CN106370344A - Kalman filter based tire pressure and temperature optimization estimating method - Google Patents

Abstract

The invention relates to a Kalman filter based tire pressure and temperature optimization estimating method, which belongs to the technical field of electronics of vehicles. The method comprises an estimator correction process and a tire temperature and pressure estimation process. The estimator correction process can correct the gain of the estimator according to the external disturbance of the vehicle and the sensor noise and improve the accuracy and anti-interference ability of the tire pressure and the temperature estimator. The tire pressure and temperature estimation process is mainly based on the state equation composed of the tire state and the vehicle state to predict. Based on the predicted state, the correction gain is used to correct the predicted state and calculates the optimal estimation values of the tire temperature and pressure. The tire pressure and temperature estimating method serves as a component of a tire pressure monitoring system. The estimated tire pressure and temperature are used as strategic inputs into the tire pressure monitoring system for early warnings. When the tire is in an abnormal state, the early warnings are available so that traffic accidents due to tire burst can be avoided.

Description

A kind of tire pressure based on Kalman filtering and the optimal estimation method of temperature

Technical field

The invention belongs to technical field of automotive electronics, it is related to one kind and is applied to tire pressure monitoring system, based on Kalman filtering Tire pressure and temperature optimal estimation method.

Background technology

According to statistics, in the vehicle accident that highway occurs, 70%-80% is caused by blowing out.And modal rotating radial Tire relies on artificial observation deficency below 25% for the None- identified, leads to more than 85% tire all to there is tire pressure in use not enough Problem.Tire pressure monitoring system is made to become the third-largest security system after abs, air bag.Produce with safety such as air bags Condition ratio, before tire pressure monitoring system acts on accident generation.And ensure that tire pressure is normal, automobile fuel consumption can be saved, extend tire Life-span.Continue the U.S. after September in 2007 implements tire pressure monitoring system solar obligation regulation on 1st, the countries and regions such as European Union also go out Platform is similar to regulation, promotes market accelerated development.

Exploitation tire pressure monitoring system is conducive to improving travel safety, is also current automotive electronic technology and market development Inexorable trend.Compared to traditional body electronics, tire pressure monitoring system is integrated with radio-frequency communication module, tire-like in the confined space The perception of state and anomalous identification module, simultaneously need to realize for a long time may be used under the conditions of no externally fed, high temperature and high acceleration By work, compacter, energy consumption is lower, environment is more severe, reliability requirement is higher.

Content of the invention

In view of this, it is an object of the invention to provide the optimum of a kind of tire pressure based on Kalman filtering and temperature Method of estimation, on the basis of the method obtains noise and the statistical nature of external disturbance by off-line data, using known vehicle With tire condition equation, realize the optimal estimation of tyre temperature and pressure based on optimal theoretical, improve the anti-of tire pressure monitoring system Interference performance, thus realize relatively reliable anomalous identification and early warning.

For reaching above-mentioned purpose, the present invention following technical scheme of offer:

A kind of optimal estimation method of tire pressure based on Kalman filtering and temperature operates in tire pressure monitoring controller On, including initial setting up, estimator makeover process, tyre temperature and pressure estimation procedure.

Described initial setting up is that original state and initial variance are designed, to carry out the estimation of subsequent time；Estimate Device makeover process is modified to the gain of estimator according to the statistical law of outside vehicle interference and sensor noise；Tire temperature Degree and pressure estimation procedure be predicted according to state equation, and on the basis of predicted state using correcting gain to predicted state It is modified, be calculated the optimal estimation value of tyre temperature and pressure.

Further, speed, tyre temperature and the pressure that current sensor measurement is obtained by described initial setting up is as initial State, initial variance is set to offline statistical value or unit matrix；Speed is obtained by wheel speed sensors measurement, and by abs control Device passes through can bus transfer to tire pressure monitoring controller；Tyre temperature and pressure are obtained by tyre pressure sensor measurement, and by penetrating Frequency communications are to tire pressure monitoring controller.

Further, described estimator makeover process includes covariance calculating, correcting gain calculating process；Described covariance meter Calculation process calculated priori covariance square according to state-transition matrix, the covariance matrix in a upper moment, process noise covariance matrix Battle array

Described correcting gain calculating process according to new covariance matrix, observing matrix, observation noise variance matrix meter The optimal estimation value of new correcting gain and error co-variance matrix.

Further, described tyre temperature and pressure estimation procedure include subsequent time status predication, state correction and tire State computation process；Described subsequent time status predication predicts subsequent time according to state equation input and state-transition matrix State value.

Described state correction process, according to status predication value, correcting gain, measures the tyre temperature obtaining and pressure, meter Calculate the optimal estimation value obtaining state.

Described tire condition calculating process, according to state optimization estimated value and observational equation, is calculated tyre temperature and pressure The optimal estimation value of power.

