GB2392257A

GB2392257A - Regulating vehicle drive slip on a rough surface

Info

Publication number: GB2392257A
Application number: GB0327636A
Authority: GB
Inventors: Rolf-Hermann Mergenthaler; Ansgar Traechtler
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1999-10-12
Filing date: 2000-09-13
Publication date: 2004-02-25
Anticipated expiration: 2020-09-13
Also published as: GB0327636D0; GB2392257B

Abstract

A process and device for controlling at least one variable of vehicle movement, the variable describing a movement of the vehicle. The device contains control means by means of which actuators 109 (eg. brake actuators) for controlling the variable of vehicle movement are controlled, and detection means 107 for detecting a variable of rough roads (eg. from wheel speeds), whereby said variable describes a drive of the vehicle on a rough road. The control means are influenced according to the variable of rough roads in such a way that the sensitivity of the control means is adapted to the drive of the vehicle on a rough road. A desired value of drive slip contains a first part representing the desired traction and a second part representing required vehicle stability, and which of the parts predominates is a function of rough stretch quantity.

Description

Device and Process for Regulating at Least One Vehicle Movement Quantity

Prior Art

The present invention relates to a device and a process for regulating at least one vehicle movement quantity that describes a movement of a vehicle. Many modifications of appropriate devices and processes are known from the prior 10 art.

For example, a device for regulating at least one vehicle movement quantity is known from the publication "FDR - Die Fahrdynamikregelung von Bosch" (Bosch Vehicle Dynamics 15 Regulation System) that appeared in Automobiltechnische Zeitschrift (ATZ)g6, 1994, Vol. 11, on pages 674 to 689.

This vehicle movement quantity is the yawing rate of the vehicle. In order to regulate the yawing rate of the vehicle the measured yawing rate is compared with a desired 20 value for the yawing rate. In this comparison process a regulation deviation of the yawing rate is determined, involving braking interventions and/or engine interventions on individual wheels independently of the driver. In particular, a yawing moment is applied co the vehicle by 25 these braking interventions, by means of which the actual yawing rate approaches the desired value.

The subject matter of the aforementioned ATZ article will be incorporated in the present application.

The aforedescribed vehicle dynamics regulation, which is commonly also known as ESP (electronic stability program) was developed in the first place for road vehicles. The program is also now being increasingly employed in offroad 35 vehicles. However, in offroad situations undesirable interventions of the vehicle regulator with which the yawing rate of the vehicle is to be regulated may occur.

One object of the invention is accordingly to modify existing devices for regulating at least one vehicle movement quantity, in particular the yawing rate of the vehicle, in such a way that such devices can also be used 5 in offroad vehicles.

This object is achieved by the features of claim 1 and by those of claim lo.

10 At this point reference may be made to DE 39 33 652 Al.

This specification describes an antiblocking regulation

system and a drive slip regulation system that is suitable for offroad driving. The antiblocking regulation system contains measurement transducers for determining the wheel 15 velocities. A vehicle deceleration is calculated from the wheel velocities in an evaluation circuit. Signals from a vehicle deceleration transducer are also processed in the evaluation circuit. The vehicle deceleration determined from the wheel velocities and the signals from the vehicle 20 deceleration transducer are compared with one another. If the measured vehicle deceleration is larger, then in the event of braking the ADS regulation is altered so as to effect a coarser regulation. A corresponding procedure is employed for the drive slip regulation system.

Reference may also be made to DE l9S 44 445 Al. This specification describes a process for improving the

regulation behaviour of a blocking safety regulation system for offroad vehicles. In order to improve the regulation 30 behaviour of the blocking safety regulation system for offroad vehicles, the regulation is effected at a vehicle reference velocity that is below a predetermined limiting velocity value in such a way that in each case only after one wheel of an axle has been blocked does the blocking 35 safety regulation come into effect for the second wheel of the axle. In principle therefore the blocking of in each case one wheel of an axle is permitted at a low velocity.

Furthermore the regulation system can also be designed so that, on recognition of offroad conditions and low vehicle velocity, a special regulation mode is activated.

5 The devices described in the two specifications discussed

above relate to devices for regulating one of the quantities describing the wheel behaviour, namely the wheel slip. In other words, with these devices the wheel behaviour is adjusted corresponding to a regulation 10 algorithm, and/or the wheel behaviour or the wheel movement is regulated. The regulation of a vehicle movement quantity that describes a movement of the vehicle, for example the rotation of the vehicle about its vertical axis, is not possible with these devices since on the one 15 hand no information about the vehicle movement can be obtained from the wheel information, and secondly with these devices furthermore no quantity can be determined by means of which information can be specifically obtained on the vehicle movement and that can be incorporated as a 20 regulating quantity in the regulation. In the offroad braking slip regulators or drive slip regulators belonging to the prior art the wheel slip is of primary importance

from the regulation technology aspect, i.e. the wheel is stabilised by the intervention feedback on the regulation.

25 Accordingly the behaviour of the vehicle movement is initially of secondary importance. On the other hand in the regulation of a vehicle movement the said vehicle movement is of primary importance from the regulating technology aspect, i.e. it is the vehicle that is 30 stabilized. The behaviour of the wheels in this form of regulation is accordingly of secondary importance to start with. Advantages of the Invention The device according to the invention is a device for regulating at least one vehicle movement quantity that

describes a vehicle movement of a vehicle. The device contains regulating means with which actuators for regulating the vehicle movement quantity are controlled.

