ASCERTAINING AN OFFSET OF AN INERTIAL SENSOR

• US 20170096127A1
• Filed: 12/15/2016
• Published: 04/06/2017
• Est. Priority Date: 04/23/2014
• Status: Active Grant

• Current Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Zhang, Chen, Levrier, Julien
• Granted Patent: US 10,766,468 B2
• Time in Patent Office: Days
• CPC Class Codes: B60T 2250/02 Vehicle mass
• CPC Class Codes: B60T 2250/03 Vehicle yaw rate
• CPC Class Codes: B60T 2250/06 Sensor zero-point adjustment; Offset compensation
• CPC Class Codes: B60T 7/042 by electrical means, e.g. using travel or force sensors
• CPC Class Codes: B60T 8/17551 determining control parameters related to vehicle stability used in the regulation, e.g. by calculations involving measured or detected parameters

Abstract

A method of providing an additive offset of a longitudinal acceleration signal of a traveling motor vehicle. The signal being measured by an inertial sensor is ascertained. At least the longitudinal acceleration signal, a braking signal, and a drive signal are detected. A force balance of the longitudinal dynamic of the motor vehicle is analyzed. The signals are detected both during at least one acceleration process as well as during at least one braking process. The signals during the acceleration processes are detected and/or analyzed separately from the signals during the braking processes, and the additive offset is ascertained by comparing the signals detected during the acceleration processes or the values calculated therefrom with the signals detected during the braking processes or the values calculated therefrom. The invention further relates to an electronic controller.

Claims

1. A method for measuring an additive displacement of a longitudinal acceleration signal of a traveling motor vehicle with an intertial sensor comprising:

detecting at least the longitudinal acceleration signal, a brake signal and a drive signal;

analyzing a balance of forces of the longitudinal dynamics of the motor vehicle;

detecting the signals for at least one acceleration process and for at least one braking process, wherein the signals for acceleration processes are detected separately from the signals for braking processes; and

determining the additive displacement from a comparison of one of;

the signals detected during acceleration processes, values calculated from the signals detected during acceleration processes, with the signals detected during braking processes, and values calculated from the signals detected during braking processes.

2. The method of claim 1, wherein the analysis of the balance of forces of the longitudinal dynamics is only carried out if a stable driving state.

3. The method of claim 2, wherein the stable driving state is traveling straight ahead.

4. The method of claim 2, wherein the stable driving state is detected if at least one of the following conditions are met:

a magnitude of an acceleration demand by the driver lies within a predetermined acceleration interval;

a gas pedal operation by the driver exceeds a predetermined threshold value;

a brake pedal operation by the driver exceeds a predetermined threshold value;

a speed of travel of the traveling motor vehicle lies within a predetermined speed interval;

a magnitude of a steering angle set by the driver;

a measured yaw rate below a predetermined steering angle threshold value;

a predetermined yaw rate threshold value;

a magnitude of a change with time of the drive signal lies below a predetermined fluctuation threshold value;

a magnitude of a change with time of the brake signal lies below a predetermined fluctuation threshold value;

the magnitude of the longitudinal acceleration signal exceeds a predetermined minimum threshold value;

magnitude of a measured lateral acceleration lies below a predetermined turn threshold value; and

none of drive dynamics control, brake slip control nor drive slip control is active.

5. The method of claim 1, wherein the analysis of the balance of forces of the longitudinal dynamics includes a determination of a longitudinal force acting on the vehicle using at least one of the drive and brake signal,

6. The method of claim 5, wherein a wind resistance force is determined and taken into account using the speed of travel of the vehicle.

7. The method of claim 5, further comprising:

determining a first longitudinal acceleration a_acc during an acceleration process using the longitudinal acceleration signal,

determining a first longitudinal force F_acc at least using the drive signal;

determining a second longitudinal acceleration a_dec during a braking process using the longitudinal acceleration signal;

determining a second longitudinal force F_dec at least using the brake signal; and

determining the additive displacement a_x^drift of the longitudinal acceleration according to;

8. The method of claim 5, wherein detecting of the sensor signals is carried out continuously at fixed time intervals,

9. The method of claim 8, further comprising

determining a first mass using the signals measured during acceleration processes

determining a second mass using the signals measured during braking processes, and

wherein the determining the additive displacement of the longitudinal acceleration signal is carried out if the difference between the first mass and the second mass exceeds a predetermined tolerance threshold value.

10. The method of claim 9, wherein the determining the additive displacement is carried out recursively further comprising:

determining a plurality of the first mass values and the second mass values;

calculating an expected value for the first mass and an expected value for the second mass;

minimizing the difference between the first expected value for the first mass and the expected value for the second mass;

j and

maintaining the determined additive displacement when the difference between the expected values lies below a termination threshold.

