DE102018217523B4 - Method for determining an energy requirement of a motor vehicle and test stand for carrying out the method - Google Patents

Abstract

Method (2) for determining an energy requirement of a motor vehicle (4), in which
- the motor vehicle (4) is arranged on a roller test bench (20),
- A driver assistance system (12) of the motor vehicle (4) is activated, and
- the motor vehicle (4) is operated according to a predetermined cycle (42),
- wherein a sensor (14), which is coupled in terms of signals to the driver assistance system (4), is stimulated by means of an external actuator (26) in accordance with the predetermined cycle (42), or
- The driver assistance system (12) being placed in a test mode and sensor data corresponding to the specified cycle (42) being transmitted from an external unit (28) to the driver assistance system (12) via an interface (16).

Description

When making a purchase decision for a motor vehicle, the energy requirement of the motor vehicle is taken into account, among other things. A need for a certain type of fuel is usually shown in a sales prospectus. In particular, the need is broken down between inner-city and extra-urban consumption. Furthermore, any charges are usually determined on the basis of an energy requirement. For example, a tax for the motor vehicle is determined at least in certain jurisdictions according to the emission of CO2, with the emission being dependent on the energy requirement.

Even in the case of fully electrically operated motor vehicles, the specification of the energy requirement is decisive for a purchase decision. For example, this results in a maximum range of the respective motor vehicle.

The energy requirement is determined in accordance with a certain predetermined cycle that essentially applies to all manufacturers and all motor vehicle types. This is intended to ensure that future energy requirements can be compared. The energy requirement is determined, for example, by means of a roller test stand. Here, the motor vehicle is placed on the roller test stand, so that when the drive wheels accelerate, the rollers of the test stand are set in rotation. However, the motor vehicle itself is not moved from one place.

By adjusting the resistance of the rollers, different driving situations are simulated according to the specified cycle. It is thus not necessary to move the motor vehicle in real environments, which increases comfort and reproducibility.

However, the cycle is only determined essentially based on the rolling resistance and a desired acceleration and/or deceleration of the drive wheels of the motor vehicle, which is why the energy requirement can deviate during actual operation.

The invention is based on the object of specifying a particularly suitable method for determining an energy requirement of a motor vehicle and also a particularly suitable test stand, with the reproducibility and reliability of determined values and comfort and safety advantageously being increased.

With regard to the method, this object is achieved according to the invention by the features of claim 1 and with regard to the test stand by the features of claim 4 . Advantageous developments and refinements are the subject of the respective dependent claims.

The method is used to determine an energy requirement of a motor vehicle. The motor vehicle preferably has a number of wheels. In the intended state, the wheels in particular make contact with an environment, expediently with a floor, such as a lane. The motor vehicle is land-bound and was preferably moved independently of rails or the like. For example, the motor vehicle is a passenger car (car) or a commercial vehicle, such as a truck (truck) or bus. The motor vehicle is a commercial vehicle, for example. However, the motor vehicle is particularly preferably a passenger car. For propulsion, the motor vehicle has, for example, an internal combustion engine, an electric motor or a combination thereof. At least one, preferably two or all of the possible wheels are expediently driven by the respective motor. In particular, the motor vehicle is suitable, in particular provided and set up, to be moved autonomously, in particular in an automated manner. In this case, an automation level greater than or equal to 2 or 3 according to the SAE definition is preferably achieved by means of the motor vehicle.

The method provides that the motor vehicle is first placed on a roller test stand. The roller dynamometer expediently has a number of rollers that are operatively connected to any drive wheels of the motor vehicle. In particular, the drive wheels are placed on the rollers. When the drive wheels are driven, the rollers are thus driven and the motor vehicle is not moved. For example, the motor vehicle is additionally fixed, for example by means of a rope or a rod. In particular, a supply of fresh air to the motor vehicle is also prepared or ensured, for example by means of a fan. Here, in particular, a possible relative wind is simulated by means of the blower.