Furthermore the device contains determining means with 5 which a rough stretch quantity is determined that describes a journey of the vehicle on a rough stretch or rough terrain. Depending on the rough stretch quantity the regulating means are adjusted in such a way that the sensitivity of the said regulating means is adapted to the 10 driving of the vehicle on a rough stretch.

The regulating means contained in the device according to the invention consist of a master regulator and at least one subordinate regulator. According to the invention both IS regulators are influenced as a function of the rough stretch quantity.

The master regulator is a regulator for regulating a transverse dynamics quantity that describes the transverse 20 dynamics of the vehicle. As soon as a deviation quantity that describes the deviation between an actual value and a desired value for the transverse dynamics quantity exceeds an excitation threshold, at least braking interventions on individual wheels that are independent of the driver are 25 carried out. The transverse dynamics quantity is a quantity that describes a yawing rate of the vehicle.

According to the invention the excitation threshold of the master regulator is raised depending on the rough stretch quantity. When the vehicle is travelling on a rough stretch, i.e. in offroad situations, such as for example when driving on rutted tracks or on crushed stone tracks, relatively large deviations between the actual value and the desired value 35 of the transverse dynamics quantity may arise without any regulating intervention being necessary. For this reason

the excitation threshold of the master regulator is raised and thus the master regulator is made less sensitive.

By acting on the master regulator, braking interventions on 5 the individual wheels independently of the driver that are carried out in order to regulate the at least one vehicle movement quantity, are suppressed when the vehicle is travelling on a rough stretch or the frequency or intensity of such interventions are reduced compared to when the 10 vehicle is travelling on a stretch that is not rough.

Consequently there are no interfering interventions when the vehicle is travelling on a rough stretch.

Preferably the at least one subordinate regulator is a 15 drive slip regulator with which the drive slip of the driven wheels is adjusted according to a desired value for the drive slip. According to the invention the desired value for the drive slip is determined depending on the rough stretch quantity. A sufficient traction is ensured 20 by this measure when the vehicle is travelling on a rough stretch. By influencing the at least one subordinate regulator when the vehicle is travelling on a rough stretch, a larger 25 drive moment or a larger drive slip on the driven wheels is permitted when the vehicle is travelling on a rough stretch compared to when the vehicle is travelling on a stretch that is not rough. By influencing the at least one subordinate regulator braking interventions and/or engine 30 interventions that are carried out in order to reduce the drive slip are suppressed when the vehicle is travelling on a rough stretch or their frequency or intensity are reduced compared to when the vehicle is travelling on a stretch that is not rough.

The desired value for the drive slip advantageously consists of a first component that represents the desired

traction, and a second component that represents the required vehicle stability. Which of the two components predominates in the desired value for the drive slip is determined by means of a special factor. According to the 5 invention the first component is raised according to the rough stretch quantity. Alternatively or in a complementary manner the factor is influenced depending on the rough stretch quantity so that the first component is greater than the second component in the desired value for 10 the drive slip.

Advantageously a quantity that is a measure of how quickly the engine moment transmitted by the engine is to be reduced, is influenced depending on the rough stretch 15 quantity.

The rough stretch quantity is advantageously determined as a function of the wheel velocity quantities that describe the wheel velocities of the individual wheels and a 20 velocity quantity that describes the velocity of the vehicle. A wheel vibration quantity that is a measure of the wheel vibrations that occur when the vehicle is travelling on a rough stretch is determined as a function of the wheel velocity quantities. The rough stretch 25 quantity is determined as a function of this wheel vibration quantity.

Advantageously the rough stretch quantity is a continuous quantity that adopts arbitrary values between a minimum 30 value and a maximum value. In the case where the rough stretch quantity adopts the minimum value, no influencing of the regulating means is carried out. In the case where the rough stretch quantity adopts the maximum value, the largest possible influencing of the regulating means is 35 carried out. In the case where the rough stretch quantity adopts an arbitrary value between the minimum and the

maximum values, a continuous influencing of the regulating means is carried out.

The wheel vibration quantity is converted into a first 5 continuous quantity that adopts a minimum value below a predetermined first value for the wheel vibration quantity, and a maximum quantity above a predetermined second value for the wheel vibration quantity. The first continuous quantity increases continuously between the first and the 10 second value for the wheel vibration quantity. The velocity quantity is converted into a second continuous quantity that adopts a maximum value below a predetermined first value for the velocity quantity, and a minimum value above a predetermined second value for the velocity 15 quantity. The second continuous quantity falls continuously between the first and the second values for the velocity quantity. Preferably the rough stretch quantity is determined as a minimum of the first and the second continuous quantities.

Preferably, for vehicles that are equipped with a gear change mechanism that has an offroad gear that can be selected by the driver, it is envisaged that the rough stretch quantity is determined simply when the offroad gear 25 is selected.

To summarize, it may be said that the advantage of the device according to the invention compared to the device described in the aforementioned ATZ article is that offroad 30 situations, i.e. so-called rough stretches or rough terrain driving, can be recognized and the regulating means, i.e. the vehicle regulator, can be adjusted more coarsely.

