DE102016224982A1 - Method for determining the road condition of a section of road traveled by a vehicle - Google Patents

Abstract

The invention relates to a method for determining the road condition of a road section traveled by a vehicle, in which an acceleration along a vehicle vertical axis is detected by an acceleration sensor (12) in which, depending on the detected acceleration signal of the acceleration sensor (12) at least between a road trip and a An off-road course (s_z_sensor) along the vehicle's vertical axis of the vehicle is calculated from the detected acceleration signal of the acceleration sensor (12) from the detected acceleration signal of the acceleration sensor (12). Depending on the calculated signal curve (s_z_sensor), the road condition of the road section traveled by the vehicle is finally determined, and the transmission control program is correspondingly adapted or selected.

Description

The invention relates to a method for determining the road condition of a road section traveled by a vehicle, in which an acceleration along a vertical axis of the vehicle is detected by an acceleration sensor, is distinguished depending on the detected acceleration signal of the acceleration sensor at least between a road trip and an off-road drive and in which at least one control program for transmission control is adapted accordingly when a change in the road condition is detected. Furthermore, the invention relates to a control device, which is designed to carry out the method and a corresponding computer program product.

Automated vehicle controllable devices, such as an automated manual transmission, require different control characteristics depending on the field of application of the vehicle, e.g. in view of a low wear in the drive train and a low fuel consumption of the drive motor to achieve optimum switching behavior of the automated transmission. Thus, in off-road driving, which can be generally described as driving on a relatively rough and unpaved roadway, higher gear shift speeds and smaller gear jumps are advantageously provided in comparison with road driving due to the higher road resistance in an automated manual transmission to avoid high circuit-related drive torque collapse.

For vehicles that can be used as road-going trucks both on paved roads and in the field, therefore, a switchover of the respective control program corresponding vehicle facilities of road driving on off-road and vice versa of off-road driving is required, the switching of the control program each by a change all or part of the control program or by exchanging certain control parameters within a control program. In some known vehicle devices it is provided that the switching of the relevant control program must be performed manually by the driver.

From the US 4,569,255 B1 a transmission control of an automatic transmission of a vehicle is known, which has a special terrain mode for off-road operation or for driving under high driving resistance, which can be activated by the driver by an adjustment of the selector lever in an off-highway position within the selection of the shift console is. In activated terrain mode, in particular, upshifts are performed according to specific shift characteristics, which are designed such that the engine power of the drive motor after an upshift is at least as high as before the upshift. On a return to the road, the driver must deactivate the off-road mode by setting the selector lever in a highway position or activate a road mode to the subsequent road driving optimized shift behavior of the gearbox with low wear in the drive train and low fuel consumption of the To achieve drive motor.

However, manual switching between a road mode and an off-road mode involves the risk that the activation of the respective optimum control program will be inadvertently omitted by the driver, i. that the vehicle equipment in question is operated in road driving in off-road mode or in off-road driving in road mode. This can lead to an above-average wear in the drive train and an increased fuel consumption of the drive motor in an affected transmission control of an automated manual transmission.

In order to avoid these disadvantages and to increase driving comfort, a plurality of methods have therefore been developed for automatically determining the road condition of a section of a road traveled by a vehicle, distinguishing between at least a road trip and an off-road drive and the control program of an automatically controllable vehicle device with a recognized change of the road condition is automatically adjusted.

From the DE 10 2008 054 476 A1 is a method for determining a road condition of a road section traveled by a vehicle known, in which by means of at least one sensor, an operating parameter of the vehicle is detected, which has sudden changes in occurring road bumps. Depending on the determined changes in the operating parameter, a distinction is made between a road trip and an off-road drive, and a control program of an automatically controllable vehicle device is correspondingly adapted in the event of a recognized change in the road condition. It is provided that the relevant operating parameter is detected in a predetermined time cycle and evaluated with regard to the amount of its sudden change. Depending on the magnitude of the sudden change, a signal for the presence of a road surface unevenness or for the absence of a road surface unevenness is output, wherein the signals for the presence and the absence of a Road unevenness in a bump counter are counted and it is decided depending on the count of the bump counter, whether currently a road trip or an off-road drive is present. The DE 10 2008 054 476 A1 also discloses that signals from wheel speed sensors are preferably used to determine the operating parameter or the road condition or a signal of a longitudinal acceleration sensor, a lateral acceleration sensor or a vertical acceleration sensor is evaluated accordingly.

