KR100495966B1 - Method and apparatus for determining variables representing vehicle speed - Google Patents

Abstract

The present invention relates to a method and apparatus for determining a parameter indicative of the speed of a vehicle. The variable depends on the wheel speed selected. At least one or two queries are made based on the wheel speed, the results of which are taken into account when selecting the wheel. The first feasibility query confirms whether a variable indicative of the speed of the vehicle can be determined according to a wheel having a higher speed than the variable indicative of the speed of the vehicle. The second feasibility query confirms whether the variable indicative of the speed of the vehicle can be determined according to the wheel having a lower speed than the variable indicative of the speed of the vehicle.

Description

Method and apparatus for determining variables indicative of the speed of the vehicle

The present invention relates to a method and apparatus for determining a parameter indicative of the speed of a vehicle.

Methods and apparatus for determining variables indicative of the speed of a vehicle are known in the art in various modifications.

DE-OS 38 33 212 (US Pat. No. 5,272,634) describes the setting of a reference parameter of the vehicle speed outside of the braking pressure regulator for a single-axis drive vehicle equipped with ABS. In essence, for this purpose, the average wheel speed is determined from the speeds of both drive wheels. If this average wheel speed value of the wheel becomes larger and larger than zero with time, the reference variable is determined as the speed of the slower wheel of both driving wheels, and if the mean speed of the averaged wheel becomes smaller and smaller with zero with time, The reference variable is determined by the speed of the faster wheel of both drive wheels. In this case, the increase of the reference variable with respect to the vehicle speed is limited to the maximum value.

DE-OS 40 09 195 (US Pat. No. 5,364,174) describes the setting of reference speeds that require slip control in ABS installed in four-wheel drive vehicles. In essence, here the reference speed is determined by the speed of the slowest wheel as the speed increases and by the speed of the third fastest wheel when the speed decreases. In the transition region between the ascending and descending speeds, the value reached at the slowest wheel speed remains constant. In the case where the third fastest wheel speed deviates much from the auxiliary reference speed, the reference speed is formed parallel to the auxiliary reference speed. The auxiliary reference speed is formed by raising by the third fastest wheel speed and decreasing by the fastest wheel speed. In addition, the auxiliary reference speed is kept constant in the transition region. If an unstable condition occurs due to the braking deflection, the increase of the reference speed is determined by the increase of the auxiliary reference speed. As the wheels rotate, the reference speed remains constant and the rise of the auxiliary reference speed is limited to the acceleration of the vehicle that is physically possible. If the rear wheels of all four-wheel drive vehicles are driven by the drive from the braking state, a slightly modified reference speed is used. In addition to this control system, the reference speed is increased when the speed of all wheels is above the reference speed. If two or three wheels are faster than the reference speed, they remain constant. If only one of the wheels is faster than the reference speed or none is faster than the reference speed, the reference speed is adjusted to a value below the reference speed of these wheels.

Control systems for braking slip or traction are known, for example, as a general form in the first edition of the "Vehicle Braking System" of VDI, published by Robert Bosch GmbH in 1994, Düsseldorf.

A system for controlling variables indicative of the driving force of a vehicle is known, for example, from the Automotive Technical Bulletin (ATZ) No. 96, 11, published in 1994 and in pages 674-689 of the "FDR-driving force control of Bosch products" publication.

It is an object of the present invention to improve a method of determining a parameter indicative of the speed of a vehicle.

This object can be solved through the features of claims 1 to 12.

1 is a view of an embodiment of a vehicle equipped with a slip control system in which a method according to the invention or a device according to the invention is installed;

2-4 show an embodiment of a method according to the invention.

5 is a time diagram of a problem avoided by a method according to the invention or an apparatus according to the invention.

Compared to the prior art mentioned at the outset, the advantages of the method and apparatus according to the invention are that the speed of the vehicle with respect to a vehicle according to any drive system, ie front wheel drive or rear wheel drive or four wheel drive vehicle, with this method and device. That is, any driving state of the vehicle can be determined by a variable indicating. At this time, the determination of the variable indicating the speed of the vehicle is independent of the braking slip control or the driving slip control in the vehicle, or for example, the braking slip control or the driving slip control that controls any one of the variables indicating the driving force of the vehicle. It is irrelevant to the regulation system.

The variable representing the speed of the vehicle is expressed as the reference speed of the vehicle.