Interfering braking interventions as well as also a traction loss are thereby avoided. At the same time the 35 regulation of the at least one vehicle movement quantity, i.e. the yawing rate of the vehicle, is maintained. With the device described in the aforementioned ATZ article, it

happens that, since the vehicle regulator cannot automatically be adjusted more coarsely in an existing offroad situation, on the one hand interfering braking interventions arise and on the other hand there is a loss 5 of traction. Both factors result in an uncomfortable driving sensation and intrusive noise. In the device described in the ATE article the driver can simply press a passive button incorporated in the instrument panel, by means of which the vehicle regulator is switched off (and 10 also switched on again), in order to prevent the interfering braking interventions and loss of traction.

This however has the major disadvantage that in critical situations the stability of the vehicle is no longer assisted by the regulating means.

Further advantages as well as advantageous modifications and embodiments are disclosed in the sub-claims as well as in arbitrary combinations of the sub-claims, in the drawings as well as in the description of the example of

20 implementation.

Drawings The drawings consist of Figs. 1 to 3. Figs. 1 and 2 25 illustrate the device according to the invention in varying degrees of detail with the aid of block diagrams. Fig. 3, which consists of the partial figures 3a, 3b and 3c, illustrates various quantities that are employed in the device according to the invention.

Example of Implementation Fig. 1 shows regulating means 108 in generalized form.

These regulating means are for example those that are 35 employed within the framework of a drive dynamics regulation system. For further details reference may be made at this point to the aforementioned publication 'iFDR

Die Fahrdynamikregelung von Bosch''. Various input quantities are fed to the regulating means: the transverse acceleration aq determined by means of a transverse acceleration sensor lOl, the turning angle delta determined 5 by means of a turning angle sensor 102, the yawing rate omega of the vehicle determined by means of a yawing rate sensor 103, the preliminary pressure Pvor adjusted by the driver and determined by means of a pressure sensor 104, the wheel velocities vij determined by means of wheel 10 velocities sensor 105ij, as well as a velocity quantity vf that describes the velocity of the vehicle and that is determined in a block 106 in a known manner as a function of the wheel velocities. The abbreviation lO5ij employed hereinbefore for the wheel rotational speed sensors has the 15 following meaning: the index i indicates whether a front wheel (v) or a rear wheel (h) is involved. The index j indicates whether a right (r) vehicle wheel or a left (l) vehicle wheel is involved. This form of abbreviation is used identically for all quantities and/or blocks in which 20 it is employed.

The sensors 101, 102, 103, 104 and 105ij, as well as the block 106, are assembled to form a block 110. Block 107 represents determining means with which a rough stretch 25 quantity kooffroad is determined. This rough stretch quantity kooffroad is passed to the regulating means 108 for further processing. The determination of the rough stretch quantity kooffroad is carried out in block 107 as a function of the wheel velocity quantities vij fed to the 30 block as well as the velocity quantity vf fed to the block.

In order to determine the rough stretch quantity kooffroad, a wheel vibration quantity toffroad, which is a measure of the wheel vibrations that occur when the vehicle is driven on a rough stretch, is first of all determined as a 35 function of the wheel velocity quantities vij. In order to determine the wheel vibration quantity toffroad, an evaluation is made as to whether frequent alternations

in, between large and small wheel velocities, such as are typical of a vehicle driving on a rough stretch, occur within relatively few computation cycles. The wheel vibration quantity toffroad is also passed to the 5 regulating means 108.

The determination of the rough stretch quantity kooffroad in block 107 is now described hereinafter with the aid of Figs. 3a and 3b. On the one hand the wheel vibration 10 quantity toffroad is converted into a first continuous quantity Kol. This state of affairs is illustrated in Fig. 3a. The continuous quantity Kol adopts a minimum value an below a first predetermined first value tl for the wheel vibration quantity. According to Fig. 3a this has 15 the value 0. Above a predetermined second value t2 for the wheel vibration quantity, the continuous quantity Kol adopts a maximum value. According to Fig. 3a this maximum i value is 1. The first continuous quantity Kol increases or rises linearly between the predetermined first value and 20 the predetermined second value of the wheel vibration quantity. The following is ensured through the behaviour of the first continuous quantity Kol illustrated in; Fig. 3a: the wheel vibration quantity toffroad is a measure of the wheel vibrations that occur when the vehicle is 25 travelling on a rough stretch. In this connection the value of the wheel vibration quantity toffroad should be larger the greater the wheel vibrations that are attributed to the rough stretch. Fairly slight wheel vibrations that are represented by values of the wheel vibration quantity 30 toffroad that are less than the value tl are regarded as not critical and should therefore not result in any influencing of the regulating means. Accordingly, in this situation the value 0 is ascribed to the first continuous quantity Kol, i.e. the wheel vibration quantity toffroad is 35 factored out. If wheel vibrations occur that are characterized by values of the wheel vibration quantity toffroad that are larger than the value t2, then these

- wheel vibrations should be regarded as critical, and accordingly a maximum possible influencing of the regulating means should take place. In this case the value 1 is ascribed to the first continuous quantity. In the 5 case of wheel vibrations that are characterized by a value of the wheel vibration quantity toffroad that lies between the first value tl and the second value t2, a continuous influencing of the regulating means should take place. For this reason, in this range a continuous value is ascribed to to the first continuous quantity.

