Method to determine drivability parameters of a vehicle

Abstract

The present invention relates to a method to determine drivability parameters of a vehicle, comprising the following steps, performed by a control unit (10): receiving recorded data, recorded during a

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of automobiles. More specifically, the present invention relates to a method to determine drivability parameters of a vehicle. BACKGROUND INFORMATION

[0002] Drivability describes the customer's perception of how the vehicle responds to driver input. Various sources report subjective drivability scores for new vehicles. One key source measures the rate of customer complaints / problems, and general drivability trends can be made based on the problems reported in the sources. In order to better understand these subjective ratings and to develop specific plans for future drivability improvements, it is necessary to correlate them with measurable drivability parameters. SUMMARY OF THE INVENTION

[0003] It is an object of the present invention to provide a method to determine drivability parameters of a vehicle.

[0004] This object is solved by a method to determine drivability parameters of a vehicle according to the independent claim. Advantageous embodiments are presented in the dependent claims.

[0005] The present invention is related to a method to determine drivability parameters of a vehicle. The method comprises the following steps, performed by a control unit. The control unit may be configured as an on-board control unit in the vehicle or an off-board control unit outside the vehicle. The method may be performed during or after operation of the vehicle.

[0006] A step comprises a receipt of recorded data. The data are recorded during an operation of the vehicle. The recorded data comprise a progression of an acceleration input signal of an acceleration pedal of the vehicle. The recorded data further comprise a progression of a longitudinal acceleration of the vehicle;

[0007] A next step comprises an identification of a respective start point, indicating a time of a respective positive step in the progression of the acceleration input signal.

[0008] A next step comprises an identification of a respective end point which is later than the respective start point according to a predefined criterion.

[0009] A next step comprises a definition of a respective reference time segment for analyzing the operation of the vehicle, extending from the respective start point to the respective end point.

[0010] A next step comprises an evaluation of the drivability parameters of the vehicle according to a predefined evaluation method as a function of the recorded data recorded in the respective reference time segment.

[0011] A next step comprises a sending of a signal comprising the drivability parameters of the vehicle by the control unit.

[0012] According to an embodiment of the present invention, the predefined evaluation method comprises a response delay evaluation method. The response delay evaluation method comprises the following steps.

[0013] A step of the response delay evaluation method comprises a filtering of the progression of the longitudinal acceleration of the vehicle using a low pass filter of a cutoff frequency between including 2 Hz and including 5 Hz to receive a progression of a filtered longitudinal acceleration.

[0014] A next step of the response delay evaluation method comprises an identification of one of the drivability parameters comprising an absolute maximum acceleration value of the progression of the filtered longitudinal acceleration during the respective reference time segment, and a corresponding point of occurrence of the absolute maximum acceleration value.

[0015] According to an embodiment of the present invention, the response delay evaluation method comprises a step of identifying a predefined relative acceleration value of the progression of the filtered longitudinal acceleration during the respective reference time segment and a corresponding point of occurrence of the predefined relative acceleration value. The predefined relative acceleration value is a predefined portion of the absolute maximum acceleration value.

[0016] According to an embodiment of the present invention, the response delay evaluation method comprises a step of identifying an absolute delay value being a corresponding point of occurrence when a predefined absolute acceleration value is exceeded for a first time by the filtered longitudinal acceleration during the respective reference time segment.

[0017] According to an embodiment of the present invention, the predefined evaluation method comprises a shock evaluation method. The shock evaluation method comprises the following steps.

[0018] The shock evaluation method comprises a step of filtering the progression of the longitudinal acceleration of the vehicle using a low pass filter of a cut-off frequency of 10 Hz to receive a progression of a filtered high frequency longitudinal acceleration.

[0019] The shock evaluation method comprises a step of identifying gradient inversion points in the progression of the filtered high frequency longitudinal acceleration.

[0020] The shock evaluation method comprises a step of identifying a maximum gradient inversion point of the gradient inversion points.

[0021] The shock evaluation method comprises a step of determining one of the drivability parameters being a post amplitude of the maximum gradient inversion point.

[0022] The shock evaluation method comprises a step of determining one of the drivability parameters being a frequency of the maximum gradient inversion point.