In a further step, a driver assistance system of the motor vehicle is activated. The driver assistance system is, for example, a pilot or assistance system. This work step takes place, for example, after the motor vehicle has been positioned on the roller test bench, beforehand or at the same time. The driver assistance system is provided and set up to support/relieve a driver of the motor vehicle. In particular, an intervention in a control of the motor vehicle is carried out during operation by means of the driver assistance system. In particular, this takes place in the intended state by means of the driver assistance system an intervention by means of which a movement direction and/or a movement speed are changed. A steering intervention and/or an intervention in an acceleration or braking system are expediently carried out by means of the driver assistance system. The interventions are suitably autonomous and dependent on a specific driving situation. In other words, the interventions take place independently of a driver and expediently only as a function of a specific driving situation.

In a further work step, the motor vehicle is operated according to a predetermined cycle. The cycle is thus independent of the motor vehicle and the respective type of motor vehicle. In particular, the cycle applies to a number of motor vehicle types. Thus, a comparability is realized. The energy requirement of the motor vehicle is recorded during operation according to the cycle. For example, a tank content before the start of the cycle is compared with a tank content after the end of the cycle, and the energy requirement is determined from this. As an alternative to this, a state of charge of a battery before the start of the cycle is compared with a state of charge after the end of the cycle, for example, and the energy requirement is determined from this.

The driver assistance system is thus activated during the operation of the motor vehicle according to the cycle, so that an energy requirement of the driver assistance system is taken into account when determining the energy requirement of the motor vehicle. The driver assistance system also intervenes during the cycle, for example, so that the determined energy requirement essentially corresponds to the energy requirement actually required in a real environment. At least, however, an influence of the driver assistance system on the energy requirement is taken into account. The reliability of the determined energy requirement is thus increased. It is also possible to reproduce the respective energy requirement under real conditions with the driver assistance system activated. Furthermore, there is a comparability between the energy requirements of different motor vehicle types, since, for example, the energy requirement of the driver assistance system is different for the respective motor vehicle types. Since the determination of the energy requirement takes place on a test bench, the convenience for operators who determine the energy requirement is increased, as is safety, since, for example, there is no need to pay attention to any traffic flow or the like.

For example, the driver assistance system can be activated or deactivated by means of a manual intervention. As an alternative to this, the driver assistance system is always active as soon as the motor vehicle is started, for example. The driver assistance system is thus activated, for example, when the motor vehicle is activated, in particular when an ignition is actuated. A further driver assistance system, expediently all driver assistance systems of the motor vehicle, is suitably activated. The energy requirement of all driver assistance systems is therefore also taken into account for the operation of the motor vehicle according to the cycle, which increases comparability and reproducibility.

For example, the motor vehicle has a sensor that is coupled to the driver assistance system in terms of signals. In this case, the driver assistance system is expediently operated as a function of data ascertained by means of the sensor. The data from the sensor is, for example, data that has already been processed. In particular, the sensor is a distance sensor, and the data from the sensor thus correspond during operation to a distance of an object that is located in a specific direction with respect to the motor vehicle. For example, the sensor is a radar sensor, a lidar sensor, an infrared sensor or a camera. The motor vehicle preferably has a number of sensors which are suitably connected to one another. As an alternative to this, the driver assistance system is acted upon by means of a plurality of sensors, and the driver assistance system has suitable interfaces for this.

The method provides that the sensor is preferably stimulated by means of an external actuator according to the predetermined cycle. The external actor is a projector, for example, especially if the sensor is a camera. As an alternative to this, the external actuator is a sensor/actuator or includes such a sensor/actuator that works in accordance with the motor vehicle's sensor. The external actuator is expediently a part of a test stand that includes the roller test stand. In particular, the external actuator can be moved or pivoted with respect to the roller test stand, so that it can be arranged in a detection range of the sensor of the motor vehicle.

Due to the stimulation of the sensor by means of the external actuator, the driver assistance system is triggered, so that it makes one or more interventions in particular. As a result, an energy requirement of the motor vehicle is changed during the cycle due to the interventions of the driver assistance system. Due to the stimulation by means of the external actuator, it is not necessary to change the motor vehicle itself, so that the effort is reduced. Reproducibility is also improved and acceptance of the energy requirement determined in this way is increased.

