Sensor system including a magnetized shaft
View Patent ↗A sensor includes a shaft and a magnetic sensor. The shaft may have at least one magnetized active region. The magnetic sensor may be configured to sense a magnetic field about the shaft, and may provide an output representative of torque applied to the shaft, shaft rotational speed and shaft rotational position.
1. A sensor comprising:
a solid, homogeneous shaft having at least one magnetized active region in an axial extent of said shaft, said at least one active region having at least partially opposing magnetic polarizations in a radial cross-section taken in said axial extent; and
at least one magnetic sensor positioned adjacent said active region and configured to sense each of said opposing magnetic polarizations and provide a sinusoidal output in response to said opposing magnetic polarizations as said shaft rotates, said sinusoidal output being representative of a torque applied to said shaft.
2. The sensor of claim 1 , wherein an amplitude of said sinusoidal signal is representative of a rotational position of said shaft.
3. The sensor of claim 1 , wherein a frequency of said sinusoidal signal is representative of a speed of said shaft.
4. The sensor of claim 1 , wherein said shaft comprises magnetized saturation zones on opposing sides of said active region.
5. The sensor of claim 1 , said sensor comprising a plurality of said magnetic sensors.
6. The sensor of claim 1 , wherein said at least one magnetic sensor comprises a flux gate sensor.
7. The sensor of claim 1 , said sensor comprising a plurality of said magnetized active regions, each of said magnetic regions having at least one of said magnetic sensors positioned adjacent thereto.
8. A sensor comprising:
a solid, homogeneous shaft having at least one magnetized active region in an axial extent of said shaft, said at least one active region having at least partially opposing magnetic polarizations in a radial cross-section taken in said axial extent;
a first fluxgate coil positioned about said shaft and configured to provide a first sinusoidal signal in response to said active region as said shaft is rotated;
a second fluxgate coil positioned about said shaft configured to provide a second sinusoidal signal in response to said active region as said shaft is rotated, said second sinusoidal signal being ninety degrees out of phase with said first sinusoidal signal; and
torque circuitry configured to accept said first and second sinusoidal signals and provide an output signal representative of torque applied to said shaft.
9. The sensor of claim 8 , wherein said torque circuitry is configured to calculate a square root of a sum of said first sinusoidal signal squared and said second sinusoidal signal squared to provide said output signal representative of torque applied to said shaft.
10. The sensor of claim 8 , further comprising shaft speed circuitry configured to accept at least one of said first and said second sinusoidal signals and to provide an output signal representative of a speed of said shaft, wherein a frequency of said at least one of said first and second sinusoidal signals is representative of said speed of said shaft.
11. The sensor of claim 8 , further comprising positioning circuitry to calculate an arc tangent of a ratio of said second sinusoidal signal to said first sinusoidal signal, wherein a result of said arc tangent operation is representative of a position of said shaft.
12. The sensor of claim 8 , said sensor comprising a plurality of said magnetized active regions.