System for measuring angular position and method of stray field cancellation
First Claim
1. A system comprising:
- a dipole magnet having an axis of rotation, the dipole magnet being configured to produce a magnetic field;
a first magnetoresistive (MR) sensor configured to produce a first output signal in response to the magnetic field, the first output signal including a first stray field component; and
a second MR sensor configured to produce a second output signal in response to the magnetic field, the second output signal including a second stray field component;
a third MR sensor configured to produce a third output signal in response to the magnetic field, the third output signal including a third stray field component;
a fourth MR sensor configured to produce a fourth output signal in response to the magnetic field, the fourth output signal including a fourth stray field component, each of the first, second, third, and fourth MR sensors being configured to operate in a saturation mode such that the first output signal is indicative of a first direction of the magnetic field, the second output signal is indicative of a second direction of the magnetic field, the third output signal is indicative of a third direction of the magnetic field, and the fourth output signal is indicative of a fourth direction of the magnetic field; and
a processing circuit coupled with the first, second, third, and fourth MR sensors and configured to combine the first, second, third, and fourth output signals to obtain a rotation angle value in which the first, second, third, and fourth stray field components are substantially cancelled.
1 Assignment
0 Petitions
Accused Products
Abstract
A system for determining angular position includes a dipole magnet having an axis of rotation, wherein the dipole magnet produces a magnetic field. A first magnetic field sensor produces a first output signal and a second magnetic field sensor produces a second output signal in response to the magnetic field. The magnetic field sensors are operated in a saturation mode in which the magnetic field sensors are largely insensitive to the field strength of the magnetic field. Thus, the first output signal is indicative of a first direction of the magnetic field and the second output signal is indicative of a second direction of the magnetic field. Methodology performed by a processing circuit entails combining the first and second output signals to obtain a rotation angle value of the magnet in which angular error from a stray magnetic field is substantially cancelled.
-
Citations
11 Claims
-
1. A system comprising:
-
a dipole magnet having an axis of rotation, the dipole magnet being configured to produce a magnetic field; a first magnetoresistive (MR) sensor configured to produce a first output signal in response to the magnetic field, the first output signal including a first stray field component; and a second MR sensor configured to produce a second output signal in response to the magnetic field, the second output signal including a second stray field component; a third MR sensor configured to produce a third output signal in response to the magnetic field, the third output signal including a third stray field component; a fourth MR sensor configured to produce a fourth output signal in response to the magnetic field, the fourth output signal including a fourth stray field component, each of the first, second, third, and fourth MR sensors being configured to operate in a saturation mode such that the first output signal is indicative of a first direction of the magnetic field, the second output signal is indicative of a second direction of the magnetic field, the third output signal is indicative of a third direction of the magnetic field, and the fourth output signal is indicative of a fourth direction of the magnetic field; and a processing circuit coupled with the first, second, third, and fourth MR sensors and configured to combine the first, second, third, and fourth output signals to obtain a rotation angle value in which the first, second, third, and fourth stray field components are substantially cancelled. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method for determining the angular position of a dipole magnet, the dipole magnet having an axis of rotation, wherein the magnet is configured to produce a magnetic field, the method comprising:
-
operating first, second, third, and fourth magnetoresistive (MR) sensors in a saturation mode in which each of the first, second, third, and fourth MR sensors are sensitive to a direction of the magnetic field; producing a first output signal at the first MR sensor, the first output signal being indicative of a first direction of the magnetic field at a first location of the MR sensor, the first output signal including a first stray field component; producing a second output signal at the second MR sensor, the second output signal being indicative of a second direction of the magnetic field at a second location of the second MR sensor, the second output signal including a second stray field component; producing a third output signal at the third MR sensor, the third output signal being indicative of a third direction of the magnetic field at a third location of the third MR sensor, the third output signal including a third stray field component; producing a fourth output signal at the fourth MR sensor, the fourth output signal being indicative of a fourth direction of the magnetic field at a fourth location of the fourth MR sensor, the fourth output signal including a fourth stray field component; and combining the first, second, third, and fourth output signals to obtain a rotation angle value of the dipole magnet in which the first, second, third, and fourth stray field components are substantially cancelled. - View Dependent Claims (11)
-
Specification