JP2002538039A - Method for controlling the running state of a vehicle - Google Patents

Abstract

(57) Abstract: The present invention is a method in which a force acting on a wheel and a tire is detected by a wheel force sensor or a tire sensor, and is used as a control variable for an automobile control system such as ABS, TCS, EHB, and the like. A method for controlling the driving state of a vehicle, wherein the control variable is used to determine and / or change the brake pressure and / or the driving torque in the wheel brakes of the wheels. In order to provide a method for controlling the driving state of the vehicle, the operating point and / or operating range of the control variable is adjusted by the detected wheel slip.

Description

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, a force acting on a wheel and a tire is detected by a wheel force sensor or a tire sensor, and is used as a control amount for an automobile control system such as ABS, TCS, EHB, or the like. The present invention relates to a method for controlling the driving state of a vehicle, which is used to determine and / or change the brake pressure and / or the driving torque in a wheel brake of a wheel.

[0002] Many such methods are known for controlling the running state of a vehicle. This method uses a tire sensor to detect the force and torque acting on the tire. In EP 0 444 109 a change in the tread area (tire tread contact area) of the tire is monitored, and in WO 96/10505 the deformation of the tire sidewall (twist deformation) is arranged at different radii with respect to the axis of rotation. Detected by measuring the time between passing at least two marks on the rotating wheel. A tire sensor that detects a change in phase position between measurement signals generated by a measurement element due to a force acting on the tire when the tire is deformed; and a phase position indicating torque and / or instantaneous coefficient of friction transmitted from the wheels to the road. This change is described in WO 97/44673. The force acting on the tire in this way and detected by the tire sensor is used in a vehicle control system to determine and / or change the brake pressure in the wheel brakes of the wheel.

[0003] In addition to this vehicle control system which controls the determination and / or modification of the brake pressure in the wheel brakes based on the forces detected by the tire sensors and / or the torque between the tires and the road, the four wheels of the vehicle ABS and / or TCS control systems for motor vehicles with conventional sensor devices for detecting the rotational speed or the wheel speed are known. During braking or during acceleration, the ABS control or the TCS control is automatically activated if the wheels exceed the optimum slip range and there is a risk of locking or idling the wheels.

In the case of this known ABS control system or TCS control system, the information required for control is obtained by detecting the rotational state of the individual wheels. In this case, the vehicle reference speed which approximately indicates the vehicle speed is determined by the logical combination of the wheel rotation signals. This reference vehicle speed can be used as a reference variable for determining wheel slip and other control variables and as a reference variable for determining or controlling the brake pressure in the wheel brakes. In the case of known ABS or TCS control systems, the determination of the slip limit, i.e. the wheel slip up to a critical point (to which only the transmittable braking force or drive torque only increases) is determined by the vehicle. Achieved by braking or driving over a critical slip. Then, the wheel peripheral speed changes with respect to the vehicle reference speed so that the tendency of the wheel to lock or spin is detected. In the case of ABS control or TCS control, a control cycle of maintaining pressure, increasing pressure, and decreasing pressure from phases occurring in an arbitrary order is repeated a plurality of times per wheel.

The fact that a critical slip has to be exceeded in order to detect the slip limit reduces the brake or drive power in each ABS or TCS control cycle. At the same time, the braking distance increases. Exceeding the critical slip reduces tire side force. Vehicle stability and steerability of the vehicle are reduced.

[0006] Thus, without exceeding a slip limit or a critical slip for detection or determination, a slip limit or a wheel slip of a vehicle suitable for ABS control or TCS control is detected via a sensor. A method for controlling the driving state of a vehicle, which is capable or determinable, is desired.

A tire sensor transmitted from a wheel to a road and detecting a force acting on a tire can be basically used as a control amount in an ABS control system or a TCS control system. This is because the force is directly detected at the place where the tire sensor generates. However, in the μ-slip characteristic curve, the friction coefficient (
μ) increases in proportion to the slip, thereby increasing the force between the tire and the road when the wheels are locked, so that a slip value suitable for ABS control or TCS control can be obtained via the force detected by the tire sensor. It cannot be determined uniquely.

[0008] The problem underlying the present invention is to provide a method for controlling the running state of a vehicle, which can optimize the effect of the movement of the vehicle.

This object is achieved in the method described at the outset by the features of claim 1.

