Magnetic displacement sensor for vehicle

• US 20030001565A1
• Filed: 09/03/2002
• Published: 01/02/2003
• Est. Priority Date: 02/24/1999
• Status: Abandoned Application

• Current Assignee: Donnelly Corporation (Magna International Incorporated)
• Original Assignee: Donnelly Corporation (Magna International Incorporated)
• Inventors: Hoekstra, Eric J.
• Application Number:
  US10/233,875
• Publication Number:
  US 20030001565A1
• Time in Patent Office: Days
• US Class Current: 324/207.21
• CPC Class Codes: B60G 17/01933 Velocity, e.g. relative velocity-displacement sensors
• CPC Class Codes: B60G 2200/142 with a single lateral arm, e.g. MacPherson type
• CPC Class Codes: B60G 2200/422 Driving wheels or live axles
• CPC Class Codes: B60G 2204/11 Mounting of sensors thereon
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2401/17 Magnetic/Electromagnetic
• CPC Class Codes: G01D 18/001 Calibrating encoders
• CPC Class Codes: G01D 2205/14 by converting the linear movement into a rotary movement
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/2448 Correction of gain, threshold, offset or phase control
• CPC Class Codes: G01D 5/2449 using hard-stored calibration data

Abstract

A magnetic level sensor is adapted for interconnecting with a vertically moving component of a vehicle such that the level sensor determines a vertical orientation of the component of the vehicle relative to the frame or chassis of the vehicle. The magnetic level sensor includes a magnetic angular measurement device interconnected to the component of the vehicle such that vertical movement of the component causes a corresponding relative rotational movement of a magnetic element associated with the angular measurement device. An electronic control is included for analyzing an output of the angular measurement device and determining an angle of rotation of the magnetic element and thus a vertical movement of the component. The control further determines an error or offset in the output of the angular measurement device and adjusts an output of the control in response to the error or offset. The control thus continuously calibrates an output of the angular measurement device to account for manufacturing irregularities and drift in sensor output due to temperature variations and aging of the sensors and magnets over time.

Claims

1. A vehicular magnetic device for determining a displacement of an element of a vehicle via a measured displacement, said magnetic device comprising:

a magnetic element which generates a magnetic field;

at least one magnetoresponsive sensor for sensing the magnetic field generated by said magnetic element, said magnetic element being spaced from said at least one magnetoresponsive sensor and being movable relative thereto, said at least one magnetoresponsive sensor being operable to detect a change in the magnetic field associated with a movement of said magnetic element relative to said at least one magnetoresponsive sensor; and

an electronic control which is operable to analyze an output of said at least one magnetoresponsive sensor and determine a degree of movement of said magnetic element relative to said at least one magnetoresponsive sensor from the output of said at least one magnetoresponsive sensor, said electronic control being further operable to determine an offset in the output of said at least one magnetoresponsive sensor and adjust a control output of said electronic control as a function of the offset.

2. The vehicular magnetic device of claim 1, wherein said electronic control is operable to continuously monitor and adjust the output of said at least one magnetoresponsive sensor.

3. The vehicular magnetic device of claim 1, wherein said at least one magnetoresponsive sensor comprises at least one of a magnetoresistive sensor, a magnetoinductive sensor, a magnetocapacitive sensor and a flux gate sensor.

4. The vehicular magnetic device of claim 1, wherein said at least one magnetoresponsive sensor includes two magnetoresponsive sensors oriented at a predetermined angle relative to one another.

5. The vehicular magnetic device of claim 4, wherein said two magnetoresponsive sensors are oriented at approximately a 45 degree angle relative to one another.

6. The vehicular magnetic device of claim 1, wherein said at least one magnetoresponsive sensor is saturated by the external magnetic field of said magnetic element.

7. The vehicular magnetic device of claim 1, wherein said electronic control is operable to determine the offset by sampling at least two data points and averaging corresponding values associated with each of said at least two data points.

8. The vehicular magnetic device of claim 7, wherein said electronic control is operable to sample at least one equal and opposite pair of data points and average an opposite component of each data point.

9. The vehicular magnetic device of claim 7, wherein the output of said at least one magnetoresponsive sensor is associated with a coordinate system associated with one of said at least one magnetoresponsive sensor and said magnetic element, the coordinate system being defined by data points having first and second ordinates, the at least two data points comprising one common ordinate and one uncommon ordinate, the corresponding values being ordinate values of the uncommon ordinates.

