Research On Electro-hydraulic Servo System Of Towed Load

Electro-hydraulic servo system of towed load, the function of which is to simulatethe towed load exerted on the heave compensation device in a towing system of marinevessel for detecting the technical performance, is an important equipment of the halfhardware-in-the-loop simulation system. Developing the electro-hydraulic loadsimulation system with high performance can shorten the development cycle of the heavecompensation device and reduce its cost.Firstly, according to the functional requirements and technical specifications, theoverall program, the technology roadmap of the hydraulic system and control system aredetermined in the paper. The task of calculating key parameters and selecting the mainhardware of the system is completed. The mechanical construction of the key componentsis designed and the hardware design of the system is achieved.Secondly, the mathematical model of the electro-hydraulic load simulation system isestablished in the paper. The stability and closed-loop frequency characteristic of theelectro-hydraulic load simulation system are studied. Then, a control method PID isproposed and a simulation on the system with the PID controller is implemented. Theresults show that the performance of the system could satisfy the requirements throughthe PID controller.Thirdly, the passive loading performance of the system is researched. To eliminatethe surplus torque is a key issue when the system is loaded passively. According to theanalysis of the obtaining mechanism and characteristics of the surplus torque, a speedfeed-forward compensator is designed based on structure invariance principle. The resultsof the simulation show that speed forward-feed compensator has a good effect toeliminate the surplus torque.Finally, owe to the load inertia time-varying of the system, based on speed forward-feed compensator, a fuzzy PID controller is designed, which combines theadvantages of the conventional PID controller and fuzzy controller. The simulationresults show that the fuzzy PID controller can effectively reduce the influence caused bythe load inertia time-varying when the system is loaded passively.The research on the electro-hydraulic servo system of towed load presented in thispaper lays a foundation for the future experiment.