In an alternative or in combination with this, the motor vehicle has an interface which is expediently coupled to the driver assistance system in terms of signals. Using an external unit, sensor data is transmitted to the driver assistance system via the interface according to the specified cycle. The transmitted sensor data preferably correspond essentially to recorded real or generated sensor data, so that the driver assistance system carries out any interventions depending on the sensor data fed in. In particular, the sensor data correspond to an object that is positioned at a specific distance from the motor vehicle. For example, the sensor data is transmitted directly to the driver assistance system and consequently fed into the driver assistance system. As an alternative to this, for example, the sensor data are routed to any sensor that transmits the sensor data made available by means of the external unit to the driver assistance system. Thus, no sensor data are expediently generated by the sensor or sent to the driver assistance system that correspond to actual measured values.

Due to the transmission of the sensor data to the driver assistance system by means of the external unit, it is not necessary to actually position an object with respect to the motor vehicle. A hardware requirement is thus reduced. In addition, any erroneous evaluation of a sensor is prevented in this way, so that the energy requirement of the driver assistance system and thus of the entire motor vehicle can be determined precisely without any malfunction of the sensor leading to a falsification of the determined energy requirement.

The external unit is, for example, a computer and/or a control unit. In particular, the motor vehicle is additionally operated according to the cycle by means of the external unit. Thus, only the single external unit is required both for operation and for providing the sensor data, which reduces manufacturing costs. This also simplifies and improves matching of the feeding of the sensor data to the cycle.

For example, the interface is coupled directly to the driver assistance system and is expediently only used to transmit the sensor data to the driver assistance system. However, the motor vehicle particularly preferably comprises a bus system which is, for example, a CAN bus system or a FlexRay bus system. The method provides for the sensor data to be fed into the bus system of the motor vehicle. The driver assistance system is expediently coupled to the bus system in terms of signals, as is the external unit. Because of the bus system, cabling is reduced. It is also possible to use the interface for any other additional tasks, for example. In particular, the motor vehicle is operated according to the cycle via the interface, which is preferably coupled to the external unit. In other words, the cycle or at least operating parameters are fed in according to the cycle via the interface into the bus system. Because the sensor data are fed into the bus system, it is also possible for them to be taken into account by another driver assistance system. This reduces the effort involved in determining the energy requirement, in particular if there are a number of such driver assistance systems.

For example, during the determination of the energy requirement, the possible sensor is operated in a mode in which no measured values are generated but only sensor data that are made available by the external unit are forwarded to the driver assistance system. The driver assistance system has a test mode and a normal mode. When the motor vehicle is operated as intended, the driver assistance system is expediently set to normal mode. In this case, any sensor data are preferably processed in accordance with a desired specification. The test mode particularly preferably deviates from the normal mode. In the test mode, sensor data that are recorded or generated by the sensor of the motor vehicle are suitably not further processed with the driver assistance system. Thus, for example, actually measured distances to real objects are not processed. In the test mode, only the sensor data fed in by means of the external unit are suitably processed with the driver assistance system.

Because of the test mode, actual sensor data measured by the respective sensor of the motor vehicle is not taken into account. It is thus possible for operators to move in the area of the motor vehicle without this having an effect on the function of the driver assistance system and consequently on the determination of the energy requirement. In this way, comfort for the operators is increased.

The test mode is expediently maintained during the cycle. After the end of the cycle, the test mode is suitably ended and the driver assistance system is switched back to normal mode, for example. For example, the transfer takes place in the Testmo dus by means of the external unit or a switch of the motor vehicle. The driver assistance system is suitably controlled by the external unit to be transferred to the test system, for example by transmitting a single command. As an alternative to this, the sensor data that is transmitted to the driver assistance system is identified, for example. The transmitted sensor data are provided, for example, by means of a suitable identifier/identification/identification. If the identifier is detected by means of the driver assistance system, sensor data that do not have this identifier, for example, are not processed further. With such an embodiment, it is not necessary to put the driver assistance system back into normal mode after the end of the cycle. Consequently, the test mode is ended when no sensor data is transmitted to the driver assistance system by means of the external unit. Safety is thus increased, in particular removing the motor vehicle from the roller test stand, since in this case the driver assistance system is already switched to normal mode.

The invention also relates in particular to a motor vehicle with a driver assistance system that can be put into a test mode. In other words, the driver assistance system has the test mode. In the test mode, only sensor data are processed, which are transmitted to the driver assistance system by means of an external unit. In particular, the test mode is provided and set up for determining the energy requirement of the motor vehicle.