A feature of the method is that when starting ABS control or TCS control, the operating point and / or operating range of the force detected by the wheel force sensor or the tire sensor is adjusted by the detected wheel slip. is there. Wheel slip is determined as a function of variables such as wheel speed and vehicle reference speed, which are measured and / or calculated as a function of conventional sensors, and on the evaluation of dynamic wheel rotation conditions.
The operating point and / or operating range of the control variable detected by the wheel force sensor or the tire sensor is determined by the force during a critical wheel slip and / or at least one wheel slip and at a wheel reversal point of speed. And its derivative is determined at the same time in the first ABS control cycle or TCS control cycle. The determination of the maximum force is determined by increasing the brake slip or traction slip or negative acceleration (ABS) or positive acceleration (TC
It takes place at the beginning of S), ie in the range of critical slip values during the first ABS control cycle or TCS control cycle. Further, the determination of the minimum force is made when a positive acceleration occurs from a brake slip or when a negative acceleration from a propulsion slip or re-acceleration from a wheel slip occurs. By adjusting the estimated rotational state of the individual wheels and the vehicle reference speed during a critical slip by means of the forces detected by the wheel force sensors or the tire sensors, in particular the longitudinal forces, the control amount "force" The operating point and / or operating range is adjusted. Therefore, the present invention determines the wheel slip, i.e. the critical slip, via the rotational speed condition and the vehicle reference speed so that the operating point or operating range of the force detected by the wheel force sensor or the tire sensor is initially controlled. It is based on the recognition that it is detected at the beginning of the cycle. Thereby, the frictional connection between the tire and the road is clearly determined, and errors in the control variable are eliminated. This error is based on the μ slip curve. In the case of this μ-slip characteristic curve, the coefficient of friction (μ) increases in proportion to the slip, thereby increasing the force between the tire and the road when the wheels are locked or the wheel is spinning.

With the method according to the invention, the operating point and / or operating range of the forces acting on the vehicle tires is adjusted within the ABS or TCS control range of the wheel slip. For this purpose, the rotational state of the wheels is initially determined within the unstable range at the beginning of the control process and is evaluated, possibly taking into account other variables. continue,
The next ABS control cycle or TCS control cycle, the control of the wheel slip, the wheel force sensor or the tire as long as the external action, for example a change in the coefficient of friction, does not move the operating point and / or operating range and exceeds the slip limit. Via the force detected by the sensor, it is adjusted below or by the critical slip (slip limit value).

In a particularly advantageous embodiment of the method, the above-mentioned determination of the operating point and / or operating range is started anew, so that the operating point and / or operating range is adapted to the new characteristic or state variable.

[0013] A particularly advantageous series of embodiments of the method according to the invention is described in the dependent claims.

In an advantageous embodiment, at least a critical wheel slip and / or at least one wheel slip within the ABS control range or the TCS control range are determined by a wheel sensor or a tire sensor based on a quantity detected by a conventional sensor. Is determined simultaneously with the detection of the force. Because, by using the conventional control method, when entering the ABS control or TCS control,
This is because it is possible to easily adjust the operating point or operating range determination of the control amount, that is, the force.

In another embodiment, in the first ABS control cycle or TCS control cycle, the force is determined when the brake slip or traction slip increases and / or when the wheel is accelerating, and the force or the derivative of the wheel reversal point of the speed or its derivative value is determined. By the way, the force is determined when acceleration occurs from a brake slip or when deceleration occurs from a wheel propulsion slip. Because, in the event of an increase in brake slip or traction slip or acceleration of the wheel, the force depends not only on slip and / or deceleration, but also on the increase in force. This increase in force is influenced by various characteristic quantities, for example, low tire pressure or wheels with high slip demand.

The force is determined at the time of the increase of the brake or traction slip and / or at the start of the acceleration of the first ABS or TCS control cycle, so that immediately after the determination, the control determined by the wheel force sensor or the tire sensor is determined. Since the quantity can be used for ABS control or TCS control, the control quantity determined by the sensor can be adjusted within a stable wheel slip range. As a result, it is possible to avoid a decrease in tire side force that occurs in an unstable wheel slip range, and the accompanying deterioration in vehicle steerability and a decrease in brake output.

According to another embodiment, when entering the driving stability range, the determination and / or the change of the brake pressure and / or the driving torque is controlled according to the formula F = k ₁ × F _max , where k ₁ = Proportionality factor, F = actual longitudinal force between tire and road. The longitudinal force is adjusted stepwise to avoid vibrational excitation of the drive. After the above-mentioned determination of the first operating point has been made and the wheel slip has been reduced by the control variable F _max × k ₁ and the braking pressure or the basic drive torque which exercises on the force has been adjusted, the force and the wheel slip or Acceleration is observed. When the product F _max × k ₁ is greater than the force F measured by the wheel force sensor or the tire sensor, AB
S control or TCS control is the following formula

[0018]

(Equation 2) , Where T ₀ is a nominal time of 60-90 ms, especially 70-80 ms, and T _{ABS / TCS} is the exit time.

By determining the product F _max × k ₁ and the evaluation, ie when the product F _max × k ₁ is greater than the force F measured by the wheel force sensor or the tire sensor, a constant brake pressure control by the driver is performed. Alternatively, an increased coefficient of friction between the tire and the road can be estimated when setting the driving torque. In this case, the difference k ₁ · F _max -F
Departs from ABS mode and TCS mode, accelerated by an exit time that is indirectly proportional to This is because the state of the vehicle can be estimated from a decrease in the tendency of locking or the tendency of traction slip.

