Method for determining a tire brake radius, method for steering brake, controller, and
Through the combination of asymmetric braking process and steering torque sensor, the problem of inaccurate detection of tire radius is solved, and the accuracy and safety of steering braking is achieved, and the ability to adapt to changes in tire state is achieved.
Patent Information
- Application Number
- CN202380043229.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-06-14
- Filing Date
- 2023-05-17
- Publication Date
- 2024-12-31
AI Technical Summary
The detection of tire radius in the prior art is not accurate enough, resulting in unreliable steering braking processes, especially when wheel replacement or tire inflation pressure changes, which may cause incorrect steering braking.
Through an asymmetric braking process, the steering torque sensor is used to measure the steering torque, and combined with the wheel steering angle and steering wheel angle, the steering process is evaluated to know the symbol of the tire radius, and then adjust the braking force and steering predefined signals to ensure steering braking accuracy and safety.
Reliable detection of the tire radius is achieved, erroneous steering braking caused by assumptions is avoided, and the accuracy and safety of steering braking is improved. Especially during the vehicle driving, the braking force can be adjusted in time to adapt to changes in tire state.
Smart Images
Figure CN119233916A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for determining a tire wear radius. Furthermore, a method for steering braking, a control unit and a commercial vehicle are provided using the method. Background Art
[0002] The wear radius is defined as the distance of the intersection of the pivot axis of the wheel with the roadway relative to the center point of the tire contact surface of the wheel on the roadway. Depending on the wear radius, a steering torque is applied to the wheel during the braking process. Thus, a steering process can be induced in the wheels of the steered axle, in particular the front axle.
[0003] In the case of a positive wear radius, which is usually present in commercial vehicles, for example, the right front wheel is braked more strongly than the left front wheel, for example, in order to be able to turn to the right. In vehicles with a negative wear radius, the opposite wheel can be braked more strongly accordingly.
[0004] The use of brakes for steering functions is described, for example, in DE 196 055 53 C1, DE 196 32 251 A1, DE 10 2006 046 497 A, EP 2 998 175 B1, EP 3 293 064 A1 and EP 3 293 065 A1.
[0005] DE 10 2010 029 058 A1 describes steering the wheels at different positions and determining the axis of rotation, from which the axle geometry and thus the tire wear radius can then be determined based on a model.
[0006] Static axle measurements are described, for example, in EP 1277027 B1 and DE 10393821 B4. DE 10 2014113 596 A1 describes a system for compensating for self-steering behavior in a vehicle including a steering gear, in which a lateral selective brake is provided in addition.
[0007] In such systems, the tire-shaving radius is therefore usually assumed or determined once, in order to be able to subsequently carry out a steering braking process.
[0008] It has been shown that the assumption of a once detected tire wear radius is relatively inaccurate. Therefore, when other wheels are installed, a significant change in the tire wear radius may occur, so that the subsequent implementation of the steering braking process is carried out on an unreliable basis. Summary of the invention
[0009] The object of the present invention is to provide a method for reliably determining the radius of the tire wear. In addition, a method, a controller and a commercial vehicle for steering braking when using this method should be provided.
[0010] This object is to be achieved by a method according to claim 1 ; for this purpose, a method for steering braking using the method, a control unit for carrying out the method and a commercial vehicle are also provided.
[0011] After the start of travel, an asymmetrical braking process of the steered axle of the vehicle is thus performed, wherein one wheel of the steered axle is braked more strongly than the other wheel. Here, the other, less strongly braked wheel can also be braked, for example, with a braking force of zero in absolute value, i.e. not braked at all, and thus only the first wheel is braked. Furthermore, a steering specification signal is determined, which reflects a steering specification, i.e. in particular a steering intention of the driver or a steering specification of an autonomous system; here, the determined steering specification signal can also be zero in absolute value, i.e. no steering specification is performed.
[0012] In addition, the steering process caused by the braking process is evaluated. Subsequently, at least one sign of the wear radius of at least one of the steered wheels, in particular both steered wheels, is determined from the evaluation of these data.
[0013] Depending on the embodiment, the steering process can be evaluated by measuring the steering torque generated, in particular by means of a steering torque sensor. Alternatively, the steering process can also be evaluated, for example, by determining the resulting wheel steering angle and / or steering wheel angle, for example by means of a steering angle meter or by means of determining a change in the driving direction, for example by means of a camera or radar.
