Research on APS system for wheel loader based on embedded RTOS

Owing to frequent operating of gear shifting and high strength of driver, Automatic Power Shift (APS) is urgently needed in new-style of construction machinery. This paper aims at a new strategy of APS for wheel loader based on the National High Technology Research and Development Program of China (863 Program). The APS adopts AMT mode, consists of a central controller and a gearbox from ZF in Germany. The central controller of system uses DSP TMS320LF2407A from TI as the main hardware workbench, and the Embedded Real-time Multitask Operating System mu c/os-II as the software workbench. And there is a LCD monitoring real-timely the machine state by CANbus. This article presented briefly the hardware structure of the micro-control system, then placed emphasis upon the strategy of automatic gear shifting based on embedded software system and the mechanism of fault diagnosis. We realize the APS by the gear state shifting, after acquiring the condition of road, state of vehicle and the wills of the operator In addition, when the machine cannot shift gear normally, the program can acquire the transmission oil pressure continuously on requested, and can return the data to server for diagnosis. The system has been applied on certain new-style wheel loader All the operator has to do is select forward, reverse or kick-down, and APS automatically selects the right gear, depending on road status, engine revs, speed and the mode selector.