Research of Mechanical Resonance Analysis and Suppression Control Method of the Servo Drive System

Transmission mechanisms of the servo drive system are not a pure rigid body, and the existence of the elastic transmission mechanisms will make the system generate mechanical resonance. Aiming at mechanical resonance of the servo drive system, the resonance generation mechanism is analyzed, the four-mass model considering the time-varying meshing stiffness of the gear is established, and the influence of different stiffness parameters on the mechanical resonance of the system is researched in this paper. The composite controller of Model Predictive Control (MPC) with Notch Filter is used to simulate the mechanical resonance suppression of the four-mass servo system considering time-varying meshing stiffness, and it is compared with the mechanical resonance suppression method based on Model Predictive Control. The simulation results show that when the step speed is 200 r/min, the overshoot is reduced from 11.6 r/min to 1.1 r/min, which is reduced by 90.5%. Under the impact load condition, from 10 Nm to 30 Nm, overshoot is reduced from 34.3 r/min to 12.8 r/min, reduced by 62%, and torque oscillation is reduced by 81.5%. Therefore, the composite controller of Model Predictive Control with Notch Filter can suppress the mechanical resonance problem effectively, caused by elastic transmission, and improve the robustness of servo drive system.

Application of fuzzy sliding mode control method based on cyber-physics fusion system in mechanical resonance suppression

Modern high-end digital manufacturing has continuously improved the performance requirements for servo drive systems. High-performance servo drive systems should have excellent dynamic performance and steady-state performance. At present, an AC permanent magnet servo drive system using a permanent magnet synchronous motor as the drive motor has become the mainstream of contemporary servo drive systems. Servo system (servo mechanism), also known as servo systems, generally contains feedback control links, mainly used to accurately follow or reproduce a certain process. The servo system is mainly composed of a controller, a power drive device, a feedback device, a transmission device, a motor, and a load. In a servo system, the existence of mechanical resonance will cause serious damage to the transmission mechanism of the system and will reduce the reliability and accuracy of the system. When the performance of the system deteriorates severely, it will lead to system instability or even safety accidents. This article aims to study the use of fuzzy sliding mode control methods to control the generation of mechanical resonance, to further eliminate the phenomenon of mechanical resonance in the servo system. This paper puts forward the methods to eliminate chattering generated by sliding mode control, mainly including filtering method, eliminating uncertainty, intelligent algorithm optimization, reducing switching gain, and fan shape. The experimental results in this paper show that when the angular speed feedback of the motor is adopted, the maximum value of the speed difference is close to 3rad/s. It can be considered that there is resonance in the system, and the load resonance is the main factor. When the angular velocity feedback at the load end is used, the maximum value of the speed difference is about 0.05rad/s, and it can be considered that the resonance has been successfully suppressed.

Vibration Diagnosis and Treatment for a Scrubber System Connected to a Reciprocating Compressor

Severe vibration was observed at a scrubber system connected to a reciprocating compressor during commissioning stage. Field measurements including vibration, pressure pulsation, and modal experiment were conducted to determine the causes of vibration, which showed that the excessive vibration was caused by pressure pulsation-induced mechanical resonance. Vibration reduction treatment for mechanical resonance avoidance via the installation of support on scrubber was proposed and then validated by resonance analysis and one-way fluid structure interaction (FSI) analysis. Resonance analysis showed both the dominant frequencies of pressure pulsation and rotational frequencies of compressor were beyond resonance regions, and FSI analysis indicated that the vibration levels of the scrubber system at its design conditions were within the allowable limit. Installation of two braces with a band clamp on the scrubber was implemented. The effectiveness of the treatment was verified by comparison of measured data before and after scrubber modification; the peak amplitudes occurring at the dominant excitation frequencies in both vibration and pulsation spectra declined greatly after modification, which guaranteed the long-term stable operation of the scrubber.