[0014] Several advantages have been achieved as a result:
[0015] The wear radius can be determined without knowing, for example, geometrical dimensions. By knowing the steering torque and the steering specification signal and in particular correlating them with one another, the steering process produced by asymmetrical braking can be directly associated with the steering effect. For example, if the steering torque is determined even though the driver or (for example in an autonomous vehicle system) a virtual driver has not input a steering request, a steering braking process can be inferred and the wear radius can thus be determined at least from the sign.
[0016] In particular, the sign of the scrub radius can thus be determined, that is, whether a positive scrub radius or a negative scrub radius is present. It is recognized that knowledge of the sign is important for a subsequently deliberately initiated turning braking process, in order, for example, not to initiate a turning braking process in the wrong direction. The exact size of the scrub radius is not as important as the sign, since, for example, during a turning braking process, an asymmetrical braking effect can be increased or decreased. In particular, knowledge of the sign of the scrub radius can exclude, for example, that a positive scrub radius is used to intensify the turning, even though a negative scrub radius is assumed, which should lead to self-resistance to turning.
[0017] In this context, on the one hand, the braking force, ie the brake pressure in a pressure medium-actuated brake system, as well as the steering torque and the steering specification signal are measured variables which are usually already available in the vehicle system and therefore do not require additional sensor data.
[0018] According to a preferred embodiment, the introduction of the asymmetric first braking process and / or the subsequent asymmetric braking process is implemented based on a braking criterion, thereby ensuring in particular that the detection is carried out early enough and / or is sufficiently effective. In addition, the braking criterion can include the following evaluations or sub-criteria:
[0019] The travel time is compared with the first time limit value. The travel time is in particular taken into account the time since the start of travel, ie in particular the time since a non-zero travel speed or the time since the vehicle was started (for example since the ignition was turned on). This allows early knowledge before a more intensive braking process and, if necessary, a steering braking process due to a steering system fault is carried out.
[0020] According to other sub-criteria, the time duration between the end of the previous run and the start of the current run is evaluated, that is, in particular compared with a limit value. If the time duration since the end of the previous run exceeds a second time limit value, then a current determination of the wear radius can be provided, since important features of the wheel may have changed. Thus, for example, a wheel change may be carried out, wherein the wheel rim may also be changed as a result, and the penetration depth may have changed as a result.
[0021] Based on further sub-criteria, a possible wheel change is detected by determining and evaluating the tire inflation pressure, and when a change above a change limit value since the previous trip is detected, it is detected that a wheel change may have occurred, and the method is therefore executed and the wear radius is re-determined. Alternatively or in addition, the identification number of the tire pressure sensor can also be read. When the number changes, it is detected that a wheel change may have occurred, and the method is applied.
[0022] Another sub-criterion may be the knowledge of straight-line driving. For this purpose, the current wheel steering angle or steering wheel angle may be used. Thus, for example, it may be provided that an asymmetrical braking process is performed during straight-line driving in order to avoid critical driving situations or to keep them low.
[0023] According to a preferred development, in particular when an asymmetrical braking process is initiated autonomously as a test brake, an autonomous compensating steering process is initiated, in particular to fully or partially compensate for the steering braking effect. This can be based on, for example, a current value or a currently known value of the tire wear radius in order to at least reduce the steering braking effect by the autonomous compensating steering process. The driver thus does not notice the asymmetrical braking process or does not notice it significantly.
[0024] According to other refinements, a subsequent asymmetrical braking process with other braking forces and / or other signs of the difference between the braking forces can be performed in order to increase accuracy. Additionally or alternatively, the braking process can be performed on different surfaces and therefore with different friction values.
[0025] In the case of pressure medium-operated brake systems, the brake pressure can in particular be used as the braking force.
[0026] According to a particularly preferred embodiment, the validity of the determined tire wear radius is determined. For this purpose, a confidence index or a trust index (Confidential Index) can be determined, which indicates the validity of the evaluation process or the evaluation progress. Thus, the accuracy of the tire wear radius can be improved by continuous measurement and the improvement can be determined. When the confidence index reaches a relevant value that enables or enables the autonomous steering braking process to be carried out with high accuracy, this can be displayed to the driver, for example.
[0027] Furthermore, a confidence index of an autonomous vehicle system, in particular an autonomous driver assistance system or an autonomous safety system, can be taken into account as a usage criterion, so that a steering braking process is only used if it is sufficiently effective.
