Research On Mechanical System Of Liquid Automatic Unloading Equipment Based On Paralell Mechanism

With the growing scale of petrochemical enterprises, the efficiency and performance of the Liquid Loading/Unloading Equipment has attracted more and more attention. At present, Most enterprises in China is still in use of the traditional Liquid Loading/Unloading Equipment inclueding the Metal Hose and the Crane Arm, which has the disadvantage of inaccurate docking, larger labor intensit and lower efficiency. In order to improve the situation, this paper proposed the idea that the Six Degrees of Freedom Parallel Mechanism technology is applied to the design of an innovative automatic Liquid Unloading Equipment used in automobile transportation mode. This paper mainly focused on the research, design and optimization of mechanical structure of the innovative automatic Liquid Unloading Equipment, designed the pneumatic driving metal hose and the parallel mechanism with a large work space, established the coordimated simulation experiment platform which validated the feasibility of the design.Firstly, on the basis of the analysis of the functional requirements and the key technical indicators of the innovative automatic Liquid Unloading Equipment, the paper analyzed the docking process between the pipeline and the discharge outlet, and studyed the docking method based on the kindliness. Combined with the actual working condition, the docking method that bonded the metal hose on the hyfraulic driving paraller platform was determined and the mechanical overall plan of the innovative automatic Liquid Unloading Equipment based on parallel mechanism was established.Then, to realize the docking between the pipeline and the discharge outlet automatically and reliably, the pneumatic driving metal hose was designed adaptively based on the principle of offset slider-crank mechanism, which can satisfy the automatic clamping operation requirement of hand w ith small size.Due to the kinematic performance of the innovative automatic Liquid Unloading Equipment is directly related to the structure parameters of parallel mechanism, the paper preliminary selected the structure parameters of the parellel mechanism and analyzed its kinematics,dynamics and work space on the basis of the theory of parallel mechanism. Further more, the relationship between structure parameters with work space, elongation of hydraulic cylinder, dexterity was analyzed in this paper. And the structure parameters was optimized based on the genetic algorithm, so the parallel mechanism with better performance and compact structure was obtained which has a large movement space with lateral to 0.5m, surge to 0.5m, lift to 0.2m, pitch to 20°, yaw to 20°and rolling to 20°.Finally, the integrated coordimated simulation experiment platform was built to validated the feasibility of the design and study the performance of the system. The simulation model of the hydraulic servo system was established based on Matlab/Simulink; the virtual prototype of mechanical system was established based on Adams; and the coordimated simulation experiment platform integrated control system and virtual prototype was built by Adams/Controls interface module completing kinematics simulation validation successfully. In addition, the paper proposed the PID control method with feedforward compensation which keep the tracking error of displacement within 0.5mm and keep the tracking error of angle with 0.028°. the innovative automative Liquid Unloading Equipment was proved to be feasible.