The method according to the invention or the device according to the invention has been found to be particularly advantageous for installation in four-wheel drive vehicles. In a four wheel drive vehicle, the reference speed value of the vehicle is driven under certain preconditions which are determined to be high compared to the actual speed value of the vehicle. Through the method according to the invention or the device according to the invention, it is ensured that the reference speed of the vehicle approaches the actual speed of the vehicle in this situation.

In the method according to the invention embodied in the apparatus according to the invention, the reference speed of the vehicle is determined according to the speed of the selected one wheel, and the selected wheel determines the vehicle reference speed at that time, It is most appropriate in the driving state. Depending on the driving state of the vehicle, a plausibility query is performed at different times or in different driving states.

In this regard, it is particularly preferable that two plausibility queries are carried out based on the speed of the wheels. Based on the first validity query, it is detected whether the reference speed of the vehicle can be determined according to the wheel whose speed is larger than the reference speed of the vehicle. Therefore, from this first validity query, the reference speed of the vehicle is set high, i.e., a larger value. In the second validity query, it is checked whether the reference speed of the vehicle can be determined according to the wheel whose speed is lower than the reference speed of the vehicle. Therefore, from this second validity query, the reference speed of the vehicle is detected low, in particular with a smaller value.

As for the 3rd validity query, it is preferable to confirm whether the result of a 1st validity query or the result of a 2nd validity query is examined. In this regard, the third validity query has at least two queries.

The first validity query has at least two queries. This query forms one variable that represents the differential speed of both wheels from the speed of two wheels, respectively. In the first query, the first differential speed formed based on the fastest wheel speed and the slowest wheel speed, and in the second query, the second differential speed at which the slowest wheel speed and the second slowest wheel speed are formed are It is preferable to compare. Through these inquiries, the synchronization of the speeds of the wheels of the vehicle is determined.

The first validity query preferably includes a third query. In this third query, a first variable representing the acceleration of the vehicle, in particular corresponding to cardinal acceleration of the vehicle, is compared with a second variable representing at least the acceleration of the vehicle, in particular a variable consistent with the longitudinal acceleration of the vehicle. Further, the second variable is preferably modified by an offset value determined according to a variable representing the state of the vehicle.

The second validity query, which determines whether a variable indicative of the speed of the vehicle can be determined according to the wheel whose wheel speed is slower than the reference speed of the vehicle, has at least one query. In this query, the corresponding limit value is compared with the variable, which determines the variables that emerge from the slip values of the wheels. This variable is also preferably formed in accordance with a first variable representing the sum of the individual slip values and a second variable representing the absolute value of each slip value.

Another advantage of the method according to the invention or the device according to the invention is that essentially no additional sensors are required in known slip control systems. However, the method according to the invention or the device according to the invention may use a sensor mounted in the slip control system, for example, to detect the wheel speed of the individual wheels.

Other advantages and preferred formations are set forth in the detailed description of the dependent claims, the figures and the embodiments.

The present invention relates to a control system disclosed in the prior art, for example related to braking slip or drive slip of wheels of a vehicle. Of course, this does not limit the basic concept according to the invention. The method according to the invention or the device according to the invention can be used, for example, in a system for controlling a variable indicative of the driving force of the vehicle, in particular the yaw velocity of the vehicle. However, this requires that an additional sensor as shown in FIG. 1 be mounted on the vehicle.

The problem with determining a variable indicative of the speed of the vehicle, referred to below as the reference speed of the vehicle, is first described. The reference speed vref of the vehicle is particularly important in relation to the traction control system, since the brakes of the wheels or the operating signal for the engine of the vehicle are determined based on this variable.

In a single-axis drive vehicle or a four-wheel drive vehicle, all four wheels of the vehicle are determined from the reference speed. In single-drive vehicles, the reference speed of the vehicle is determined without problems from the non-driven wheels of the vehicle during driving. However, in the four-wheel drive vehicle, the reference speed of the vehicle is extremely complicated due to the coupling effect. Become.

In this regard, a case where the four-wheel drive vehicle travels is shown in FIG. 5. In the figure, FIG. 5 shows progress of the wheel speed vradij of the four-wheel drive vehicle, the reference speed vref of the vehicle, and the actual speed vfz of the vehicle over time. 5 shows two states over time. State 1 lasts from time point t0 to time point t1, and state 2 lasts from time point t1 to time point t2. At time t2, the driver must activate the brake.