[0028] The steerable axle can be the front axle in particular. In addition, for example, the wear radius of the steerable rear axle can also be evaluated.
[0029] According to a preferred embodiment, the temporal characteristics of the determined steering command signal and / or steering torque are evaluated. This improves the accuracy of the determination. In particular, the driver's steering intention can be better separated from the steering torque applied by the asymmetric braking process based on the steering torque applied by the driver.
[0030] According to the invention, a method for steering braking is therefore also provided, which method can also realize a safe steering braking process in the event of a steering system failure and thus improve safety. In particular, due to the known trust index, a more intense steering braking process can also be initiated. For example, the initiation of the steering braking process can only be carried out when the trust index exceeds a limit value. In addition, it can also be provided that the intensity of the steering braking process is realized as a function of the size of the trust index.
[0031] Furthermore, a control unit containing instructions for executing the method according to the invention and a vehicle, in particular a commercial vehicle, having a control unit and / or for executing the method are provided. The sensor for determining the steering torque can be arranged in the steering shaft in a conventional manner; for example, the steering presetting can be realized by measuring the steering wheel angle or the steering presetting signal in the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The present invention will be described in detail below with the aid of some drawings showing some embodiments.
[0033] Figure 1 The vehicle is shown in a front view;
[0034] Figure 2 The vehicle is shown in a top view during a braking process;
[0035] Figure 3 The diagram shows the braking and steering process. Figure 2 vehicles;
[0036] Figure 4 Shows Figure 1 A partial enlarged view of
[0037] Figure 5 Shows Figure 2 The tire contact patch of the front axle;
[0038] Figure 6 A flow chart of a method according to the invention is shown. DETAILED DESCRIPTION
[0039] A commercial vehicle 1 is traveling on a roadway 2. The commercial vehicle 1 has a steered front axle VA and, according to the embodiment shown here, a rear axle HA; a further rear axle and, if necessary, a liftable additional axle or rear axle may also be provided.
[0040] In the following description, elements on the left side of the commercial vehicle 1 are indicated by the index -1, and elements on the right side of the commercial vehicle 1 are indicated by the index -2 accordingly. Thus, the commercial vehicle 1 has a steerable left front wheel VA-1 and a steerable right front wheel VA-2. A left front wheel brake 4-1 is provided on the left front wheel VA-1, and a right front wheel brake 4-2 is provided on the right front wheel VA-2 accordingly, which can be designed as pneumatic brakes, in particular pneumatic disc brakes, for example. Correspondingly, rear wheel brakes 5-1 and 5-2 are provided on the wheels HA-1, HA-2 of the rear axle HA.
[0041] In accordance with Figure 2 and Figure 3 In the vehicle coordinate system XYZ of the vehicle 1, X denotes the longitudinal direction; Y denotes the transverse direction accordingly. The different coordinate systems of the road, the vehicle and the individual wheels can be converted to one another accordingly; in the following, the vehicle coordinate system XYZ is considered for simplification. Thus, when driving in a straight line, the driving direction F corresponds to the longitudinal direction X in the vehicle coordinate system XYZ.
[0042] The front wheel brakes 4-1, 4-2 and the rear wheel brakes 5-1, 5-2 are part of a pneumatic brake system 6, which also has a brake controller 8, such as an EBS controller 8, and a compressed air system with electropneumatic valves not further described here, so that the EBS controller 8 can control the wheel brakes 4-1, 4-2, 5-1, 5-2 by controlling the electropneumatic valves with separate pneumatic brake pressures P41, P42, P51, P52.
[0043] Furthermore, the commercial vehicle 1 has Figure 1 , Figure 3 1 and 2, which has a steering wheel 14 operable by the driver, a steering shaft 15 and a steering torque sensor 16 arranged in or on the steering shaft 15 according to the present embodiment. The steering torque sensor 16 can be formed, for example, by means of a torsionally weak region of the steering shaft 15. The steering torque sensor 16 serves here to determine the steering process, wherein the steering process can also be determined in different ways.
[0044] Front wheels VA-1 and VA-2 Figure 5 The tire contact surfaces 20-1, 20-2 shown more precisely in FIG. 2 are located on the roadway 2. The left front wheel VA-1 can pivot about a left pivot axis 22-1, wherein the left pivot axis 22-1 intersects the roadway 2 at an intersection point 23-1, which is offset in the transverse direction Y from the center point 24-1 of the left tire contact surface 20-1 by a left wear radius LRH-1.