[0023] According to an embodiment of the present invention, it is intended that in the step of identifying the maximum gradient inversion point of the gradient inversion points, gradient inversion points whose pre amplitudes and post amplitudes are equal or smaller than zero and / or whose halves of the frequencies are outside a range of 0.04 Hz and 0.075 Hz may be ignored.

[0024] According to an embodiment of the present invention, the predefined evaluation method comprises a dip evaluation method. The dip evaluation method comprises the following steps.

[0025] The dip evaluation method comprises a step of filtering the progression of the longitudinal acceleration of the vehicle using a first low pass filter of a cut-off frequency of 2 Hz to receive a progression of a filtered low frequency longitudinal acceleration.

[0026] The dip evaluation method comprises a step of filtering the progression of the longitudinal acceleration of the vehicle using a first low pass filter of a cut-off frequency of 10 Hz to receive a progression of a filtered high frequency longitudinal acceleration.

[0027] The dip evaluation method comprises a step of identifying gradient inversion points in the progression of the filtered low frequency longitudinal acceleration and in the progression of the filtered high frequency longitudinal acceleration.

[0028] The dip evaluation method comprises a step of identifying a maximum gradient inversion point of the gradient inversion points of the filtered low frequency longitudinal acceleration and the filtered high frequency longitudinal acceleration.

[0029] The dip evaluation method comprises a step of determining one of the drivability parameters being a post amplitude of the maximum gradient inversion point.

[0030] The dip evaluation method comprises a step of determining one of the drivability parameters being a frequency of the maximum gradient inversion point.

[0031] According to an embodiment of the present invention, in the step of identifying the maximum gradient inversion point of the gradient inversion points, gradient inversion points whose pre amplitudes and post amplitudes are equal or smaller than zero and / or gradient inversion points of the filtered high frequency longitudinal acceleration whose halves of the frequency are outside a range of 0.075 Hz and 0.4 Hz may be ignored; and / or gradient inversion points of the filtered low frequency longitudinal acceleration whose halves of the frequency are outside a range of 0 Hz and 0.8 Hz may be ignored.

[0032] According to an embodiment of the present invention, the predefined evaluation method comprises an initial tip in acceleration evaluation method, the initial tip in acceleration evaluation method comprising the following steps.

[0033] The initial tip in acceleration evaluation method comprises a step of identifying a first tip in value being a corresponding point of occurrence when a predefined absolute first initial tip in acceleration value is exceeded for a first time by the filtered longitudinal acceleration during the respective reference time segment.

[0034] The initial tip in acceleration evaluation method comprises a step of identifying a second tip in value being a corresponding point of occurrence when a predefined absolute second initial tip in acceleration value is exceeded for a first time by the filtered longitudinal acceleration during the respective reference time segment.

[0035] The initial tip in acceleration evaluation method comprises a step of determining the initial tip in acceleration value by dividing the difference between the predefined absolute first initial tip in acceleration value and the predefined absolute second initial tip in acceleration value by the difference between the point of occurrence of the absolute first initial tip in acceleration value and the point of occurrence of the absolute second initial tip in acceleration value.

[0036] According to an embodiment of the present invention, the predefined evaluation method comprises an initial tip out acceleration evaluation method. The initial tip out acceleration evaluation method comprises the following steps.

[0037] The initial tip out acceleration evaluation method comprises a step of identifying a respective second start point, indicating a time of a respective negative step in the progression of the acceleration input signal.

[0038] The initial tip out acceleration evaluation method comprises a step of identifying a respective second end point which is later than the respective second start point according to a predefined criterion.

[0039] The initial tip out acceleration evaluation method comprises a step of defining a respective second reference time segment for analyzing the operation of the vehicle, extending from the respective second start point to the respective second end point.

[0040] The initial tip out acceleration evaluation method comprises a step of identifying a first tip out value being a corresponding point of occurrence when a predefined absolute first initial tip out acceleration value is exceeded for a first time by the filtered longitudinal acceleration during the respective second reference time segment.

[0041] The initial tip out acceleration evaluation method comprises a step of identifying a second tip out value being a corresponding point of occurrence when a predefined absolute second initial tip out acceleration value is exceeded for a first time by the filtered longitudinal acceleration during the respective second reference time segment.