Secondly, the velocity quantity of is converted into a second continuous quantity Ko2. This state of affairs is represented in Fig. 3b. If the velocity quantity vf has 15 values that are less than a predetermined first value vl for the velocity quantity, then the second continuous quantity adopts a maximum value. According to Fig. 3b this quantity then has the value 1. If on the other hand the velocity quantity vf has values that lie above a 20 predetermined second value v2 for the velocity quantity, then the second continuous quantity Ko2 adopts a minimum; value. According to Fig. 3b this quantity has the value 0.

If the velocity quantity vf adopts values that lie between the value vl and the value v2, then the second continuous 25 quantity falls continuously, i.e. it drops linearly from the maximum value to the minimum value. The characteristics illustrated in Fig. 3b were chosen for the second continuous quantity for the following reason: in a velocity range that is described by the velocity O and the 30 velocity vl, the braking interventions of the vehicle regulator that are attributed to the vehicle driving on a rough stretch, act in an interfering manner. Accordingly the maximum value is ascribed to the second continuous quantity for this velocity range. The value vl 35 corresponds, depending on the type of vehicle, to a vehicle velocity of 20 to 30 km/hour. Above a velocity v2 it should therefore be assumed that the vehicle is not

/ travelling on a rough stretch. For this reason braking interventions by the vehicle regulator are permitted above the velocity v2. Accordingly the minimum value is ascribed to the second continuous quantity Ko2 above the value v2.

The rough stretch quantity kooffroad is the minimum of the first and second continuous quantities. Accordingly, the rough stretch quantity kooffroad is likewise a continuous quantity that adopts an arbitrary value between a minimum 10 value and a maximum value. On account of the determination of the rough stretch quantity kooffroad, the minimum value has the value 0, and the maximum value has the value 1. In order to assign the values of the rough stretch quantity kooffroad so as to influence the regulating means, the 15 following conditions apply: for the case where the rough stretch quantity adopts the minimum value, there should be no influencing of the regulating means. This is the case when the wheel vibration quantity toffroad is less than the value tl or when the velocity quantity vf is greater than 20 the value v2. In the case where the rough stretch quantity kooffroad adopts the maximum value, the regulating means should be influenced to the greatest possible extent. This is the case when the wheel vibration quantity toffroad is greater than the value t2 or when the velocity quantity vf 25 is smaller than the value vl. In the case where the rough stretch quantity kooffroad adopts an arbitrary value between the minimum and the maximum value, then a continuous influencing of the regulating means should be carried out. The execution of the influencing of the 30 regulating means is described in detail hereinafter in connection with Fig. 2.

Fig. 1 includes a block 111 shown in dotted lines. This block 111 is a changing means that is optionally present or 35 not depending on the nature of the gear change mechanism used in the vehicle. If the vehicle is equipped with a gear change mechanism that has an offroad gear that can be

r selected by the driver, then the block 111 is included. If on the other hand a gear change mechanism is involved that does not have an offroad gear, then the changing means 111 is not included. With the aid of the signal GelOb 5 generated by the block 111, the block 107 is notified whether or not the driver has selected the offroad gear.

The determination of the rough stretch quantity kooffroad can be modified as follows in block 107 on the basis of the signal Gelub passed to the block 107: if the driver has 10 selected the offroad gear, then it should be assumed that the vehicle is travelling on a rough stretch, i.e. is travelling overland. Consequently care must be taken in this situation to ensure that the regulating means are influenced according to the invention, i.e. the rough 15 stretch quantity kooffroad must be determined in block 107.

If on the other hand the block 107 is notified that the driver has not selected the offroad gear, then it should be assumed that the vehicle is not travelling on a rough stretch, i.e. is not travelling overland. Accordingly the 20 regulating means do not have to be influenced in accordance with the invention, i.e. the rough stretch quantity kooffroad does not have to be determined in block 107.

Owing to the fact that the rough stretch quantity kooffroad is then simply determined and/or processed when the driver 25 has selected the offroad gear, computer capacity and/or computer performance is not blocked unnecessarily.

On the basis of the input quantities aq, delta, omega, Pvor, vij as well as vf fed to the regulating means 108, 30 the said regulating means produce according to the regulation concept incorporated therein control signal S1 for the actuators 109 associated therewith. The actuators are for example means for influencing the moment transmitted by the engine and/or brakes associated with the 35 wheels of the vehicle, wherein the brakes may be part of a hydraulic, an electrohydraulic, a pneumatic, an electropneumatic or an electromechanical braking system.

Starting from the actuators 109, signals S2 are passed to the regulating means that provide the said regulating means with information on the operational state of the actuators.

With regard to the regulation concept incorporated in the 5 regulating means 108, reference may be made to the aforementioned publication "FDR Die Fahrdynamikregelung von Bosch". This regulation concept and thus also the regulating means 108 are influenced by means of the quantities kooffroad and/or toffroad passed to the 10 regulating means 108 from the block 107.

Fig. 2 will now be discussed. Fig. 2 shows the block 110 that processes the determined and collated quantities aq, delta, vf, omega, Pvor as well as vij. All the 15 aforementioned quantities are passed to block 204 as well as to a block 206. The quantities aq, delta, vf as well as omega are passed to blocks 201, 202 and 203. The quantities vij as well as vf are passed to a block 207 as well as to a block 208.