[0045] Accordingly, the right front wheel VA-2 can pivot about a right pivot axis 22-2, which intersects the roadway 2 at a right intersection point 23-2, which is offset in the transverse direction Y by a right wear radius LRH-2 relative to the right center point 24-2.
[0046] In the embodiment shown here, positive wear radii LRH- 1 and LRH- 2 are present, as are usually found in commercial vehicles 1 , for example.
[0047] Thus, during the braking process, the EBS control unit 8 introduces a brake pressure p41 into the left front wheel brake 4-1, which thus decelerates the left front wheel VA-1, so that the left front wheel VA-1 is subjected to a braking force 26-1 on the roadway 2 (counter to the driving direction F or the longitudinal direction X), which occurs due to the interaction with the roadway 2, wherein the magnitude of the left braking force 26-1 is correspondingly dependent on the friction value parameter or friction coefficient mue between the left front wheel VA-1 and the roadway 2, as well as on slippage, etc. Accordingly, due to the braking force 26-1 and the left wear radius LRH-1, a left steering torque LM-1 is applied to the left front wheel VA-1, which thus pivots the left front wheel VA1 and, due to the kinematic connection, also the right front wheel VA-2. When the front axle A is designed as a rigid axle, the sum of the steering torques LM-1 and LM-2 is thus obtained as the total steering torque LM.
[0048] Figure 2 shows straight-line travel; Figure 3 In the process, the front wheels turn accordingly, that is, the wheel steering angles alpha-1 and alpha-2 are not equal to zero.
[0049] In the embodiment shown, there is an electronically or electrically controlled steering system with a steering controller 30, which is connected to the EBS controller 8, for example via a CAN bus 32. The steering controller 30 enables autonomous initiation of steering at the left front wheel VA-1 and the right front wheel VA-2.
[0050] according to Figure 6 , the method according to the invention has at least the following steps: The method starts with step St0 in the above-described commercial vehicle 1 and its above-described features. The commercial vehicle 1 then starts its travel according to step St1, i.e. the travel speed v is not equal to 0 (forward travel or reverse travel). After the travel starts, the commercial vehicle 1 first travels in a straight line at its travel speed v, for example, so that the travel direction F corresponds to the longitudinal direction X.
[0051] In steps St2 and St3, an asymmetrical first braking process BV-a is initiated. The first braking process BV-a can be implemented, for example, in a first automatic braking of the commercial vehicle 1, which is implemented via the EBS controller 8 according to the driver's wishes, that is, by operating the brake pedal 34. Figure 6 As shown, in step St2, a braking criterion K1 for automatically initiating braking by the EBS controller 8 may be provided. The braking criterion K1 may include a plurality of sub-criteria, for example:
[0052] The driver's braking or other braking has not yet been initiated and, for example due to instabilities, the EBS control unit 8 has also not automatically initiated a first braking process BV-a.
[0053] - As a sub-criterion, it can also be included that the asymmetric first braking process BV-a is initiated during straight-line driving without lateral dynamics and / or without road inclination, i.e. the driving direction F corresponds to the longitudinal direction X of the vehicle 1 and the wheel steering angles alpha-1, alpha-2 are equal to zero.
[0054] Alternatively, however, a cornering trip may also be provided, ie with a steering torque LM≠0.
[0055] - The tire inflation pressure signal S2, in particular the temporal behavior of the tire pressure signal S2, can also be taken into account in order to detect at the start of a journey when the detected tire pressure changes, that a tire with a high probability needs to be replaced in order to meet the braking criterion K1, so that a new tire or a new wheel VA-1 or VA-2 can be measured if necessary.
[0056] The time period t1 since the start of travel or the time period since the “ignition” or start of the commercial vehicle 1 can also be evaluated as a sub-criterion, so that the asymmetrical first braking process BV-a is initiated within a sufficiently short period of time after the start of travel or the start of the commercial vehicle 1 .
[0057] - A sufficiently long time period t >delta-t2 after the end of the previous journey and before the start of a new journey can also be considered as a subcriterion; thus, for example, the method does not have to be executed again immediately when the vehicle stops briefly.
