Method and device for detecting the contact of hands on a steering wheel

• US 20020170900A1
• Filed: 05/06/2002
• Published: 11/21/2002
• Est. Priority Date: 05/04/2001
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Heinebrodt, Martin, Braeuchle, Goetz, Boecker, Juergen
• Granted Patent: US 7,109,862 B2
• Time in Patent Office: Days
• US Class Current: 219/204
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60W 2040/0881 Seat occupation; Driver or passenger presence
• CPC Class Codes: B62D 1/06 Rims, e.g. with heating means; Rim covers B62D1/11 takes precedence
• CPC Class Codes: B62D 1/065 Steering wheels with heating and ventilating means heating and ventilation of steering wheel when connected to vehicle HVAC B60H1/00292
• CPC Class Codes: B62D 51/002 comprising safety arrangements safety devices for vehicle propulsion unit control B60K28/00
• CPC Class Codes: G08B 21/06 indicating a condition of sleep, e.g. anti-dozing alarms

Abstract

A method and a device are described for detecting the contact between hands and a steering wheel, which assures that the driver of a vehicle has his hands on the steering wheel.

Claims

1. A method for detecting a contact between hands of a vehicle driver and a steering wheel, comprising:

generating a first signal having a first frequency, the first frequency being a function of whether the hands are in contact with the steering wheel;

generating a second signal having a second frequency; and

generating an output signal as a function of the first frequency and the second frequency.

2. The method as recited in claim 1, wherein the output signal is generated as a function of a difference between the first frequency and the second frequency.

3. The method as recited in claim 1, wherein the output signal is generated as a function of an absolute value of a difference between the first frequency and the second frequency.

4. The method as recited in claim 1, further comprising:

causing a frequency-voltage converter to generate an output voltage as a function of the first frequency and the second frequency.

5. The method as recited in claim 1, further comprising:

detecting the contact between the hands and the steering wheel if the output signal is greater than a first threshold value.

6. The method as recited in claim 1, wherein a compensation is present for a change in the first frequency due to an external disturbance variable.

7. The method as recited in claim 6, further comprising:

feeding a frequency into a first resonant circuit having a capacitance, the capacitance of the first resonant circuit being changed by the contact between the hands and the steering wheel; and

compensating for changes in the first frequency due to the external disturbance variable.

8. A device for detecting a contact between hands and a steering wheel, comprising:

an arrangement for generating a first signal having a first frequency, the first frequency being a function of whether the hands are in contact with the steering wheel;

an arrangement for generating a second signal having a second frequency; and

an arrangement for generating an output signal as a function of the first frequency and the second frequency.

9. The device as recited in claim 8, wherein the arrangement for generating the first signal includes a first oscillator and a first capacitor that is connected in parallel to the first oscillator, the first capacitor being arranged on the steering wheel.

10. The device as recited in claim 9, wherein a steering wheel heating system is a part of the first capacitor.

11. The device as recited in claim 10, wherein the steering wheel heating system can be switched off for determining a capacitance.

12. The device as recited in claim 9, wherein the arrangement for generating the second signal includes a second oscillator having a second capacitor.

13. The device as recited in claim 8, wherein the arrangement for generating the first signal and the arrangement for generating the second signal are exposed to the same external condition.

14. The device as recited in claim 12, wherein the first capacitor and the second capacitor are arranged in an immediate vicinity of each other.

15. The device as recited in claim 8, wherein the arrangement for generating the second signal includes a capacitor that is connected in parallel to an oscillator.

16. The device as recited in claim 8, further comprising:

a mixer for calculating a difference between the first frequency and the second frequency.

17. The device as recited in claim 8, further comprising:

a frequency-voltage converter for converting a difference between the first frequency and the second frequency into an output voltage that is proportional to an absolute value of the difference.

18. The device as recited in claim 17, wherein the contact between the hands and the steering wheel is detected if the output signal is greater than a first switching threshold.

19. The device as recited in claim 15, wherein a compensation of the second frequency due to an external disturbance variable is present.

20. The device as recited in claim 19, wherein the compensation of the second frequency due to the external disturbance variable takes place by adjusting a third capacitor that is connected in parallel to the oscillator.

21. The device as recited claim 8, wherein the first frequency and the second frequency are the same if the hands are not in contact with the steering wheel.

22. A computer program that when executed causes a performance of:

generating a first signal having a first frequency, the first frequency being a function of whether the hands are in contact with the steering wheel;

generating a second signal having a second frequency; and

generating an output signal as a function of the first frequency and the second frequency.

23. The computer program as recited in claim 22, wherein the computer program is stored on a storage medium.

24. A control unit associated with a computer program that when executed causes a performance of the following:

generating a first signal having a first frequency, the first frequency being a function of whether the hands are in contact with the steering wheel;

generating a second signal having a second frequency; and

generating an output signal as a function of the first frequency and the second frequency.