Against this background, the object of the invention is to propose a method for determining the road condition of a section of the road traveled by a vehicle with improved response. In addition, a corresponding control device and a computer program product for carrying out the method should be specified.

From a procedural point of view, a solution to this problem is based on the preamble of patent claim 1 in conjunction with its characterizing features. A control device and a computer program product are also the subject of the further independent claims. Advantageous developments are the subject of the dependent claims and the following description.

According to the invention, a method is provided for determining the road condition of a road section traveled by a vehicle, in which an acceleration along a vehicle vertical axis is detected by an acceleration sensor. Depending on the detected acceleration signal of the acceleration sensor, a distinction is made at least between a road trip and an off-road drive, and upon a detected change of the road state, at least one control program for transmission control is changed or adapted accordingly.

• - Berechnung des Verlaufs einer Auslenkung entlang der Fahrzeughochachse aus dem erfassten Beschleunigungssignal des Beschleunigungssensors;
• - Vergleichen des berechneten Signalverlaufs mit einem ersten Schwellwert;
• - Starten eines Zeitgebers, falls der berechnete Signalverlauf den ersten Schwellwert erreicht oder überschreitet;
• - Berechnen von lokalen Minima des Signalverlaufs, falls der Zeitgeber abgelaufen und der berechnete Signalverlauf größer als der erste Schwellwert ist;
• - Vergleichen des berechneten Signalverlaufs mit einem zweiten Schwellwert, der größer ist als der erste Schwellwert;
• - Erkennen des Fahrbahnzustands Geländefahrt, falls der berechnete Signalverlauf den zweiten Schwellwert erreicht oder überschreitet und zumindest zwei lokale Minima aufweist.

It is provided that the following method steps are carried out to determine the roadway condition:

• Calculating the course of a deflection along the vehicle vertical axis from the detected acceleration signal of the acceleration sensor;
• Comparing the calculated waveform with a first threshold;
• - starting a timer if the calculated waveform reaches or exceeds the first threshold;
• Calculating local minima of the waveform if the timer has expired and the calculated waveform is greater than the first threshold;
• Comparing the calculated waveform with a second threshold greater than the first threshold;
• Detecting the road condition off-road if the calculated waveform reaches or exceeds the second threshold and has at least two local minima.

By evaluating the acceleration signal detected by the acceleration sensor along the vertical axis of the vehicle, the method according to the invention can be easily implemented in the program and rapid response is achieved in determining the change between a road trip and an off-road drive.

By means of a dual integration of the acceleration signal detected by the acceleration sensor, a corresponding position can be determined. When the vehicle is at rest, the gravitational acceleration acting on the acceleration sensor in the vehicle's vertical axis (z-direction) is initially compensated, so that a reference acceleration of 0 m / s ² results for the rest position of the acceleration sensor. Different methods for the double integration of an acceleration signal with corresponding signal processing and filtering are well known in the art and will not be described in detail here.

Has a driver the ability to manually set the switching of the relevant control program for a road trip or off-road driving by means of an actuator, then can be provided according to a preferred embodiment that the selection made manually by the driver is suppressed, if the procedurally determined signal does not matches the manual selection. The control program for transmission control activated by the method according to the invention thus has priority over a control program selected manually by the vehicle driver. This ensures that the control program for transmission control which is optimal for the currently present road condition is also activated if the driver fails to manually switch over the control program. An above-average wear in the drive train and an increased fuel consumption of the drive motor can be avoided accordingly.

Does not the activated transmission control program match the one selected by the manual control Control program match, then it is provided that the driver is informed of this via a display or an acoustic signal. Thus, it can be ensured that the driver is not surprised by the converted operating mode.

The acceleration along the vertical axis of the vehicle can be detected by means of a single-axis acceleration sensor by means of a two-axis acceleration sensor which can detect not only acceleration in the vertical direction but also acceleration in the vehicle longitudinal direction or by means of a three-axis acceleration sensor, which in addition to the Acceleration in the vertical direction can also detect an acceleration in the vehicle longitudinal direction and an acceleration in the vehicle transverse direction can be detected.

Depending on the determined road condition of the road section traveled by the vehicle, control programs of, for example, a driving stability system (ABS, ASR, ESP), a steering with variable ratio and / or power assistance, and a variable suspension damping can be adjusted in addition to the control program of the transmission control.

