Method, control device and computer program product for determining a position of a motor vehicle

Abstract

Disclosed is a method for determining a position of a motor vehicle by means of a location device of the motor vehicle. First, a first position (x.sub.1) related to an installation point of the location device in the motor vehicle is determined. In order to determine a position suitable for controlling the motor vehicle, with reference to the said first position (x.sub.1) a second position (x.sub.2) related to a center of gravity of the vehicle is determined, in that the first position (x.sub.1) is offset by a distance (a) between the said installation point of the location device and the center of gravity of the vehicle.

Claims

1. A method for determining a position of a motor vehicle, the method comprising: determining, by a location device of the motor vehicle, a first position related to an installation point of the location device in the motor vehicle; determining, by the location device, a second position related to a vehicle center of gravity based on the first position, wherein the first position is offset by a distance between the installation point of the location device and the vehicle center of gravity; and initiating a gearshift of the motor vehicle, by a transmission control unit, based at least in part on the position of the motor vehicle and the vehicle center of gravity, the position of the motor vehicle being related to the first position and the second position.

2. The method according to claim 1, wherein determining the first position is performed using an antenna.

3. The method according to claim 2, wherein determining the second position is performed using an antenna.

4. The method according to claim 1, further comprising determining the distance between the installation point and the vehicle center of gravity, wherein a first curve of a parameter calculated from physical magnitudes is compared with a second curve of the parameter which has been determined, having regard to the location device, with reference to carriageway parameters of a route segment of the motor vehicle.

5. The method according to claim 4, wherein the parameter is a driving resistance of the motor vehicle.

6. The method according to claim 5, wherein with reference to the comparison, determining a time offset between the first curve is performed using the physical magnitudes; determining the second curve is performed with reference to the carriageway parameters; and determining the distance of the installation point from the center of gravity of the vehicle is calculated from the time offset and a current driving speed of the motor vehicle.

7. The method according to claim 1, wherein determining the second position, includes determining a distance based on a time that has lapsed since determining the first position and based on a current driving speed of the vehicle.

8. The method of claim 1, wherein initiating the gearshift further takes into account a forthcoming route segment ahead of the motor vehicle.

9. The method of claim 8, wherein the forthcoming route segment ahead of the motor vehicle includes an uphill stretch or a downhill stretch of road.

10. The method of claim 9, wherein the motor vehicle is a truck with one or more trailers.

11. The method of claim 9, wherein initiating the gearshift further takes into account one or more parameters selected from an engine torque, a current driving speed, a driving resistance, a vehicle acceleration, and a vehicle mass.

12. A transmission control unit configured to operate with a location device in a motor vehicle, the transmission control unit configured to determine a first position relative to an installation point of the location device in the motor vehicle and to determine a second position with reference to the first position and to a center of gravity of the vehicle, and initiate a gearshift based at least in part on a position of the motor vehicle, wherein the transmission control unit offsets the first position by a distance between the installation point of the location device and the center of gravity of the vehicle, the position of the motor vehicle being related to the first position and the second position.

13. The transmission control unit according to claim 12, wherein the transmission control unit comprises an antenna and wherein determining the first position is performed using the antenna and determining the second position is performed using the antenna.

14. A computer program product for a transmission control unit configured to carry out a method comprising determining, by a location device in a motor vehicle, a first position related to an installation point of the location device in the motor vehicle, determining a second position related to a vehicle center of gravity based on the first position, wherein the first position is offset by a distance between the installation point of the location device and the vehicle center of gravity, and initiate a gearshift based at least in part on a position of the motor vehicle, the position of the vehicle being related to the first position and the second position, wherein a routine for determining a position of the motor vehicle is implemented by corresponding control commands stored in software.

15. A data carrier with a computer program product according to claim 14.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An advantageous embodiment of the invention, which is explained in what follows, is illustrated in the drawings, which show:

(2) FIG. 1: A schematic view of a drivetrain of a motor vehicle;

(3) FIG. 2: A flow chart of a method for determining a position of the motor vehicle, in accordance with a preferred embodiment of the invention; and

(4) FIGS. 3A to 3D: Aspects of the carrying out of a determination of a distance between a location device and a vehicle center of gravity of the motor vehicle, in the context of the method.

DETAILED DESCRIPTION

(5) FIG. 1 shows a schematic view of a drivetrain 1 of a motor vehicle, which is preferably a utility vehicle such as a truck. The drivetrain 1 comprises a drive engine 2, preferably in the form of an internal combustion engine, which is followed on the drive output side by a motor vehicle transmission 3. In this case, between the drive engine 2 and the motor vehicle transmission 3 there may be provided a torsion fluctuation damper and/or a starting element by means of which a driving connection between the drive engine 2 and the motor vehicle transmission 3 can be formed and also separated, such that this element can be in the form of a separator clutch or even a hydrodynamic torque converter. The motor vehicle transmission 3 is in particular an automated manual transmission or an automatic transmission, such that in that case the motor vehicle transmission 3 is of group design and can consist of a plurality of individual gear systems.

(6) Within the drivetrain 1, downstream from the motor vehicle transmission 3 there is also a differential transmission 4 by way of which drive power is distributed to drive wheels 5 and 6 of a drive axle 7.

