Research On Control Strategy Of Multi-motor Servo System Based On Discrete Mode

With the ongoing promotion of "China Manufacturing 2025," the needs for servo systems are increasing as a result of the development of high-end equipment processing,digital manufacturing,and other developing sectors.Using many medium and small inertia motors to drive a big inertia load simultaneously is an efficient control method when faced with a large inertia load.Additionally,digital computers are used for sampling and control in the majority of discrete systems represented by high-precision CNC machine tools,and in industrial servo systems,control design methods based on discrete systems outperform controllers using continuous system design in terms of stability and realizability.This work investigates the high-performance discrete control approach of the multi-motor drive servo system while taking into account the impact of the inevitable nonlinear disturbance torque and input saturation on the control performance of the multi-motor servo system.In addition,the discrete control approach of servo system based on feature model of data identification is investigated since it is frequently challenging to construct precise mathematical models of controlled objects in complicated engineering applications.In conclusion,based on the backstepping method,this paper comprehensively applies the theoretical knowledge and technical means such as fuzzy logic system,command filtering technology,terminal sliding mode and Lyapunov stability theory to study the highprecision servo control problem of multi-motor drive.The main work of this paper is summarized as follows:Firstly,for the dual-motor drive servo system with disturbance torque,based on the backstepping method,combined with the command filtering technology,the problems of ’computational explosion ’ and ’ causal contradiction ’ are avoided.The adaptive technology of discrete system and fuzzy logic system are used to deal with the uncertain nonlinear term,and the error compensation equation is established to deal with the filtering error generated by the filter and further improve the tracking accuracy.The stability of the system is proved by Lyapunov stability theory.The simulation results show that the designed discrete control method can make the dual motor servo system track the desired signal stably under the influence of disturbance torque,and the tracking error converges to a very small neighborhood near the origin.Secondly,aimed at the inevitable input saturation phenomenon in the practical engineering application of dual-motor servo system,a dual-motor servo control method considering input saturation is designed.Firstly,the common input saturation problem in the motor is analyzed mathematically,and it is limited to a certain range by combining the piecewise function.Secondly,the command filter is used to filter the virtual control signal.By obtaining the difference of the signal,the calculation amount of the traditional backstepping method is effectively reduced,and the ’ causal contradiction ’ problem in the design process of the traditional backstepping method is overcome.The compensation mechanism is introduced to deal with the filtering error,and the stability of the closed-loop system is proved by Lyapunov stability theory.Finally,the simulation results show that the control strategy designed in this paper can make the dual-motor servo system with input saturation achieve better position tracking performance.Thirdly,the control performance of the dual-motor servo system based on the traditional discrete model is affected by the model complexity and modeling accuracy.The controller form is complex and highly nonlinear,which brings difficulties for engineering implementation.Therefore,based on the characteristic model theory and the terminal sliding mode control method,a discrete adaptive terminal sliding mode controller based on the characteristic model is designed.In addition,the finite-time stability of the closed-loop system is proved.Finally,in the experiment of dual-motor servo turntable,it is verified that the proposed control method has better control performance when tracking three typical command signals of step,slope and sine,and the tracking error can be kept in a sufficiently small neighborhood near the origin.