[0042] The initial tip out acceleration evaluation method comprises a step of determining the initial tip out acceleration value by dividing the difference between the predefined absolute first initial tip out acceleration value and the predefined absolute second initial tip out acceleration value by the difference between the point of occurrence of the absolute first initial tip out acceleration value and the point of occurrence of the absolute second initial tip out acceleration value.

[0043] The control unit, configured to perform the method comprises means for performing the method.

[0044] The control unit may be designed as an on board unit of the vehicle. The control unit may receive the recorded data of the vehicle via a vehicle network. The vehicle network may comprise a Controller Area Network, a Local Interconnect Network and / or an Ethernet Network. Therefore, the method to determine the drivability parameters of the vehicle may be performed by the control unit of the vehicle itself.

[0045] The control unit may also be designed as an off board unit. The control unit may be located outside the vehicle. The control unit may be designed as an entity external to the vehicle. The control unit may receive the recorded data of the vehicle directly or indirectly from the vehicle via a wireless connection. The control unit may also receive the recorded data of the vehicle from a memory unit provided to the control unit. Therefore, the method may be performed off board the vehicle.

[0046] The control unit comprises a computing unit.

[0047] A computing unit may in particular be understood as a data processing device, which comprises processing circuitry. The computing unit can therefore in particular process data to perform computing operations. This may also include operations to perform indexed accesses to a data structure, for example a look-up table, LUT.

[0048] In particular, the computing unit may include one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits, ASIC, one or more field-programmable gate arrays, FPGA, and / or one or more systems on a chip, SoC. The computing unit may also include one or more processors, for example one or more microprocessors, one or more central processing units, CPU, one or more graphics processing units, GPU, and / or one or more signal processors, in particular one or more digital signal processors, DSP. The computing unit may also include a physical or a virtual cluster of computers or other of said units.

[0049] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more memory units.

[0050] A memory unit may be implemented as a volatile data memory, for example a dynamic random access memory, DRAM, or a static random access memory, SRAM, or as a non-volatile data memory, for example a read-only memory, ROM, a programmable read-only memory, PROM, an erasable programmable read-only memory, EPROM, an electrically erasable programmable read-only memory, EEPROM, a flash memory or flash EEPROM, a ferroelectric random access memory, FRAM, a magnetoresistive random access memory, MRAM, or a phase-change random access memory, PCRAM.

[0051] Further advantages, features, and details of the present invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and / or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The novel features and characteristic of the present disclosure are set forth in the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and / or methods in accordance with embodiments of the present subject matter are now described below, by way of example only, and with reference to the accompanying figures.

[0053] The drawings show in:

[0054] Fig. 1 a schematic illustration of a progression of an acceleration input signal and a longitudinal acceleration of the vehicle;

[0055] Fig. 2 a schematic illustration of a progression of an acceleration input signal a longitudinal acceleration of the vehicle and a shift position;

[0056] Fig. 3 a schematic illustration of drivability parameters related to a response delay;

[0057] Fig. 4 another schematic illustration of drivability parameters related to a response delay;

[0058] Fig. 5 a schematic illustration of drivability parameters related to a shock;

[0059] Fig. 6 a schematic illustration of drivability parameters related to a dip;

[0060] Fig. 7 a schematic illustration of drivability parameters related to an initial tip in acceleration value; and

[0061] Fig.8 a schematic illustration of drivability parameters related to an initial tip out acceleration value.

[0062] In the figures the same elements or elements having the same function are indicated by the same reference signs. DETAILED DESCRIPTION

[0063] In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0064] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawing and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0065] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion so that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus preceded by “comprises” or “comprise” does not or do not, without more constraints, preclude the existence of other elements or additional elements in the system or method.

[0066] In the following detailed description of the embodiment of the present disclosure, reference is made to the accompanying drawing that forms part hereof, and in which is shown by way of illustration a specific embodiment in which the disclosure may be practiced. This embodiment is described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0067] Fig. 1 shows a schematic illustration of a progression of an acceleration input signal and a longitudinal acceleration of the vehicle.