(7) Associated with the drive engine 2 there is an engine control unit 8 by means of which the operation of the drive engine 2 is regulated. This engine control unit 8 is connected via a data bus system 10 of the motor vehicle to a further control unit 9, and besides the engine control unit 8 and the control unit 9, in particular further control units are part of the said data bus system 10. By way of the data bus system 10 the individual control units can exchange data with one another. In the present case the control unit 9 is a transmission control unit of the motor vehicle transmission 3 by means of which, among other things, gearshifts in the motor vehicle transmission 3 can be controlled.

(8) In the present case, for that purpose the control unit 9 can carry out the gearshifts in the motor vehicle transmission 3 in an anticipatory manner having regard to a route segment to be covered by the motor vehicle, and in that way adapt to forthcoming driving situations. For example, a selective downshift in the motor vehicle transmission 3 can be carried out to react to a forthcoming uphill inclination of the road or else a longer downhill stretch, in order in the latter case to be able to utilize the higher effective drag torque of the drive engine 2. On the other hand, by carrying out an early upshift in the motor vehicle transmission 3 fuel-saving operation of the drive engine 2 having regard to the forthcoming route segment can be realized. Besides information about the route segment to be covered, the control unit 9 must also be supplied with information about the current position of the motor vehicle. For that purpose, the control unit 9 is connected with a location device 11 of the motor vehicle, which is preferably an antenna of a GPS system. Then, by virtue of the GPS system a satellite-supported determination of the position of the motor vehicle can be achieved.

(9) However, for the control of the gearshifts in the motor vehicle transmission 3 it is advantageous to know a position related to a vehicle center of gravity of the motor vehicle in order to be able to initiate gearshifts at a position as accurately determined as possible and at the right time. Particularly with long vehicles such as trucks with one or more trailers, the position determined by way of the location device 11 can sometimes deviate substantially from the position related to the center of gravity of the vehicle, so that if the position related to the location device 11 were used this could result in gearshifts that are too early or even too late.

(10) For this reason, in the present case and in the context of a method according to the invention a position is determined in accordance with a preferred embodiment of the invention, by virtue of which the position of the motor vehicle related to the center of gravity of the vehicle can be determined. As can be seen in FIG. 2, which shows an example of a flow chart of the method according to the invention, at the beginning of the process in a step S1 a first position x.sub.1 is first called for, which position is related to an installation point of the location device 11 in the motor vehicle and is called for by the control unit 9 on the part of the location device 11. After this, in a step S2 a distance a is determined, between the location device 11 and a center of gravity of the motor vehicle at the time.

(11) The distance a is determined by computer means with reference to various variation curves of a driving resistance F.sub.W of the motor vehicle, which are represented by the curves shown in FIG. 3A. In FIG. 3A variation curves of the driving resistance F.sub.W are plotted against time t. The curve 12 shows a variation of the driving resistance F.sub.W which has been calculated from physical magnitudes, namely magnitudes such as engine torque, acceleration and vehicle mass. By contrast, the respective variations 13 or 13 or 13 were determined with reference to carriageway parameters of the route segment ahead, taking account of the location device 11. Here, the curve 13 shows the variation of the driving resistance F.sub.W for the motor vehicle shown in FIG. 3B, whereas the curve 13 is associated with the motor vehicle shown in FIG. 3C and the curve 13 is associated with the motor vehicle shown in FIG. 3D. In FIGS. 3B to 3D, in each case an installation position 14 of the location device is shown in the front area of the motor vehicle, with the respective vehicle centers of gravity 15, 15 and 15 shown as well.

(12) During the course of step S2, from a respective time offset t or t or t between the curve 12 and the respective curves 13 or 13 or 13 and a current driving speed v.sub.Fzg the distance a is computed in each case using the equation:
a=t.Math.v.sub.Fzg

(13) With this distance a determined in that way, in a further step S3 a second position x.sub.2 related to the respective vehicle center of gravity is calculated, and in doing this a time t.sub.x1 that has lapsed since the determination of the first position x.sub.1 is taken into account. Thus, the second position x.sub.2 is calculated using the equation:
x.sub.2=x.sub.1+t.sub.x1.Math.v.sub.Fzg+a.

(14) This second position x.sub.2 is then subsequently used for the control of the motor vehicle transmission 3.

(15) By means of a method according to the invention for determining a position of a motor vehicle, a position suitable for the control of a motor vehicle can be determined in a simple manner.

(16) TABLE-US-00001 Indexes 1 Drivetrain 2 Drive engine 3 Motor vehicle transmission 4 Differential transmission 5 Drive wheel 6 Drive wheel 7 Drive axle 8 Engine control unit 9 Control unit 10 Data bus system 11 Location device 12 Variation curve 13, 13, 13 Variation curve 14 Installation point 15, 15, 15 Center of gravity of the vehicle x.sub.1 First position a Distance F.sub.W Driving resistance t Time t, t, t Time offset v.sub.Fzg Driving speed x.sub.2 Second position t.sub.x1 Time S1 to S3 Individual steps