Starting from the determining means 107 the rough stretch quantity kooffroad is passed for processing to the blocks 201, 202 as well as 203. Moreover, starting from the recognition means 107 the wheel vibration quantity toffroad 25 is passed to the block 202. The blocks 201, 202 as well as 203, on the basis of which the influencing of the regulating means takes place, are combined to form a block 209. 30 Block 204 represents a master regulator by means of which a transverse dynamics quantity that describes the transverse dynamics of the vehicle is regulated. In the present example of implementation the transverse dynamics quantity is the yawing rate omega of the vehicle. In order to 35 regulate the transverse dynamics quantity a deviation quantity is determined. In the present example of implementation this is the deviation between the actual

value omega and a desired value for the yawing rate of the vehicle. The desired value for the yawing rate is determined by the block 204 starting from the velocity quantity vf and the turning angle delta by means of the 5 Ackermann equation. As soon as the deviation quantity exceeds an excitation threshold, quantities slSoAJ3Sij are determined in block 204 and passed to block 208. The quantities slSoABSij are the desired value of the braking slip of the individual wheels that has to be adjusted by lo means of the subordinate braking slip regulator 208. The adjustment of the desired braking slip slSoABSij leads to braking interventions on the individual wheels independently of the driver. By means of these braking interventions acting on the individual wheels independently 15 of the driver, the measured yawing rate omega now approaches the desired value of the yawing rate.

Furthermore, block 204 provides a quantity deltaomega that describes the deviation between the measured yawing rate omega and the desired value for the yawing rate. In the 20 normal case the quantity deltaomega is the aforedescribed deviation quantity. It is however also conceivable that the quantity deltaomega is determined in a different way and manner. The quantity deltaomega is passed from block 204 to block 206.

The desired value for the yawing rate is limited to physically meaningful values as a function of the transverse acceleration passed to the block 204. The quantities Pvor as well as vij are required, in connection 30 with the determination of the theoretical values slSoABSij, for the braking slip regulator.

The excitation threshold AnSch required in block 204 is determined in block 201 and is then passed to block 204.

35 The excitation threshold AnSch is determined in block 201 for example according to the following equation:

AnSch(new) = AnSch(old) + P_OffrUnempf x Kooffroad (1).

The quantities employed in the above equation have the following meanings: the quantity AnSch (old) is the 5 excitation threshold that is determined for the normal operation of the vehicle, i.e. when the vehicle istravelling on a stretch that is not rough. The quantity AnSch (old) is determined as a function of the quantities aq, delta, vf as well as omega fed to the block 201. The 10 quantity P_OffrUnempf is a parameter applied on the test apron by driving tests. As can be seen from the preceding equation, the excitation threshold AnSch (new) to be used when the vehicle is driving on a rough stretch consists of a first addend and a second addend. The first addend -

15 corresponds to the excitation threshold that is employed for the normal operation of the vehicle. The second addend represents a correction to the excitation threshold, which is made on account of the vehicle's travelling on a rough stretch. The following therefore applies: the greater the 20 second addend, the less sensitive the master regulator becomes. If the rough stretch quantity Kooffroad adopts the value 0, which is equivalent to saying that the vehicle is not travelling on a rough stretch, then there is no increase in the excitation threshold. If on the other hand 25 the rough stretch quantity Kooffroad adopts the value 1, which is equivalent to saying that the vehicle is travelling on an extremely rough stretch, then the excitation threshold rises by the maximum possible amount.

For a value of the rough stretch quantity lying between 0 30 and 1, there is a continuous rise in the excitation threshold. Since the braking interventions on the individual wheels independently of the driver are only carried out when a 35 deviation quantity that describes the deviation between an -

actual value and a desired value for the yawing rate exceeds the excitation threshold, the rise in the

/ excitation threshold means that the master regulator is adjusted more coarsely since these braking interventions on the individual wheels independently of the driver are in this case carried out only when there is a relatively large 5 deviation of the actual yawing rate from the desired yawing rate. By the influencing of the master regulator, i.e. by raising the excitation threshold, the braking interventions on the individual wheels independently of the driver that are carried out in order to regulate the yawing rate are 10 suppressed when the vehicle is travelling on a rough stretch or their frequency or their intensity is reduced compared to when the vehicle is travelling on a stretch that is not rough, which forms the basis for the excitation threshold AnSch(old). -

At this point it may be stated once more that if the vehicle is travelling on a stretch that is not rough, then for this situation the value of the rough stretch quantity kooffroad is ideally 0. This means, on the basis of 20 equation (1), that the excitation threshold AnSch(old) is employed as excitation threshold. If on the other hand the -

vehicle is travelling on a rough stretch, then in this situation the value of the rough stretch quantity kooffroad is different from 0. Having regard to equation (1), in 25 this case the value of the excitation threshold is raised starting from the value AnSch(old).

A quantity slSoMax that is incorporated in the desired value SlSoASR for the drive slip is determined in block 30 202. The quantity slSoMax represents in the desired value SlSoASR the part that describes the desired traction to be adjusted. The quantity slSoMax is determined for example according to the following equation: 35 slSoMax(new) = (l+ P_slSoAnhmult x Kooffroad) x (slSoMax(old)+slSoAdd) (2).

f ' The quantity slSoMax, which is also termed the traction slip, consists of a multiplicative part, namely the first brackets and an additive part, namely the second brackets.