When the evaluated product F _max × k ₁ substantially matches the force F measured by the wheel force sensor or the tire sensor, braking or acceleration with a uniform coefficient of friction is assumed. The evaluation of k ₁ · F _max then depends on an exact determination of the force F _max which is determined when increasing the brake or traction slip or when accelerating the wheels. It depends on the brake output during ABS control and on the output and acceleration of the drive device during TCS control.

Through the self-test cycle, the determined forces F _max and F _min are constantly updated,
Corrected if necessary. To that end, after a nominal time, a change or increase in the brake pressure takes place by means of a pressure increase pulse supplied to the control system and / or by the addition of a drive torque in the TCS control system.
In this case, positive or negative acceleration and force of the wheel are detected. From the evaluation and change of the measured force and acceleration, for example, when the force F increases and the acceleration does not change, that is, when the increase in the force F is detected without the increase in the acceleration, the braking force or the driving force is not improved. It is assumed that it is sufficient. In other words, the force F measured and evaluated by the tire sensor, in particular the longitudinal force detected between the tire and the road, does not correspond to the force that can be transmitted from the wheels to the road. In this case, a new finding of the operating point or operating range is started.

In an embodiment of the invention, the force F _max or the acceleration is evaluated by comparison with a threshold value (S), and when the threshold value is exceeded, by changing or increasing the brake pressure or by increasing the drive torque. Instability and hence brake slip or traction slip occur. This instability, as described above, causes readjustment of the operating point due to wheel slip. This re-adjustment or re-determination of the operating point due to wheel slip is initiated when driving at high speed or when large forces are generated.

According to another embodiment, the maximum force F _max or the acceleration is evaluated by comparison and is at least 1 when it is below a threshold value (S), in particular when F _max or a (speed) <S. The measured force F is provided by supplying one pressure increase pulse to the control system and typically supplying a plurality of pressure increase pulses and / or at least one additional drive torque to the control system to change or increase the brake pressure. Is approached to the maximum force (F _max ). In doing so, the wheels considered slip slightly. That is, a critical slip or slip limit is exceeded and a new operating point is created. This control is advantageous when the force or vehicle acceleration is low.

In another embodiment of the method, the force F is almost constant or does not increase,
Is related to negative acceleration or measured force F> k₁. F_maxIf it increases according to
, Wheels are wheel slip ABS control range or TCS control range
Is within. In this case, the driving torque reduction or the brake pressure reduction is about T_p= 2m
s brake pressure drop pulse or by adding drive torque, F ≦ k _Two × F_minControlled up to. Where k_Two> 1.

An embodiment of the present invention is shown in the figures. Next, this embodiment will be described in detail.

The basic structure of the electronics of the ABS or TCS controller 19 is shown in FIG. The signals V1 to V4 obtained by the conventional wheel sensors are first processed and amplified in a circuit 11. By comparing the output signals of this circuit 11 using a predetermined selection criterion, the reference speed V _{Ref which} serves as a reference value for the brake pressure control in the individual wheel brakes or control channels of the conventional brake system Is required. Furthermore, the signal processing determines, from the wheel signals, the deceleration and acceleration of the individual wheels, changes in these values (so-called sudden fluctuations), wheel slips and the like, as is known. In parallel with the circuit 11, wheel force signals F1 to F4 obtained by wheel force sensors or tire sensors are
Treated with 2, to determine the force maximum F _{ma x} and force a minimum value F _min in accordance with predetermined criteria in logic unit within 13. At that time, _Fmax and _Fmin are understood to be the following forces.

In an ABS control cycle, F _max is the force at which a pronounced brake slip increase or deceleration is determined. F _min is the force at which a distinct speed reversal or acceleration reversal (re-acceleration from a brake slip) is determined.

In a TCS control cycle, F _max is the force at which a pronounced fractional slip increase or acceleration is determined. F _min is the force at which a distinct speed reversal (deceleration from towing slip, re-acceleration from slip) is determined.

The circuit 11 is connected to a logical operation unit 13 to determine F _max and F _min . Here, the wheel force signals F1 to F are determined in the logic circuit determined in the first ABS control cycle or TCS control cycle in the circuit 11.
The evaluation of the information on the wheel slip coupled to 4 determines the _Fmax and _Fmin . The critical wheel slip determined by conventional wheel sensors and / or the wheel slip within the ABS control range or the TCS control range is used to adjust the operating point and / or operating range of the determined actual force F.

The output unit of the logical operation unit 13 is connected to a unit 14 for determining an immediate force component k1 × _Fmax . This unit 14 supplies a control deviation in the form of an electrical signal to a circuit 15. Thereby, in this circuit 15,
Depending on the determined force and its operating point, at least one pressure increase pulse F × t
Is supplied to the activator 16. In order to avoid excitation of the drive, in the circuit 15 a particularly rapid succession of several partial rise pulses is generated and supplied to the activator due to the pressure increase.