The invention further relates to a transmission control unit, which is designed for carrying out the method according to the invention. The transmission control unit comprises means which serve to carry out the method according to the invention. These resources are hardware resources and software resources. The hardware-side means are data interfaces in order to exchange data with the assemblies of the drive train involved in carrying out the method according to the invention. For this purpose, the transmission control unit is also connected with necessary sensors and, if necessary, also with other control devices, for example the engine control unit, in order to record the decision-relevant data or to forward control commands. An acceleration sensor for detecting acceleration along a vertical axis of the vehicle may preferably be integrated in the transmission control unit.

The hardware-side means of the transmission control unit is also a processor for data processing and a memory for data storage. The software resources are program modules for carrying out the method according to the invention.

The solution according to the invention can also be embodied as a computer program product which, when running on a processor of a control device, instructs the processor by software to carry out the associated process steps according to the invention. In this context, a computer-readable medium is the subject of the invention, on which a computer program product described above is stored retrievably.

The invention is not limited to the specified combination of the features of the independent claims or the claims dependent thereon. It also results in ways to combine individual features, even if they emerge from the claims, the following description of embodiments or directly from the drawings. The reference of the claims to the drawings by use of reference numerals is not intended to limit the scope of the claims.

• 1 eine schematische Darstellung eines Antriebsstrangs mit einem Steuersystem zur Durchführung des erfindungsgemäßen Verfahrens;
• 2 ein Ablaufdiagramm eines erfindungsgemäßen Verfahrens zur Ermittlung des Fahrbahnzustands eines von einem Fahrzeug befahrenen Streckenabschnitts;
• 3 einen Signalverlauf bei einer vorliegenden Geländefahrt; und
• 4 einen Signalverlauf bei einer Einzelanregung sowie einen Signalverlauf bei einer rampenförmigen Anregung des Beschleunigungssensors.

To clarify the invention, the description is accompanied by a drawing with exemplary embodiments. In these shows:

• 1 a schematic representation of a drive train with a control system for carrying out the method according to the invention;
• 2 a flow diagram of a method according to the invention for determining the road condition of a traveled by a vehicle track section;
• 3 a waveform in an existing off-road drive; and
• 4 a waveform in a single excitation and a waveform at a ramp-shaped excitation of the acceleration sensor.

Out 1 is a schematic representation of a powertrain 1 of a vehicle, which is a commercial vehicle, such as a truck. This powertrain 1 It has a drive motor, which on its output side via an intermediate separating clutch 3 can be coupled with a drive side of an automated transmission. On the output side, the automated manual transmission then communicates with further output components, which are well known to the person skilled in the art, and the vehicle wheels of the commercial vehicle.

The vehicle further includes a control system 2 in which several different control devices via a data bus system 5 , for example, via a CAN bus system, communicate with each other. Among other things, in the data bus system 5 a transmission control unit TCU and a Engine control unit ECU provided by which the engine control unit ECU a control of the drive motor and the transmission control unit TCU a control of the automated transmission, and - under certain circumstances indirectly via another control unit - also a control of the clutch 3 performs. The transmission control unit TCU can communicate bidirectionally with the transmission on the one hand and with the engine control unit on the other. About the data bus system 5 the control units are supplied with the data relevant to them. The controllers are capable of receiving, processing and outputting sensor signals in response to it.

Thus, the transmission control unit TCU comprises a processor 6 and storage means 7 for storing and retrieving parameters, signals and information as well as a computer program product 11 , which is designed such that it can determine the road condition of a traveled by the vehicle track section in the sense of the method described above. Furthermore, the transmission control unit TCU has at least one reception interface 8th which is designed to receive all relevant data from sensors and the engine control unit TCU. The transmission control unit TCU also has a data processing device 9 on to process and evaluate the received data or the information of the received data and a transmission interface 10 , via which appropriate signals can be output for controlling drive train components.

The transmission control unit TCU controls the operation of the transmission by means of driving state data and driver's desired data. A shift strategy stored in the transmission control unit TCU in the form of a computer program determines respective switching reactions, in particular a gear change from a current actual gear to a desired gear, or a temporary traction interruption in the drive train 1 ,

The driving state data used may be, in addition to the determined road condition, the current driving resistance, the current vehicle inclination, the current vehicle mass, the current vehicle speed, the current vehicle acceleration, the current engine torque, the current engine speed, and other values. This data may be provided, at least in part, by the engine control unit ECU and suitable sensor devices.

Driver request data can be signaled, for example, sensed by the operation of an accelerator pedal or a brake pedal and fed to the transmission control unit TCU directly or indirectly.