In state 1, the reference speed vref of the vehicle coincides with the actual speed vfz of the vehicle. The minute vibrations shown in the wheel speed vradij do not cause a separation of the reference speed from the actual speed vfz.

Due to the coupling effect in the drive train at the start of state 2, the overvalue of the reference speed vref relative to the actual speed vfz of the vehicle (the value at which the reference speed vref is kept higher than the actual speed) Is identified. The overvalue of the reference speed vref of the vehicle causes the rotating wheels to be perceived late, for example, and this leads to drive train vibrations, which indicate a strong vibration of the wheel speed vradij in the remaining progression of state 2. . This strong vibration of the wheel speed completely separates the reference speed vref and the actual speed vfz of the vehicle.

Although the ABS control need not be implemented at least directly from the actual speed vfz of the vehicle, in the brake operation shown in Fig. 5, the ABS control can be directly implemented through the above complete separation.

Through the method according to the invention or the device according to the invention, the determination of the reference speed of the vehicle, in particular when driving a four-wheel drive vehicle, is improved so that the strong vibration shown in state 2 is prevented within the wheel speed vradij. The separation of the reference speed vref from the actual speed vfz of the vehicle does not occur. This improvement is achieved by keeping the vrefs consistent with the results of the at least two validity queries.

Therefore, it can be seen that the method according to the present invention or the device according to the present invention can be used for each type of slip control system and vehicle traveling plan installed in the vehicle.

In FIG. 1 a vehicle is shown at block 101. The vehicle 101 includes a block 103 showing a control device of a control system implemented in the vehicle. The control system attached to the vehicle may relate to a system for controlling the brake slip and / or a system for controlling the drive slip and / or a system for controlling a variable indicative of the driving force of the vehicle.

The control device 103 comprises a controller 104 and a block 108 for implementing the method according to the invention. Both blocks are described below.

The vehicle 101 also includes means 102vr, 102vl, 102hr, 102hl for detecting variables indicative of the speed of the wheels. This means relates in particular to a wheel speed sensor. 1 does not show wheels equipped with wheel speed sensors. In the following, the wheel speed sensor is indicated using a simplified symbol 102ij. In this regard, the subscript i indicates whether the wheel speed sensor is attached to the axis rear face h or to the axis front face v. Subscript j indicates vehicle right side r or vehicle left side l. This symbolization through the two subscripts i or j is used consistently in every variable or component in which they are used.

The signals nij generated at the wheel speed sensor 102ij are guided to a block 105 included in the controller 104. In addition to the signal nij, block 105 receives the variables Po and Pu from block 108 and signal S1 from block 107.

On the one hand, block 105 generates a reference velocity vradij that is guided from the signals nij to blocks 107, 108. On the other hand, in block 105, a wheel is selected in which the reference speed (vaus) is guided to the block 106 from the variables Po and Pu or the signal S1.

The selection of the wheels in block 105 is carried out, for example, as follows, i.e. first the driving state of the vehicle is determined from the signal S1. Further, for example, the driving state in which the vehicle is braked and the driving state in which the vehicle is accelerated are distinguished according to the variables included in the signal S1. According to the determined driving state of the vehicle, the wheel is selected by the validity query. The wheel selected in this way is best suited for determining the reference speed of the vehicle being driven at the time. In the validity query, at least two variables Po and Pu are related as well as signals or variables included in the signal S1.

In this case, the signal included in the signal S1 relates to, for example, a signal for transmitting information or transmitting a signal input to a slip control system mounted at an observed time step, and a signal indicating the number of controlled wheels. The signal may also include, for example, a variable representing the acceleration state of the vehicle, in particular a state in which an excessive delay occurs after the vehicle is accelerated, or a variable indicating that each of the wheels is inclined. In addition, the signal S1 may include additional signals or variables in addition to the above-described signals or variables.

The speed of the car selected at block 105 is directed to block 106. From the speed one of the variables representing the speed of the vehicle in the block, i.e. the reference speed vref of the vehicle, is determined. The reference speed vref is guided to blocks 107 and 108. When determining the reference velocity vref besides the velocity, it relates to another variable S2 that is guided from block 107 to block 106. The variable S2 relates to at least one factor, for example, to which intensity the velocity of the selected vehicle is limited in determining one of the variables representing the acceleration of the vehicle or the reference speed vref.