The output unit of the logical operation unit 13 is connected to an observer (observation unit) 17 in addition to the unit 14. A force signal F1~F4 which is filtered of wheel force sensors and the tire sensor, the signal of the F _max and F _min is supplied to the observer.
In the observer, situational recognition is performed by evaluating various information which are combined and / or generated in the logic circuit and compared with the force signal. The situation recognition information obtained by the comparison is stored in the logic circuit 13, the unit 14, and the circuit 1
5 and taken into account in determining the values F _max , F _min , k1 × F _max and F × t.

FIG. 2 shows the basic method leading to the start of the ABS or TCS function. Logical branches are shown as diamond blocks in the flowchart. Starting from a predetermined situation to be determined (start 20), it is first ascertained in a diamond-shaped block 21 whether braking is taking place. For this purpose, the longitudinal acceleration along is compared with a threshold value. If the value along is smaller than the threshold along _min , it means that there is a negative longitudinal acceleration, that is, there is a deceleration for which braking can be inferred when viewed in a simplified manner. If the longitudinal acceleration is higher than the threshold,
The vehicle is traveling at a constant speed without acceleration or braking. If the previous run recognized braking, the diamond block 22 is queried for wheel instability. If the instability exists and the ABS function is working, the ABS control (ABS block 23) in FIG. 3 is started.

On the other hand, when it is confirmed in the diamond-shaped block 21 that there is no braking, in the diamond-shaped block 24, there is a traction instability of the wheel, and switching is performed so that the TCS function is activated. The question is asked. In this case, TC in FIG.
The S control (TCS block 25) is started. If wheel instability is identified in diamond block 22 or diamond block 24, no control is required. The system is switched back to the start 20 of the question and the question is repeated anew.

The processing procedure of the ABS control will be described with reference to FIG. 3 with reference to FIG.
In this FIG. 5, the relationship between the wheel speed v, the pressure p and the force signal F during controlled braking with a uniform coefficient of friction is shown very simply. At time t1, the wheel x considered here, which is in the pressure build-up phase, becomes unstable. At this point, the brake pressure in the wheel brakes for this wheel is p. To determine the force between the tire and the road at time t1, first of all, in diamond block 30, a brake slip determined by a conventional wheel speed sensor, in which case wheel x becomes unstable. Is interrogated in the first ABS control cycle. at the same time,
The force signal _Fmax determined based on the wheel force sensor or the tire sensor is at time t1
Is determined and stored (31). This force signal confirms a clear increase in the brake slip of the wheel or a corresponding deceleration (reduction of the wheel peripheral speed). Then, at time t1, the considered wheel becomes unstable. Since the electronic controller closes the inlet valve of the brake system based on the determined locking tendency, the brake pressure p at time t2 no longer increases when the operating pressure further increases. The force measured by the wheel force sensor or the tire sensor decreases as brake slip increases during the pressure holding phase. This is because the frictional connection between the tire and the road is weakened. If the brake slip further increases even though the brake pressure p is constant until time t3, a pressure drop 32 is started. To that end, the electronic controller keeps the inlet valve closed and opens the outlet valve for a short period of time. In the diamond-shaped block 33, it is inquired whether or not the wheel has re-accelerated (increased wheel peripheral speed) from the brake slip based on the decrease in the pressure in the wheel brake. When it is confirmed in the execution in the diamond-shaped block 33 that the wheel re-acceleration has not occurred, the pressure drop 32 is repeated again. In the diamond-shaped block 33, the wheel x
Is confirmed, i.e., if the wheel is within the wheel reversal point of speed or acceleration, the force at 34 at which re-acceleration occurs from the brake slip determined by the wheel force sensor or tire sensor. Signal F _min is determined and stored at time t4. The ABS control cycle enters the operating mode at 35. That is, the control is switched to the control circuit 43. Then, another brake control is advanced by a force signal as a control amount determined by the wheel force sensor or the tire sensor. After the determination of F _max and F _min has been completed, thereby determining the operating point or operating range in the first ABS control cycle, stabilizing at time t5,
In step 46, the determination and / or modification of the brake pressure is performed according to the relationship F = k1 × _Fmax . k1 <1 is a proportional coefficient, and by this proportional coefficient,
The force is adjusted to less than _Fmax . In order to ensure that the pulses F × t generated thereby do not excite the drive, in circuit 15 the force signal is converted into a control variable, in particular a brake pressure (or valve switching time, etc.) and a rapid succession Is supplied to the wheel brake in the form of a partial rise pulse.

After the wheel slip has been reduced and a brake pressure corresponding to the determined force signal has occurred, the observer 17 begins to observe the force of the wheel x and the brake slip or deceleration.

