DE102004004805A1 - Control system for safety system of automotive vehicle, has controller which generates a final reference vehicle velocity, and controls safety system in response to final reference vehicle velocity - Google Patents

Abstract

A controller is coupled to wheel speed sensors, a steering actuator angle sensor, a yaw rate sensor, and a lateral acceleration sensor. The controller generates a final reference vehicle velocity in response to wheel velocity signals, steering angle signal, yaw rate signal and lateral acceleration signal, and controls safety system in response to final reference vehicle velocity. The wheel speed sensors generate wheel velocity signals. The steering actuator angle sensor generates a steering angle signal. The yaw rate sensor generates yaw rate signal. The lateral acceleration sensor generates lateral acceleration signal. An independent claim is also included for a method for controlling safety system for automotive vehicle.

Description

The invention relates to a system the the vehicle wheel speed sensor signals compensated by means of a learning algorithm. The compensated vehicle wheel speeds are then used in brake control systems (such as an anti-lock braking system and a drive control system) and vehicle dynamics control systems used.

It is a well known practice that control different operating dynamics of a motor vehicle, to achieve active safety, for example by means of the so-called Gierstabilitäts- and roll stability control systems. at a newer development combines all available subsystems, to better vehicle safety and better dynamic To achieve driving behavior than ever. The effective operation of the different Control devices require a highly accurate determination of the operating states of Motor vehicles with a short response time, regardless of the road conditions and driving conditions. Such operating states of a Vehicle have the vehicle's longitudinal speed, the Vehicle lateral speed and the vehicle vertical speed, the along the body's longitudinal axis, the body's own Transverse axis or the body's own vertical axis are measured, the position of the vehicle body, the direction of movement of the vehicle etc. on.

One of the important information which is the basis for the above-mentioned vehicle condition calculation is the linear velocity the respective center of rotation of the four vehicle wheels. This Information can be used, for example, to control anti-lock controls and to calculate vehicle wheel slip used in drive controls or assess and the longitudinal speed too calculate or estimate. At those linear corner speeds the vehicle wheel speed sensors are used. The vehicle wheel speed sensors give the product of the respective vehicle wheel rotation speeds and the respective Vehicle wheel rolling radii out. The vehicle wheel speeds are measured directly and the respective vehicle wheel roll radii are at their nominal values accepted. There during dynamic maneuvers the changes the vehicle wheel normal load and the change the vehicle tire would affect the vehicle wheel roll radii, the Vehicle wheel nominal roll radii are not the actual vehicle wheel roll radii correspond and therefore errors in the calculation of the respective vehicle wheel speeds cause. Therefore it is of interest to calculate the respective Compensate vehicle wheel speeds.

The differences between the vehicle wheel speeds while Driving on a straight road can be used to check the tire inflation become.

The invention is based on the object to provide a means for more accurately determining vehicle wheel speeds, that in vehicle dynamics controls via vehicle wheel speed sensors be determined.

This is done with a means of correction the vehicle wheel speed solved with the features in claim 1. preferred Further developments of the invention are described in the dependent claims.

The invention will now be more preferred based on embodiments with reference to the accompanying drawing described in more detail.

1 shows a view showing the longitudinal speed and the transverse speed at the corners of the vehicle body.

2 shows a schematic view of a vehicle wheel, wherein according to 2 the vehicle _corner speed along the longitudinal direction of a vehicle _{wheel is} equal to the sum of the contact point slip speed ν _cp and the product of the rotation rate or angular velocity ω _{whl of} the vehicle _wheel and the vehicle _wheel rolling radius r ₀ .