Block 107 relates to the control body of control device 104. The control body 107 performs various functions. Firstly, the control body 107 is provided for the actuator 109ij mounted on the wheels of the vehicle corresponding to a controller implemented in the control device from at least the wheel speed vradij guided to the control body and the reference speed vref of the vehicle. The control signal Aij is determined and may be set to a braking moment that affects the respective wheels by the control signal. The actuators 109ij are for example related to valves for adjusting the pressure of the brake cylinder of the wheel. In the system for driving slip control, it is also possible to take into account the output of a signal which may affect the driving moment transmitted from the motor of the vehicle. 1 does not show a motor.

A system for controlling a brake slip in a generally known manner for braking slips is known that the braking moment affecting the respective wheels is changed by actuating the brake. In a system for controlling the drive slip, the drive slip of the wheel in a known manner is usually set by the generation of a drive moment in the respective wheels or by the action of the drive moment transmitted by the motor. The same applies to the setting of the corresponding slip in the control of the braking and / or drive slip control system. In a system for controlling any one of the variables indicative of the driving force of a vehicle, the braking moment necessary for controlling the same slip can be applied individually to the same wheel according to the driver. For example, the driving moment transmitted by the motor in the sense of controlling the driving moment is supplementally affected.

In block 107, the above-described signals S1 and S2 are determined. At least the wheel rotation speed vradij is transmitted to determine the signals S1 and S2. Also at block 107 a variable ax representing the acceleration of the vehicle is determined. In particular, the variable relates to the longitudinal acceleration of the vehicle. The variable ax is determined, for example, from the vehicle speed vradij. However, one may consider determining this variable using appropriate sensors or using a mathematical model to determine this variable. The variable ax is directed to block 108 for further processing.

If other processing is required at block 108, then at block 107 another variable (axoff) to be guided to block 108 is determined. The variable axoff represents an offset value, ie a variable representing acceleration. Accordingly, in block 107, the variable axoff is determined according to any one of the variables representing the state of the vehicle, for example, the reference speed vref of the vehicle.

In block 108 a method according to the invention is carried out. At least when the offset value axoff is needed from at least the wheel speed vradij, the reference speed vref of the vehicle, and the variable ax representing the acceleration of the vehicle, block 108 has a first validity query and a second validity query. From the validity query two variables Po, Pu, which are guided to block 105 are determined. Hereinafter, the method of the two variables Po and Pu will be described in detail with reference to FIGS. 2, 3, and 4.

The sensor technology described so far in connection with FIG. 1 shows the sensor technology which is basically necessary in connection with the method according to the invention and also in connection with the device according to the invention. If the vehicle is equipped with a brake slip control system or drive slip control system, the wheel speed sensor 102ij already exists based on such a system. If the vehicle is equipped with any one of the variables indicative of the driving force of the vehicle, in particular the system for controlling the deflection speed of the vehicle, at least one further rotational or pivot angle sensor and / or lateral acceleration sensor from the sensor shown in FIG. Or steering angle sensor is required.

In an embodiment, the use of the method according to the invention or the device according to the invention is not limited. The method according to the invention or the device according to the invention can also be installed in other systems that require one of the variables indicative of the speed of the vehicle.

2 is a flow chart illustrating the basic process of the method according to the invention. Through the method according to the invention shown in FIG. 2, for example, the reference speed vref according to the current time step can be obtained using a validity query from the reference speed value vref of the vehicle for all time steps. The result for the decision is made. It also determines whether the reference speed vref of the vehicle can be kept high or low. Each time step is not shown below.

Alternatively to the arrangement of time steps described above, one may consider executing the result of the reference speed vref of the next time step from the reference speed value vref of the current time step.

The method according to the invention begins with step 201. Following step 201, step 202 is executed, in which the reference velocity vradij of the current time step is stored. Also at step 202 a reference speed vref of the previous time step is provided.

Step 203 is followed by step 202. In step 203, the wheel speed vradij is classified according to the wheel variable. For the wheel speed vradij classified according to the wheel variable, the following classification applies, for example: The variable vrad1 is classified as the slowest wheel speed, ie the lowest wheel speed vradij. The variable vrad2 is the second slowest wheel speed, the variable vrad3 is the second fastest wheel speed and the variable vrad4 is classified as the fastest wheel speed, i.e. the highest wheel speed vradij. This classification is expressed as a relationship (vrad1 <vrad2 <vrad3 <vrad4).