FIG. 6 shows, in connection with FIG. 3, a very simplified relationship between the wheel speed v, the pressure p and the force signal F during controlled braking with a decreasing coefficient of friction. Until time t7, the procedure corresponds to the procedure for determining _Fmax and _Fmin described in connection with FIG. 5, and the force signals F1-F determined by the wheel force sensors or the tire sensors.
4 corresponds to the subsequent braking force control. If the wheel x considered here in the pressure-increasing phase becomes unstable again at time t7, for example, based on a decrease in the coefficient of friction, the operating point and / or operating range of the control variable is related to FIG. It is newly adjusted by wheel slip as described above. Another control cycle is based on the decreasing coefficient of friction. This control cycle, unstable wheel x is the signal of the conventional wheel sensors, determining F _max 2 and F _{mi n} 2 to F _max Y and F _min Y. At that time, the proportionality factor k1 _max 2, is performed following the first F _max determined and F _min determined, is introduced into the assessment and or modification of the brake pressure based on the relationship _{F = k1 max 2 × F max} 2. This proportionality factor takes into account the height of the brake pressure drop of the preceding instability and the deceleration of the wheel x in the unstable phase.

FIG. 7 shows the change in the speed of one wheel, the brake pressure of the wheel and the force between the tire and the road during antilock control for the same time when the coefficient of friction increases. .

Up to time t8, the procedure corresponds to the procedure for determining F _max and F _min described in connection with FIG. 5, and subsequent processing with a force signal determined by a wheel force sensor or a tire sensor. Matches braking force control. Due to the increase in the coefficient of friction and the constant pressure set by the driver, the relation F <k1 × F _max queried in the diamond block 37 (where the relation between the tire and the tire determined by the wheel force sensor or the tire sensor). When the longitudinal force F between the roads is less than the brake pressure at time t9 caused by the force signal k1 × _Fmax ), the ABS control cycle becomes

[0039]

(Equation 3) To finish early. In this case, k1 is a proportional constant, T ₀ is a nominal time 60～90Ms, in particular 70~80ms, T _{ABS / TCS} is the end time indirectly proportional to the difference k × F _max.

The processing procedure of FIG. 3 is newly repeated. In this case, the operating point and / or operating range of the control amount (F _max2 , F _min 2 in FIG. 7) is determined in consideration of the ratio of the large friction value when the instability of the wheel x newly occurs. Newly adjusted by the wheel.

In the diamond-shaped block 37, when it is confirmed that the force signal F determined by the wheel force sensor and the tire sensor is not smaller than k1 × _Fmax , the diamond-shaped block 3
At 8, the relationship F ≒ k1 × _Fmax is interrogated. When the actual force F measured by the sensor substantially matches the product k1 × _Fmax , at time t6 (FIG. 5), 100 to 20
Within a time window of 0 ms, in particular according to a determined or predetermined stability criterion, a pressure-increasing pulse is supplied to the wheel brakes in step 39.1.
Magnitude of the pressure increase pulses, at time t6, determined by a constant factor of the remaining or actual control deviation F _max -F _max or characteristic curve from a table derived from × k1 having brake pressure pi Can be When the actual increase in force F is measured by a wheel force sensor or a tire sensor, the conventional wheel speed sensor does not detect an increase in wheel deceleration and the brake pressure applied to the wheel brakes is greater than the maximum brake pressure. Low. A braking force smaller than the maximum braking force is estimated. At this maximum braking force, the frictional coupling force that matches the instantaneous coefficient of friction is fully utilized. The operating point or range of the control variable "force F" is newly adjusted by the wheel slip. To this end, in step 39.2, the operating point is updated by correcting the forces _Fmax and _Fmin . In the embodiment, the control after the diamond-shaped block 37 is newly performed. If F ≒ k1 × _Fmax is still confirmed after the first pressure rise pulse in diamond-shaped block 38, another pressure rise pulse is given in step 39.1. After one or more other pressure-increasing pulses have been supplied to the wheel brakes in step 39.1, the next determination of the actual force is started.
The actual force F is gradually increased by approaching the force maximum with a small pressure rise pulse, preferably at high vehicle deceleration or a large frictional connection force between the tire and the road. This increase in force takes place until it is ascertained at the diamond 38 that the actual force F measured by the wheel force sensor or the tire sensor no longer corresponds to the adjusted force k1 × _Fmax . Then, in diamond block 40, it is asked whether the force F measured by the wheel force sensor or the tire sensor is F> k1 × _Fmax or whether the deceleration of the wheel x is increasing.
In fact, an increase in the force F cannot be detected. Starting from the confirmation in the diamond-shaped block 40, if F> k1 × _Fmax , the full utilization of the friction coupling action is assumed. The wheel x considered is at the maximum of the μ-slip-curve. Then, at step 41, at least one short pressure drop pulse should be about tpｔ
It is supplied to the wheel brakes for a time of 2 ms. The supply is performed until the _{F ≦ k 2 × F mi n} . Here, k ₂ > 1. Subsequently, the processing procedure of FIG. 3 is newly performed.

