WO2019227112A1

WO2019227112A1 - Determining the altitude of a vehicle and a carriageway gradient from the air pressure

Info

Publication number: WO2019227112A1
Application number: PCT/AT2019/060164
Authority: WO
Inventors: Manuel BOPP; Emre KURAL; Rolf Hettel; Camillo SIGNOR
Original assignee: Avl List Gmbh
Priority date: 2018-05-30
Filing date: 2019-05-16
Publication date: 2019-12-05
Also published as: AT521277B1; AT521277A4

Abstract

In order to permit precise determination of the altitude of a vehicle from the measured air pressure over a large velocity range, there is provision that the altitude (h_p) calculated from the air pressure is corrected with a correction term (K) as a function of the vehicle velocity (v) at the position of the vehicle and at least one velocity-dependent correction parameter (P_v(v)), in order to determine a corrected altitude (h_comp) of the vehicle (1).

Description

Determining the height of a vehicle and a road gradient from the air pressure

The subject invention relates to a method for determining the height of a ve hicle from measured values of the air pressure along a route of the vehicle, wherein the height of the vehicle is calculated at a certain vehicle position of the route with a given before formula from the air pressure, and the use of the type calculated height to determine a road gradient of the route and to carry out a test on a test bench, the time course of ermit teten road gradient is used to control the test.

For the development or testing of vehicles and components of vehicles, such as internal combustion engines, power units (eg hybrid drives), on drivelines, gearboxes, power supplies, etc., usually tests are used on test benches. In this case, the test object (vehicle or component of the driving tool) is constructed on the test bench and is subjected to certain load conditions. The load for the DUT may be generated at the test stand by a load machine, such as a dynamometer, a battery tester, etc., which is connected to the DUT on the test bench. To carry out the test, the test specimen and the loading machine are controlled according to the specifications of a test run. A test run is usually a time course of at least one size that influences the operating state of the test object. Such a time course can be used directly to control the device under test and / or the loading machine on the test bench. For example, an engine speed and an engine torque of an internal combustion engine as a test piece or part of a test specimen (eg drive train) can be specified as a time course as a test run. These can then be used on the test stand to control the engine, for example to adjust the engine speed, and to control the load machine, for example, to adjust engine torque. However, it is also known to use the time course of such a variable on the test bench in a simulation in order to calculate with the simulation target values or manipulated variables for the test object and / or a loading machine, which are then set on the test bench. An example of this is the simulation of a virtual driving of a vehicle by means of a simulation model along a virtual driving route, the simulation receives the gradient of the route and a Fahrzeuggeschwin speed as a time course and from a manipulated variable for an internal combustion engine as a test, for example, an accelerator pedal position, and a setpoint for the load machine, for example, a load torque calculated. As is known, such a simulation model is generally composed of several interacting submodels, such as a vehicle model, a road model, a tire model, a driver model, etc. The aim of carrying out the test runs on the test bench is to best approximate a real drive with the vehicle on a real route. This is partly driven by changing legislation regarding the emission and consumption behavior of vehicles with internal combustion engines, as it is often required to demonstrate compliance with emission and consumption levels under real conditions.

The required time courses for the test run are therefore often obtained from real test driving th with a vehicle. For this purpose, a certain distance is traversed with a vehicle and thereby measured variables are recorded, from which the time profiles are derived. For example, during such a real test drive, vehicle speed, road grade and road grade, the geometry of the road (e.g., turns), etc. are detected. The test run for carrying out the test is then generated from the recorded measured variables.

The determination of altitude from GPS (Global Positioning System) data would be sufficiently accurate, but is subject to the problem that it must not give reliable GPS data at all points of the route, for example because no (eg tunnels) or too few (eg in a city with high buildings or in narrow mountain valleys) satellites are available, which is why GPS data may not be able to determine a reliable altitude for the entire journey. Therefore, the height is often determined from the air pressure.

JP 2001 108 580 A1 describes, for example, that a height and therefrom a slope of the roadway (road gradient) are determined via the changing air pressure in the environment of the vehicle during the test drive. For this purpose, the altitude of the vehicle is first determined with a PRE-enclosed formula from the pressure and the derivation of the altitude over the distance covered the road gradient. The course of the roadway gradient is then used on the test stand to derive a load for the test object to carry out the test.