Step 204 is followed by step 203. In this step, the reference speed value vref is compared with the wheel speed value vrad1, that is, the lowest wheel speed. If the query determines that the reference speed value vref is greater than the wheel speed value vrad1, then step 204 is followed by step 205.

In step 205, the variable Po is assigned a FALSE value. As a variable Po, it is passed to block 105 whether the reference velocity vref can be kept high or low. Since the reference speed value vref is larger than the wheel speed value vrad1 in step 204, and for this reason the reference speed vref is set unnecessarily high, in step 205 a FALSE value is assigned to the variable Po. do.

Step 206 is followed by step 205. In step 206, the reference speed value vref is compared with the wheel speed value vrad4, which is the fastest wheel speed, and the query is compared with the reference speed value vref and the wheel speed vrad1, which is the slowest wheel speed. Is carried out. If it is found in the query that the reference speed value vref is slower than the wheel speed value vrad4 and faster than the wheel speed value vrad1, then step 207 is executed following step 206. In step 207 the variable value P2 is read. The variable P2 has a TRUE value and is led to step 208 after step 207.

If it is confirmed in step 207 that the variable P2 has a TRUE value, the reference speed vref of the vehicle can be kept low. Therefore, in step 208, the value TRUE is assigned to the variable Pu. Through this assignment, block 105 includes information in which the wheel speed of the wheel can be selected lower than the reference speed vref. Accordingly, in block 106, the reference speed vref is determined according to the wheel whose wheel speed is lower than the reference speed. Step 214 is performed after step 208. In step 214 the method according to the invention shown in FIG. 2 ends.

Conversely, if it is found in step 207 that the variable P2 does not have a TRUE value, then step 207 is executed following step 207. Since the variable P2 does not have a TRUE value, the reference speed vref is not kept low, and therefore a FALSE value is assigned to the variable Pu in step 207. Step 209 is followed by step 209.

In step 206 it is confirmed that the reference speed value vref does not satisfy the condition representing the relationship (vrad4 &gt; vref &gt; vrad1), and therefore, step 206 is followed by step 209 previously presented.

If the query made in step 204 confirms that the reference speed value vref is smaller than the wheel speed vrad1 value, then step 210 is followed by step 210. In this step, the FALSE value is assigned to the variable Pu, and the reference speed verf cannot be kept low because the vehicle state seen in the same step 204 is explained from the query result. In this case, it is meaningful that the reference speed verf is set high.

Step 210 is followed by step 211. In this step, the variable value P1 is queried. If it is confirmed in step 211 that the variable P1 has a TRUE value, i.e., it is determined that the reference speed vref can be kept high, step 212 is executed following step 211. In step 212, a value TRUE is assigned to the variable Po. Through this assignment, block 105 receives information from which wheels with wheel speeds greater than the reference speed vr can be selected. Accordingly, in block 106, the reference speed vref is determined according to the wheel whose wheel speed is greater than the reference speed. After step 212, step 214 is executed.

On the contrary, if it is confirmed in step 211 that the variable P1 does not have a TRUE value, step 213 is executed following step 211, and a FALSE value is assigned to the variable Po. Step 213 is followed by step 214.

Finally, the query executed in step 204 and step 205 of FIG. 2 together form a validity query. In addition, it proceeds continuously based on the slip control implemented in the vehicle by the method shown in FIG.

Figure 2 also shows: The results of the first validity query are analyzed when the first query determines that the reference speed of the vehicle is slower than the slowest wheel speed. The result of the second validity query is examined when the second query confirms that the reference speed of the vehicle is faster than the slowest wheel speed and the reference speed is slower than the fastest wheel speed. That is, as a result of the first validity query, it is checked whether the reference speed of the vehicle can be determined according to the wheel whose speed is faster than the reference speed of the vehicle, and examines when the reference speed of the vehicle is slower than the slowest wheel speed. Analyze This is because it is important to stay high in this case. If the reference speed of the vehicle is faster than the slowest wheel speed, the results of the second inference query are reviewed. This is because the reference speed of the vehicle can be kept low in this case. Therefore, an appropriate validity query is selected by the third validity query corresponding to the driving state of the vehicle indicated by the wheel speed of the vehicle, and the result of the appropriate validity query is examined.