The multiplicative part, which can be adjusted via the 5 parameter P_slSoAnhmult, should act only in the lower velocity range. For this reason this part contains only the rough stretch quantity kooffroad as multiplier. The parameter P_slSoAnhmult is determined on the test apron by driving tests. The parameter adopts values between 0.5 and 10 3 or 4. The additive part slSoAdd should act over the whole velocity range. For this reason the additive part depends simply on the wheel vibration quantity toffroad and not on the velocity quantity. The determination of the additive part slSoAdd is illustrated as a function of the 15 wheel vibration quantity toffroad in Fig. 3c.

At this point it may be repeated once more that if the vehicle is travelling on a stretch that is not rough, then for this situation the value of the rough stretch quantity 20 kooffroad is ideally 0. This means, on the basis of equation (2), that the quantity slSoMax simply consists of the sum of slSoMax(old), the traction slip for the vehicle travailing on a stretch that is not rough, and slSoAdd. If however the vehicle is travailing on a rough stretch, then 25 in this situation the value of the rough stretch quantity kooffroad is different from o. As can be seen from equation (2), in this case the value of the quantity slSoMax is increased.

30 The maximum additive part P_slSoAddMax contained in Fig. 3c is applied on the test apron by driving tests. The additive part slSoAdd itself adopts a minimum value for values of the wheel vibration quantity toffroad that are less than a first predetermined value t3. According to 35 Fig. 3c this is the value 0. For values of the wheel vibration quantity toffroad that are greater than a second predetermined value t4, the additive part slSoAdd adopts a

f 'N maximum value. According to Fig. 3c the maximum value is the quantity P_slSoAddMax. The additive part slSoAdd rises continuously between the value t3 and the value t4 of the wheel vibration quantity toffroad.

The value slSoMax (old) corresponds to the traction slip that is employed when the vehicle is travelling on a stretch that is not rough. This value is determined in block 202 as a function of the quantities aq, delta, vf as 10 well as omega. The traction slip slSoMax is fed from block 202 to a block 205.

Two quantities are determined in block 203. One of the quantities is the quantity KoslSoASR, which is determined 15 for example according to the following equation: KoslSoASR(new) = (1-(1-P_mult) x Kooffroad) x (KoslSoASR(old) - P_add x Kooffroad) (3).

20 The two quantities P_mult and P_add can be freely chosen between 0 and 1 and are applied on the test apron by driving tests. The quantity P_add represents a response threshold for the factor KoslSoASR. The parameter P_mult represents the maximum attenuation. The quantity KoslSoASR 25 (old) , which corresponds to the value of the factor that is used when the vehicle is travelling on a stretch that is not rough, is determined in block 203 as a function of the quantities aq, delta, vf as well as omega. The factor KoslSoASR is passed from block 203 to block 205.

At this point it may be stated once more that if the vehicle is travelling on a stretch that is not rough, then for this situation the value of the rough stretch quantity kooffroad is ideally 0. This means, on the basis of 35 equation (3), that the quantity KoslSoASR (old) is used as quantity KoslSoASR. If on the other hand the vehicle is travailing on a rough stretch, in this situation the value

of the rough stretch quantity kooffroad is different from 0. Having regard to equation (3), in this case the quantity KoslSoASR is reduced.

5 Secondly, a quantity Antred is determined in block 203.

This quantity is a measure of how quickly the engine moment transmitted by the engine is reduced. The quantity Antred is determined for example according to the following equation: Antred(new) = (1-(1-P_mult') x Kooffroad) x (Antred(old) P_add x Kooffroad) (4).

The above equation corresponds in form to equation (3), and 15 what has been said as regards equation (3) applies also to equation (4). The quantity Antred is passed from block 203 to block 207.

In block 206 a quantity SlSoMin is determined that 20 corresponds to the drive slip that is permitted in order to safeguard the vehicle's stability. The quantity SlSoMin is determined according to whether the vehicle understeers or oversteers. If the vehicle understeers, then the quantity SlSoMin corresponds to a braking slip. If the vehicle 25 oversteers, then the quantity SlSoMin corresponds to a drive slip. The quantity SlSoMin is basically determined as a function of the quantity deltaomega, which describes the difference between the actual value for the yawing rate and the desired value for the yawing rate, and thus contain 30 information on the understeering or oversteering of the vehicle. In addition the remaining quantities fed to block 206 are used in the determination of the quantity SlSoMin.

The quantity SlSoMin is passed from block 206 to block 205.

35 The desired value slSoASR for the drive slip is determined in block 205. This determination is carried out for example according to the following equation:

j slSoASR - slSoMax + KoslSoASR x (slSoMin - SlSoMax) (5) Equation (5) contains two parts, namely a first part 5 SlSoMax that represents the desired traction, and a second part slSoMin that represents the required vehicle stability. It is established by means of the factor KoslSoASR which of the two parts predominates in the desired value for the drive slip. The first part SlSoMax 10 is intrinsically greater than the second part slSoMin. In this way it is ensured with the aid of the first part SlSoMax that in the driving situation sufficient drive slip is available. The second part ensures, having regard to the vehicle's stability, that the drive slip is 15 correspondingly small and thus a sufficient cornering force is available.

With the aid of the factor KoslSoASR, when determining the desired value slSoASR for the drive slip the situation is 20 correspondingly changed to whether, in the respective driving situation, there is a traction requirement or a stability requirement between the first part slSoMax and the second part slSoMin.