[0058] Further sub-criteria of brake criterion K1 may be:
[0059] The asymmetrical first braking process should also be carried out below a limit speed v-lim of, for example, 30 km / h, ie v<v-lim.
[0060] There is no yawing movement of the vehicle about its vertical axis GA and / or no rolling movement or lateral bending of the commercial vehicle 1 on, for example, an inclined roadway 2 .
[0061] If the braking criterion K1 is met, then according to step St3, an asymmetrical first braking process BV-a is initiated, wherein one of the wheels VA-1, VA-2 is braked more strongly than the other wheel. In the embodiment described here, the left front wheel VA-1 is braked more strongly by the left front wheel brake 4-1 than the right front wheel VA-2 by the right front wheel brake 4-2, i.e. the left braking force 26-1 is greater than the right braking force 26-2, i.e., for example, the left brake pressure p41 is greater than the right brake pressure p42.
[0062] According to step St4, data are recorded during the braking process BV-a, in particular the measured steering torque LM, the steering target signal LW, and also data about the initiated braking process, that is, data about the braking forces 26-1, 26-2. For this purpose, for example, the introduced brake pressures p41, p42 can be used.
[0063] In step St5, the collected data is evaluated. It is thus known whether a steering process can be detected and, if necessary, the realized steering process can be evaluated. To this end, according to one embodiment, the steering torque LM built up by the driver can be detected when the driver resists (gegenhalten) the introduced steering process. In addition or alternatively, the resulting steering process can also be known as a steering wheel angle change when the driver does not resist or only partially resists. Therefore, it is also possible to measure in which direction the vehicle is being pulled; it is also possible to quantitatively detect the wheel steering angle, wherein, in principle, the knowledge of the direction is sufficient. According to another design, the introduced brake pressure can be correlated to the resulting wheel steering angle.
[0064] If the driver does not currently input a steering request via the steering wheel 14 and therefore intends to drive in a straight line, the detected steering torque LM can be assigned directly to an asymmetrical braking of the front wheels VA- 1 , VA- 2 , ie as a steer-by-brake effect.
[0065] Therefore, in step St5, at least the signs of the left and right scrub radii LRH-1 and LRH-2 can be determined from the determined steering torque.
[0066] If the braking process BV-a has been initiated autonomously, i.e. as a test brake, then full or partial compensation of the steering braking process can be achieved in step St3 by an active steering intervention, wherein the steering controller 30 thus initiates an active steering process which compensates the detected steering torque LM so that the vehicle 1 does not turn or does not turn significantly and thus does not change its driving direction F. Thus, a compensating steering process can be calculated and initiated from the steering torque determined and / or the measured yaw rate ω.
[0067] According to step St6, before and during the first braking process BV-a, validity data VAL-BV-a are collected, which are used to determine the confidence index CI. Here, one or more of the following subsequent data are recorded as validity data VAL-BV-a:
[0068] The current steering torque LM(t), the left front wheel brake pressure P41 and the right front wheel brake pressure P42, for example the temperature Tp and for example the current adhesion values HW-1, HW-2 ascertained, in addition for example the data ascertained about the road inclination, the driving direction F, the driving speed V, the wheel steering angles alpha-1, alpha-2 of the front wheels VA-1, VA-2. Therefore, the plausibility of the evaluation of the first braking process BV-a is evaluated from these data.
[0069] Furthermore, the longitudinal acceleration can be determined by a longitudinal acceleration sensor as part of the validity data VAL-BV-a or, for example, as a time derivative of the driving speed v.
[0070] Advantageously, a plurality of braking processes BV-a and subsequent BV-b, BV-c, ... are performed in order to obtain accurate data for acquisition. Here, the brake pressures P41, P42 can be changed, wherein in particular, the difference of the brake pressures P4, P42 or the sign of the difference is changed, for example; thus, for example, in the subsequent braking process BV-b, a higher right front wheel brake pressure P42 than the left front wheel brake pressure P41 is input.
[0071] However, even in non-ideal driving situations, ie when driving around a bend, the wear radius LRH-1, LRH-2 can be inferred by taking into account other influences.
[0072] Firstly, the wear radii LRH-1, LRH-2 can be set to be identical. In a further embodiment, these wear radii can be determined individually and thus can be determined differently.
