The Research And Implementation Of Tire Pressure Monitor System Of Automobile Based On Estimation Of Tire Longitudinal Stiffness

Nowadays automobile have gradually become tools of family going out.The safetyissue of automobile is also getting more and more concerns.An abnormal tire pressure isable to lead to tire burst on a running vehicle,which is very dangerous to passengers’safety.Besides,for fuel economy,an abnormal tire press would bring more consumption ofgas.So, how to monitor a tire pressure exactly and efficiently in real time is a problem tobe resolved.American famous specialist of automobile dynamics Doctor ChristopherR.Carlson’s theory indicates that tire longitudinal stiffness is inversely proportional totire pressure.The thesis bases on this theory,judge the abnormalities of pressure of a tireby evaluate tire longitudinal stiffness timely,and design a indirect tire pressure monitorsystem with a DSP as a core,this system could help detect the abnormalities and then takenecessary measures.To begin with,the thesis introduces the history of development,recent status andclassification of tire pressure monitor system.Then it takes the mechanical property of atire as a hitting-point,associated with the analysis of force analysis of an automobile,builds a mathematical model.As domestic scholar generally adopted pattern searchmethod, and the precision of which is not ideal,this thesis use variable step length toimprove the precision and analyze the theory with comparison and simulation.Aftergetting tire longitudinal stiffness,compare it with preset stand threshold,then it couldjudge the abnormal situation and alarm the user.In the hardware circuit,for the powerful data processing ability of DSP,this thesisdesigned a hardware circuit based on TMS320F2812,which is special for its four layerspipe-line,rapid operation.And it has two event managers,exactly can be applied incollecting four wheel speed signals.Peripheral circuits mainly include power circuit,signal collecting circuit and alarm circuit.Using the signal from the ABS speedsensor,after being processed by DSP,the system could judge the abnormality and give analarm.In the code development,this thesis mainly adopt C language to realize all functionon CCS platform.This tire pressure monitor system is special for its brief structure,rapid operationand accessibility of realization.It can deduce the possibility of inaccuracyalarming,possessing a high used value.