Reliability And Routing Optimization Of High-level Order-picking Trucks In The Stereoscopic Warehouse

With the rapid development of modern logistics transportation, the number ofstereoscopic warehouse is increasing gradually. The high-level order-picking truck is one kindof warehouse forklifts. It is an important transport tool in the order-picking task of thewarehouse, which can alleviate labor strength and improve operation efficiency to a greatextent. At present, self-owned brand advanced warehouse forklifts in domestic market is veryrare, especially high-level order-picking trucks with more than seven meters lifting height arefully dependent on imports. This dissertation was sponsored by regional cooperation program“Research and Development on Key Technology of High-level Order-picking Equipment”,which studies on reliability, design and development, stability and routing optimization ofhigh-level order-picking trucks.In this dissertation, the reliability of current high-level warehouse forklifts was studiedsystematically. According to fault datum of high-level warehouse forklifts collected fromusers, weakness and potential defects of high-level warehouse forklifts were found by meansof FMECA and FTA. The reliability analysis results provided a basis for functions such asoverall scheme, structural optimization, control strategy design, hydraulic system design,manufacturing process improvement and fault diagnosis and maintenance of high-levelorder-picking trucks.Based on the reliability analysis of high-level warehouse forklifts, mechanical systemdesign, electrical control system design and hydraulic system design of the order-pickingtruck with lifting height up to nine meters was finished separately. First of all, the mechanicalsystem of high-level order-picking truck was designed and developed based onmodularization, which is composed of chassis unit, mast system unit and operator platformunit. According to their own functions and features, the detailed structure of each unit wasdesigned. During the design process, finite element method and digital simulation technologywere used to optimize vehicle structure repeatedly. Secondly, hydraulic system circuit of thetruck which realized lifting and lowering of the mast system was designed according to itslifting speed, lifting height and rated load. Lastly, control strategy of the order-picking truckwas designed and the hardware platform of control system was built. As a result ofcommunication of CAN bus, the reliability and data rate of control system was improved tosome extent.The dynamic stability of high-level order-picking trucks was studied comprehensively.Firstly, the dynamics equations of the model of high-level order-picking truck in differentmotion states were established based on the D’Alembert principle, the equations of theprototype in this dissertation were solved, and then its dynamic stability was analyzed.Secondly, the travelling process of high-level order-picking truck was simulated using virtual prototyping. The simulation result coincided with theoretical result to some extent, whichverified the rationality of dynamic model established in this dissertation. Finally, the stabilityof the high-level order-picking truck was verified by the tilt platform test. In order to improvethe stability and maneuvering performance of high-level order-picking trucks further, thecenter of gravity self-balanced method of order-picking truck was presented in thisdissertation for the first time.Based on characteristics of order picking of high-level order-picking trucks in thewarehouse, a mathematical optimization problem in three-dimensional space was modeled.Genetic-Ant colony hybrid algorithm was constructed and applied to solve the optimizationmodel. Experimental results showed that the algorithm presented in this paper had goodoverall search ability and astringency. It reduces order-picking time and improves operationefficiency to a great extent by using Genetic-Ant colony hybrid algorithm. What’s more, theenergy of battery was saved and the continuous working time of the truck was extended.