EP 2 988 095 A1 again describes that the altitude of the vehicle during the test drive can also be derived from GPS data. In order to calculate a height in sections where no or no reliable (for example, because there are too few satellites available) GPS data is available, the height determination via the air pressure is used in such sections.

JP H9159447 A2 describes that the determination of the height from the air pressure is erroneous due and in particular is influenced by the vehicle speed. It is therefore proposed to correct the determined height with a speed-dependent term in order to increase the accuracy of the height determination. For this purpose, a correction curve is given before, taken from the correction term as a function of the speed becomes. The correction term is therefore only dependent on the speed, whereby a good correction over a larger speed range, as is usual in a vehicle, is insufficiently possible.

It is the object of the subject invention to allow an accurate determination of the altitude of a vehicle from the measured air pressure over a large Geschwindigkeitsbe rich.

This object is achieved by correcting the height calculated from the air pressure with a correction term as a function of the vehicle speed at the vehicle position and a speed-dependent correction parameter in order to determine a corrected height of the vehicle. About the at least one additional Geschwindigkeitsab dependent correction parameters can now be taken into account that the Un accuracy in the determination of the altitude from the air pressure is heavily dependent on the Fahrzeuggeschwin speed. By means of this additional correction parameter and the functional relationship, different corrections can now be made at different vehicle speeds and the correction parameter can assume different values in different speed ranges. Thus, the accuracy of the height calculation from the air pressure can be significantly improved.

In order to further increase the accuracy, the at least one correction parameter for different ranges of the vehicle speed may preferably have different values. In this way, the influence of vehicle speed can be even better be taken into account. Likewise, the accuracy can be increased if the at least one correction parameter for different vehicles or vehicle types and / or for different vehicle environments has different values. Thus, the influence of the vehicle itself can be better represented.

When GPS data is available, the accuracy of the method can be improved by using a GPS altitude from available GPS data to calculate a mean GPS altitude, calculating a corrected mean altitude from the corrected altitudes, and from the two averages Offsethhehe is calculated, with which the corrected height is corrected to an offset-corrected compensated height.

The subject invention will be explained in more detail with reference to Figures 1 to 4, the exemplary, schematic and non-limiting advantageous Ausgestal lines of the invention. It shows

1 shows a determination of the height of a vehicle from measured values of the air pressure,

FIG. 2 shows an exemplary sequence of height and roadway gradient determination, FIG.

3 shows a result of the height determination according to the invention and 4 shows a use of the determined road gradient on a test rig for carrying out a test.

The detection of the required measured values for the air pressure for height determination is explained by way of example with FIG. A vehicle 1 is moved along a route 2 at a vehicle speed v, where the vehicle speed v is, of course, a function of the time or distance traveled s. The route 2 has a certain height profile with heights h. When the application speaks of altitude, it is to be understood, of course, a height referring to a reference altitude, e.g. the sea level. On the vehicle 1, a pressure sensor 3 is arranged, which measures the air pressure pi_ in the vicinity of the vehicle 1. In this case, the air pressure pi_ is repeatedly measured over the path s in order to obtain a height profile over the path s. Likewise, while driving with the vehicle 1, further measured variables can also be detected, for example a vehicle speed v. For this purpose, further measuring sensors can be provided on the vehicle 1.

The height h could now be calculated with known formulas from the measured air pressure pi_

J f p ^ 5,255. Often the well-known international altitude formula h = -1 - for it

^P L l Po J

used. Therein T [° K] denotes the ambient temperature at the location of the measured air pressure (in [bar]), L [K / m] a decrease rate and p _o a reference pressure. With a usual decrease rate L = 0.0065 K / m and a reference pressure at sea level of p _o =

1013 mbar results then h = Also other formulaic To p 0, 0

Relationships for calculating the altitude from the air pressure are known, e.g. as described in JP 2001/108580 A1. The required in the formulas other sizes, insbesonde the ambient temperature T can of course also measured while driving who the. Normally, the variables measured during the journey are evaluated after the trip and the heights h are calculated via the path s. Of course, the height h could also be calculated while driving. The calculation is done with suitable computer hardware and appropriate software. However, this calculation of the height h from the air pressure pi_ is inaccurate due to various influences, for example, the mounting position of the pressure sensor 3 and the vehicle speed v.

