APPARATUS AND METHOD FOR DIAGNOSTICS OF A CAPACITIVE SENSOR

• US 20130187664A1
• Filed: 01/08/2013
• Published: 07/25/2013
• Est. Priority Date: 01/20/2012
• Status: Active Grant

• Current Assignee: Lear Corporation
• Original Assignee: Lear Corporation
• Inventors: Ferre Fabregas, Antoni, Deumal Herraiz, Marc, Castillo-Vazquez, Laura
• Granted Patent: US 9,791,494 B2
• Time in Patent Office: Days
• US Class Current: 324/548
• CPC Class Codes: G01D 1/00 Measuring arrangements giving results other than momentary value of variable, of general application G01D3/00 takes precedence; in tariff metering apparatus G01D4/00; transducers not specially adapted for a specific variable G01D5/00
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: G01D 2218/10 Testing of sensors or measuring arrangements
• CPC Class Codes: G01D 5/24 by varying capacitance
• CPC Class Codes: G01R 1/00 Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00 constructional details particular to electromechanical arrangements for measuring the electric consumption G01R11/02
• CPC Class Codes: G01R 31/2829 Testing of circuits in sensor or actuator systems testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844
• CPC Class Codes: G01R 31/64 Testing of capacitors
• CPC Class Codes: G06F 2101/00 Indexing scheme relating to the type of digital function generated

Abstract

In at least one embodiment, an apparatus for diagnosing a state of a capacitive sensor is provided. The apparatus includes a control unit for being operably coupled to a decoupling device that exhibits a drift condition and to the capacitive sensor. The control unit being configured to determine an impedance of the capacitive sensor and to determine a characteristic of the capacitive sensor based on at least the impedance. The control unit being further configured to determine a characteristic of the decoupling device based on the characteristic of the capacitive sensor and to provide an estimated capacitance based on the characteristic of the decoupling device, the estimated capacitance being indicative of the state of the capacitive sensor.

Claims

1. An apparatus for diagnosing a state of a capacitive sensor, the apparatus comprising:

a control unit for being operably coupled to a decoupling device that exhibits a drift condition and to the capacitive sensor, the control unit being configured to;

determine an impedance of the capacitive sensor;

determine a characteristic of the capacitive sensor based on at least the impedance;

determine a characteristic of the decoupling device based on the characteristic of the capacitive sensor; and

provide an estimated capacitance based on the characteristic of the decoupling device, the estimated capacitance being indicative of the state of the capacitive sensor.

2. The apparatus of claim 1 wherein the characteristic of the capacitive sensor corresponds to a resistance of the capacitive sensor.

3. The apparatus of claim 2 wherein the resistance of the capacitive sensor corresponds to a minimum resistance value of the capacitive sensor.

4. The apparatus of claim 1 wherein the characteristic of the decoupling device corresponds to a capacitance of the decoupling device.

5. The apparatus of claim 1 wherein the characteristic of the capacitive sensor and the characteristic of the decoupling device compensate for the drift exhibited at the decoupling device.

6. The apparatus of claim 1 wherein the control unit is further configured to compare the estimated capacitance to a predetermined capacitance value to diagnose the capacitive sensor.

7. The apparatus of claim 6 wherein the control unit is further configured to determine that the capacitive sensor is exhibiting a fault condition in the event the estimated capacitive exceeds the predetermined capacitance value.

8. A method for diagnosing a state of a capacitive sensor, the method comprising:

determining an impedance of the capacitive sensor;

determining a characteristic of the capacitive sensor based on at least the impedance;

determining a characteristic of a decoupling device that exhibits a drift condition based on the characteristic of the capacitive sensor; and

providing an estimated capacitance based on the characteristic of the decoupling device, the estimated capacitance being indicative of the state of the capacitive sensor.

9. The method of claim 8 wherein the characteristic of the capacitive sensor corresponds to a resistance of the capacitive sensor.

10. The method of claim 9 wherein the resistance of the capacitive sensor corresponds to a minimum resistance value of the capacitive sensor.

11. The method of claim 8 wherein the characteristic of the decoupling device corresponds to a capacitance of the decoupling device.

12. The method of claim 8 further comprising compensating for the drift exhibited at the decoupling device with the characteristic of the capacitive sensor and the characteristic of the decoupling device.

13. The method of claim 8 further comprising comparing the estimated capacitance to a predetermined capacitance value to diagnose the capacitive sensor.

14. The method of claim 13 further comprising determining that the capacitive sensor is exhibiting a fault condition in the event the estimated capacitive exceeds the predetermined capacitance value.

15. An apparatus for diagnosing a state of a capacitive sensor, the apparatus comprising:

a control unit for being operably coupled to a decoupling device and the capacitive sensor, the decoupling device exhibiting a drift condition and being configured to prevent a transfer of energy to the capacitive sensor, the control unit being configured to;

determine an impedance of the capacitive sensor;

determine a characteristic of the capacitive sensor based on at least the impedance;

determine a characteristic of the decoupling device based on the characteristic of the capacitive sensor; and

provide an estimated capacitance based on the characteristic of the decoupling device, the estimated capacitance being indicative of the state of the capacitive sensor.

16. The apparatus of claim 15 wherein the characteristic of the capacitive sensor corresponds to a resistance of the capacitive sensor.

17. The apparatus of claim 16 wherein the resistance of the capacitive sensor corresponds to a minimum resistance value of the capacitive sensor.

18. The apparatus of claim 15 wherein the characteristic of the decoupling device corresponds to a capacitance of the decoupling device.

19. The apparatus of claim 15 wherein the characteristic of the capacitive sensor and the characteristic of the decoupling device compensate for the drift exhibited at the decoupling device.

20. The apparatus of claim 15 wherein the control unit is further configured to compare the estimated capacitance to a predetermined capacitance value to diagnose the capacitive sensor.