11. The method of claim 10, wherein the additive displacement is redetermined when the expected value at least one of meets and exceeds the termination threshold.

12. The method of claim 1, further comprising determining the speed signal using at least one wheel revolution rate sensor.

13. The method of claim 1, further comprising determining the brake signal is determined using one of a brake pressure sensor and a pedal travel sensor on the brake pedal

14. The method of claim 1, further comprising determining the drive signal from at least one of:

a drive torque signaled by an engine control unit of an internal combustion engine, by a motor control unit of an electrical drive, and a revolution rate measured on a motor shaft.

15. An electronic control unit for a brake system of a motor vehicle, comprising:

interfaces for the connection of at least one wheel revolution rate sensor and at least one brake operation sensor;

at least one inertial sensor disposed in the longitudinal direction and an interface to a vehicle data bus; and

a computing unit with instructions for;

detecting at least the longitudinal acceleration signal, a brake signal and a drive signal;

analyzing a balance of forces of the longitudinal dynamics of the motor vehicle;

detecting the signals for at least one acceleration process and for at least one braking process, wherein the signals for acceleration processes are detected separately from the signals for braking processes; and

determining the additive displacement from a comparison of one of;

the signals detected during acceleration processes, values calculated from the signals detected during acceleration processes, with the signals detected during braking processes, and values calculated from the signals detected during braking processes.

16. The electronic control unit of claim 15, wherein the analysis of the balance of forces of the longitudinal dynamics is only carried out if a stable driving state, wherein the stable driving state is traveling straight ahead.

17. The electronic control unit of claim 16, the stable driving state is detected if at least one of the following conditions are met:

a magnitude of an acceleration demand by the driver lies within a predetermined acceleration interval;

a gas pedal operation by the driver exceeds a predetermined threshold value;

a brake pedal operation by the driver exceeds a predetermined threshold value;

a speed of travel of the traveling motor vehicle lies within a predetermined speed interval;

a magnitude of a steering angle set by the driver;

a measured yaw rate below a predetermined steering angle threshold value;

a predetermined yaw rate threshold value;

a magnitude of a change with time of the drive signal lies below a predetermined fluctuation threshold value;

a magnitude of a change with time of the brake signal lies below a predetermined fluctuation threshold value;

the magnitude of the longitudinal acceleration signal exceeds a predetermined minimum threshold value;

magnitude of a measured lateral acceleration lies below a predetermined turn threshold value; and

none of drive dynamics control, brake slip control nor drive slip control is active.

18. The electronic control unit of claim 16, the analysis of the balance of forces of the longitudinal dynamics includes a determination of a longitudinal force acting on the vehicle using at least one of the drive and brake signal.

19. The electronic control unit of claim 16, wherein a wind resistance force is determined and taken into account using the speed of travel of the vehicle.

20. The electronic control unit of claim 16 comprising further instructions for:

determining a first longitudinal acceleration a_acc during an acceleration process using the longitudinal acceleration signal,

determining a first longitudinal force F_acc at least using the drive signal;

determining a second longitudinal acceleration a_dec during a braking process using the longitudinal acceleration signal;

determining a second longitudinal force F_dec at least using the brake signal; and

determining the additive displacement a_x^drift of the longitudinal acceleration according to;

21. The electronic control unit of claim 16, detection of the sensor signals is carried out continuously at fixed time intervals.

22. The electronic control unit of claim 21 comprising further instructions for:

determining a first mass using the signals measured during acceleration processes determining a second mass using the signals measured during braking processes, and

wherein the determining the additive displacement of the longitudinal acceleration signal is carried out if the difference between the first mass and the second mass exceeds a predetermined tolerance threshold value.

23. The electronic control unit of claim 22 wherein the determining the additive displacement is carried out recursively, and electronic control unit comprises further instructions for:

determining a plurality of the first mass values and the second mass values;

calculating an expected value for the first mass and an expected value for the second mass;

minimizing the difference between the first expected value for the first mass and the expected value for the second mass;

j and

maintaining the determined additive displacement when the difference between the expected values lies below a termination threshold.

24. The electronic control unit of claim 23, wherein the additive displacement is redetermined when the expected value at least one of meets and exceeds the termination threshold.

25. The electronic control unit of claim 15, further comprising determining the drive signal from at least one of:

a drive torque signaled by an engine control unit of an internal combustion engine, by a motor control unit of an electrical drive, and a revolution rate measured on a motor shaft.

26. The electronic control unit of claim 15, further comprising

an actuator for building up a brake force on one or more vehicle wheels independently of the driver, wherein the actuator is an electrically operated hydraulic pump and at least one solenoid valve;

and

a computing unit that implements drive dynamics control, wherein a longitudinal acceleration signal corrected by the determined additive displacement is fed into the drive dynamics control.