Research On Vibration Suppression For Boom Luffing Of Telescopic Boom Aerial Work Platform

Aerial work platforms, a type of engineering machinery equipment, are applied to elevate workers, tools and materials to the specified location for working. Because of its flexibility, high efficiency and security, aerial work platforms are widely used. With the addition of boom length and reducing of boom stiffness during lightweight design, the boom vibration of the aerial work platform will be caused in the rapid movement, so how to suppress the vibration, making it more stable and safe is important, which has theoretical and practical significance. In this paper, the analysis model of the luffing system of the aerial work platform has been established considering certain working conditions based on the phenomenon of boom vibration during the luffing process. Then the detailed calculation is performed on the parameters from the actual equipment. Through the simulation, the vibrant behaviors of the boom response are gained and the feedback gain is presented. Finally a closed loop system is built which suits to suppress the vibration of the boom efficiently. Main researched contents as follows:(1) Base on every aspect of luffing hydraulic system of telescopic boom aerial work platform, the transfer functions of electro-hydraulic proportional control system are built. In order to improve its performance as well as eliminate the tracking error basicly, compound regulation containing PID and feedforward are used.(2) According to the structure dimension of aerial working platform, the geometry relation between luffing angle and length of the luffing hydraulic cylinder is obtained. Then based on the homogeneous beam bending vibration theory, at the same time, considering the centralized quality and varying section of boom, the vibration partial differential equation is obtained, with boundary and continuity conditions. In the end, the state space expression of boom system with luffing angle as input is obtained.(3) The whole simulation model of the boom luffing system is established in Simulink and the luffing angle of boom is designed. Through simulation, the response of angle displacement, velocity and acceleration of boom tip are analyzed.(4) Base on the original open control system, according to the state space equation, pole placement method and linear quadratic optimal control theory are respectively applied to design the feedback gain vector and the feedback value, which is compared with the input signal, is send to input plot of electro-hydraulic valve. Finally the closed control system is obtained. Through simulation, the effect of vibration suppression is analyzed.As the result of the simulation, the closed loop control system based on pole placement method can suppress the vibration of the boom efficiently, nevertheless there is steady-state error. The closed loop control system which based on linear quadratic optimal control theory not only suppresses the vibration of the boom efficiently, but also eliminates steady-state error to an extent.