For example, there is no further influence on the motor vehicle when it is operated according to the cycle. However, a maximum deceleration of the motor vehicle is particularly preferably limited, ie in particular a braking power of any braking system and/or recuperation system. In this way, overloading of the dynamometer is prevented, especially in the case of a comparatively strong deceleration effect. For example, the deceleration value is formed by means of the driver assistance system or an actuation of the brake system in accordance with the driver assistance system. In particular, the desired deceleration is the intervention that is carried out using the assistance system. For example, emergency braking or the like is triggered by means of the driver assistance system. Due to the limitation of the maximum deceleration, the dynamometer is not damaged and detachment of the motor vehicle from the dynamometer is avoided. Injury to any persons located in the vicinity of the motor vehicle is thus also avoided, as is damage to any objects located there. In particular, the maximum deceleration is limited by putting the driver assistance system into the test mode, if it has the test mode. Alternatively or in combination with this, a maximum acceleration and/or speed of the motor vehicle is suitably limited.

Expediently, a driver assistance system is used as the driver assistance system, which during normal operation of the motor vehicle is active essentially permanently or at least over a period of time that is longer than 1 minute, 2 minutes or 5 minutes. A longitudinal regulation of the motor vehicle is suitably effected by means of the driver assistance system. For example, an emergency brake assistant is used as a driving assistance system. In this case, emergency braking is triggered in particular according to the cycle. For this purpose, the sensor is preferably stimulated accordingly or corresponding sensor data is fed in/supplied. The driver assistance system is particularly preferably used at least partially to move the motor vehicle autonomously, for example according to a level 2, level 3, level 4 or level 5. The driver assistance system is suitably a distance control system by means of which a distance between the motor vehicle and a motor vehicle driving ahead is set during normal operation, so that the motor vehicle follows the vehicle in front. Appropriately, a certain minimum distance is not fallen below or a certain speed of the motor vehicle is not exceeded. In the cycle, in particular the sensor is stimulated according to the distance or corresponding sensor data is preferably transmitted to the driver assistance system. Such a distance control system is used comparatively frequently, so that the energy requirement determined in this way also corresponds to an energy requirement that is present during normal operation of the motor vehicle.

For example, the driver assistance system was used to move the motor vehicle autonomously from a specific position to a further position, that is to say to operate the motor vehicle autonomously. For example, the cycle is defined by entering a starting point and a target point. Here, for example, a suitable route is determined by means of the driver assistance system. The cycle is thus defined, for example, only on the basis of the two points and any simulated traffic flow.

The dynamometer includes a roller dynamometer, which expediently has a number of rollers. The rollers are coupled, for example, by means of a speed sensor and/or a unit for adjusting a resistance to rotation of the rollers. For example, at least one of the roles with coupled to any electric motor, which can also be operated as a generator, for example. The test stand is suitable, in particular provided and set up, to carry out a method for determining an energy requirement of a motor vehicle. In this case, the method provides that the motor vehicle is placed on the roller test bench and a driver assistance system of the motor vehicle is activated. In addition, the motor vehicle is operated with a predetermined cycle.

The test stand has, for example, an external actuator for stimulating a sensor of the motor vehicle. The sensor is coupled in terms of signals to the driver assistance system of the motor vehicle. The external actuator is thus suitable, in particular provided and set up, to stimulate the sensor, in particular in accordance with the predefined cycle. Alternatively or in combination with this, the test stand includes an external unit for connection to an interface of the motor vehicle. The test bench preferably includes a control unit in which the cycle is stored. The control unit is preferably suitable, in particular provided and set up, for the operation of the motor vehicle. For example, the possible external unit is formed by the control unit.

The advantages and developments described in connection with the method can also be transferred to the test stand and vice versa.

• 1 ein Verfahren zum Ermitteln eines Energiebedarfs eines Kraftfahrzeugs,
• 2 schematisch vereinfacht einen Prüfstand mit einem Rollenprüfstand, auf dem das Kraftfahrzeug angeordnet ist.

An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. Show in it:

• 1 a method for determining an energy requirement of a motor vehicle,
• 2 schematically simplified a test stand with a roller test stand on which the motor vehicle is arranged.

Corresponding parts are provided with the same reference symbols in all figures.