[0068] The progression of the acceleration input signal 12 and the progression of the longitudinal acceleration 14 of the vehicle may be provided to a control unit 10 in recorded data. The recorded data may be recorded during an operation of the vehicle, The acceleration input signal 12 may describe an input of an acceleration pedal of the vehicle.

[0069] The figure shows a respective start point 18, identified by the control unit 10. The start point 18 may indicate a time of a respective positive step in the progression of the acceleration input signal 12. The start point 18 may indicate the time a driver pressed the pedal. The start point 18 may define a beginning of a respective reference time segment 22 for analyzing an operation of the vehicle. The respective reference time segment 22 may extend from the respective start point 18 to a respective end point 20. The end point 20 may be identified by the control unit 10 according to a predefined criterion.

[0070] The drivability parameters of the vehicle may be evaluated by the control unit 10 according to a predefined evaluation method as a function of the recorded data.

[0071] The drivability parameters may comprise an absolute maximum acceleration value 24. The absolute maximum acceleration value 24 may be evaluated in a response delay evaluation method, the response delay evaluation method may comprise a filtering of the progression of the longitudinal acceleration 14 of the vehicle using a low pass filter of a cut-off frequency between including 2 Hz and including 5 Hz to receive a progression of a filtered longitudinal acceleration 14. The control unit 10 may identify one of the drivability parameters comprising the absolute maximum acceleration value 24 of the progression of the filtered longitudinal acceleration 14 during the respective reference time segment 22, and a corresponding point of occurrence of the absolute maximum acceleration value 26.

[0072] The control unit 10 may identify one of the drivability parameters comprising a predefined relative acceleration value 28 of the progression of the filtered longitudinal acceleration 14 during the respective reference time segment 22 and a corresponding point of occurrence of the predefined relative acceleration value 30, the predefined relative acceleration value 28 being a predefined portion of the absolute maximum acceleration value 24. Fig. 1 shows the predefined relative acceleration values 28 being portions of 60% and 90% of the absolute maximum acceleration value 24.

[0073] The control unit 10 may identify one of the drivability parameters comprising an absolute delay value 32 being a corresponding point of occurrence when a predefined absolute acceleration value 34 is exceeded for a first time by the filtered longitudinal acceleration 14 during the respective reference time segment 22. The absolute delay value 32 may give the predefined absolute acceleration value of 0.5 m / s2. The corresponding time may be the initial delay time.

[0074] The control unit 10 may identify one of the drivability parameters comprising a shock amplitude 46, according to a predefined shock evaluation method. The shock may be evaluated by filtering the progression of the longitudinal acceleration 14 of the vehicle using a low pass filter of a cut-off frequency of 10 Hz to receive a progression of a filtered high frequency longitudinal acceleration 36. Gradient inversion points 50 may be identified in the progression of the filtered high frequency longitudinal acceleration 36. A maximum gradient inversion point 40 of the gradient inversion points 50 may be identified by the control unit 10. One of the drivability parameters may be a post amplitude 44 of the maximum gradient inversion point 40. The post amplitude 44 may be the amplitude of the longitudinal acceleration 14 between the maximum gradient inversion point 40 and a following gradient inversion point 38 of the maximum gradient inversion point 40. A pre amplitude 42 of the maximum gradient inversion point 40 may be an amplitude of the longitudinal acceleration 14 before the maximum gradient inversion point 40. Another one of the drivability parameters may be a frequency of the maximum gradient inversion point 40 related to the time between the maximum gradient inversion point 40 and the following gradient inversion point 38 of the maximum gradient inversion point 40.

[0075] It may be possible that in the identification of the maximum gradient inversion point 40 of the gradient inversion points 50, whose pre amplitudes 42 and post amplitudes 44 are equal or smaller than zero and / or whose halves of the frequencies are outside a range of 0.04 Hz and 0.075 Hz may be ignored by the control unit 10. The pre amplitude 42 of the maximum gradient inversion point 40 may be the amplitude of the longitudinal acceleration 14 between the maximum gradient inversion point 40, and a preceding point of the maximum gradient inversion point 40. The preceding point may have a same time distance to the maximum gradient inversion point 40 as the following gradient inversion point 38 of the maximum gradient inversion point 40.

