Pressure sensor with correction of offset drift in cyclic signal

Patent metadata

Field	Value
Publication number	US-10054511-B2
Application number	US-201414504358-A
Country	US
Kind code	B2
Filing date	Oct 1, 2014
Priority date	Oct 1, 2014
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

A method for correcting offset drift in a sensor used in cyclic sensing is provided. The method includes: identifying a target value for a parameter of a signal between sensing cycles of the sensor; ascertaining a difference between a measured value for the signal and the target value; ascertaining a duration between the sensing cycles; using the difference and the duration, calculating a number of steps to attain the target value from the measured value; and adjusting the measured value by the number of steps to substantially agree with the target value. A pressure sensor is disclosed.

First claim

What is claimed is:

1. A method for correcting offset drift of a sensor assembly used in cyclic sensing in an engine, wherein the engine has an engine control unit (ECU) in communication with the sensor assembly, which has a sensing element in communication with an application specific integrated circuit (ASIC), the method comprising:
generating a cyclic signal indicative of a performance parameter of the engine, wherein the cyclic signal varies with an ambient engine parameter to create offset drift in the cyclic signal;
identifying a target value for a parameter of the cyclic signal between sensing cycles of the sensor by the ASIC, wherein the signal is generated by the sensor assembly;
ascertaining a difference between a measured value for the cyclic signal and the target value by the ASIC;
ascertaining a duration between the sensing cycles by the ASIC;
using the difference and the duration, calculating, by the ASIC, a number of steps to attain the target value from the measured value;
adjusting, by the ASIC, the measured value by the number of steps to substantially agree with the target value and remove the offset drift to create an adjusted output signal; and
utilizing the adjusted output signal, by the ECU, to control the engine during operation of the engine without compensation based on the ambient engine parameter for the sensor assembly.

2. The method as in claim 1 , wherein the sensor comprises a pressure sensor and the ambient engine parameter is temperature.

3. The method as in claim 2 , wherein the pressure sensor comprises a plurality of piezoresistive elements arranged in a Wheatstone bridge.

4. The method as in claim 1 , wherein duration of a step is calculated as a duration of a cycle divided by a number of steps.

5. The method as in claim 4 , wherein the duration of the step adjusted by using a feedback control loop.

6. The method as in claim 1 , wherein the output comprises one of voltage, current, pulse width modulation (PWM/Frequency), LIN, SENT, I2C, and CAN-bus outputs.

7. The method as in claim 1 , wherein ascertaining the duration comprises referencing the duration of the prior cycle.

8. The method as in claim 1 , wherein the measured value indicates one of force, torque, positioning, speed, acceleration, chemical composition, temperature and flow.

9. A sensor and control system configured for use in cyclic sensing of a combustion engine, the sensor and control system comprising:
an engine control unit (ECU) including an application specific integrated circuit (ASIC); and
a pressure sensor in communication with the ECU including at least one piezoresistive element configured for sensing pressure and outputting a cyclic signal, wherein the cyclic signal varies with an ambient engine parameter to create offset drift in the cyclic signal, wherein the ECU is configured for receiving the cyclic signal of the piezoresistive element and identifying a target value for the cyclic signal for between sensing cycles of the sensor; ascertaining a difference between a measured value for the voltage and the target value; ascertaining a duration between the sensing cycles; using the difference and the duration, calculating a number of steps to attain the target value from the measured value; and, adjusting the cyclic signal by the number of steps to substantially agree with the target value so that the offset drift is removed; providing the adjusted cyclic signal as a corrected output of the sensor; and utilizing the adjusted cyclic signal to control the combustion engine during operation of the combustion engine without compensation based on the ambient engine parameter for the sensor assembly.

10. The sensor and control system as in claim 9 , wherein the at least one piezoresistive element comprises an arrangement of piezoresistive elements in a Wheatstone bridge.

11. The sensor and control system as in claim 10 , wherein the application specific integrated circuit (ASIC) is configurable for a time-out mode.

12. The sensor and control system as in claim 9 , wherein size of the steps is obtained from data storage.

13. The sensor and control system as in claim 9 , wherein the size of the steps is calculated as a function of cycle duration.

14. The sensor and control system as in claim 9 , wherein the circuit is configured for being internally triggered by detection of an event.

15. The sensor and control system as in claim 9 , wherein the circuit is configured for being externally triggered.

16. A sensor and control system for use in cyclic sensing of an engine, the sensor and control system comprising
a sensor assembly including: an element configured for sensing a performance parameter of the engine and outputting a cyclic signal indicative of the performance parameter, wherein the cyclic signal varies with an ambient engine parameter to create offset drift in the cyclic signal; and a circuit coupled to the element, the circuit including an application specific integrated circuit (ASIC) with firmware; and
an engine control unit in communication with the sensor assembly and operable to:
receive the cyclic signal during operation of the engine;
determine a baseline value of the cyclic signal, the baseline value being measured between at least two cycles;
store a target value of the cyclic signal for sensing cycles of the sensor;
ascertain a difference between the baseline value and the target value, wherein the difference includes the offset drift;
calculate a number of steps to adjust the cyclic signal in order to attain the target value with substantially linear behavior;
adjust the cyclic signal, during operation of the engine, according to the number of steps to create an output signal with the offset drift removed; and
utilize the adjusted output signal to control the engine during operation of the engine without compensation based on the engine parameter for the sensor assembly.

17. A sensor and control system as recited in claim 16 , wherein each step is small enough such that each step cannot be distinguished from a typical noise-level of the cyclic signal.

18. A sensor and control system as recited in claim 16 , wherein the number of steps creates substantially linear behavior with a slope determined in an adaptive way.

Assignees

• Sensata Technologies Inc

Inventors

• Sloetjes Jan-Willem
• Groenhuijzen Serge
• Salden Bart Jan Mathijs

Classifications

• G01D3/032

  affecting incoming signal, e.g. by averaging; gating undesired signals · CPC title

• G01L19/02

  Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means (for aneroid barometers G01L7/14) · CPC title

• G01L23/10

  by pressure-sensitive members of the piezoelectric type · CPC title

• G01L27/002 Primary

  Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination · CPC title

• G01D3/036

  on measuring arrangements themselves · CPC title