > 0) and η is the switching gain of the sliding mode surface (η > 0). The traditional sliding mode control law can be designed as follows by combining them:…”

“…The state of a system can be decomposed into the sum of the states of two subsystems; one of the two subsystems can be designed at will and the other can be expressed as the difference between the original system and the designed subsystem [7]. In this paper, the state of the system was decomposed into IMC sub-state and SMC sub-state.…”

“…Next, the performance difference between the SMC based on the DOB and the SMC based on IMC was verified by comparative simulation. To show the superiority of the proposed algorithm, three different DOBs were designed and are presented in this subsection; they were: the conventional DOB (CDOB) [43], the dual-compensator DOB (DCDOB) [44] and the novel sliding mode DOB (NSMDOB) [7]. To ensure the relative fairness of the comparison, the SMC with the same parameters was invoked as the closed-loop controller.…”

“…Zhou and Li [6] proposed a fractional order control scheme to solve the contradiction between the error suppression ability and the stability margin in high-precision tracking control. Ren et al [7] proposed a new nonlinear sliding mode DOB to compensate the high-frequency disturbance of electrooptical tracking. Zhou and Li [8] designed a trajectory-tracking control scheme for an ETS with nonlinear disturbance (such as friction) based on the super twisting extended state observer and the fractional order non-singular terminal sliding mode with the switchingtype reaching law.…”

“…Among various control schemes, sliding mode control (SMC) is a powerful nonlinear control technology, which has a simple control structure, easy to implement, with fast response, insensitivity and strong robustness to system external disturbance and model uncertainties [9][10][11][12]; therefore, it has attracted a lot of attention and has been applied in the ETS [7,8,[13][14][15][16]. However, the traditional SMC suppresses external disturbance and model uncertainties mainly by adding a discontinuous switching term.…”