[0076] The control unit 10 may identify one of the drivability parameters comprising a dip according to a dip evaluation method, the dip evaluation method may comprising a filtering of the progression of the longitudinal acceleration 14 of the vehicle using a first low pass filter of a cut-off frequency of 2 Hz to receive a progression of a filtered low frequency longitudinal acceleration 48 and a filtering the progression of the longitudinal acceleration 14 of the vehicle using a first low pass filter of a cut-off frequency of 10 Hz to receive a progression of a filtered high frequency longitudinal acceleration 36. The control unit 10 may identify gradient inversion points 50 in the progression of the filtered low frequency longitudinal acceleration 48 and in the progression of the filtered high frequency longitudinal acceleration 36 and identifying a maximum gradient inversion point 54 of the gradient inversion points 50 of the filtered low frequency longitudinal acceleration 48 and the filtered high frequency longitudinal acceleration 36.

[0077] One of the drivability parameters may be a post amplitude 58 of the maximum gradient inversion point 54. Another one of the drivability parameters may be a frequency of the maximum gradient inversion point 54.

[0078] For identifying the maximum gradient inversion point 54 of the gradient inversion points 50, the control unit 10 may ignore gradient inversion points 50 whose pre amplitudes 56 and post amplitudes 58 are equal or smaller than zero. The control unit 10 may also ignore gradient inversion points 50 of the filtered high frequency longitudinal acceleration 36 whose halves of the frequency 90 are outside a range of 0.075 Hz and 0.4 Hz. The control unit 10 may also ignore gradient inversion points 50 of the filtered low frequency longitudinal acceleration 48 whose halves of the frequency 90 are outside a range of 0 Hz and 0.8 Hz.

[0079] Fig. 2 shows a schematic illustration of a progression of an acceleration input signal 12, a progression of a longitudinal acceleration 14 of the vehicle and a progression of a shift position 16 of a gear.

[0080] The start point 18 may indicate the time of the respective positive step in the progression of the acceleration input signal 12. The start point 18 may indicate the time the driver pressed the pedal. The start point 18 may define a beginning of a respective reference time segment 22 for analyzing an operation of the vehicle. The respective reference time may extend from the respective start point 18 to the respective end point 20. The end point 20 may be identified by the control unit 10 according to a predefined criterion. The end point 20 may be a second start point 82, when the second reference time segment 86 starts. The second reference time segment 86 may end at the second end point 84.

[0081] The predefined absolute delay value 32 may be exceeded at the point of occurrence of the predefined absolute acceleration value 34.

[0082] At a change of the shift position 16 of a gear, the maximum gradient inversion point 40 may occur. The longitudinal acceleration 14 may form a pre amplitude 42 before the maximum gradient inversion point 40 and a post amplitude 44 after the maximum gradient inversion point 40. The amplitudes may describe the dip amplitude 60 and / or the shock amplitude 46.

[0083] After the gradient inversion point 38, occurring after the maximum gradient inversion point 38, the filtered longitudinal acceleration 14 may rise up to the absolute maximum acceleration value 24. Before, the filtered longitudinal acceleration 14 may exceed the predefined relative acceleration values 28 at corresponding points of occurrence of the predefined relative acceleration values 30, the predefined relative acceleration value 28 may be 60% and 90% of the absolute maximum acceleration value 24.

[0084] At a next change of the shift position 16 of the gear, another maximum gradient inversion point 40 may occur, followed by the following gradient inversion point 38. The amplitudes of the longitudinal acceleration 14 between the gradient inversion points 40, 38 may describe another dip amplitude 60 and / or another shock amplitude 46.

[0085] Fig. 3 shows a schematic illustration of drivability parameters related to a response delay.

[0086] The figure shows the initial delay, giving the point of occurrence of a predefined absolute acceleration value 34, when a predefined longitudinal acceleration value 32 of 0.5 m / s2 is reached, the point of occurrence 30 of the predefined relative acceleration value 28 at 60% of the absolute maximum acceleration value 24 and the point of occurrence 30 of the predefined relative acceleration value 28 at 90% of the absolute maximum acceleration value 24and the absolute maximum acceleration value 24, which occurs at the point of occurrence of the absolute maximum acceleration value 26..

