The Design And Implementation Of Dynamic Vehicle Weighing Instrument Based On SMALLRTOS51 Embedde Operating System

By the economic soar of motherland,Chinese government increasingly invests in communications construction.For instance,the communications construction investment scale of Shan'xi Province in 2008 is about 22 billion yuan.However,because of money's driving,the serious phenomena of vehicles which exceed the weight limits can be found in every region.Those vehicles have done great damage to the pavements and bridges,chocked up traffic and caused out of estimating economic losses.Not only has the phenomena greatly shorted the lifespan of these roads and bridges,but also greatly increased road maintenance charge of the government.Dynamic vehicle weighbridge system has been designed for restraining the phenomena of vehicles which exceed the weight limits.Because of its many virtues such as simply weighing process, high calculate precision,not easily chock up traffic and etc,the system has been used universally.Making use of dynamic vehicle weighbridge system has controlled the phenomena of vehicles which exceed the weight limits,decreased the stress of pavements and bridges and saved large expenses for the government to a great extent.The technology of dynamic vehicle weighbridge has been developed for many years in our country.The research and development for the key technology of the system which is the weighing instrument has always been paid close attention.According the previous study,some people use PC motherboard or DSP as hardware platform and some others use embedded Linux operating system for system support.These methods either bring high cost or not easy to carry out in technical.In this paper,a realization of a new dynamic vehicle weighing instrument has been put forward.The new instrument uses single chip microcontroller as the platform and used the SMALLRTOS51 embedded operating system for system support.This method not only decreases the cost of instrument but also puts it easy to carry out in technical.The main contents can be summed up as follows:Firstly,make hardware design,including the circuit design of the single chip microcontroller,data sampling,data communication and display.Secondly,make analysis for the sample data to the choice and designing the digital filter.When a vehicle passes the weighing platform,the sample data not only includes the true value but also includes some others interferences.So a mass of sample data and many times simulate experiment should be need to determine the best digital filter.Thirdly,do the choice for the effective sample data.Because of the wobbling interference by the vehicle when weighing,there are some sample data have large error according the true value.The choice for the effective sample data has been need to save calculating time,to simple calculation and to improve the calculate precision.Finaly,make the realization of weighing algorithm in c language.This paper adopts check table method which compiles the best digital filter's coefficient into code then programs into the single chip microcontroller. Checking table when calculating,this method not only simples the calculation but also saves calculating time.The result can be acquired after a convolution had been done between the sample data and the digital filter's coefficient.