Application Of Disturbance Observer Based On Friction Compensation In Aerial Photoelectric Stabilized Platform

Aerial photoelectric stabilized platform is widely used in the field of investigation and target location.The platform can effectively isolate the disturbance of the carrier to maintain the stability of optic axis.The higher accuracy the optic axis stability,the more accurate the target information is.Among all the disturbances,the effect of friction is particularly obvious on optic axis stability.To solve this problem,the control scheme of disturbance observer based on friction compensation is designed.The main contents of this paper include the following studies:(1)The model of the speed loop of the platform is established,which lays the foundation of the control strategy design.The model of the system is established according to the dynamic equation of the DC torque motor and the relationship between the motor and load,and then a system model with disturbance is established by means of "equivalent disturbance voltage".(2)The friction torque is modeled on Lu Gre model.The friction parameters are identified by two steps.First,the static parameters of the Lu Gre model are obtained by measuring the Stribeck curve and fitting the data.Next,the ranges of the dynamic parameters of the Lu Gre model are obtained by simplifying the friction model at low speed.Then the genetic algorithm is used to get the value of dynamic parameters.The friction model was established on the basis of parameter identification,the validity of which was verified by experiments.Finally,the friction compensation control is designed based on the identified friction model.(2)Based on the friction compensation control strategy,the disturbance observer control strategy is designed.This paper introduces the design steps and improvement methods of the disturbance observer.At last,the control scheme of disturbance observer based on friction compensation is designed.Besides,simulation results show the feasibility of the control strategy.(3)In order to test the feasibility and necessity of the control scheme,experiments are performed.When the system is running at low speed,the tracking performance is improved obviously.The experimental results show that system disturbance isolation degree is increased in the range of 14.52 d B to 20.98 d B,when the flight simulation turntable produces a disturbance within 3Hz.This control strategy also has strong robustness,which allows the system parameter change in the range of +-10%.In conclusion,this control strategy has higher practical value...