[0087] Fig. 4 shows a schematic illustration of drivability parameters related to a shock.

[0088] Fig. 4 shows a shock amplitude 46 defined by the post amplitude 58 between the maximum gradient inversion point 54 and a following gradient inversion point 52, as well as a half of the frequency 90 of the maximum gradient inversion point 54. Fig. 4 also shows a pre amplitude 56 of the maximum gradient inversion point 54.

[0089] Fig. 5 shows a schematic illustration of drivability parameters related to a dip.

[0090] Fig. 5 shows a dip amplitude 60 defined by the post amplitude 58 between the maximum gradient inversion point 54 and a following gradient inversion point 52.

[0091] Fig. 6 shows a schematic illustration of drivability parameters related to an initial tip in acceleration value 62.

[0092] Fig. 6 shows a progression of the filtered high frequency longitudinal acceleration 36 and a progression of the filtered low frequency longitudinal acceleration 48.

[0093] Fig. 6 shows a first tip in value being a corresponding point of occurrence 68 when a predefined absolute first initial tip in acceleration value 64 is exceeded for a first time by the filtered longitudinal acceleration 14 during the respective reference time segment 22 and a point of occurrence 70 when a predefined absolute second initial tip in acceleration value 66 is exceeded for a first time by the filtered longitudinal acceleration 14 during the respective reference time segment 22. The initial tip in acceleration value 62 may be evaluated by dividing the difference between the predefined absolute first initial tip in acceleration value 64 and the predefined absolute second initial tip in acceleration value 66 by the difference between the point of occurrence of the absolute first initial tip in acceleration value 68 and the point of occurrence of the absolute second initial tip in acceleration value 70.

[0094] Fig. 7 shows a schematic illustration of drivability parameters related to determining an initial tip out acceleration value 72 based on an initial Ax gradient value 88 during the second time reference segment 86 (Fig. 2). In another embodiment, the initial Ax gradient value 88 may be determined during the reference time segment 22 (Fig. 2).

[0095] Fig. 7 further shows the initial Ax gradient value 88 may be determined between two points of occurrence, which includes a point of occurrence 78 when a predefined absolute first initial tip out acceleration value 74 is exceeded for a first time by the filtered longitudinal acceleration 14 during the respective second reference time segment 86 (Fig. 4) and a point of occurrence 80 (Fig. 4) when a predefined absolute second initial tip out acceleration value 76 is exceeded for a first time by the filtered longitudinal acceleration 14 during the respective second reference time segment 86 (Fig. 4). The initial Ax gradient value 88 for determining the initial tip out acceleration value 72 may be evaluated by dividing the difference between the predefined absolute first initial tip out acceleration value 74 and the predefined absolute second initial tip out acceleration value 76 by the difference between the point of occurrence of the absolute first initial tip out acceleration value 78, where the pedal box 10 is lifted off, and the point of occurrence of the absolute second initial tip out acceleration value 80, which occurs around 60% of maximum acceleration.

[0096] Fig. 8 shows a schematic illustration of a method to determine drivability parameters of a vehicle performed by a control unit 10.

[0097] In a first step S1, the control unit 10 may receive recorded data, recorded during an operation of the vehicle, the recorded data comprising a progression of an acceleration input signal 12 of an acceleration pedal of the vehicle and a progression of a longitudinal acceleration 14 of the vehicle.

[0098] In a second step S2, the control unit 10 may identify a respective start point 18, indicating a time of a respective positive step in the progression of the acceleration input signal 12.

[0099] In a third step S3, the control unit 10 may identify a respective end point 20 which is later than the respective start point 18 according to a predefined criterion.

[00100] In a fourth step S4 the control unit 10 may define a respective reference time segment 22 for analyzing the operation of the vehicle, extending from the respective start point 18 to the respective end point 20.

[00101] In a fifth step S5, the control unit 10 may evaluate the drivability parameters of the vehicle according to a predefined evaluation method as a function of the recorded data recorded in the respective reference time segment 22.

[00102] In a sixth step S6, the control unit 10 may send a signal comprising the drivability parameters of the vehicle.