3 shows a first validity query as a flow chart, which shows whether the reference speed vref of the vehicle is kept high by the first validity query, i.e., the reference speed vref of the vehicle is greater than the reference speed vref of the vehicle. Check if it can be determined according to the wheel with fast wheel speed. The result of the validity query shown in FIG. 3 is delivered by the variable P1. As shown in relation to FIG. 2, the variable is examined to send the same information to block 105 via the query implemented in step 209.

In an embodiment of the present invention, the first validity query shown in FIG. 3 as well as the second validity query shown in FIG. 4 is selected such that the controller implemented in the vehicle continues to operate. It is checked whether the result of the first validity query or the result of the second validity query is examined with the third validity query included in FIG. 2. In addition, the method according to the present invention may first examine whether the first validity query or the second validity query is performed according to the result of the third validity query.

The first validity query shown in the figure starts at step 301. Step 302 follows step 301. In this step, two differential speeds are determined from two wheel speeds, respectively. The first differential speed dvrad41 is formed by the slowest wheel speed vrad1 and the fastest wheel speed vrad4. The second differential speed dvrad21 is formed by the slowest wheel speed vrad1 and the second slowest wheel speed vrad2.

Following step 302, a first query is made in step 303. In the first query, the first derivative speed vrad41 is compared with the first threshold value S1. If the query carried out in step 303 confirms that the first differential speed dvrad41 is not smaller than the first threshold value S1, step 304 is executed following step 303. In step 304 the second differential speed dvrad21 is compared with the second threshold value S2 in the second query. In this second query, if it is confirmed that the second differential speed dvrad21 is smaller than the second threshold value S2, step 304 is followed by step 305.

In step 303, if it is confirmed that the first differential speed dvrad41 is smaller than the first threshold value S1, step 305 is followed by step 305. If it is confirmed in step 304 that the second differential speed dvrad21 is not less than the second limit value S2, then step 309, which has not yet been described, proceeds following step 304.

In step 305 an additional variable aradm representing the acceleration of the vehicle is determined. The variable relates, for example, to drive shaft acceleration of the vehicle. The acceleration is determined, for example, by the formation of the median value and the time derivative based on the wheel speed vradij. In this regard, we also propose the filtering of variables (aradm).

According to the diagram of FIG. 3, step 305 is followed by step 306. Step 306, indicated by the dashed line, indicates that the determination of the axoff carried out in step 306 is optional and not essential for the implementation of the method according to the invention. An offset value associated with a variable (axoff) or a variable (ax) representing the acceleration of the vehicle is indicated and is also optional in the comparison made in step 307 as described above.

If the offset value axoff associated with the variable ax is taken into account, then step 305 is followed by step 306, after which step 307 is performed. If the offset value axoff associated with the variable ax is not taken into account, step 306 is not carried out and step 305 directly follows step 307.

The offset value axoff is determined in step 306 according to the vehicle situation or the driving state of the vehicle. In order to determine the driving state of the vehicle, a variable representing the state of the vehicle is used. For example, the offset value axoff is determined according to the reference speed vref of the vehicle.

In step 307, a third query for the first validity query is performed. If the above-described offset value axoff is not taken into account, in this third query, the variable aradm representing the acceleration of the vehicle is compared with the second variable ax representing the acceleration of the vehicle. If the offset value axoff is considered together, the variable aradm in the third query is compared with the sum of the variable ax and the offset value axoff. An optional consideration of the offset value axoff in step 307 is indicated by the parentheses of axoff in FIG. 3.

In step 307, the variable aradm indicating the acceleration of the vehicle is found to be smaller than the same comparison value, which means that the driving condition is generally good through the first query, the second query or the third query. Step 308 is performed after 307. Since the running state of the vehicle is good, a TRUE value is assigned to the variable P1 in step 308. Through this, as described above, the reference speed vref is determined according to the wheel of the vehicle having a speed greater than the reference speed vref. Step 310 is followed by step 310 where the first validity query ends.

In comparison, in step 307 the variable aradm indicating the acceleration of the vehicle is found not to be smaller than the same comparison value, which indicates that the driving condition is not good through the first query, the second query or the third query. In a sense, step 307 is followed by step 309. In this step, the variable 309 is assigned a FALSE value. Step 310 is followed by step 310.