In order to reduce these inaccuracies, it is provided according to the invention that the height h _p calculated from the air pressure pi with a nonlinear correction term K as a function of the vehicle speed v and at least one correction parameter P _v (v) dependent on the vehicle speed v to a corrected height h _COmp Height h of the vehicle

1, for example of the type h _comp = h _p -K with K = f (v, P _v (v)). About the At least one additional speed-dependent correction parameter P _v (v) can now be taken into account that the inaccuracy in determining the altitude from the air pressure pi_ is dependent on the vehicle speed v and different corrections may be required at different vehicle speeds v. The correction parameter P _v (v) can therefore assume different values in different speed ranges.

The correction term K can be calculated, for example, from K = (k * v) ^e , with the two

Correction parameters P _v (v) = [k, e], where the correction parameters P _v (v) could result according to the following table as a function of the vehicle speed v.

Of course, more speed ranges are conceivable and other formulas for the calculation of the correction term K possible.

The at least one correction parameter P _v (v) can be determined empirically. The at least one correction parameter P _v (v) can also be calculated from an optimization who the. In this case, an error (eg the mean square error of the deviation) between known height values (for example from digital map material or highly accurate measurements) and the calculated height h _COmp in different speed _ranges can be minimized in order to calculate the correction parameters P _v (v). Such known optimizations are often numerical, iterative mathematical methods which are carried out until a defined termination criterion is reached, for example the achievement of a certain error or a number of iterations.

The at least one correction parameter P _v (v) can also be determined for different vehicles or different types of vehicles (eg sedan, wagon, van, etc.).

Furthermore, the at least one correction parameter P _v (v) can additionally be made dependent on other influencing factors. For example, another correction parameter P _v (v) can be used on a free route than in a tunnel or on a bridge. Of the

This is due to the different ambient-dependent flow influences on the pressure sensor 3, which can be compensated in this way. It can be assumed that the air pressure pi_ will change only slowly along the path s, which is why the measured values of the air pressure pi_ can also be low-pass filtered before the calculation of the height in order to compensate for measurement influences such as measurement noise, etc. For this purpose, any known low-pass filter, such as a Butterworth filter or an infinite impulse response filter (IIR filter) can be used, which preferably have a low cutoff frequency, for example 0.05 Hz. Alternatively or additionally, the calculated height h _p and / or the compensated height h _CO mp can also be low-pass filtered. For filtered sizes, the index F is also used below, eg

h _p , F, etc.

A further improvement in the accuracy of the determined, compensated altitude h _CO m _P can be achieved if GPS data are available from which, at least in sections, a height hcps of the vehicle 1 along the route 2 is also known. In section of the route 2, in which a certain number n of GPS satellite 4 is available, the GPS altitude hcps can be used for the inventive method. For example, n> 5 may be required.

From the GPS altitude hcps in the sections of the route 2 with at least n GPS satellites, a mean GPS altitude h _GPS , for example as an arithmetic mean of the measured values, can be calculated. Likewise, from the calculated compensated heights h _CO m _P a mean value h _comp can be calculated. From the two mean values, an offset height h ₀ ttset can then be calculated, in the form h _offset = h _comp- h _GPS . The offset height can then be subtracted from the compensated height h _CO m _P , which yields a more accurate offset-corrected compensated height hcom _P , offset. Of course, the offset height hoffset and / or the offset-adjusted compensated height hcomp, ottset can again be low-pass filtered, just as the quantities required for the calculation may be low-pass filtered.

From the thus calculated compensated height h _CO mp, or the offset-corrected compensated height hcomp, ottset, a roadway gradient can then be determined in a simple manner by deriving the resulting altitude profile according to the path s, ie, grad = or grad = -

, After the heights at certain discrete times ds

points, for example every second, can be determined, the road gradient grad

also be approximated by the difference quotient. After the vehicle

ace

speed v is known, it can be generated in a simple manner, a temporal course of the Fahrbahngradienten degree.

In order to be able to estimate the quality of the ascertained height hcomp, h _CO mp, ottset or the determined roadway grade, an error Err can also be calculated and output. the. For example, a height error Err _h can be calculated using

Err _h = ^ comp (, offset) ^ GPS, or a gradient error Err _grad with Err _grad = | grad - degree _GPS | where gradcps is the road gradient calculated from the GPS heights hcps.