[00103] A test procedure is designed for objective analysis and quality control of passenger car characteristics based on the driver's experience. The system uses various sensors inputs to capture the most significant data and vehicle parameters, such as longitudinal acceleration, engine speed, velocity, pedal position, and vibrations.

[00104] The process for the test procedure may use the following input as a test case: Drive vehicle in any operation state and perform step input of acceleration pedal for 5 seconds. The process includes recording data for the analysis of delay time until certain percent of peak acceleration is reached on vehicle. signs control unit acceleration input signal longitudinal acceleration shift position start point end point reference time segment absolute maximum acceleration value point of occurrence of the absolute maximum acceleration value predefined relative acceleration value point of occurrence of the predefined relative acceleration value predefined absolute delay value point of occurrence of a predefined absolute acceleration value filtered high frequency longitudinal acceleration gradient inversion point maximum gradient inversion point pre amplitude post amplitude shock amplitude filtered low frequency longitudinal acceleration post amplitude gradient inversion point maximum gradient inversion point pre amplitude post amplitude dip amplitude initial tip in acceleration value predefined absolute first initial tip in acceleration value predefined absolute second initial tip in acceleration value point of occurrence of the absolute first initial tip in acceleration value point of occurrence of the absolute second initial tip in acceleration value initial tip out acceleration value predefined absolute first initial tip out acceleration value predefined absolute second initial tip out acceleration value point of occurrence of the absolute first initial tip out acceleration value point of occurrence of the absolute second initial tip out acceleration value second start point second end point second reference time segment initial Ax gradient value halves of the frequency steps of method

Claims

1. A method to determine drivability parameters of a vehicle, comprising the following steps, performed by a control unit (10): - receiving recorded data, recorded during an operation of the vehicle, the recorded data comprising a progression of an acceleration input signal (12) of an acceleration pedal of the vehicle and a progression of a longitudinal acceleration (14) of the vehicle;- identifying a respective start point (18), indicating a time of a respective positive step in the progression of the acceleration input signal (12);- identifying a respective end point (20) which is later than the respective start point (18) according to a predefined criterion;- defining a respective reference time segment (22) for analyzing the operation of the vehicle, extending from the respective start point (18) to the respective end point (20);- evaluating the drivability parameters of the vehicle according to a predefined evaluation method as a function of the recorded data recorded in the respective reference time segment (22), and- sending a signal comprising the drivability parameters of the vehicle.

2. The method according to claim 1, characterized in that the predefined evaluation method comprises a response delay evaluation method, the response delay evaluation method comprising the following steps:- filtering the progression of the longitudinal acceleration (14) of the vehicle using a low pass filter of a cut-off frequency between including 2 Hz and including 5 Hz to receive a progression of a filtered longitudinal acceleration; and- identifying an absolute maximum acceleration value (24) of the progression of the filtered longitudinal acceleration during the respective reference time segment (22), and a corresponding point of occurrence of the absolute maximum acceleration value (26).

3. The method according to claim 2, characterized in thatthe response delay evaluation method comprises the following step:- identifying a predefined relative acceleration value (28) of the progression of the filtered longitudinal acceleration during the respective reference time segment (22) and a corresponding point of occurrence of the predefined relative acceleration value (30), the predefined relative acceleration value (28) being a predefined portion of the absolute maximum acceleration value (24).

4. The method according to claim 2 or 3, characterized in thatthe response delay evaluation method comprises the following step:- identifying an absolute delay value (32) being a corresponding point of occurrence when a predefined absolute acceleration value (34) is exceeded for a first time by the filtered longitudinal acceleration (14) during the respective reference time segment (22).

5. The method according to claim 1, characterized in thatthe predefined evaluation method comprises a shock evaluation method, the shock evaluation method comprising the following steps:- filtering the progression of the longitudinal acceleration of the vehicle using a low pass filter of a cut-off frequency of 10 Hz to receive a progression of a filtered high frequency longitudinal acceleration (36);- identifying gradient inversion points (38) in the progression of the filtered high frequency longitudinal acceleration (36);- identifying a maximum gradient inversion point (40) of the gradient inversion points (38);- determining a post amplitude (44) of the maximum gradient inversion point (40); and- determining a frequency of the maximum gradient inversion point (40).