The tax system 2 also includes means for actuating the automated transmission and the disconnect clutch 3 , These means include suitable switching valves via which an actuator of the automated transmission or the separating clutch can be controlled. The said means each comprise a data-transmitting connection 4 to the respective control unit.

The data-transmitting connection 4 between the control units and the powertrain components 1 For example, they can also be implemented by one or more electronic bus systems.

The tax system 2 may include an actuator that allows the driver to manually switch between a road travel control program and an off-road steering program. Via a display, the driver can be shown which control program is currently being executed.

In the present case, it is now provided that the transmission control unit TCU, under execution of the method according to the invention, determines the roadway condition of a section of road traveled by the vehicle and changes at least one control program for transmission control or adapts to the newly present roadway condition when a change in road condition is detected. To determine the road condition, the powertrain 1 an acceleration sensor 12 by means of which an acceleration along a vehicle vertical axis is detected. The acceleration sensor 12 may preferably be integrated in the transmission control unit TCU. In order to carry out the control program adapted to the road condition, the TCU may communicate with the engine control unit ECU and control the disconnect clutch 3 according to the adapted control program.

In order to determine the road condition of the section of road traveled by the vehicle, the transmission control unit TCU transmits the in 2 Process illustrated as a flow chart completed, to which now with the aid of 2 to be received:

At the beginning of the process, the vehicle is in a driving operation in which the control program for a road trip is active. In a first step of the in 2 The flowchart shown is that of the acceleration sensor 12 detected acceleration signal using a known per se algorithm calculates a course of a deflection (s_z_sensor) along the vehicle's vertical axis. The so determined signal profile (s_z_sensor) is compared in a further method step with a first threshold. If the first threshold value is not reached by the calculated signal curve (s_z_sensor), the road condition for road travel is recognized and the procedure starts again. The transmission control unit TCU then continues to execute the control program for driving on the road. If the calculated signal curve reaches or exceeds the first threshold value, a timer is started and, in a further method step, it is checked whether the signal profile (s_z_sensor) is above the first threshold value even after the predetermined time interval has elapsed. If this is not the case, then the road condition road traffic is detected and the process starts from the beginning. If the calculated signal curve (s_z_sensor) is above the first threshold value even after the predetermined period has elapsed, it is determined in a subsequent method step, using an algorithm known per se, whether the signal profile (s_z_sensor) has local minima. In a subsequent method step, it is finally checked whether the calculated signal curve (s_z_sensor) reaches or exceeds a second threshold value. If this is not the case, the procedure starts from the beginning and the lane state street driving is recognized and the road traffic control program is executed. If the calculated signal curve (s_z_sensor) reaches or exceeds the second threshold value, the signal curve (s_z_sensor) is still evaluated with respect to the calculated local minima. If the calculated signal curve (s_z_sensor) has no or only one local minimum, then the procedure starts again and the lane state road traffic is recognized and the control program for road travel is executed by the transmission control unit TCU. On the other hand, when the calculated signal course (s_z_sensor) reaches or exceeds the second threshold value and has at least two local minima, the road condition is detected off-road. From the transmission control unit TCU then the control program based on the detected off-road driving is adjusted or selected accordingly. The method according to the invention is re-executed after a recognized off-road drive, so that the road condition of the track section traveled by the vehicle is constantly redetermined.

3 shows a waveform (s_z_sensor), which is characteristic for a road condition off-road. The integrated in the transmission control unit TCU acceleration sensor 12 is first adjusted to a reference value for its rest position in the vehicle (s_z_sensor = 0). When driving on an uneven or unpaved section of the route experiences the acceleration sensor 12 due to the roadway excitation shown a deflection along the vehicle vertical axis, whereby this generates a corresponding acceleration signal. From the acceleration signal of the acceleration sensor 12 is calculated using a per se known algorithm, the course of the deflection (s_z_sensor) along the vertical axis of the vehicle. The signal curve thus determined (s_z_sensor) first exceeds a first threshold value. After expiration of the time period predetermined by the timer, the signal curve (s_z_sensor) is still above the first threshold value and then exceeds a second predetermined threshold value. Also, the waveform (s_z_sensor) has two local minima, with the first local minimum between the two thresholds and the second local minimum above the second threshold. Thus, all conditions for recognizing road condition off-road are met, and the transmission control unit TCU executes the off-road control program.