Check whether the first derivative speed dvrad41 is smaller than the first threshold value S1 in the first query and / or whether the second derivative speed dvrad21 is smaller than the second threshold value S2 in the second query. If it is confirmed in the third query that the first variable aradm representing the acceleration of the vehicle is smaller than the same comparison value, the first validity query shown in FIG. 3 is summarized as follows. By this, the reference speed of the vehicle is determined according to the wheel of the speed which is larger than the reference speed of the vehicle.

4 shows a second validity query as a flowchart, wherein the first validity query can be used to determine whether the reference speed vref of the vehicle can be kept low, that is, the reference speed vref of the vehicle is the wheel speed, and the reference speed vref of the vehicle. Make sure that it can be determined by the wheels that are slower than). The result of the validity query shown in FIG. 3 is delivered by the variable P2. As already shown in FIG. 2, the variable is examined to transmit the same information in block 105 via the query made in step 206.

The second validity query starts at step 401. Step 402 follows step 401. Step 401 is followed by step 402. In step 402, a variable representing the slip of each wheel (slvradij) is determined from the wheel speed vradij, in particular a parameter that matches the slip value of each wheel. Step 402 is followed by step 403. In step 403, a first variable sli is formed from the variable slvradij. The first variable sli is used to form the sum of the respective slip values slvradij, thus describing the sum of the slip values.

After step 403, a step 404 is carried out in which a second variable abssli is formed from the variable slvradij. The second variable (abssli) is used to form the sum of the respective slip values (slvradij), thus describing the absolute slip value. Step 404 is followed by step 404. In step 405, the sign of the first variable sli is determined by the query.

In the query, if it is confirmed that the first variable sli is greater than zero, that is, a positive value, step 406 is carried out as the next step. In step 406, a slip is formed from the first variable sli and the second variable abssli. The difference represents the deviation of absolute slip and total slip. Step 406 is followed by step 408. In contrast, in the query executed at step 405, if it is confirmed that the first variable sli is less than zero, that is, a negative value, step 407 is executed as the next step. In step 407, the first variable sli and the second variable abssli are summed. The sum may also indicate a deviation between absolute slip and total slip since the first variable is a negative value. Step 407 is followed by step 408.

In step 408, the variable Slipiff formed in step 406 or step 407 is compared with the corresponding threshold value S4. In the query, it is confirmed that the variable (slidiff) is larger than the corresponding limit value, which means that all the wheels are controlled to be in an unstable state, which determines the execution of step 409 following the step 408, and the step In 409, the TRUE value is assigned to the variable P2. As described above, the reference speed vref of the vehicle is determined according to the wheel having a speed smaller than the reference speed vref. The variable sliding is, for example, larger than the corresponding limit value S4 in state 2 included in FIG. 5. This is because the reference speed vref of the vehicle is set higher than the actual speed vfz of the vehicle. On the basis of this, it is necessary to correct, that is, keep the reference speed low.

In contrast, in step 408 the query confirms that the variable slip is lower than the corresponding threshold S4 in which all the wheels are controlled in a stable state, which is followed by step 410 followed by step 410. In step 410, the variable P2 is assigned a FALSE value. The confirmed vehicle state in this case corresponds to state 1 of FIG. 5, for example. In this state, the actual speed vfz and the reference speed vref of the vehicle coincide with each other, and therefore, no modification is necessary. Also for this reason it is not necessary to keep the reference speed vref low, and for this reason the variable P2 is assigned a FALSE value.

Following step 409 and step 410, step 411 is performed, whereby the second validity query ends.

If the query confirms that the car or the sliding is greater than its threshold, the second validity query shown in Figure 3 is summarized as follows: From the second validity query, the wheels are slower than the reference speed of the vehicle. The reference speed of the vehicle is determined accordingly.

The method according to the invention or the device according to the invention selected in the drawings does not limit the basic concept of the invention.