In 1 a method 2 for determining an energy requirement of a motor vehicle 4 is shown, which in 2 is shown. The motor vehicle 4 has a number of wheels 6, at least some of which are driven by a drive that is not shown in detail. Furthermore, the motor vehicle 4 includes an on-board computer 8, by means of which the drive and other functions of the motor vehicle 4 are controlled. The onboard computer 8 is coupled in terms of signals to the other components of the motor vehicle 4 by means of a bus system 10 .

In addition, the motor vehicle 4 has a driver assistance system 12 in the form of a distance control system. During normal operation of the motor vehicle 4, the distance control system is used to maintain a certain distance from a motor vehicle driving in front. For this purpose, the motor vehicle 4 includes a sensor 14 which is coupled to the driver assistance system 12 in terms of signals. The sensor 14 is designed, for example, as a radar sensor, lidar sensor or, as shown here, as a camera that is sensitive, for example, in the visible light range or in the infrared light range. In particular, this involves a number of sensors that are connected to one another and are therefore used in combination.

During operation, sensor data determined by means of sensor 14 are sent to driver assistance system 12, in particular the distance from a motor vehicle driving ahead. Based on this, the driver assistance system 12 sends a specification via the bus system 10 to the on-board computer 8, by means of which a drive power is increased or decreased.

In addition, the motor vehicle 4 has an interface 16 which is connected to the bus system 10 . It is thus possible to feed data into the bus system 10 from outside by means of the interface 16 .

The method 2 provides that in a first work step 18 the motor vehicle 4 is arranged on a roller test stand 20 of a test stand 22 . The roller test stand 20 has a number of rollers 24 and the wheels 6 of the motor vehicle 4 are positioned on the rollers 24 . When the wheels 6 are driven, the rollers 24 are thus rotated and the motor vehicle 4 is not moved. By means of units that are not shown in detail, it is possible to change a rotational resistance of the rollers 24 or, if necessary, to drive them.

Furthermore, the test stand 22 has an external actuator 26 in the form of a projector. The projector, ie the external actuator 26, is matched to the sensor 14 and is positioned in such a way that images projected by the external actuator 26 can be detected by the sensor 14. In addition, the test stand 22 has an external unit 28 which is connected to a plug 32 by means of a line 30 for signaling purposes.

As soon as the motor vehicle 4 has been arranged on the roller test stand 20, a second work step 34 is carried out and the plug 32 is coupled to the interface 16, so that the external unit 28 is connected to the bus system 10 in terms of signals. In a subsequent third work step 36, driver assistance system 12 of the motor vehicle 4 activated, for which the external unit 28 is used. A corresponding activation signal is fed into the bus system 10 by means of this.

In addition, a fourth work step 38 is carried out and driver assistance system 12 is placed in a test mode. For this purpose, a suitable command is fed into the bus system 10 by means of the external unit 28 via the interface 16 . In the test mode, sensor data from sensor 14 or other sensors not shown in detail are not processed by means of driver assistance system 12 . In addition, in the fourth work step 38 the outer actuator 26 is arranged in a detection range of the sensor 14 if this has not yet taken place. Furthermore, a maximum deceleration of the motor vehicle 4 is limited here, ie a maximum braking power of the motor vehicle. This is done by setting the onboard computer 8 using the external unit 28.

In a subsequent fifth work step, motor vehicle 4 is operated according to a predefined cycle 42 . Cycle 42 corresponds to driving a specific route using motor vehicle 4. Using external unit 28, driving commands are sent via bus system 10 to on-board computer 8 in accordance with cycle 42, and thus using on-board computer 8, motor vehicle 4 is sent in accordance with the cycle operated. The rollers 24 are also controlled by the external unit 28 according to the cycle 42 .

In addition, during cycle 42 sensor data is fed into bus system 10 of motor vehicle 4 by means of external unit 28 and is transmitted in this way to driver assistance system 12 . Using the driver assistance system 12, interventions are thus carried out on the basis of the sensor data fed in, and corresponding requests are transmitted to the on-board computer 8, which lead to a change in the energy requirement.

If, for example, no sensor data are fed into the bus system 10 by means of the external unit 28, the external actuator 26 is operated by means of the external unit 28 and a suitable image is projected. The sensor 14 captures the image and uses it to generate sensor data that is transmitted to the driver assistance system 12 . In this case, the test mode is suitably adapted, for example. Consequently, the sensor 14 is stimulated by the external actuator 26 according to the predetermined cycle 42 .