The invention is described below with reference to preferred embodiments relating to a motor vehicle that is moving on a road surface. The transverse speed and the longitudinal speed at the center of gravity of the motor vehicle are denoted by V _x and V _y , the yaw rate and yaw rate of the motor vehicle are denoted by ω _z , and the front wheel steering angle of the motor vehicle is denoted by δ. Using those vehicle motion variables, the respective speeds of the vehicle at its four corner positions at which the vehicle wheels are attached to the vehicle can be calculated according to the following rule, the respective vehicle corner speeds being extrapolated along the body-specific longitudinal direction and along the body-specific transverse direction: V lfx = V x - ω z t f , V lfy = V y + ω z l f V rfx = V x + ω z t f , V rfy = V y + ω z l f V lrx = V x - ω z t r , V lry = V y - ω z l r V rrx = V x + ω z t r , V rry = V y - ω z l r (1), where t _f and t _r denote the respective half-track for the front axle and for the rear axle, respectively, and l _f and l _r denote the respective distance between the center of gravity of the vehicle and the front axle and the rear axle, respectively. V _lf , V _rf , V _lr and V _rr denote the linear speeds of the four corners of the vehicle along the respective direction of travel of the vehicle _wheels and can be calculated according to the following regulation: V lf = V lfx cos (δ) + V lfy sin (δ) V rf = V rfx cos (δ) + V rfy sin (δ) V lr = V lrx V rr = V rrx (2)

The vehicle wheel speed _sensor outputs are usually calibrated to provide the linear direction velocities ν _lf , ν _rf , ν _lr , and ν _rr by multiplying the respective rotational angular velocity of the vehicle wheel by a nominal vehicle wheel roll radius, where ω _{lf sensor} , ω _{rf sensor} , ω _{lr sensor} and ω _{rr sensor are} the respective vehicle _wheel angular velocities on the left front vehicle _corner , on the right front vehicle _corner , on the left rear vehicle corner and on the rear right vehicle _corner , respectively. For the following, the vehicle wheel nominal rolling radius, which is used in an ABS system to calculate the vehicle wheel speeds from the vehicle wheel speeds or the vehicle wheel angular velocities, is denoted by r ₀ , the following rule applying: ν lf = ω lf-sensor r 0 ν rf = ω rf-sensor r 0 ν lr = ω LR sensor r 0 ν rr = ω rr-sensor r 0 (4)

It should be noted that the vehicle wheels have a different rolling radius than the nominal rolling radius r ₀ . Consequently, in order to calculate the actual linear speeds at the four vehicle corners precisely, certain correction factors must be taken into account. For the following, those correction factors for the left front vehicle _corner , the right front vehicle _corner , the left rear vehicle _corner and the right rear vehicle _{corner are} referred to as κ _lf , κ _rf , κ _lr and κ _rr, respectively, with the following rule: ν lf = κ lf ω lf-sensor r 0 ν rf = κ rf ω rf-sensor r 0 ν lr = κ lr ω LR sensor r 0 ν rr = κ rr ω rr-sensor r 0 (4)

It should also be noted that the vehicle wheels do not only perform the rotary movement, but also a linear sliding movement, that is to say that the vehicle wheels also have a longitudinal slip. The longitudinal slip is caused by the relative movement between the respective vehicle wheel and the road at its contact point. For the following, the longitudinal velocities of such relative movements at the contact points between the respective vehicle _wheel and the road are referred to as ν _cp-lf , ν _cp-rf, ν _cp-lr and ν _cp-rr , so that the vehicle _{corner velocities are} the sums of, as in the following regulation two speeds can be expressed: V lf = ν cp-lf + ν lf V rf = ν cp-rf + ν rf V lr = ν cp-lr + ν lr V rr = ν cp-rr + ν rr (5)

Taking into account the following regulation: V y = V x tan (β) (6), where β is the vehicle drift angle, the correction _factors κ _lf , κ _rf , κ _lr and κ _rr can be calculated according to the following rule:

If one considers the product term tan (β) sin (δ) as negligible in comparison with the term cos (δ), then regulation (7) can be further simplified to the following regulation, the correction factors being independent of the vehicle drift angle β:

In the case of low vehicle _wheel longitudinal _slip ratios, the longitudinal _speeds ν _cp-lf , ν _cp-rf, ν _cp-lr and ν _{cp-rr of} the relative movements at the contact points are almost zero and regulation (8) can be further simplified as for the following regulation become:

bezeichnet, so dass ein Lernalgorithmus verwendet werden kann, um die Durchschnitts-Korrekturfaktoren zu berechnen. Die jeweiligen Korrekturfaktoren werden wie gemäß folgender Vorschrift alle N Berechnungsabfragen aktualisiert:

For the following, the respective digital value of the above-mentioned vehicle _wheel speed correction _factors κ _lf , κ _rf , κ _lr and κ _rr becomes at a certain point in time t = kΔT

referred to, so that a learning algorithm can be used to calculate the average correction factors. The respective correction factors are updated every N calculation queries as follows:

Using the above learning algorithm (regulation 10), the vehicle wheel speeds can be corrected according to the following regulation:

It should be noted that the above learning algorithm only realizes the speed correction for the individual vehicle wheels. There are also cases for the vehicle wheels in which the average rolling radii of the four vehicle wheels are reduced together due to a change in the vehicle weight or the vehicle load. If the vehicle wheel speeds corrected above are fed back into the algorithm used in the vehicle dynamics control, a vehicle reference speed V _{ref is} provided which has to be calibrated again depending on the available longitudinal acceleration sensor signal of the vehicle.

It should be noted that the following rule applies to the actual vehicle reference speed: V ref = κV ref (12) where κ is the correction factor based on the total vehicle load and is usually a slowly changing parameter. κV ref = α x - gθ y (13)

dann kann eine Fehler-Quadratberechnung des Korrekturfaktors gemäß folgender Vorschrift: ^ = inν(V ^ T V ^)V ^ T(Ax – gΘy] (15)oder gemäß folgender Vorschrift erzielt werden:

The following variables are defined according to the following regulation:

then an error square calculation of the correction factor can be carried out according to the following rule: ^ = inν (V ^ T V ^) V ^ T (A x - gΘ y ] (15) or according to the following rule:

Note that ^ every N calculation queries are updated. The digital implementation of regulation (16) can be achieved as shown in the following regulation:

The end signals of the vehicle wheel speed sensors corrected by means of the aforementioned factors can be obtained in accordance with the following regulation:

Bibliography:

• [1] US 6055488 , "Device for calculating initial correction factor for correcting rotational velocity of tire," (Sumitomo, 2000).
• [2] US 5959202 , "Device for detecting initial correction factor for correcting rotational velocity of tire," (Sumitomo, 1999).
• [3] US 5852788 , "Wheel speed correction method that accounts for use of a mini tire," (Nisshinbo, 1998).
• [4] US 5699251 , "Correcting the wheel speed of a wheel having a different diameter than other wheels," (HONDA, 1997).

Claims (5)

Means for correcting the vehicle wheel speed, comprising, in particular consisting of: individual means for learning a vehicle wheel speed adjustment factor, and Common means for learning a vehicle wheel speed adjustment factor. Vehicle wheel speed correction means according to claim 1, the single means for learning a vehicle wheel speed adjustment factor uses the following measured and calculated signals: - vehicle wheel speed sensor signals, - a steering wheel angle sensor signal, - a yaw rate sensor signal, and - a calculated vehicle longitudinal speed. Vehicle wheel speed correction means according to claim 1, the single means for learning a vehicle wheel speed adjustment factor closed formulas used to match the respective matching factor for each of the four vehicle wheels to calculate which is used to calculate the difference between each Compensate vehicle wheel roll radii so that all four vehicle wheel speeds using a common adjustment factor after the correction with the four true values. Vehicle wheel speed correction means according to claims 1 and 3, the common vehicle wheel speed adjustment factor is obtained using the following measured sensor signals and the calculated signals: - vehicle longitudinal acceleration sensor signal, - vehicle pitch angle, which is calculated from a pitch rate sensor signal, and - vehicle reference speed, using the individual vehicle wheel speed adjustment factors is calculated from the individual, balanced vehicle wheel speeds. Vehicle wheel speed correction means according to claims 1 and 3, the common vehicle wheel speed adjustment factor an online least squares algorithm used.