10. The vehicular magnetic device of claim 1, wherein the output of said at least one magnetoresponsive sensor is associated with a coordinate system associated with one of said at least one magnetoresponsive sensor and said magnetic element, the coordinate system being defined by data points having a first and second ordinate, said electronic control being operable to sample data points and determine the offset in response to the data points.

11. The vehicular magnetic device of claim 10, wherein said control is operable to sample a first data point and a second data point, each of the first and second data points comprising a common ordinate and an uncommon ordinate, said control being operable to average the uncommon ordinates to determine an approximate first ordinate of the offset.

12. The vehicular magnetic device of claim 11, wherein said control is operable to sample a third data point which comprises a third uncommon ordinate and a third common ordinate which is approximately equal to one of the uncommon ordinates of the first and second data points, said control being operable to average the third uncommon ordinate with a corresponding one of the common ordinates of the first and second data points to determine an approximate second ordinate of the offset.

13. The vehicular magnetic device of claim 12, wherein said control is operable to sample additional data points, said control subtracting the first and second ordinates of the offset from the respective ordinate values of the additional data points to account for the offset.

14. The vehicular magnetic device of claim 1, wherein one of said magnetic element and said at least one magnetoresponsive sensor is positioned at a movable element of the vehicle and the other of said magnetic element and said at least one magnetoresponsive sensor is positioned at a frame member of the vehicle.

15. The vehicular magnetic device of claim 14, wherein said one of said magnetic element and said at least one magnetoresponsive sensor is pivotally mounted at the movable element such that substantially linear movement of the movable element relative to the frame member is translated into rotational movement of said one of said magnetic element and said at least one magnetoresponsive sensor relative to said other of said magnetic element and said at least one magnetoresponsive sensor.

16. The vehicular magnetic device of claim 1, wherein said magnetic element is rotatable relative to said at least one magnetoresponsive sensor, said electronic control being operable to determine an angle of rotation of said magnetic element relative to said at least one magnetoresponsive sensor.

17. The vehicular magnetic device of claim 1, wherein said control includes a processor which is operable to calculate the offset in the output of said at least one magnetoresponsive sensor.

19. The vehicular magnetic level sensor of claim 18, wherein the movable component is one of a control arm and a suspension unit and said generally linear movement is a generally vertical movement of one of the control arm and the suspension unit relative to the frame member of the vehicle.

20. The vehicular magnetic level sensor of claim 19, wherein said electronic control is operable to activate at least one of a pump and a valve in response to the output of said at least one magnetoresponsive sensor, at least one of the pump and the valve being operable to adjust a suspension device of the vehicle.

21. The vehicular magnetic level sensor of claim 18, wherein said magnetic element is rotatably interconnected with the movable component and said at least one magnetoresponsive sensor is fixedly secured to the frame member of the vehicle.

22. The vehicular magnetic level sensor of claim 21, wherein the movable component is one of a control arm and a suspension unit and the generally linear movement is a generally vertical movement of one of the control arm and the suspension unit relative to the frame member.

23. The vehicular magnetic level sensor of claim 18, wherein the output of said at least one magnetoresponsive sensor is associated with a coordinate system associated with one of said at least one magnetoresponsive sensor and said magnetic element, said coordinate system being defined by data points having a first and second component, said electronic control being operable to average corresponding values of sampled data points to determine the offset.

24. The vehicular magnetic level sensor of claim 23, wherein said electronic control is operable to determine the offset by sampling at least two pair of data points and averaging a corresponding value associated with each of the at least two pair of data points.

25. The vehicular magnetic level sensor of claim 24, wherein said electronic control is operable to sample at least one equal and opposite pair of data points and average an opposite component of each data point of the at least one equal and opposite pair of data points.

26. The vehicular magnetic level sensor of claim 24, wherein the at least two pair of data points define a first pair of data points and a second pair of data points, the first pair of data points having a common first component and an uncommon second component associated with the coordinate system, a first set of corresponding values being ordinate values of the uncommon second components of the first pair of data points, while the second pair of data points having a common second component and an uncommon first component, a second set of corresponding values being ordinate values of the uncommon first components of the second pair of data points, said control being operable to average each set of corresponding values to determine the offset for each component of the coordinate system.