Brief description

In order that the purpose of the present invention, technical scheme and beneficial effect are clearer, the present invention provides drawings described below to carry out Illustrate:

Fig. 1 estimates flow chart for tire condition of the present invention.

Specific embodiment

The invention provides a kind of optimal estimation method of tire pressure based on Kalman filtering and temperature, improve tire The accuracy of temperature and pressure measurement and capacity of resisting disturbance, thus reduce the rate of false alarm of tire pressure monitoring system.The carried side of the present invention The calculation flow chart of method is estimated as shown in figure 1, including initial setting up, estimator correction, tyre temperature and pressure.The present invention provides Tyre temperature and pressure method of estimation execute in tire pressure monitoring controller.Wherein, initial setting up is only on tire pressure controller The electric moment executes once, and estimator correction and tyre temperature and the execution of pressure cycle estimator, until tire pressure controller power down, execute Cycle may be configured as 10ms and runs once.

The tyre temperature that the present invention provides and pressure method of estimation need the data of Real-time Collection to include car speed, acceleration Degree, tire pressure, tyre temperature, vehicle acceleration and speed pass through can bus transfer to tire pressure monitoring control by abs controller Device, tyre temperature and pressure are obtained by tyre pressure sensor measurement, and are transferred to tire pressure monitoring controller by radio communication.

On tire pressure controller during electricity, run initial setting up first, by initial setting up to the original state of estimator and Initial variance is defined, to carry out the estimation of subsequent time.When carrying out initial setting up, by the speed of real-time measurement, tire As the original state of estimator, initial variance may be defined as offline statistical value or unit matrix to temperature and pressure, that is,Offline statistical value can be obtained by existing test data statistics, and computing formula is as follows:

In formula, n is the data volume of offline sampling, v (i) andBe respectively the speed that obtains of ith sample point measurement with Actual vehicle speed, t_t(i) andIt is respectively tyre temperature and the actual tire temperature that ith sample point measurement obtains.

After completing initial setting up, next step carries out estimator correction, including covariance calculating, correcting gain calculating process, As shown in the estimator correcting module in Fig. 1.Covariance calculating process is first carried out, that is, according to state-transition matrix a, upper a period of time Covariance matrix p (k-1), the process noise covariance matrix q carving calculates priori covariance matrixComputing formula is as follows:

$\hat{p}\left(k\right)-ap(k-1)a^t+q$

In formula, k- discrete sampling point；

- state-transition matrix；

t_sCycle of operation in the tire pressure controller for-method of estimation of the present invention；

k_thThe thermal conversion efficiency of-rolling resistance；

M- complete vehicle quality；

G- acceleration of gravity；

F- coefficient of rolling resistance；

c_thThe thermal capacitance of-whole tire；

k_trHeat transfer efficiency between-tire and environment.

After completing covariance calculating, execute correcting gain process, according to new covariance matrixObserving matrix h, sight The variance matrix r surveying noise calculates optimal estimation value p (k) of new correcting gain g (k) and error co-variance matrix, calculates public Formula is as follows:

$g\left(k\right)=\frac{\hat{p}\left(k\right)h^t}{h\hat{p}\left(k\right)h^t+r}$

$p\left(k\right)=\[i-g\left(k\right)h\]\hat{p}\left(k\right)$

In formula,- observing matrix；

The molal quantity of gas in n- tire；

ω=8.314j/mol k- ideal gas constant；

The volume of gas in v- tire.

The variance matrix of r- observation noise, is determined by the data of off-line measurement, and computing formula is as follows:

$r=\left[\begin{array}{ccc}{r}_{11}& r_{12}& r_{13}\\ r_{12}& r_{22}& r_{23}\\ r_{13}& r_{23}& r_{33}\end{array}\right]$

$r_{11}=\sqrt{\frac{1}{n}\underset{i=1}{\overset{n}{\σ}}{\[v\left(i\right)-\stackrel{\&overbar;}{v}\left(i\right)\]}^2}$

$r_{12}=\sqrt{\frac{1}{n}\underset{i=1}{\overset{n}{\σ}}|\[v\left(i\right)-\stackrel{\&overbar;}{v}\left(i\right)\]\[t_t\left(i\right)-\stackrel{\&overbar;}{t_t}\left(i\right)\]|}$

$r_{13}=\sqrt{\frac{1}{n}\underset{i=1}{\overset{n}{\σ}}|\[v\left(i\right)-\stackrel{\&overbar;}{v}\left(i\right)\]\[p_t\left(i\right)-\stackrel{\&overbar;}{p_t}\left(i\right))|}$

$r_{22}=\sqrt{\frac{1}{n}\underset{i=1}{\overset{n}{\σ}}{\[t_t\left(i\right)-\stackrel{\&overbar;}{t_t}\left(i\right)\]}^2}$

$r_{23}=\sqrt{\frac{1}{n}\underset{i=1}{\overset{n}{\σ}}|\[t_t\left(i\right)-\stackrel{\&overbar;}{t_t}\left(i\right))\[p_t\left(i\right)-\stackrel{\&overbar;}{p_t}\left(i\right)\]|}$

$r_{33}=\sqrt{\frac{1}{n}\underset{i=1}{\overset{n}{\σ}}{\[p_t\left(i\right)-\stackrel{\&overbar;}{p_t}\left(i\right)\]}^2}$

In formula, p_t(i) andIt is respectively tire pressure and the actual tire pressure that ith sample point measurement obtains.