[0073] Since the first braking process BV-a is short enough, a sufficient first knowledge can be achieved in the case of the initially unknown tire wear radii LRH-1, LRH-2, which can be adjusted more accurately in the subsequent braking processes BV-b, BV-c,..., that is, the effectiveness or the trust index CI representing the effectiveness increases, and then reaches the limit value CI-min, which indicates sufficient safety, so that an autonomous steering braking process can be introduced.
[0074] Therefore, in step St7 it can be checked whether CI is large enough and when a limit value CI-min is reached it can be decided that a steering braking process LV can be initiated, as described in step St8 .
[0075] Thus, if the steering controller 30 detects a complete or partial failure of the steering system 12, the steering controller 30 informs the EBS controller 8 of this via the CAN bus 32, so that it can then check, for example, whether the confidence index CI is sufficiently large to initiate an SBB process, so that the EBS controller 8 initiates a brake steering process SBB. Advantageously, information about the sign of the tire wear radius is additionally transmitted or taken into account, so that the EBS controller 8 can react to targeted actuation.
[0076] The coordination between the brake control 8 and the steering control 30 can be based on either of the two controllers 8, 30. A superordinate controller can also be provided for the method according to the invention, which thus assists in controlling both controllers 8, 32.
[0077] Thus, starting from t=0 until, for example, a limit value of the confidence index CI-min is known, a learning phase LPH is performed. Thus, when CI-min is reached, it is recognized that brake steering is possible. This can be indicated to the driver via a display signal S1, so that the driver can adjust his driving behavior and in particular his steering behavior or his active steering.
[0078] Brake steering can be used in particular by EBS controller 8 in one or more subsequent driving dynamics control and / or driver assistance systems: ABS (anti-lock braking system), EBS (electronic braking system), ESP (electronic stability program), FDR (driving dynamics control), ACC (automatic cruise control).
[0079] Therefore, the SBB process described here is particularly achieved by changing Figure 3 In addition, it should be taken into account that even if the wheel steering angles alpha-1, alpha-2 do not change, the asymmetrical braking BV-a itself already achieves a braking steering effect in the case of the non-steerable axle HA and also in addition on the steerable axle VA. Therefore, asymmetrical braking of the rear axle HA can be considered.
[0080] List of reference numerals (part of the description)
[0081] 1 Commercial Vehicles
[0082] 2 lanes
[0083] VA front axle
[0084] VA-1 left front wheel
[0085] VA-2 right front wheel
[0086] HA rear axle
[0087] HA-1 left rear wheel
[0088] HA-2 right rear wheel
[0089] 4-1 Left front wheel brake
[0090] 4-2 Right front wheel brake
[0091] 5-1 Left rear wheel brake
[0092] 5-2 Right rear wheel brake
[0093] 6Pneumatic brake system, especially EBS
[0094] 8Brake controller
[0095] 10. Compressed air system
[0096] 11Electric pneumatic valve
[0097] 12 Steering system
[0098] 14 Steering Wheel
[0099] 15 Steering shaft
[0100] 16 Steering torque sensor
[0101] 17 Steering wheel angle sensor
[0102] 20-1 Left tire contact surface
[0103] 20-2 Right tire contact surface
[0104] 22-1 Left pivot axis
[0105] 22-2 Right pivot axis
[0106] 23-1 left intersection point
[0107] 23-2 right intersection
[0108] 24-1 Left center point of left tire contact surface 20-1
[0109] 24-2 Right center point of right tire contact surface 20-2
[0110] 26Tire pressure sensor
[0111] 26-1 Left braking force acting on the left front wheel VA-1
[0112] 26-2 Right braking force acting on right front wheel VA-2
[0113] 30 Steering Controller
[0114] 32 CAN bus
[0115] 34Brake pedal
[0116] 43 Longitudinal acceleration sensor
[0117] 45 Vehicle systems, especially autonomous or semi-autonomous vehicle systems
[0118] 45a Autonomous or semi-autonomous driving dynamics control
[0119] 45b Autonomous or semi-autonomous driver assistance systems
[0120] 46 Pre-stored value for compensating steering torque (LM-K)
[0121] Alpha-1 and alpha-2 wheel steering angles
[0122] B1 The first condition of termination criterion K3
[0123] B2 The second condition of termination criterion K3
[0124] BV-a first braking process
[0125] CI trust index