During a cycle 42, the energy requirement of the motor vehicle 4 is recorded. Once cycle 42 is complete, the energy demand recording is terminated. The energy requirement of motor vehicle 4 during cycle 42 corresponds to the last recorded value. For example, the energy requirement is determined on the basis of a tank filling, the energy requirement corresponding to the difference between the tank contents before the start of cycle 42 and the tank contents after cycle 42 has ended. In particular, the energy requirement is normalized to a corresponding value.

As soon as cycle 42 has ended, a sixth work step 44 is carried out and the test mode of driver assistance system 12 is ended. In other words, driver assistance system 12 is switched back to normal mode. In addition, the limitation of the maximum deceleration of the motor vehicle 4 is lifted. Following this, a seventh work step 46 is carried out, in which the plug 32 is removed from the interface 16 and the signal-technical coupling of the external unit 28 to the interface 16 is thus canceled. In a subsequent eighth work step 48, the motor vehicle 4 is removed from the roller test bench 20.

In summary, reproducible energy requirement measurements take place on the basis of method 2, with vehicle networking, ie bus system 10 in particular, not having to be changed, in particular when using the test mode.

Based on method 2, a reproducible test for determining consumption, everything related to energy requirements, is possible, with driver assistance system 12 being used, which is an assistance and/or pilot system. The determination is carried out under controlled conditions. For example, sensor 14 installed in motor vehicle 4 is stimulated by external actuator 26 . The energy requirement is thus determined without interventions or changes in the motor vehicle 4 itself. Alternatively or in combination with this, the test mode is used, in which the sensor data are fed into the bus system 10 without the existing sensor 14 being used for this purpose. Thus, clearly reproducible determinations are possible, with the environmental conditions being controlled. In addition, there is a realistic assessment of the energy requirement of driver assistance system 12 and a comparison with merely manual operation of motor vehicle 4, ie with driver assistance system 12 deactivated, is provided.

An object is suitably simulated for the sensor 14 by means of the external actuator 26 without the external actuator 26 being moved. For example, in addition to 20 absorber materials positioned around the chassis dynamometer to avoid reflections or signal distortions. The sensor 14 is a camera, a lidar sensor or a laser sensor, for example. In particular, the external unit 28 is used to simulate an environment, based on which the cycle 42 is expediently created and/or processed. In this case, the sensor data are also preferably created in accordance with the simulation.

The invention is not limited to the embodiment described above. On the contrary, other variants of the invention can also be derived from this by a person skilled in the art without departing from the subject matter of the invention. In particular, all of the individual features described in connection with the exemplary embodiment can also be combined with one another in other ways without departing from the subject matter of the invention.

Reference List

2

Proceedings

4

motor vehicle

6

wheel

8th

on-board computer

10

bus system

12

driver assistance system

14

sensor

16

interface

18

first step

20

roller dynamometer

22

test bench

24

role

26

external actor

28

external unit

30

Management

32

Plug

34

second step

36

third step

38

fourth step

40

fifth step

42

cycle

44

sixth step

46

seventh step

48

eighth step

Claims (4)

Method (2) for determining an energy requirement of a motor vehicle (4), in which - the motor vehicle (4) is arranged on a roller test stand (20), - A driver assistance system (12) of the motor vehicle (4) is activated, and - the motor vehicle (4) is operated according to a predetermined cycle (42), - wherein a sensor (14), which is coupled in terms of signals to the driver assistance system (4), is stimulated by means of an external actuator (26) in accordance with the predetermined cycle (42), or - The driver assistance system (12) being placed in a test mode and sensor data corresponding to the specified cycle (42) being transmitted from an external unit (28) to the driver assistance system (12) via an interface (16). Method (2) according to claim 1 , characterized in that a maximum deceleration of the motor vehicle (4) is limited. Method (2) according to one of Claims 1 until 2 , characterized in that a distance control system is used as the driving assistance system (12). Test stand (22) for carrying out a method (2) according to one of Claims 1 until 3 , having a roller dynamometer (20) and an external actuator (26) for stimulating a sensor (14) which is coupled in terms of signals to a driver assistance system (12) of a motor vehicle (4), and/or to an external unit (28) for connection with an interface (16) of the motor vehicle (4) and for providing sensor data.

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