After completing estimator correction, next step, carry out tyre temperature and pressure using revised result and estimate, including under One moment status predication, state correction and tire condition calculating process, as shown in tire pressure and temperature estimation module in Fig. 1. First, carry out subsequent time status predication, input u (k) according to state equation and state-transition matrix a predict subsequent time State valueComputing formula is as follows:

$\hat{x}\left(k\right)=ax(k-1)+bu\left(k\right)$

In formula, the state variable of x (k-1)-tire condition estimator；

- control matrix；

- measurement in real time obtains vehicle acceleration a (k) and ambient temperature t₀K vector that () is constituted.

After completion statuses prediction, next step executes state correction process, according to status predication valueCorrecting gain g K (), measures the tyre temperature t obtaining_tAnd pressure p (k-1)_t(k-1), it is calculated optimal estimation value x (k) of state, calculate public Formula is as follows:

$x\left(k\right)=\hat{x}\left(k\right)+g\left(k\right)\[y(k-1)-h\hat{x}\left(k\right)\]$

In formula,It is the tyre temperature t being obtained by k 1 moment measurement_tAnd pressure p (k-1)_t (k-1) vector constituting.

After completion statuses correction, next step executes tire condition calculating process, is calculated according to state optimization estimated value x (k) Obtain the optimal estimation value of tyre temperature and pressureWithComputing formula is as follows:

$\left[\begin{array}{c}{\tilde{t}}_t\left(k\right)\\ {\tilde{p}}_t\left(k\right)\end{array}\right]=\left[\begin{array}{ccc}0& 1& 0\\ 0& 0& 1\end{array}\right]x\left(k\right).$

The beneficial effects of the present invention is, the present invention, by setting up the relation between vehicle-state and tire condition, designs Optimal estimation device, it is possible to increase tyre temperature and tonometric accuracy and capacity of resisting disturbance, thus reduce tire pressure monitoring system The rate of false alarm of system.

Finally illustrate, preferred embodiment above only in order to technical scheme to be described and unrestricted, although logical Cross above preferred embodiment the present invention to be described in detail, it is to be understood by those skilled in the art that can be In form and various changes are made to it, without departing from claims of the present invention limited range in details.

Claims (4)

1. a kind of tire pressure based on Kalman filtering and temperature optimal estimation method it is characterised in that: include initially set Put, estimator makeover process, tyre temperature and pressure estimation procedure.

Described initial setting up is that original state and initial variance are designed, to carry out the estimation of subsequent time；Estimator is repaiied Positive process is modified to the gain of estimator according to the statistical law of outside vehicle interference and sensor noise；Tyre temperature and Pressure estimation procedure is predicted according to state equation, and using correcting gain, predicted state is carried out on the basis of predicted state Revise, be calculated the optimal estimation value of tyre temperature and pressure.

2. the optimal estimation method of a kind of tire pressure based on Kalman filtering according to claim 1 and temperature, its It is characterised by: speed, tyre temperature and the pressure that current sensor measurement is obtained by described initial setting up, will used as original state Initial variance is set to offline statistical value.

3. the optimal estimation method of a kind of tire pressure based on Kalman filtering according to claim 1 and temperature, its It is characterised by: described estimator makeover process includes covariance calculating, correcting gain calculating process；Described covariance calculating process New covariance matrix is calculated according to state-transition matrix, the covariance matrix in a upper moment, process noise covariance matrix；Described Correcting gain calculating process calculates new correction according to the variance matrix of new covariance matrix, observing matrix, observation noise and increases Benefit, the optimal estimation value of calculation error covariance matrix.

4. the optimal estimation method of a kind of tire pressure based on Kalman filtering according to claim 1 and temperature, its It is characterised by: described tyre temperature and pressure estimation procedure include subsequent time status predication, state correction and tire condition meter Calculation process；Described subsequent time status predication predicts the state of subsequent time according to state equation input and state-transition matrix Value；Speed, tire pressure and temperature, the predictive value of state, observing matrix that described state correction obtains according to sensor measurement New covariance matrix calculated with estimator makeover process, is calculated the optimal estimation value of state；Described tire condition Calculating process, according to state optimization estimated value and observing matrix, is calculated the optimal estimation value of tyre temperature and pressure.