In another embodiment, preferably when the frictional connection is weak and the vehicle deceleration is small, in step 39.1 a significant pressure build-up, ie the wheel created by the frictional connection between the tire and the road, A pressure increase in the brake takes place. This increase in pressure causes the wheel to become unstable in step 39.2, resulting in a correction of _Fmax and _Fmin by the new procedure of FIG.

The processing procedure of the TCS control will be described with reference to FIG. At some point, the driven wheel x considered here becomes unstable. At this point, drive torque is applied to the wheels. This drive torque tends to cause the wheel x to spin. To determine the force between the tires and the road at this point, first, in diamond block 50, the start of a drive slip at which wheel x becomes unstable, as measured by a conventional wheel rotational speed sensor, is determined by the following: Asked in one TCS control cycle. At the same time, a force signal _Fmax detected based on the wheel force sensor or the tire sensor is determined and stored. This force signal confirms a pronounced increase in drive slip of the wheels or a corresponding acceleration (increase in wheel peripheral speed). The electronic controller reduces the driving torque based on the confirmed tendency of the wheel x to spin. For this purpose, the electronic controller closes, for example, the shut-off valve of the known brake device, so that when the inlet valve is open and the outlet valve is closed, the brake pressure medium can be supplied to the wheel brakes from the auxiliary pressure source. . The electronic controller can further reduce engine torque. The force determined by the wheel force sensor or the tire sensor increases based on the onset of a decrease in drive torque when the traction slip decreases. Because
This is because the frictional connection between the tire and the road is increased. In the diamond-shaped block 53, it is asked whether or not a reduction in the driving torque or a deceleration of the wheel from the traction slip based on the reduction in the driving torque has occurred. In the execution of the diamond-shaped block 53, if it is confirmed that the drive torque has not decreased and / or the wheel deceleration or the traction slip has not decreased, the pressure increase and / or the drive torque decrease 52 is newly executed. If a reduction in traction slip and / or a deceleration of the wheel x is confirmed in the diamond shaped block 53, that is, if the wheel x is in the range of the wheel reversal point of speed or acceleration (deceleration from the propulsion slip), a wheel force sensor or The force signal F _min detected by the tire sensor is determined at this point and stored. In this force signal, deceleration from traction slip or re-acceleration from slip occurs. The TCS control cycle starts operating. That is, the control is switched to the control circuit 70, and another traction control is advanced by a force signal as a control amount detected by the wheel force sensor or the tire sensor. After the determination of _Fmax and _Fmin has been completed, and thus the operating point or operating range has been determined in the first TCS control cycle, once stability has been achieved, the determination and / or correction of the drive torque In step 56
= K1 × _Fmax . k1 <1 is a proportionality factor that adjusts the force to be less than _Fmax . In order to ensure that the pulses F × t generated thereby do not excite the vibrations of the vehicle, the force signal is converted into a control variable, in particular a brake pressure and / or an engine torque, in a circuit 15 and adjusted stepwise.

After the wheel slip has been reduced and a braking pressure corresponding to the determined force signal has occurred, the observer 17 begins to observe the force of the wheel x and the traction slip or acceleration.

At that time, if at some point the wheel x considered here becomes newly unstable, for example based on a decreasing friction coefficient, the operating point or the steering range of the controlled variable will be described with reference to FIG. As described above, it is newly adjusted by wheel slip.

Due to the increase in the friction value and / or the reduction in the driving torque setting of the driver, the relation F <k1 × _Fmax queried in the diamond shaped block 57 results (in this relation, determined by the wheel force sensor or the tire sensor). The longitudinal force F between the tire and the road,
(Less than the drive torque setting caused by the force signal k1 × F _max ).
In step 60, the S control cycle

[0047]

(Equation 4) Ends early with an end time that is indirectly proportional to the difference k1 × F _max −F. In this case, k1 is a proportional constant, T ₀ is a nominal time 60～90Ms, especially 70
80 ms, T _{ABS / TCS} is the end time. On the other hand, if the driver does not confirm a decrease in the driving torque in the diamond-shaped block 58, the diamond-shaped block 59 asks whether the friction coefficient is increased. If it is confirmed by observation of the force of the additional drive torque that the coefficient of friction increases in proportion to the observation of the acceleration condition of the wheels, the TCS control cycle also proceeds to step 60 with the following equation:

[0048]

(Equation 5) Ends early with an end time that is indirectly proportional to the difference k1 × F _max −F. In this case, k1 is a proportional constant, T ₀ is a nominal time 60～90Ms, especially 70
80 ms, T _{ABS / TCS} is the end time. However, in the diamond-shaped block 59,
If it is determined that the coefficient of friction has not increased, a decrease in the coefficient of friction is inferred in step 61, and a traction slip finds a new TCS operating point or range as described above.

