Drive Planning And Virtual System For Self-Propelled Modular Platform Transporter

Large powered platform transporter and its multi-vehicles combination system(generally called Self-propelled Modular Platform Transporter), which is integrated product of machine-electric-hydraulic , are fundamental tools to transport huge-size and heavy-duty parts,equipment and large-scale structures and widely used in machinery manufacturing,aerospace,construction machinery and many other fields. The main features are as following:①A walking machinery with multi axles,②Hydraulic-independent suspension, which can help platform of the transporter to realize automatic leveling movement,③Independent steering between wheels,④Modular combination, which can link multi-transporter to realize synchronization,⑤Hydraulic driving.Compared to foreign products, the transporters in domestic exist great shortcomings as following:①The problem of poor harmonization and synchronization of multi-platform leveling movement and multi-transporter steering movement during multi-transporter operation;②Insufficient bearing capacity, especially for huge-size and heavy-duty parts. Besides, because of the steering system of the transporter for multi-wheel independent steering is based on CAN-BUS electric control(we can also call it digital steering system), there's no mechanical linkage between steering wheel and vehicle wheels, so drivers are lack of the manipulating force feeling during operating the steering in driving ,so it brings operation arbitrations. In this article, the kinematics analysis is taken for both one transporter and multi-transporter, based on the model of platform leveling movement and kinds of steering patterns of one transporter, harmonizing leveling and synchronizing steering movement is researched for multi-transporter. For the problem that the poor bearing capacity coming from the security issues during carrying problem, it is necessary to plan and analysis its allowable loading area under different grouping patterns on uneven road. At last, for the problem of lacking manipulating force in driving, an digital steering system with force feedback is developed for it. In addition, the models built above are taken a simulation with virtual prototyping technology, and relative conclusions are obtained at last.The innovations of the research:1) The method of kinematics modeling based on theory of mechanism of parallel robot for SPMTSPMT is equivalent to the mechanical model of the parallel robot, the knowledge of inverse kinematics solution for parallel robot is used to build the math model of platform leveling movements of one transporter, and multi-platform harmonizing leveling movement model is built based on that. Matrix operations used in equations greatly reduce the computational complexity of the control code, which improve the program running speed and real time performance and enhance responding speed among transporters.2) The method of modeling for the allowable loading area of SPMTThe hydraulic suspension system of SPMT is decomposed to groups that the cylinders of one group are connected and equivalent to one support, and the equivalent supporting point and direction of the force applied on platform is determined by force equivalent principle, then a multi-point supporting force model is built in order to find out the allowable loading area of SPMT group on a uneven road. The statically indeterminate problem is produced by multi-point support is solved based on the elastic support's deformation harmonization principle. The allowable loading area is achieved by intersection of anti-capsizing area derived from the supporting boundary formed by supporting points and securing area generated by loading limit of each group. Finally, a visual GUI is built with MATLAB to reflect the real-time change of allowable loading area during the transporter running on uneven road, so whether it is security or not in current state is easily judged.3) The digital steering system with force feedbackThe digital steering system with force feedback is developed to solve operation arbitrariness to steering wheel and to improve a sense of perception to terrain for diver. In addition, a HIC(Human Computer Interaction) based on OSG(Open Sense Graphic) is built to check the validation of the new steering system, a virtual transporter's steering movement in virtual environment is controlled by a real steering wheel outside, by the same time the steering force information from virtual environment is feedback to servo motor, then the force generated by the motor is loaded on the steering wheel, so the manipulating force sense is felt by driver.