In addition, the road gradient grad can also be set to zero when the driving tool is stationary, so if the vehicle speed is v = 0.

A possible method according to the invention for ascertaining the height and for determining the road gradient is explained with reference to FIG.

In the first step 20, measurement data (eg from the pressure sensor 3 and GPS satellite 4) are read into a calculation unit (hardware and / or software). As mentioned, the calculation could also be done online during the measurement data acquisition. In step 21, in the calculation unit, the height h _p is calculated from the measured air pressure pi_, for example with the above formula. Thereafter, in step 22, the calculation of the corrected height h _com with the correction term K and the at least one correction parameter P _v (v) takes place. In the next step 23, an offset height h ₀ ffset can be calculated, which is used in the next step 24 to calculate an offset-corrected compensated height h _CO m, offset. Thus, in step 25, a height error Err _h can be determined. From the offset-compensated compensated height h _com or the offset-corrected compensated height hcom, offset, the road gradient can then be calculated in step 26, which can then be used on a test bench 10 for carrying out a test, as will be described in detail below , In this step, the Fahrbahngradi degree at vehicle speed v = 0 can also be set to zero. In a step 27 also a gradient error Err can be calculated _degree. In this example, possible low-pass filters are not shown.

The result of the height determination according to the invention is shown in FIG. As can be seen, the accuracy of the altitude h _p calculated from the air pressure pi_ can be improved, as a comparison with the GPS altitude hcps shows.

The thus determined temporal or local course of the Fahrgradgradienten grad can be used on a test bed to carry out a test, as the example of Figure 4 is explained.

With Figure 4, a known test stand 10 for a test specimen 12 and thus, beispielswei se means of a test stand shaft 11, connected loading machine 15, for example, a dynamometer represented. The loading machine 15 generates the load for the test piece 12. The test piece 12 is in the illustrated embodiment, an internal combustion engine and the test stand 10 was an engine dynamometer. Of course, the test specimen 12 could also be a vehicle or any subsystem of the vehicle, such as a powertrain, for example Electric motor, a drive battery, a control unit, etc., and the test stand 10 is a suitable test stand, such as a chassis dynamometer, a powertrain tester, a Elekt romotorenprüfstand, a hardware-in-the-loop test stand, etc. In the case of a battery as a test piece 12, the loading machine 15 would be electrical, for example in the form of an electric bat terietesters. Suitable loading machines 15 for various specimens 12 are known Lich Lich known and available, which is why it need not be discussed in detail here.

At the test bench 10 a test bed automation in the form of a Prüfstandautomatisie is tion unit 30 (hardware and software) is provided which controls the test bench 10 durchzufüh-generating virtual test drive (= test) and all the necessary Einrichtun gene (ie in particular the required actuator) of the test bench 10 in accordance controls the specifications of the test. In particular, the test bed automation unit 30 can also control the test object 12 and the loading machine 15 by presetting required setpoint values or manipulated variables. The loading machine 15 is often on the test bench 10 of its own load machine controller 14, which in turn receives from the Prüfstandautoma unit 30 according to the specifications of the test setpoints to the test specimen 12, for example certain, often transient, load moments M or certain, often transient, speeds to regulate. The loading machine controller 14 may also be inte grated in the test bed automation unit 30 as software and / or hardware or be part of the loading machine 15 itself.

For carrying out the test, measuring equipment 13, here for example a speed measuring device 16 and / or a moment measuring device 17, are provided on the test stand 10, the corresponding actual values of the test object 12 and / or the loading machine 15, for example the loading moment Mi _st at the Test stand shaft 1 1 and the speed n, _st of the test piece 12, measure as measured variables and the Prüfstandautomatisie tion unit 30 make available. Of course, for other specimens 12, or test stand types, other or additional measures, such as an electric current or an electrical voltage, measured and the test bench automation sation unit 30 are supplied.