6. The method according to claim 5, characterized in thatin the step of identifying the maximum gradient inversion point (40) of the gradient inversion points (38), gradient inversion points (38) whose pre amplitudes (42) and post amplitudes (44) are equal or smaller than zero and / or whose halves of the frequencies are outside a range of 0.04 Hz and 0.075 Hz are ignored.

7. The method according to claim 1, characterized in thatthe predefined evaluation method comprises a dip evaluation method, the dip evaluation method comprising the following steps:- filtering the progression of the longitudinal acceleration of the vehicle using a first low pass filter of a cut-off frequency of 2 Hz to receive a progression of a filtered low frequency longitudinal acceleration (48);- filtering the progression of the longitudinal acceleration of the vehicle using a first low pass filter of a cut-off frequency of 10 Hz to receive a progression of a filtered high frequency longitudinal acceleration (36);- identifying gradient inversion points (50) in the progression of the filtered low frequency longitudinal acceleration (48) and in the progression of the filtered high frequency longitudinal acceleration (36);- identifying a maximum gradient inversion point (54) of the gradient inversion points (50) of the filtered low frequency longitudinal acceleration (48) and the filtered high frequency longitudinal acceleration (36).- determining one of the drivability parameters being a post amplitude (58) of the maximum gradient inversion point (54); and- determining one of the drivability parameters being a frequency of the maximum gradient inversion point (54).

8. The method according to claim 7,characterized in thatin the step of identifying the maximum gradient inversion point (54) of the gradient inversion points (50),- gradient inversion points (50) whose pre amplitudes (56) and post amplitudes (58) are equal or smaller than zero are ignored; and / or- gradient inversion points (50) of the filtered high frequency longitudinal acceleration (36) whose halves of the frequency (90) are outside a range of 0.075 Hz and 0.4 Hz are ignored; and / or- gradient inversion points (50) of the filtered low frequency longitudinal acceleration (48) whose halves of the frequency (90) are outside a range of 0 Hz and 0.8 Hz are ignored.

9. The method according to any one of the preceding claims, characterized in thatthe predefined evaluation method comprises an initial tip in acceleration evaluation method, the initial tip in acceleration evaluation method comprising the following steps:- identifying a corresponding point of occurrence (68) when a predefined absolute first initial tip in acceleration value (64) is exceeded for a first time by the filtered longitudinal acceleration during the respective reference time segment (22);- identifying a corresponding point of occurrence (70) when a predefined absolute second initial tip in acceleration value (66) is exceeded for a first time by the filtered longitudinal acceleration during the respective reference time segment (22); and - determining an initial tip in acceleration value (62) by dividing the difference between the predefined absolute first initial tip in acceleration value (64) and the predefined absolute second initial tip in acceleration value (66) by the difference between the point of occurrence of the absolute first initial tip in acceleration value (68) and the point of occurrence of the absolute second initial tip in acceleration value (70).

10. The method according to any one of the preceding claims, characterized in thatthe predefined evaluation method comprises an initial tip out acceleration evaluation method, the initial tip out acceleration evaluation method comprising the following steps:- identifying a respective second start point (82), indicating a time of a respective negative step in the progression of the acceleration input signal (12);- identifying a respective second end point (84) which is later than the respective second start point (82) according to a predefined criterion;- defining a respective second reference time segment (86) for analyzing the operation of the vehicle, extending from the respective second start point (82) to the respective second end point (84);- identifying one of the drivability parameters being a corresponding point of occurrence (78) when a predefined absolute first initial tip out acceleration value (74) is exceeded for a first time by the filtered longitudinal acceleration during the respective second reference time segment (86);- identifying one of the drivability parameters being a corresponding point of occurrence (80) when a predefined absolute second initial tip out acceleration value (76) is exceeded for a first time by the filtered longitudinal acceleration during the respective second reference time segment (86); and- determining the initial tip out acceleration value (72) by dividing the difference between the predefined absolute first initial tip out acceleration value (74) and the predefined absolute second initial tip out acceleration value (76) by the difference between the point of occurrence of the absolute first initial tip out acceleration value (78) and the point of occurrence of the absolute second initial tip out acceleration value (80).

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