27. The vehicular magnetic level sensor of claim 18, wherein said magnetic element is rotatable relative to said at least one magnetoresponsive sensor, said electronic control being operable to determine an angle of rotation of said magnetic element relative to said at least one magnetoresponsive sensor.

28. The vehicular magnetic level sensor of claim 18, wherein said electronic control includes a processor which is operable to calculate the offset in the output of said at least one magnetoresponsive sensor.

29. The vehicular magnetic level sensor of claim 18, wherein said at least one magnetoresponsive sensor comprises one of a magnetoresistive sensor, a magnetocapacitive sensor, a magnetoinductive sensor and a flux gate sensor.

18. A vehicular magnetic level sensor adapted for interconnecting with a generally linearly movable component on a vehicle, said level sensor being operable to determine an orientation of the movable component relative to a frame member of the vehicle and comprising:

a magnetic element which generates a magnetic field;

at least one magnetoresponsive sensor for sensing the magnetic field generated by said magnetic element, said magnetic element being spaced from said at least one magnetoresponsive sensor and being movable relative thereto, said at least one magnetoresponsive sensor detecting a change in the magnetic field associated with a movement of said magnetic element relative to said at least one magnetoresponsive sensor, one of said magnetic element and said at least one magnetoresponsive sensor being interconnected to the component of the vehicle such that a generally linear displacement of the movable component causes a corresponding movement of said one of said magnetic element and said at least one magnetoresponsive sensor relative to the other of said magnetic element and said at least one magnetoresponsive sensor; and

an electronic control for analyzing an output of said at least one magnetoresponsive 15 sensor and determining a degree of movement of said one of said magnetic element and said at least one magnetoresponsive sensor in response to the output of said at least one magnetoresponsive sensor, said electronic control being operable to determine an offset in the output of said at least one magnetoresponsive sensor and adjust an output of said electronic control as a function of the offset.

30. A calibration method of a control which is operable to calibrate a vehicular magnetic level sensor, said level sensor being operable to determine an orientation of a movable component of a vehicle relative to a frame member of the vehicle, said method comprising the steps of:

providing a magnetoresponsive sensor which is operable to sense a magnetic field generated by a magnetic element, said magnetic element being movable relative to said magnetoresponsive sensor;

sampling at least two data points of an output of said magnetoresponsive sensor;

determining an offset of the output of said magnetoresponsive sensor in response to the at least two data points; and

adjusting an output of said control in response to the offset.

31. The calibration method of claim 30, wherein after the step of sampling at least two data points, said calibration method further comprises the step of:

determining a first ordinate and a second ordinate for each of the at least two data points relative to an origin of a coordinate system associated with said magnetoresponsive sensor, the offset being an offset from a zero value of the coordinator system, the offset being determined in response to the first and second ordinates for the at least two data points.

32. The calibration method of claim 31, wherein the at least two data points define at least one corresponding pair of data points which are substantially oppositely positioned relative to one of a first and second axis of the coordinate system, the step of determining an offset comprising the step of:

averaging substantially opposite values of the at least one corresponding pair of data points to determine the offset of the values from the zero value of the coordinate system.

33. The calibration method of claim 30, wherein said control is operable to sample at least one equal and opposite pair of data points and average the substantially opposite values of each data point of the at least one equal and opposite pair of data points.

34. The calibration method of claim 30, wherein said control continuously samples data points and determines the offset, said control continuously adjusting the output of said level sensor in response to the offset.

35. The calibration method of claim 30, wherein after the step of sampling the at least two data points, said calibration method further comprises the step of determining if the at least two data points are valid by determining if a difference between the at least two data points is greater than a predetermined value.

36. The calibration method of claim 30, wherein said level sensor is mounted at a frame of a vehicle and at a movable component of the vehicle which is movable relative to the frame, said level sensor being operable to measure a generally linear movement of the movable component relative to the frame via a corresponding rotation of said magnetic element relative to said magnetoresponsive sensor.

37. The calibration method of claim 36, wherein the generally linear movement is a generally vertical movement of the movable component relative to the frame of the vehicle.

38. The calibration method of claim 37, wherein said control is operable to activate at least one of a pump and a valve to adjust a suspension device of the vehicle in response to the output of said magnetoresponsive sensor and the offset.