To carry out the test a test run is provided on the basis of which the setpoints or manipulated variables are determined. For example, a simulation of a vehicle or a part or a component thereof may be provided, for which purpose a simulation model 33 is provided. The simulation with the simulation model is executed by a simulation unit 31 and can also process measured variables for this purpose. The Simulationsein unit 31 may be integrated in the test bed automation unit 30 as hardware and / or software, but may also be separate from the test bed automation unit 30, for example in the form of its own simulation hardware and simulation software. The simulation model 33 can be implemented, for example, as software on the simulation unit 31. be mented. The test run is specified by a test run unit 32. The test run is for example a time course of certain variables, such as vehicle speed, driving grade gradient, curve, etc., and can be specified, for example, from an external point of view. The temporal course of the road gradient grad is determined, for example, to carry out the test as described above. As a calculation unit for this purpose, the test bed automation unit 30 or an external computing unit can be used. The course of the Fahrgradgradienten grad but could also be used directly to control a compo nent the test bench 10, for example in loading machine controller 14 for controlling a loading machine 15. With the specification of the test results in the interaction of the system of simulation, test bench 10, DUT 12th and Belastungsma machine 15 of the test, which is performed on the test bench 10.

During the conduct of the test often Messun conditions are performed on the test bench to make certain statements about the behavior of the test specimen 12 can. Typical and frequently provided measurements include the emission behavior of an internal combustion engine, the consumption or power requirement of the test object, the power generated by the test object, etc. Such measurements provide measured data or characteristic parameters as vehicle parameters. In the example shown, an emission measuring device is provided as a measuring device 18 to capture during the execution of the test run Emis sion variables in the exhaust gas of the internal combustion engine.

In the example illustrated in FIG. 4, the test run defines the time-based predefinition of the lane of a vehicle in the form of the road gradient and the course of the vehicle speed v. This test run is given to the simulation unit 31, in which a simulation model 33, for example a model of a vehicle, which is moved along a route is implemented, which executes the simulation. On the basis of the current engine speed n, _st and the current torque Mi _{st of} the test object 12 and the specifications of the test run, the simulation unit 31 calculates a manipulated variable for the internal combustion engine as the test object 12, for example the accelerator pedal position a _so n, as well as the desired value for the control of Loading machine 15, for example, a desired torque M _so n. In this example determines the load machine controller 14 from the current torque Mi _{st of} the DUT 12 and the target torque M _SO N, the speed n, which is set on the loading machine 15.

The setting of the manipulated variable and the setpoints leads to a specific state of the test object 12. Depending on the test stand 10 and the test object 12 and simulation, it is of course also possible to use other predefined variables, manipulated variables and measured variables.

Claims

claims

1. A method for determining the height (h) of a vehicle (1) from measured values of the air pressure (p along a route (2) of the vehicle (1), wherein the height (h _p ) of the vehicle (1) at a determined vehicle position of the route (2) with a predetermined altitude formula from the air pressure (pi_), characterized in that the thus calculated height (h _p ) with a correction term (K) as a function of Fahrzeugge speed (v) at the vehicle position and at least one speed-dependent correction parameter (P _v (v)) is corrected to determine a corrected height (h _CO m) of the vehicle (1).

2. The method according to claim 1, characterized in that the height (h _p ) of the vehicle (1) at the determined vehicle position with the height formula h _p

is calculated with the ambient temperature T [° K] at the location of the measured air pressure pi_ [bar], a decrease rate L [K / m] and a reference pressure p _o [bar].

3. The method according to claim 1 or 2, characterized in that the correction term

(K) is calculated from K = (k-v) ^e , with the two correction parameters P _v (v) = [k, e].

4. The method according to any one of claims 1 to 3, characterized in that the at least one correction parameter (P _v (v)) for different ranges of Fahrzeugge speed (v) has different values.

5. The method according to any one of claims 1 to 4, characterized in that the at least one correction parameter (P _v (v)) pen for different vehicles (1) or Fahrzeugty and / or for different vehicle environments has different values.

6. The method according to any one of claims 1 to 5, characterized in that a GPS altitude (hcps) is used from available GPS data to calculate a mean GPS altitude (h _GPS ), and from the corrected heights (h _CO m) a mean corrected height

(h _comp ) is calculated and from the two mean values an offset height (h ₀ ffset) is calculated, with which the corrected height (hcom) is corrected to an offset-corrected compensated height (hcom, offset).

7. Use of the method according to any one of claims 1 to 6 calculated height (h) of the vehicle (1) for determining a road gradient (grad) of the route

(2) by deriving the course of the calculated height (h) over the route (2) according to the route.

8. Use of the road gradient according to claim 7 for carrying out a test on a test bench (10), wherein the time course of the determined driving track gradient (grad) is used to control the test.