[0126] CI-1 minimum trust index
[0127] delta-t first time period
[0128] F Driving direction
[0129] GA vertical axis
[0130] Current attachment values of HW-1 and HW-2
[0131] K1 brake standard
[0132] K2 Usage Standard
[0133] K3 Termination Criteria
[0134] LM-K compensates steering torque
[0135] LRW steering wheel angle
[0136] LRH-1 Left front wheel V-1 left tire radius
[0137] LRH-2 Right front wheel V-2 right tire radius
[0138] LM-1 left steering torque
[0139] LM-2 right steering torque
[0140] LM(t) Current steering torque
[0141] LPH learning stage
[0142] LV autonomous steering and braking process
[0143] S1 steering torque signal
[0144] S2 tire pressure signal
[0145] S3 brake signal
[0146] S4 Autonomous Turn Signals
[0147] Delta-S2 tire pressure signal S2 time variation
[0148] sgn(LRH-1), sgn(LRH-2)Sign of the grinding radius LRH-1, LRH-2
[0149] P41 Brake pressure in left front wheel 4-1
[0150] P42 Brake pressure in right front wheel 4-2
[0151] Delta-P is the difference between the first and second braking forces (P41, P42)
[0152] Validity of the wear radius obtained from V-LRH
[0153] Accuracy of tire wear radius obtained by G-LRH
[0154] G-LV steering and braking process LV accuracy
[0155] t1 Duration of driving
[0156] t2 Time period from the start of the previous trip
[0157] t-lim-1
[0158] t-lim-2
[0159] Tp temperature
[0160] S5 Display Signal
[0161] S6 Release signal for autonomous steering braking process (LV) (6)
[0162] V Driving speed
[0163] VAL-BV-a effectiveness data
[0164] v-lim speed boundary value
[0165] X longitudinal direction (non-driving direction for correction)
[0166] Y Transverse direction of the commercial vehicle 1
[0167] Z vertical direction, vertical direction of the commercial vehicle 1
Claims
1. A method for determining a tire wear radius (LRH-1, LRH-2) of a vehicle (1), the method comprising the following steps: - during travel (St1), an asymmetrical braking process (BV-a) is initiated on the steered axle (VA) of the vehicle (1), wherein: applying a first braking force (26-1) to a first wheel (VA-1) of the steered axle (VA), the first braking force being greater than a second braking force (26-2) applied to another wheel (VA-2) of the steered axle (VA) (St3), - during the braking process (BV-a), a steering direction predetermined signal (LW) input by the driver or a vehicle system (45) is obtained, and - during the braking process (BV-a), evaluating a steering process caused by the braking process (BV-a), - evaluating the asymmetrical braking process (BV-a) (St5) on the basis of the acquired data (LW, LM, 26-1, 26-2), - as a function of the evaluation, at least one sign (sgn(LRH-1), sgn(LRH-2)) of at least the wear radius (LRH-1, LRH-2) of the first wheel (VA-1) is determined (St5).
2. The method according to claim 1, characterized in that When evaluating the steering process caused by the braking process (BV-a), one or more of the following evaluations are performed: - determining and evaluating the steering torque (LM) (ST4) applied to the wheels (VA-1, VA-2) of the braked axle (VA), - determining and evaluating at least one resulting wheel steering angle (alpha-1, alpha-2) of the wheels (VA-1, VA-2) of the braked axle (VA) (ST4), - A change in the driving direction of the vehicle is detected and evaluated (ST4).
3. The method according to any one of the preceding claims, characterized in that The temporal behavior of the steering target signal (LW) and / or of the steering process, in particular the steering torque (LM) or the change of direction, is evaluated.
4. The method according to any one of the preceding claims, characterized in that After determining the travel (v ≠ 0) (ST1), the braking criterion (K1) is checked (ST2), And when the braking criterion (K1) is met, an asymmetrical braking process (BV-a) is initiated on the steered axle (VA) (ST3).
5. The method according to any one of the preceding claims, characterized in that The braking standard (K1) includes one or more of the following sub-standards: - compare (K1-1) the driving duration (t1) from the start of the driving (t0) with the first time limit value (t-lim-1), - comparing (K1-2) the time period (t2) between the previous trip and the start of the trip (t0) with a second time limit value (t-lim-2), - evaluating a change over time (Delta-S2) (K1-3) of at least one tire pressure signal (S2), in particular one or more tire pressure signals (S2) of the first wheel (VA-1) or the second wheel (VA-2) since a previous trip, - Learn to drive in a straight line (K1-4).