25 The desired value slSoASR for the drive slip is fed from the block 205 to block 207. This desired value is converted in block 207 into corresponding control signals SlASR for the engine as well as for the brakes associated with the drive wheels. These control signals SlASR are fed 30 from the block 207 to the actuating system 109. The block 207, which is the subordinate drive slip regulator, receives the signals S2ASR as feedback from the actuating system 109.

35 As regards the subordinate drive slip regulator, the following may be stated: when an offroad situation is recognized, i.e. when the vehicle is travelling on a rough

stretch, the traction slip part slSoMax is increased. The factor KoslSoASR, which represents a stability factor, is reduced. The quantity Antred is also reduced. Due to these measures the slip demand is increased and at the same 5 time the recognition is adjusted to a coarser vehicle stability. The block 208, which is a subordinate brake slip regulator, converts the desired values slSoABSij for the braking slip 10 that are fed to it into corresponding control signals SlABS for the brakes associated with the individual wheels. The block 208 receives the signals S2ABS as feedback from the actuating system 109.

15 At this point it may be noted that the quantities SlASR and SlABS contained in Fig. 2 are combined in Fig. 1 to the quantities S1. The same applies as regards quantities S2ASR as well as S2ABS contained in Fig. 2, and the quantity S2 contained in Fig. 1.

At this point it may be mentioned once more that the increase in the excitation threshold for the master regulator and the measures that are adopted for the subordinate regulator, i.e. the increase in the traction 25 slip SlSoMax, the reduction in the factor koslSoASR and the reduction of the quantity Antred, have the overall effect that the sensitivity of the regulating means is adjusted to the situation where the vehicle is travailing on a rough stretch. Finally, it may be noted that the form of the example of implementation chosen in the description as well as the

representation chosen in the drawings are not intended to have any restrictive effect on the basic idea according to 35 the invention. For example, instead of the yawing rate the transverse acceleration may also be used for the transverse dynamic quantity.

Claims

Patent Claims

1. Device for regulating at least one vehicle movement 5 quantity (omega) that describes a movement of a vehicle, which device contains regulating means by means of which actuators for regulating the vehicle movement quantity are controlled, the regulating means consisting of a master regulator and a subordinate 10 regulator, and determining means with which a rough stretch quantity (koffroad) is determined that describes a movement of the vehicle on a rough stretch, wherein: depending on the rough stretch quantity both 15 regulators of the regulating means are influenced in such a way that the sensitivity of the regulating means is adjusted to the movement of the vehicle on a rough stretch; at least one subordinate regulator is a drive slip 20 regulator by means of which the drive slip of the driven wheels is adjusted according to a desired value (slSoASR) for the drive slip, the desired value for the drive slip being determined as a function of the rough stretch quantity; 25 the desired value for the drive slip contains a first part (SlSoMax) that represents the desired traction, and a second part (SlSoMin) that represents the required vehicle stability; by means of a factor (KoslSoASR) it is established 30 which of the two parts predominates in the desired value for the drive slip, and wherein; the first part is raised as a function of the rough stretch quantity, and/or the factor is influenced as a function of the rough stretch quantity so that the 35 first part predominates in the desired value for the drive slip.

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2. Device according to claim 1, in which by the influencing of the at least one subordinate regulator a larger driver moment or a larger drive slip on the driven wheels is permitted when the vehicle is 5 travelling on a rough stretch that is not rough, and/or by the influencing of the at least one subordinate regulator braking interventions and/or engine interventions that are carried out in order to reduce the drive slip are suppressed when the vehicle 10 is travailing on a rough stretch or their frequency or intensity are reduced compared to when the vehicle is travelling on a stretch that is not rough.

3. Device according to claim 1, in which the master 15 regulator is a regulator for regulating a transverse dynamics quantity that describes the transverse dynamics of the vehicle, with which, as soon as a deviation quantity that describes the deviation between an actual value and a desired value for the 20 transverse dynamics quantity, exceeds an excitation threshold (AnSch), at least braking interventions on the individual wheels are carried out independently of the driver, and the excitation threshold of the master regulator is raised as a function of the rough stretch 25 quantity, and in particular the transverse dynamics quantity is a quantity describing the yawing rate (omega) of the vehicle.

4. Device according to claim 1, in which a quantity 30 (Antred) that is a measure of how quickly the engine moment transmitted by the engine is reduced, is influenced depending on the rough stretch quantity.

5. Device according to claim 1, in which the rough 35 stretch quantity is determined as a function of wheel velocities (vij) that describe the wheel velocities of

) the individual wheels, and a velocity quantity (vf) that describes the velocity of the vehicle.

6. Device according to claim 5, in which a wheel 5 vibration quantity (toffroad) that is a measure of the wheel vibrations that occur when the vehicle is driven on a rough stretch, is determined as a function of the wheel velocity quantities, and the rough stretch quantity is determined as a function of this wheel 10 vibration quantity.

7. Device according to claim 1, in which the rough stretch quantity is a continuous quantity that adopts arbitrary values between a minimum value and a maximum 15 value, wherein the case where the rough stretch quantity adopts the minimum value, no influencing of the regulating means is carried out, and/or in the case where the rough stretch quantity adopts the maximum value, the regulating means are influenced to 20 the maximum possible extent, and/or in the case where the rough stretch quantity adopts an arbitrary value between the minimum value and the maximum value, a continuous influencing of the reg-ulalug means is carried out.

