The Design Of Highway Weight-calculating Charge System Of Gansu Province

With the rapid development of highways in China, all kinds of shortcomings also gradually revealed according to the model of charging, the increasing of overload vehicles caused the damage of highway-subgrade and pavement, and it greatly shortened the normal life of highway. Overload vehicles have deep impact on safety of road traffic, which is the main reason of leading to road accidents. Overloading cause the reduction of freight transport price, and also cause the damage for legal transport vehicles. Actual way of toll by vehicle type is the main reason of "small standard of big ton" and vehicle modification. With regard to the same model, empty and heavy vehicle charges the same fees, so it can not truly reflect vehicle possession on the road and use level, but charging by weight is gradually been accepted that regards as a more fair, reasonable and has the charging pattern of economic regulation mechanism.This text makes requirement analysis based on the weight-calculating charge system, and makes the modular design for the system in accordance with functional requirements. System module including:weight sensor module, vehicle separation module, tire identification module, microcomputer system module and so on. Controller adopted MC9S12DG128 produced by Freescale Company, this type of single-chip microcontroller is rich with serial communication interface, CAN bus communication interface. Bus clock frequency can up to 16 MHz and can use PLL multiplier access to higher bus frequency, which can completely satisfy the measurement speed requirements of the weight system. In the fields of software design, weight algorithm, vehicle separation algorithm, tire recognition algorithm and the state of pressure to cheat recognition algorithm are mainly analyzed and designed. And weighting system was experimentally tested by comparison between experimental data and actual weight, and it is proved that the system can meet the engineering standards of weight measurement.The following problems are mainly solved in design:First, temperature compensation and the differential amplifying of weighting sensor; Second, IR anti-interference processing in vehicle separation system; Third, principal factors affected charging accuracy by weight in charging system and how to overcome the cheating by pinning the ground.