Claims (12)

A method of determining a vehicle speed variable indicative of a speed of a vehicle comprising associated wheels, the method comprising: Determining quantities indicative of velocities of the associated wheels, Measuring wheel velocities of the associated wheels as a function of said quantity; Performing at least a first plausibility query and a second plausibility query, wherein each of the first plausibility query and the second plausibility query is performed as a function of wheel speeds, Determining if the first wheel speed of the wheel speeds is greater than the reference vehicle speed variable based on at least a first validity query if the vehicle speed variable can be measured as a function of the first wheel speed among the wheel speeds; If the vehicle speed variable can be measured as a function of the second wheel speed among the wheel speeds, determining whether the second wheel speed of the wheel speeds is greater than the reference vehicle speed variable based on at least a second validity query; Selecting one of the associated wheels according to a function of at least one of the first result of the first validity query and the second result of the second validity query; Determining a vehicle speed variable as a function of wheel speed of the selected wheel of the associated wheels. The method of claim 1, Performing a third validity query and determining which of the first and second result values to analyze based on the third validity query, wherein the third validity query includes two or more queries; At least one of the two or more queries comprises comparing a reference vehicle speed variable with a wheel speed of at least one of the associated wheels. The method of claim 2, Wheel speeds are sorted by size, Analyzing a first result of the first validity query if the reference speed variable is less than the lowest of the wheel speeds; And analyzing the second result of the second validity query if the reference speed variable is greater than the lowest of the wheel speeds and less than the largest of the wheel speeds. The method of claim 1, The first validity query includes at least two queries, wherein in each of the two queries, the difference between the wheel speed of the second wheel of the wheels in relation to the wheel speed of the first wheel of the related wheels is compared with the associated threshold. How to Determine Vehicle Speed Variables. The method of claim 4, wherein The wheel speeds are classified by magnitude, and the first query of the first validity query includes comparing a first difference variable with a first threshold value, wherein the first difference value is the highest of the vehicle speeds. Determined as a function of the lowest of the speeds and wheel speeds, the second query of the first validity query includes comparing the second difference variable with a second threshold value, the second difference value being one of the wheel speeds; A method of determining a vehicle speed variable determined as a function of the lowest speed and the second lowest speed of the wheel speeds. The method of claim 5, The first validity query includes a third query, the third query comprising comparing a first acceleration value variable indicative of the acceleration of the vehicle with a second acceleration value variable indicative of at least the acceleration of the vehicle, and the second acceleration value The variable may be calibrated using an offset value, wherein the offset value is determined as a function of a state variable representing the state of the vehicle. The method of claim 6, i) if one of the first difference variable is less than the first threshold and the second difference variable is less than the second threshold, ii) if the first acceleration value variable is less than the second acceleration value variable and the wheel speed of the first wheel of the associated wheels is greater than the reference vehicle speed variable, And based on the first validity query, the vehicle speed variable can be determined as a function of the first of the associated wheels. The method of claim 4, wherein The first validity query includes a third query, the third query comprising comparing a first acceleration value variable indicative of the acceleration of the vehicle with a second acceleration value variable indicative of at least the acceleration of the vehicle, and the second acceleration value The variable may be calibrated using an offset value, wherein the offset value is determined as a function of a state variable representing the state of the vehicle. The method of claim 1, Determining slip variables indicative of slip values of the associated wheels as a function of wheel speed, The second validity query includes one or more queries, wherein at least one query of the second validity query includes a comparison with an associated threshold, wherein the comparison is performed based at least on sleep variables. The method of claim 9, Determining a first sum value that is a sum of slip values; Determining a second sum value that is a sum of absolute values of slip values; And determining a vehicle speed variable based on a result of the second validity query if one of the difference and sum of the first sum value and the second sum value is larger than an associated threshold value. An apparatus for determining a vehicle speed variable indicative of a vehicle speed, A first apparatus for measuring individual wheel speed quantities indicative of speeds of associated wheels of the vehicle; A second device for determining wheel speeds as a function of wheel speed quantities and selecting one of the associated wheels as a function of wheel speeds; A third apparatus for determining a vehicle speed variable as a function of the selected wheel among the associated wheels; A fourth apparatus for performing a first validity query and a second validity query, Each of the first validity query and the second validity query is performed as a function of wheel speeds, and if the fourth means can be determined as a function of the first wheel among the wheels with which the vehicle speed variable is associated, the associated wheel based on the first validity query Determine whether the first wheel has a vehicle speed greater than the reference vehicle speed variable, and if the vehicle speed variable can be determined as a function of the second wheel of the associated wheels, based on the second validity query the second of the related wheels And determine whether the vehicle has a vehicle speed less than the reference vehicle speed variable, and wherein the second device selects one of the associated wheels as a function of the first and second result values.  The method of claim 1, The first validity query determines whether the operating state of the vehicle is reasonable; The second validity query determines the vehicle speed variable to determine whether all relevant wheels are being controlled in an unstable state.