Research On Active Disturbance Rejection Control Technique Of Electromagnetic Railgun Servo System

In recent years,the international situation is complex and changeable,and a strong military force is a necessary condition for China to maintain its voice and ensure peaceful development.Electromagnetic railgun is a new concept weapon that attracts much attention.Compared with traditional artillery,electromagnetic railgun can flexibly change the muzzle velocity of projectile based on adjustable voltage.With the increase of voltage,the muzzle velocity of electromagnetic railgun can be continuously improved.However,the electromagnetic rail gun barrel is long and large in mass.In order to achieve an angle of high and low 80 degrees,and take into account the fact that the total height of the gun body cannot be too high and the engineering application,the center of mass of the barrel is far away from the trunnion,bringing greater rotational inertia and unbalanced torque.When the electromagnetic railgun tracks the target,the centroid position,stiffness coefficient,damping characteristic and rotational inertia of the mechanical system change,and the mechanical system contains uncertainty.The linear control law of PID control technology has the shackles of performance improvement in the face of strong nonlinear and uncertain systems.In view of the impact of the above disturbances and uncertainties on the electromagnetic rail gun system,the purpose of this paper is to find a new control method to improve the tracking accuracy and anti-interference ability of the servo system.In this paper,combined with the development of a certain type of electromagnetic gun,aiming at the above problems,combined with the extended state observer and the super-twisting sliding mode algorithm,an improved position loop active disturbance rejection controller(ADRC)based on the super-twisting sliding mode algorithm is designed,and the control research and theoretical analysis of the electromagnetic rail gun servo system are carried out.First of all,this paper studies the characteristics of the electromagnetic rail gun system,the transmission characteristics such as friction and backlash,the nonlinear factors such as unbalanced torque and firing torque,and establishes the transfer function model of the electromagnetic rail gun servo system based on the PMSM.According to the motion relationship of the electromagnetic rail gun pitch system and azimuth system,the dynamic model of the servo system is established.Secondly,the position loop ADRC of the electromagnetic railgun servo system is designed in this paper.When tracking the target,the centroid position,stiffness coefficient,damping characteristic and moment of inertia of the electromagnetic rail gun system all change,and the mechanical system contains uncertainties.The ADRC unifies the uncertainty factors and external disturbances in the controlled system into unknown disturbances,and estimates and compensates the system deviation in real time through the control algorithm,It is suitable for application on the electromagnetic railgun servo system with uncertainties in the system and difficulty in modeling.In this paper,the ADRC for the position loop of the electromagnetic rail gun is designed,and the stability of the controller is proved.The tracking experiment of setting a variety of typical commands and applying disturbance is conducted.The dynamic performance of the ADRC and the PID controller is compared.The experimental results show that the ADRC has better anti-interference ability.Then,this paper studies the improvement of the performance of the position loop ADRC of the electromagnetic railgun.By using the super-twisting sliding mode algorithm as the error feedback law of the ADRC,the overshoot of the servo system is reduced and the dynamic response of the servo system is more stable.At the same time,the super-twisting sliding mode algorithm weakens the "chattering" phenomenon compared with the ordinary sliding mode algorithm.In this paper,the super-twisting sliding mode-active disturbance rejection controller(STSMC-ADRC)for the position loop of the electromagnetic railgun is designed,and the stability of the controller is proved.The control performance of the STSMC-ADRC,the ADRC and the PID controller are compared through a variety of typical command tracking experiments.The results show that the STSMC-ADRC has the best anti-interference ability.Finally,this paper compares the algorithm effect on the PMSM motion table,and tests the performance of the STSMC-ADRC proposed in this paper through various experiments of constant speed response,step response and sine response.The experimental results show that the performance of the STSMC-ADRC proposed in this paper has better tracking performance and better anti-interference ability than PID controller,At the same time,the feasibility of the application of ADRC technology in the system is verified,which provides a reference for improving the performance of the electromagnetic railgun servo system.