The processing procedure of FIG. 4 is newly repeated. In this case, the operating point and / or operating range (F _max , F _min ) of the control variable is newly adjusted in consideration of the ratio of small friction values when the instability of the wheel x newly occurs.

In the diamond-shaped block 57, when it is confirmed that the force signal F determined by the wheel force sensor and the tire sensor is not smaller than k1 × _Fmax , the diamond-shaped block 6
At 2, the relationship F ≒ k1 × _Fmax is interrogated. As soon as the actual force F measured by the sensor substantially corresponds to the product k1 × _Fmax , within a time window of 100 ms, in particular according to a decision or according to a predetermined stability criterion, the additional drive torque is supplied in step 63.1. A force test is performed. The magnitude of the additional drive torque is determined from a table or a characteristic curve by a constant coefficient. If the actual increase in the force F is measured by a wheel force sensor or a tire sensor, a conventional wheel speed sensor will not detect an increase in wheel acceleration and a too small driving force is assumed. This driving force is smaller than the maximum traction force. At this maximum tractive force, the frictional coupling force corresponding to the instantaneous coefficient of friction is fully utilized. The operating point or range of the control variable "force F" is newly adjusted by the wheel slip. To that end, step 63.2
Then, the operating point is updated by correcting the forces _Fmax and _Fmin . In the embodiment, the control after the diamond-shaped block 57 is newly performed. Diamond block 6
If F ≒ k1 × _Fmax is still confirmed after the first drive torque addition in 2, another drive torque addition is performed in step 63.1. After one or more other drive torque additions have been made in step 63.1, the next determination of the actual force is started. Preferably by close to force the maximum value by the drive torque added when a large frictional coupling force F _{ma x} between high vehicle acceleration or tire and the road, the actual force F is gradually increased. This increase in force takes place until it is ascertained in the diamond-shaped block 62 that the actual force F measured by the wheel force sensor or the tire sensor no longer corresponds to the adjusted force k1 × _Fmax . And further, a diamond-shaped block 64
, The force F measured by the wheel force sensor or the tire sensor is F> k1
A question is asked as to whether _{xF max} or whether the deceleration of wheel x is increasing. In fact, an increase in the force F cannot be detected. Starting from the confirmation at the diamond-shaped block 64, if F> k1 × _Fmax , full utilization of the frictional coupling effect is assumed. The wheel x considered is at the maximum of the μ-slip-curve. And
In step 65, at least one small drive torque reduction is controlled over a time period of about tp ≒ 2 ms, just in case. This control is performed until F ≦ k ₂ × F _min . Here, k ₂ > 1. Subsequently, the processing procedure of FIG. 4 is newly performed.

In another embodiment, preferably when the friction coupling action F _max is weak and the vehicle acceleration is low, in step 63.1 a large drive torque is added, ie by a friction coupling action between the tire and the road. The resulting drive torque is added. This addition of the driving force results in the correction of F _max and F _min by making the relevant wheel unstable in step 63.2 and the procedure of FIG. 4 is newly performed.

[Brief description of the drawings]

FIG. 1 schematically illustrates the integration of a force sensor device into an ABS function / TCS function.

FIG. 2 is a diagram schematically showing an initial setting of an ABS function or a TCS function.

FIG. 3 is a flowchart of an ABS function.

FIG. 4 is a flowchart of a TCS function.

FIG. 5 shows the change in wheel speed during antilock control, the brake pressure in the wheel and the force between the tire and the road for the same time on a homogeneous road.

FIG. 6 shows the change in wheel speed during anti-lock control, the change in brake pressure in the wheel and the change in force between the tire and the road for the same time when the coefficient of friction decreases.

FIG. 7 shows the change in wheel speed during antilock control, the change in brake pressure in the wheel and the change in force between the tire and the road for the same time when the coefficient of friction increases.

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number 100 06 012.9 (32) Priority date February 11, 2000 (2000.2.11) (33) Priority claim country Germany (DE) ( 81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), JP, US (72) Inventor Batistik Ivica Germany, Frankfurt am Main, Arnsburger Strasse, 20F term (reference) 3D046 BB28 BB29 CC02 HH02 HH36 KK12

Claims (16)

