Compensation algorithm for initializing yaw rate sensor's zero point offset

• US 6,314,329 B1
• Filed: 11/06/1998
• Issued: 11/06/2001
• Est. Priority Date: 11/06/1998
• Status: Expired due to Fees

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Madau, Dinu Petre, Ashrafi, Behrouz
• Primary Examiner(s): Grant, William
• Assistant Examiner(s): PATEL, RAMESH B
• Application Number:
  US09/188,050
• Time in Patent Office: 1,096 Days
• Field of Search: 700/89, 700/67, 700/68, 700/69, 700/70, 700/71, 700/73, 700/74, 701/1, 701/5, 701/37, 701/38, 701/39, 701/70, 701/72, 702/85, 702/94-96, 702/104, 702/142
• US Class Current: 700/89
• CPC Class Codes: B60G 17/019 characterised by the type of sensor or the arrangement thereof B60G17/01941 takes precedence
• CPC Class Codes: B60G 2400/0523 Yaw rate
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/082 Sensor drift
• CPC Class Codes: B60G 2800/7022 Calibration of a sensor, e.g. automatically
• CPC Class Codes: B60T 2250/06 Sensor zero-point adjustment; Offset compensation
• CPC Class Codes: B60T 2250/062 loosing zero-point calibration of yaw rate sensors when travelling on banked roads or in case of temperature variations
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60W 2050/0215 Sensor drifts or sensor failures
• CPC Class Codes: B60W 2420/00 Indexing codes relating to the type of sensors based on the principle of their operation
• CPC Class Codes: B60W 2520/14 Yaw

Abstract

When a motor vehicle is not in motion, an algorithm for establishing the initial zero point offset values for a yaw rate sensor as may be used in motor vehicle software control systems. The initial values are the manufactured values and are downloaded into the vehicle ECU at the time of the manufacture of the ECU. When the vehicle is waken at the vehicle assembly and the ignition is first turned on, the initial actual value of the zero point offset is stored both as a maximum and minimum value. At subsequent adjusting times when the vehicle is not moving, but the ignition is on, the spread between the maximum and minimum values are checked. If the spread becomes greater than a desired predetermined spread, the value, be it the maximum or minimum value reflects the measured value and the other value is adjusted to be within the desired spread. When the ignition is turned off and the vehicle is not moving, the zero point offset maximum and minimum values are stored in memory. The mean value is calculated to provide the new zero point offset value of the yaw rate sensor when the vehicle ignition is then turned on and the vehicle is not moving.

Claims

1. An algorithm stored in a memory for determining the offset value of an electronic sensor such as used in a motor control system comprising the steps of:

storing in the memory, the maximum and minimum offset values of the sensor as determined at the time of manufacture;

calculating the average of the two stored values to derive an offset value for the sensor representing the predetermined known beginning point of the sensor;

applying voltage to the sensor in response to an initialized signal;

waiting for a predetermined time period after the initialized signal;

measuring the output of the sensor for establishing the reference level of the sensor;

comparing the measured value with both the stored maximum and minimum values of the sensor;

replacing one of the stored values in the memory with the measured value if the measured value is greater than the stored value; and

then

recalculating the average of the two stored values to derive and store in the memory, a new offset value for the sensor.

2. In the algorithm of claim 1 wherein the sensor in a yaw rate sensor.

3.In the algorithm for determining the offset value of an electronic sensor according to claim 1 additionally including the step determining the state of motion of the vehicle prior to the step of applying voltage to the sensor.

3. In the algorithm according to claim 1 additionally including the step of measuring difference between the maximum and minimum stored values of the sensor and comparing the difference to a predetermined spread value.

4. In the algorithm according to claim 4 for storing the last measured value and modifying the other stored value to maintain the difference equal to the predetermined spread value.

5. In the algorithm according to claim 4 for limiting the range of either of the stored values to a predetermined constant multiple from the original values determined at the time of manufacture.