Research On Control Performance Of Hydraulically-assisted Universal Vehicle Based On Electro-hydraulic Servo Control

As the key equipment of thermal power plants,the fan mill plays the role of grinding the coal into powder.In order to perform regular maintenance on the huge fan-type impact impeller in the fan mill,a hydraulically-assisted universal vehicle equipped with a manipulator was designed to complete the tasks of dismantling,installing and transporting the fan-type impact impeller.This paper investigates the hydraulically-assisted universal vehicle,and designs a steering system based on electro-hydraulic servo control to satisfy flexible steering and inposition accuracy for the vehicle,and to realize vehicle universal control.Firstly,this paper summarizes various universal moving platforms and control methods from domestic and abroad.On the basis of learning the concept of universal moving and the theory of synchronous control,this paper proposes rack and pinion swing hydraulic cylinders as the steering actuators of the hydraulic system to improve the steering control accuracy,and uses casters as the wheels to improve the mobility and load capacity of the hydraulically-assisted universal vehicle.Secondly,according to the requirements of flexible steering and universal movement of the vehicle,a computer control system with five driving modes is designed,so that the four wheels of the hydraulically-assisted universal vehicle can be steered according to five different angle relationships to obtain smaller turning radius,universal translation and the ability to rotate in place.By using suitable driving modes in different occasions,the hydraulically-assisted universal vehicle can be operated flexibly by the driver in the complex working environment of thermal power plant.Thirdly,according to the technical requirements and steering action requirements of the hydraulically-assisted universal vehicle,the rack and pinion swing hydraulic cylinder is designed as the actuator of the hydraulic steering system,and the fatigue analysis of the rack and pinion mechanism is carried out.Then the hydraulic pump and servo proportional valve are selected.After that,the electro-hydraulic servo system of the hydraulic universal vehicle is investigated,the mathematical model of the control system is established,and the appropriate synchronization control strategy is selected by analyzing the synchronization performance of the four-cylinder synchronous control system.Then,in order to improve the synchronous control performance of the system,PID control is added into the synchronous control system of the steering cylinder group,and the parameters of the PID controller are tuned by the traditional method and seeker optimization algorithm respectively.The simulation results show that the PID control system tuned by the seeker optimization algorithm has better synchronous control performance than the traditional method.Finally,in order to improve the anti-interference ability of the control system,RBF-PID error compensation control is added to the system.The simulation results show that the synchronization performance and robustness of the system are improved significantly after the RBF-PID error compensation control was added.The hydraulically-assisted universal vehicle combines the electro-hydraulic servo system with the intelligent control algorithm,which improves the synchronous performance and antiinterference ability of the steering drive cylinder group,and provides a certain reference and theoretical basis for the research of related universal mobile platforms.