Real-time Research On 4WID Bus Of CAN Bus

Due to the shortage of resources such as oil and coal,and the air pollution caused by traditional fuel vehicles,countries around the world have begun to vigorously develop new energy vehicles.However,with the development of automotive electronic technology and control technology,as well the demand for vehicle's safety and comfort,more and more electronic control devices and communication devices are used in automobile vehicles,which leads to more information exchange frequently,increasing the load rate of the vehicle CAN bus.The traditional message arbitration scheme has gradually failed to ensure the real-time performance of CAN bus.The real-time of the automotive power's CAN bus is directly related to vehicle performance and safe driving,so it is necessary to find a way to ensure the real-time performance of the CAN bus.There are two main options for improving the real-time performance of the vehicle's bus: one is to increase the bus transmission rate,and the other is to optimize the traditional CAN bus network so that it can guarantee the real-time information under high load rate.At present,the maximum transmission rate of the CAN bus is 1 Mbps,and other buses such as FlexRay can achieve higher transmission speeds,but due to cost problems,they cannot be popularized in a short time.Other technologies such as FTTCAN/TTCAN have also caused cost increases,so that optimize the traditional CAN bus network become the only solution that can solve CAN real-time problems without causing cost increases.4WID's CAN bus causes vehicle anomalies due to real-time problems,This paper use this CAN bus introduces the CAN bus technology and 4WID CAN bus,and also analyzes the cause of the CAN bus delay.Then,analyzed several real-time scheduling algorithms,according to the waste of EDF algorithm design the DR-EDF scheduling algorithm.DR-EDF algorithm specifies when filling packets,first comparing the last transmission packet and removing duplication of byte,fill the live byte into the packets and transmitted.When met the same priority,packet with short frame was transmit first.This effectively solve the problem of EDF algorithm repeats occupy bus resources and also improve the real-time nature of the packets.In order to verify the performance of the DR-EDF algorithm,the 4WID vehicle network was tested and analyzed in the CANoe environment and the hardware experimental system environment,and obtained various parameters of the CAN bus.Through analysis,it is verified that the DR-EDF algorithm proposed in this paper can effectively improve the real-time performance of the 4WID's CAN bus.Finally,a non-critical periodic message trigger transmission scheme was proposed According to some of the possible packet data bytes in the network that remain unchanged for a period of time.And built the simulation model based on the DR-EDF scheme in the CANoe environment.The network scheduling capability of the solution provided a reference for future CAN bus optimization research.