8. Device according to claim 7, in which the wheel vibration quantity is converted into a first continuous quantity (KO1) that adopts a minimum value below a predetermined first value (tl) for the wheel 30 vibration quantity, and a maximum value above a predetermined second value (t2) for the wheel vibration quantity, wherein the first continuous quantity rises continuously between the first value and the second value for the wheel vibration quantity, 35 and the velocity quantity is converted into a second continuous quantity (ko2) that adopts a maximum value below a predetermined first value (vi) for the

velocity quantity, and a minimum value above a predetermined second value (v2) for the velocity quantity, wherein the second continuous quantity drops continuously between the first value and the second 5 value for the velocity quantity, and the rough stretch quantity is determined as a minimum of the first and second continuous quantities.

9. Device according to claim 1, in which the vehicle is

10 equipped with a gear change mechanism that has an offroad gear that can be selected by the driver, and the rough stretch quantity is determined simply when the offroad gear is selected.

15 10. Process for regulating at least one vehicle movement quantity (omega) that describes a movement of a vehicle, the vehicle having regulating means by means of which actuators for regulating the vehicle movement quantity are controlled, the regulating means 20 consisting of a master regulator and a subordinate regulator, and determining means with which a rough stretch quantity (koffroad) is determined that describes a movement of the vehicle on a rough stretch, wherein: 25 depending on the rough stretch quantity both regulators of the regulating means are influenced in such a way that the sensitivity of the regulating means is adjusted to the movement of the vehicle on a rough stretch; 30 at least one subordinate regulator is a drive slip regulator by means of which the drive slip of the driven wheels is adjusted according to a desired value (slSoASR) for the drive slip, the desired value for the drive slip being determined as a function of the 35 rough stretch quantity; the desired value for the drive slip contains a first part (SlSoMax) that represents the desired traction,

and a second part (SlSoMin) that represents the required vehicle stability; by means of a factor (KoslSoASR) it is established which of the two parts predominates in the desired 5 value for the drive slip, and wherein: the first part is raised as a function of the rough stretch quantity, and/or the factor is influenced as a function of the rough stretch quantity so that the first part predominates in the desired value for the 10 drive slip.

11. Process according to claim 10, wherein by the influencing of the at least one subordinate regulator a larger drive moment or a larger drive slip on the 15 driven wheels is permitted when the vehicle is travelling on a rough stretch compared to when the vehicle is travailing on a stretch that is not rough, and/or by the influencing of the at least one subordinate regulator braking interventions and/or 20 engine interventions that are carried out in order to reduce the drive slip are suppressed when the vehicle is travelling on a stretch that is not rough.

12. Device according to claim 10, in which the master 25 regulator is a regulator for regulating a transverse dynamics quantity that describes the transverse dynamics of the vehicle, with which, as soon as a deviation quantity that describes the deviation between an actual value and a desired value for the 30 transverse dynamics quantity, exceeds an excitation threshold (AnSch), at least braking interventions on the individual wheels are carried out independently of the driver, and the excitation threshold of the master regulator is raised as a function of the rough stretch 35 quantity, and in particular the transverse dynamics quantity is a quantity describing the yawing rate (omega) of the vehicle.

13. Process according to claim 10, in which a quantity (Antred) that is a measure of how quickly the engine moment transmitted by the engine is reduced, is 5 influenced depending on the rough stretch quantity.

14. Process according to claim 10, in which the rough stretch quantity is determined as a function of wheel velocities (vij) that describe the wheel velocities of 10 the individual wheels, and a velocity quantity (vf) that describes the velocity of the vehicle.

15. Process according to claim 14, in which a wheel vibration quantity (toffroad) that is a measure of the 15 wheel vibrations that occur when the vehicle is driven on a rough stretch, is determined as a function of the wheel velocity quantities, and the rough stretch quantity is determined as a function of this wheel vibration quantity.

16. Process according to claim 10, in which the rough stretch quantity is a continuous quantity that adopts arbitrary values between a minimum value and a maximum value, wherein in the case where the rough stretch 25 quantity adopts the minimum value, no influencing of the regulating means is carried out, and/or in the case where the rough stretch quantity adopts the maximum value, the regulating means are influenced to the maximum possible extent, and/or in the case where 30 the rough stretch quantity adopts an arbitrary value between the minimum value and the maximum value, a continuous influencing of the regulating means is carried out.

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17. Process according to claim 16, in which that the wheel vibration quantity is converted into a first continuous quantity (KO1) that adopts a minimum value

below a predetermined first value (tl) for the wheel vibration quantity, and a maximum value above a predetermined second value (t2) for the wheel vibration quantity, wherein the first continuous 5 quantity rises continuously between the first value and the second value for the wheel vibration quantity, and the velocity quantity is converted into a second continuous quantity (Ko2) that adopts a maximum value below a predetermined first value (vi) for the 10 velocity quantity, and a minimum value above a predetermined second value (v2) for the velocity quantity, wherein the second continuous quantity drops continuously between the first value and the second value for the velocity quantity, and the rough stretch 15 quantity is determined as a minimum of the first and second continuous quantities.

18. Process according to claim 10, in which the vehicle is equipped with a gear change mechanism that has an 20 offroad gear that can be selected by the driver, and that the rough stretch quantity is determined simply when the offroad gear is selected.