MASS, DRAG COEFFICIENT AND INCLINATION DETERMINATION USING ACCELEROMETER SENSOR

• US 20110172877A1
• Filed: 01/08/2010
• Published: 07/14/2011
• Est. Priority Date: 01/08/2010
• Status: Active Grant

• Current Assignee: FCA US LLC (Stellantis NV)
• Original Assignee: FCA US LLC (Stellantis NV)
• Inventors: Hartman, Peter G., Hall, Michael A., Dourra, Hussein A.
• Granted Patent: US 9,395,233 B2
• Time in Patent Office: Days
• US Class Current: 701/35
• CPC Class Codes: B60T 8/1837 characterised by the load-detecting arrangements
• CPC Class Codes: B60T 8/1887 especially adapted for tractor-trailer combinations
• CPC Class Codes: B60T 8/245 Longitudinal vehicle inclination
• CPC Class Codes: B60W 40/13 Load or weight
• CPC Class Codes: F16H 59/48 Inputs being a function of acceleration
• CPC Class Codes: F16H 59/52 dependent on the weight of the machine, e.g. change in weight resulting from passengers boarding a bus
• CPC Class Codes: F16H 59/66 Road conditions, e.g. slope, slippery
• CPC Class Codes: G01G 19/086 wherein the vehicle mass is dynamically estimated

Abstract

A method and system of determining a vehicle'"'"'s driving characteristics such as the vehicle mass, drag force coefficients and driving surface inclination. The vehicle'"'"'s mass, drag force coefficients and inclination are determined using signals input from the vehicle'"'"'s accelerometer.

Claims

1. A method of equipping a vehicle to determine and use at least one vehicle driving characteristic, the method comprising:

providing one or more accelerometers in the vehicle, at least one of the one or more accelerometers configured to output a plurality of accelerometer signals;

coupling the one or more accelerometers with a processor configured to process the plurality of accelerometer signals to determine as an output signal a mass of the vehicle based on a difference between at least a portion of the plurality of accelerometer signals and a difference between values for the vehicle'"'"'s drive force that correspond in time with the portion of the plurality of accelerometer signals; and

coupling the processor output with a vehicle control system to improve vehicle drivetrain performance.

2. The method of claim 1, wherein the processor is further configured to determine the mass of the vehicle by:

plotting the portion of the plurality of accelerometer signals against the corresponding values for the vehicle'"'"'s drive force; and

determining a line that best fits the plotted signals, the vehicle'"'"'s mass being a slope of the determined line.

3. The method of claim 2, wherein the line is determined using a least squares method.

4. The method of claim 1, wherein the processor is further configured to determine the mass of the vehicle by:

plotting the values for the vehicle'"'"'s drive force against the corresponding portion of the plurality of accelerometer signals and against a corresponding plurality of speeds of the vehicle; and

determining a surface that best fits the plotted signals, the vehicle'"'"'s mass being a slope of the determined surface in the drive force/accelerometer plane of the plot.

5. The method of claim 4, wherein the surface is determined using a least squares method.

6. The method of claim 4, wherein the portion of the plurality of accelerometer signals is a most recently input portion.

7. The method of claim 6, further comprising sensing a vehicle mass change event.

8. The method of claim 7, wherein if a vehicle mass change event is sensed while the vehicle is not moving, the processor is configured to reset the portion of the plurality of accelerometer signals used to only include signals input after the vehicle mass change event.

9. The method of claim 1, further comprising providing a memory for storing the at least a portion of the plurality of accelerometer signals, wherein the stored accelerometer signals are stored with a corresponding vehicle speed value, as determined by a speed sensor in the vehicle.

10. The method of claim 9, wherein the processor is further configured to determine the mass of the vehicle by determining a difference between accelerometer signals with same corresponding speed values.

11. The method of claim 1, wherein the processor is further configured to modify the plurality of accelerometer signals to compensate for vehicle pitch due to acceleration.

12. The method of claim 1, further comprising providing one or more brake system pressure sensors in the vehicle whose output signals are used by the processor to derive a plurality of wheel torque values to determine drive force values to supplement the already determined drive force values.

13. The method of claim 1, further comprising providing a display to an operator of the vehicle, the display using as an input the mass determined by the processor and indicating the mass of the vehicle as a function of a total mass for which the vehicle is rated to carry.

14. The method of claim 1, further comprising providing the processor output signal for use in adjusting an amount of braking asserted by a trailer brake of a trailer attached to the vehicle, said adjustment based on the determined mass.

15. The method of claim 1, wherein the processor is further configured to process the plurality of accelerometer signals to determine drag force coefficients indicating a drag force acting upon the vehicle, the drag force coefficients being recursively determined for values of said plurality of accelerometer signals at a known vehicle speed and corresponding to a known vehicle drive force.

16. The method of claim 1, wherein the processor is further configured to process the plurality of accelerometer signals to determine an incline of a driving surface upon which the vehicle operates, the incline determination based on a difference between the at least a portion of the plurality of accelerometer signals and vehicular acceleration values arising from the derivative of a wheel speed of the vehicle.

17. The method of claim 1, wherein the processor is configured using instructions provided on a computer-readable medium.

18. A system for improving a vehicle'"'"'s drivetrain performance, the system comprising:

one or more accelerometers in the vehicle;

a drivetrain of the vehicle, the drive train having a determinable drive force; and

a processor configured to receive a plurality of signals from the one or more accelerometers and to determine a mass of the vehicle based on a difference between at least a portion of the plurality of accelerometer signals and a difference between values for the vehicle'"'"'s drive force that correspond in time with the portion of the plurality of accelerometer signals.

19. The system of claim 18, further comprising:

at least one speed sensor in the vehicle; and

a memory to store the at least a portion of the plurality of accelerometer signals and a corresponding vehicle speed value as determined by the at least one speed sensor.

20. The system of claim 18, further comprising a display for indicating to an operator of the vehicle the mass of the vehicle as a function of a total mass for which the vehicle is rated to carry.

21. The system of claim 18, wherein the processor is further configured to determine drag force coefficients indicating a drag force acting upon the vehicle, the processor being configured to recursively determine the drag force coefficients for values of said plurality of accelerometer signals at a known vehicle speed and corresponding to a known vehicle drive force.

22. The system of claim 18, wherein the processor is further configured to determine an incline of a driving surface upon which the vehicle operates, the incline determination based on a difference between the at least a portion of the plurality of accelerometer signals and vehicular acceleration values arising from the derivative of a wheel speed of the vehicle.