Absolute position measurement using single magnet strip

An absolute position measurement system, comprising:

• a multipole magnet comprising alternating magnetic poles extending along a multipole extension direction, wherein the multipole magnet has a linear changing configuration relative to a linear path and the multipole magnet is configured to produce a magnetic field along the linear path, the magnetic field having a field strength that undergoes a sinusoidal change along the linear path due to the alternating magnetic poles and a linear change along the linear path according to the linear changing configuration relative to the linear path;
• and
• a magnetic sensor configured to move along the linear path,
• wherein the magnetic sensor comprises a first sensor element arrangement configured to generate a first sensor signal and a second sensor element arrangement configured to generate a second sensor signal that is phase shifted with respect to the first sensor signal,
• wherein the magnetic sensor further comprises a processing circuit configured to:
• receive the first sensor signal and the second sensor signal,
• calculate a polar coordinate based on the first sensor signal and the second sensor signal,
• generate a radius set based on the polar coordinate,
• calculate an absolute angle based on a radius included in the radius set, and
• calculate an absolute position of the magnetic sensor based on the absolute angle.

An absolute position measurement system, comprising:

• a multipole magnet comprising alternating magnetic poles extending along a multipole extension direction that is coincident with a linear path along which the multipole magnet is configured to move, wherein the multipole magnet has a linear configuration that changes relative to a fixed position as it moves along the linear path, wherein the multipole magnet is configured to produce a magnetic field at the fixed position;
• and
• a magnetic sensor movably fixed at the fixed position,
• wherein the magnetic sensor comprises a first sensor element arrangement configured to generate a first sensor signal in response to the magnetic field and a second sensor element arrangement configured to generate a second sensor signal in response to the magnetic field,
• wherein, as the multipole magnet moves along the linear path, the first sensor signal has a first sinusoidal waveform having a first linearly changing peak-to-peak amplitude and the second sensor signal has a second sinusoidal waveform having a second linearly changing peak-to-peak amplitude, wherein the second sinusoidal waveform is phase shifted with respect to the first sinusoidal waveform,
• wherein the magnetic sensor further comprises a processing circuit configured to:
• receive the first sensor signal and the second sensor signal,
• calculate a polar coordinate based on the first sensor signal and the second sensor signal,
• generate a radius set based on the polar coordinate,
• calculate an absolute angle based on a radius included in the radius set, and
• calculate an absolute position of the magnetic sensor based on the absolute angle.

A method of measuring an absolute position of a magnetic sensor, the method comprising:

• generating, by a first sensor element arrangement of the magnetic sensor, a first sensor signal in response to a magnetic field;
• generating, by a second sensor element arrangement of the magnetic sensor, a second sensor signal in response to the magnetic field,
• wherein, as the magnetic sensor moves along a linear path, the first sensor signal has a first sinusoidal waveform having a first linearly changing peak-to-peak amplitude and the second sensor signal has a second sinusoidal waveform having a second linearly changing peak-to-peak amplitude, wherein the second sinusoidal waveform is phase shifted with respect to the first sinusoidal waveform;
• calculating a polar coordinate based on the first sensor signal and the second sensor signal;
• determining a radius based on the polar coordinate;
• calculating an absolute angle based on the radius;
• and
• calculating, by a processing circuit, an absolute position of the magnetic sensor based on the absolute angle.