Research On Multi-axle Steering Electronic Control Of Heavy Vehicle

Chassis technology on Heavy Truck is particularly important, it determines the flexibility, the exercise of stability and driving safety to the Heavy Truck. Chassis technology will have a direct impact on the Heavy Truck can withstand the complexity of the work environment. At present, foreign- heavy truck has been developed to a very high level, they have a better chassis technology, tactical flexibility and cross-country ability are strong ; they could Operate in the rugged road and in moving. By comparison, domestic heavy truck is still in the preliminary stage, compared with some developed countries there is a great gap. In our country, only a handful of companies to produce Multi-axle Steering Heavy Truck, and the chassis technology is backward, mostly based on mechanical steering, and do not have automatic control features. Through access to a large number of relevant information, and analysis Modern Multi-axle Steering technology,this article made a deeply research on electronic control system of Multi-axle Steering technology of 7-axle Heavy Truck .In this paper, the overall design idea is that Select an advanced control strategy(This article is used with the laboratory control strategy of cg zero lateral angle)and migrate it to electronic control systems to control the Multi-axle truck to realize better Chassis technology.the core of Electric control system is ECU, some external circuit were layouted aroud the ECU,they connected ECU to external steering execution module and signal acquisition module,thereby ECU would control the implement mechanical components. As there are more tasks to be completed by the electric control system and the relationship between the task is complex,this paper presents a more popular handling multi-task operating systemμC/OS-II,μC/OS-II have the following characteristics: Able to respond to asynchronous events,context switching and Middle delay time have Certainty,with a priority interrupt scheduling, use of preemptive scheduling strategy, memory Locking function,to achieve the synchronization tasks. Therefore, the use ofμC/OS-II system enables a higher response rate and optimum operating procedures. In this paper, the specific contents are as follows:According modular design concept, In this paper, the electronic control system will be divided into two groups: main control module and the module.The relationship between the two is that main control module responsible for the acquisition value and the front wheel angle value,then rear-wheel angles value calculated using zero lateral angle control strategy to transfer to implement module, and then implement module deal with rear-wheel angle value,and output voltage signal which can control implementing mechanical components.In this paper , based on the vehicles to the implementation of the actual parameters of the hydraulic system, through proportional valve direction of the flow equations, non-symmetrical load hydraulic cylinder flow equation and electro-hydraulic proportional throttle direction equation derived from the electro-hydraulic proportional valve drive voltage signal to the hydraulic cylinder displacement of the transfer function. Using Simulink modules in Matlab software to simulate to test the transfer function approximation to prove transfer function is desirable. Analysised of the PID control algorithm, and use incremental PID control algorithm as the implementing mechanical components of the control method.On the electrical control system design, the first task is to choose the hardware equipment. In this design,we need to collect speed acquisition value,angle of the front wheel and rear-wheel angle, collecting information needs of some sensors. In this paper,through the experience of the broad masses of researchers,the cost-effective of components and access to a large number of relevant information. The hardware to do the following options: Hall speed sensor used to collect the speed of the truck; use EPC-755A optical encoder to collect the front wheel angle value; selection LWE series hydraulic cylinder displacement sensor to collect rear-wheel angle value (through collecting the hydraulic cylinder displacement values to achieve). Selecting AT89S52 MCU chip as the core of the ECU. Finished the hardware choice, the next step is the external circuit design, the design of this external hardware includes: Speed signal acquisition circuit,front-wheel angle signal acquisition circuits,hydraulic cylinder displacement feedback circuit,solenoid valve drive circuit and the expansion of AT89S52 data memory circuit. Also included: power supply circuit of the MCU,clock circuit,reset circuit. Finally, the structures of the main control module and implementation module of the overall circuit was done, So that the hardware design of the electronic control system would be more complete.The software of this system also includes main modules and implementation module . Because of the number of tasks in main control module is numerous,and this control system requires a higher response rate, Through studying the multi-tasking real-time operating system(μC/OS-II) in a depth way, AccordingμC/OS-II of the many characteristics, Multi-axle Steering Electronic Control of Heavy truck which based onμC/OS-II was proposed. The work in control modules is divided into 9 small task,andμC/OS-II scheduling these 9 tasks, so that they will operate in a best way. The software of implementation module was prepared by using assembly language. Including main program,rear-wheel angle of signal acquisition procedures,PID control subroutine and PWM generation subroutine.MultiSim8 simulation software used in this paper on the electrical control system of the external circuit simulation .The main simulation was on the front-wheel angle signal acquisition circuits and solenoid valve drive circuit ,and the simulation results indicate that the two circuits is correct. In the laboratory, the hardware and software of the electronic control system were debugged.In addition, PCB of the system was designed by using Protel DXP software. Finally, the article summarizes the conclusions drawn and innovation in the course of the study, as well as deficiencies in the work and future research directions.