6. The method according to any one of the preceding claims, characterized in that A steering wheel angle (LRW) and / or a target steering torque (BZZ) predetermined by a driver and / or a vehicle system (45) is used as a steering predetermined signal (LW).
7. The method according to any one of the preceding claims, characterized in that When the asymmetrical braking process (BV-a) is autonomously initiated without a steering command signal (LW), a compensation steering torque (LM-K) is input for at least partially or completely compensating the determined steering torque (LM).
8. The method according to claim 7, characterized in that The compensating steering torque (LM-K) is determined as a function of prestored values (46) and / or as a function of previously determined tire wear radii (LRH-1, LRH-2).
9. The method according to any one of the preceding claims, characterized in that performing an asymmetrical first braking process (BV-a) with a smaller braking force (26-1, 26-2) than a subsequent asymmetrical braking process (BV-b, BV-c), and / or The braking force (P41, P42) of the asymmetric first braking process (BV-a) is lower than the limit braking force (P-lim).
10. The method according to any one of the preceding claims, characterized in that At least two asymmetrical braking operations (BV-b, BV-c, . . . ) are performed with different signs of the difference (Delta-P) between the first and the second braking force (P41, P42).
11. The method according to any one of the preceding claims, characterized in that Validity data (VAL-BV-a) are recorded before or during the evaluation of the asymmetric braking process (BV-a) and a confidence index (CI) is established based on the validity data (VAL-BV-a), which represents the validity (V-LRH) or accuracy (G-LRH) of the known tire wear radius (LRH-1, LRH-2) and / or reflects an assessment of the accuracy (G-LV) of a subsequent steering braking (LV) process (St6).
12. The method according to claim 11, characterized in that The confidence index (CI) is compared with a limit value (CI-min), and when the limit value (CI-min) is reached, a display signal (S5) and / or a release signal (S6) for an autonomous brake steering process (LV) is provided.
13. The method according to any one of the preceding claims, characterized in that During the asymmetrical braking process (BV-a) and / or the subsequent asymmetrical braking process (BV-b, BV-c), in addition to the at least one steerable axle (VA), at least one further axle (HA) of the vehicle (1) is additionally braked asymmetrically.
14. The method according to any one of the preceding claims, characterized in that The asymmetrical braking process (BV-a) initiated on at least one steering axle (VA) is terminated when a termination criterion (K3) is met, The termination criterion (K3) is satisfied when one or more of the following conditions (B1, B2) are met; - knowing the sign of the tire wear radius (LRH-1, LRH-2) mentioned in (B1), - A driving situation that endangers safety is detected (B2).
15. A method for steering braking of a commercial vehicle (1), wherein: A wear radius (LRH-1, LRH-2) is determined using a method according to any of the preceding claims, and a steering braking process (LV) is initiated as a function of the determined wear radius (LRH-1, LRH-2), in which the vehicle (1) is steered by asymmetrically loading the wheel brakes (4-1, 4-2) of at least the steered axle (VA).
16. The method according to claim 15, characterized in that In particular, when a limit value (CI-min) is reached, the steering braking process (LV) is initiated as a function of the determined confidence index (CI).
17. The method according to claim 15 or 16, characterized in that The method is carried out during an autonomous driving dynamics control (45a) and / or an autonomous driver assistance system (45b), such as ABS, EBS, ESP, FDR, ACC.
18. The method according to any one of claims 15 to 17, characterized in that The steering braking process (LV) is initiated only when the determined confidence index (CI) exceeds a limit value (CI-min).
19. A control unit (8, 30) of a vehicle (1), the control unit having instructions for executing the method according to any one of the preceding claims.
20. A vehicle (1), in particular a commercial vehicle (1), comprising: at least one steerable axle (VA) having a first steerable wheel (VA-1) and a second steerable wheel (VA-2), At least one additional axle (HA), A braking system (6), comprising wheel brakes (4-1, 4-2, 5-1, 5-2) arranged on the steered wheels (VA-1, VA-2) of the steered axle (VA) and the further axle (HA), and a brake controller (8), A steering system (12) comprising a steering torque sensor (16) for detecting a steering torque (LM) and / or a steering wheel angle sensor (17) for detecting a steering wheel angle (LRW) and a steering controller (30), in, The brake controller (8) and / or the steering controller (30) is designed as a controller (8, 30) according to claim 19.