[Claims] 1. A force acting on a wheel and a tire is detected by a wheel force sensor or a tire sensor and used as a control variable for a vehicle control system such as ABS, TCS, EHB, etc. A method for controlling the driving state of a vehicle, which is used to determine and / or change the braking pressure and / or the driving torque in a wheel brake, wherein the operating point and / or operating range of the control variable is determined by the detected wheel slip. A method characterized in that it is adjusted. 2. The steering point and / or operating range of the controlled variable is determined as a function of a quantity detected and / or calculated by a conventional sensor, such as a wheel rotational speed, a vehicle reference speed or the like. The method of claim 1, wherein 3. An amount (V) detected by a conventional sensor.₁, V_Two, V_Three, V _Four , V_RefBased on at least the critical wheel slip and / or ABS
At least one wheel slide within the control range or TCS control range
Is detected by a wheel sensor or a tire sensor._max, F_min) Detection
3. Method according to claim 1 or 2, characterized in that it is determined simultaneously. 4. In a first ABS control cycle or TCS control cycle, the force (F _max ) is determined when the brake slip or traction slip is increased and / or when the wheel is accelerating, and a range of the wheel reversal point of the speed or its differential value is determined. The force (F _min ) is determined within the range.
The method according to any one of the above. 5. The method as claimed in claim 4, wherein the force _Fmax is determined at the time of an increase in brake or traction slip of the wheels of the first ABS or TCS control cycle and / or at the start of acceleration. 6. The force _Fmin is determined when a positive acceleration occurs from a brake slip of a wheel or a negative acceleration occurs from a propulsion slip in a first ABS control cycle or a TCS control cycle. A method according to any one of claims 1 to 5. 7. The method according to claim 1, wherein the operating point and / or the operating range of the control variable is newly adjusted for each wheel instability due to wheel slip. . 8. When entering the driving stability range, the determination and / or change of the brake pressure and / or drive torque is controlled according to the following formula: F = k ₁ × F _max , where k ₁ = proportionality factor, F = A method according to any of the preceding claims, characterized in that it is the actual longitudinal force between the tire and the road. 9. Maximum force (F) during ABS braking or TCS propulsion_max ) And the proportionality factor (k₁) Product (k₁× F_max) Is given by the following equation: F = k₁× F_max Where k₁= Proportionality factor, F = actual vertical direction between tire and road
Heading, which can be caused by increasing and / or changing brake pressure and / or drive torque.
T from the start to the end of the change in force_impulsIs taken into account by the proportionality factor and the product k₁× F _max Is greater than the force (F) measured by the wheel force sensor or tire sensor.
When the ABS control cycle or TCS control cycle
The following equationEnds early, where T₀Is the nominal time, T_{ABS / TCS}Is the exit time
A method according to any one of claims 1 to 8, characterized in that: 10. The method according to claim 9, wherein the nominal time is between 60 and 90 ms, in particular between 70 and 80 ms. 11. During the ABS braking or TCS propulsion, the maximum force (F _{ma x)} a proportional factor (k ₁₎ product (k ₁ × F _max) is observed according to the following equation F = k ₁ × F _max Where k ₁ = proportionality factor, F = actual longitudinal force between tire and road, time t _impuls from start to end of force change due to increase and / or change in brake pressure and / or drive torque Is taken into account by the proportional coefficient, and the product k ₁ ×
When _Fmax approximately matches the force (F) measured by the wheel force sensor or the tire sensor, the change in brake pressure and / or the addition of drive torque to the control system by the pressure increase pulse occurs within a nominal time window. In this case, the negative acceleration of the wheel and the force F are determined, and when the force (F) increases and when the acceleration is approximately the same, the determined amount of the operating point is newly determined. The method according to claim 1, wherein an evaluation is performed. 12. The maximum force (F _max ) or acceleration is evaluated by comparison with a threshold value, and when the threshold value is exceeded, instability is caused by increasing the brake pressure and / or the additional drive torque, and the instability is determined. 12. The method according to claim 11, wherein the adjustment of the operating point according to one of the claims 1 to 6 or the operating point according to claim 7 is started. 13. The method according to claim 1, wherein the maximum force (F _max ) or the acceleration is evaluated by comparing with a threshold value, and when the maximum force (F _max ) exceeds the threshold value, at least one pressure-up pulse is supplied to the control system, usually a plurality of pressure-up pulses and Or providing at least one additional drive torque to the control system to increase the brake pressure so that the determined force (F) approaches the maximum force ( _Fmax ) and the new operating point is adjusted. The method of claim 11, wherein the method comprises: 14. The method of claim 11, wherein the nominal time window is between 100 and 200 ms. 15. The maximum force (F) during ABS braking or TCS propulsion._{ma x} ) And the proportionality factor (k₁) Product (k₁× F_max) Is given by the following equation: F = k₁× F_max Where k₁= Proportionality factor, F = actual vertical direction between tire and road
Heading, which can be caused by increasing and / or changing brake pressure and / or drive torque.
T from the start to the end of the change in force_impulsIs taken into account by the proportionality factor and the product k₁× F _max Is less than the force (F) measured by the wheel force sensor or tire sensor
The brake pressure and / or drive torque
The change in force is introduced into the control system and the total force (F) is k_Two× F_{mi n} Introduced, where k_Two> 1
Item 10. The method according to any one of Items 1 to 9. 16. A method for shortening the braking distance of an at least two-wheel, four-wheel vehicle, in particular using the method according to claim 1, wherein a wheel force sensor signal or a tire sensor is provided. A method according to claim 1, wherein a first control variable is controlled on the basis of the signal, and a target value of the control variable is determined by the second control variable on the basis of a frictional connection between the tire and the road.