In the 4 waveforms are shown in which no off-road is detected. That's how it shows 4 on the one hand a waveform that results when the acceleration sensor 12 due to a single excitation undergoes a deflection along the vehicle's vertical axis. Although the signal profile (s_z_sensor) determined from the detected acceleration signal exceeds the first threshold value, the timer is started. However, the waveform (s_z_sensor) neither exceeds the second threshold nor does the waveform (s_z_sensor) have local minima. Thus it can be seen that a single excitation of the acceleration sensor 12 does not cause an off-road drive to be detected. Rather, when a detected individual excitation road condition road driving is detected and executed the control program for driving on the road.

Thus, individual obstacles lead to a specific excitation, in which a driving condition road driving is detected. Such an excitation can be detected, for example, in roadway situations, such as expansion joints of bridges, lowered or protruding manhole covers, level crossings or potholes.

On the other hand, the shows 4 still a waveform (s_z_sensor) which results when the acceleration sensor 12 undergoes a ramp-shaped excitation. Although the signal profile (s_z_sensor) determined from the detected acceleration signal exceeds both predefined threshold values, it does not have local minima. Thus it can be seen that also a ramp-shaped excitation of the acceleration sensor 12 does not lead to a recognized off-road drive. Rather, a road condition road traffic is detected here and the road traffic control program is executed.

LIST OF REFERENCE NUMBERS

1

powertrain

2

control system

3

clutch

4

connection

5

data bus system

6

processor

7

storage means

8th

Reception interface

9

evaluation

10

Transmission interface

11

A computer program product

12

accelerometer

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4569255 B1 [0004]
• DE 102008054476 A1 [0007]

Claims (8)

A method for determining the road condition of a road section traveled by a vehicle, in which an acceleration along a vehicle vertical axis by an acceleration sensor (12) is detected, is differentiated depending on the detected acceleration signal of the acceleration sensor (12) at least between a road trip and an off-road drive and wherein at a detected change of the road condition at least one control program for transmission control is changed or adjusted accordingly, characterized in that for determining the road condition following method steps are performed: - Calculation of the course of a deflection (s_z_sensor) along the vehicle's vertical axis of the vehicle from the detected acceleration signal the acceleration sensor (12); - comparing the calculated signal profile (s_z_sensor) with a first threshold value; - starting a timer if the calculated waveform (s_z_sensor) reaches or exceeds the first threshold; - Calculating local minima of the waveform (s_z_sensor), if the timer expired and the calculated waveform (s_z_sensor) is greater than the first threshold value; - Comparing the calculated waveform (s_z_sensor) with a second threshold, which is greater than the first threshold value; Detecting the road condition off-road if the calculated signal curve (s_z_sensor) reaches or exceeds the second threshold and has at least two local minima. Method according to Claim 1 , characterized in that the road condition is recognized road trip, if the calculated waveform (s_z_sensor) does not reach or exceed the first threshold, the timer has expired and the calculated waveform (s_z_sensor) is below the first threshold, the calculated waveform (s_z_sensor) the second threshold is not reached or exceeded or the calculated threshold (s_z_sensor) has less than two local minima. Method according to Claim 1 or 2 , characterized in that for adjusting the control program for transmission control in dependence of the road condition in addition to the procedurally determined road condition, a position of a manually operable by a driver actuator for selecting a mode for road or off-road driving is evaluated, wherein at different from the road condition indicating signals of procedurally determined road condition is considered prioritized. Method according to Claim 3 , characterized in that the driver is signaled via a display or acoustically when the activated control program for transmission control does not coincide with the control program selected via the manually operable actuator. Method according to one of Claims 1 to 4 , characterized in that the acceleration along the vehicle vertical axis by means of a single-axis acceleration sensor, by means of a two-axis acceleration sensor, which can detect not only the acceleration in the vertical direction but also an acceleration in the vehicle longitudinal direction or by means of a three-axis acceleration sensor In addition to the acceleration in the vertical direction and an acceleration in the vehicle longitudinal direction and an acceleration in the vehicle transverse direction can detect is detected. Transmission control unit (TCU) adapted to perform all the steps of a method according to any one of Claims 1 to 6 perform. Gearbox control unit after Claim 6 , characterized in that the acceleration sensor (12) for detecting an acceleration along the vehicle vertical axis in the transmission control unit (TCU) is integrated. A computer program product having program code means stored on a computer readable medium for carrying out all the steps of a method according to any one of Claims 1 to 5 perform when the computer program product on a computer or on a corresponding processing unit, in particular a transmission control unit (TCU) according to Claim 6 or 7 , is performed.

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