Development Of Adaptive Speed Limiting System Based On CAN Bus Online Upgrade

Automobile has become the most important means of transportation for people to travel,along with the continuous expansion of road network and the rapid development of automobile industry.People enjoy the shortcut and convenience brought by vehicles,along with the increase of road traffic accident.One of the main reason of traffic accident is speeding.To limit the vehicle speed is an effective way for avoiding traffic accident.The speed limit standard of different roads is stipulated in the road traffic safety law of China,and the maximum speed limit value of a certain section is determined.However the road conditions are more complex and different sections have different speed limit standard,so that the situation of over speed is often happing for negligence or unconsciousness of the driver,which cause the accident.Therefore,it is necessary to install a speed limit device that can control the speed of the vehicle.In this thesis,an adaptive speed limit system based on CAN bus and can online upgrade is developed.The system can automatically change the threshold of speed limit value according to different sections of vehicles,and it can overcome the shortcomings of traditional vehicle GPS navigator,which can only send out sound or light alarm,but can't control the speed of vehicle automatically.The main purpose of the system is automatically and effectively control the speed of vehicle in real time.The corresponding speed limit value is set according to the different roads.The output voltage of the accelerator pedal is changed by comparing the relationship between the driving speed and the speed limit value,so that the driving speed is controlled near the limit value for reduce the possibility of speeding.In addition,the online upgrade function is added to the system,which can accelerate the speed of system development and test.The main innovations of this thesis are as follows: put forward the accelerator pedal control algorithm,which combines the current speed,the input signal of the accelerator pedal and the speed limit value to change the output signal of the accelerator pedal,which realizes the active control of the driving speed and makes the driving experience comfortable.Using the intelligent mobile phone with the build-in GPS system instead of the traditional GPS navigator to obtain the speed limit value,it effectively reduces the space of the installation of the internal fixed equipment of the vehicle,and achieves the effect of auto changing the speed limit value of the vehicle at different speed limits.After the design of the system is completed,the system is tested on the simulated environment and real vehicle environment function.The results show that the functions of each module of the system are normal and meet the design requirements,and the overall design is reasonable.The system is simple in structure,low in cost,and occupies less space inside the vehicle,so it can effectively intervene the speed of vehicle in real time and adapt to the speed limit value of different speed limits.The CAN bus can be used to upgrade the speed limiter application online.