Multi-turn magnetic sensor mid-range reset
View Patent ↗Aspects of this disclosure relate to multi-turn magnetic sensing systems and related methods. A system can include a first multi-turn magnetic sensor and a second multi-turn magnetic sensor, in which domain walls propagate in an opposite direction in the second multi-turn magnetic sensor relative to the first multi-turn magnetic sensor in response to a magnetic field. A decoder can output a turn count that is based on states of the first and second multi-turn sensors. The first and second multi-turn sensors can have a reset state that corresponds to the turn count having a value between minimum and maximum values of a counting range relative to the reset state.
1 . A multi-turn magnetic sensing system comprising:
a first multi-turn magnetic sensor;
a second multi-turn magnetic sensor, wherein domain walls propagate in an opposite direction in the second multi-turn magnetic sensor relative to the first multi-turn magnetic sensor in response to a magnetic field; and
a decoder configured to output a turn count that is based on output signals from the first multi-turn magnetic sensor and the second multi-turn magnetic sensor, wherein the decoder is configured to determine the turn count for more than one full clockwise rotation of the magnetic field from a reset state and to determine the turn count for more than one full counterclockwise rotation of the magnetic field from the reset state.
2 . The multi-turn magnetic sensing system of claim 1 , wherein the decoder is configured to determine the turn count in a range from a first value to a second value for states of the first and second multi-turn magnetic sensors relative to the reset state, and wherein the turn count for the reset state is between the first value and the second value.
3 . The multi-turn magnetic sensing system of claim 2 , wherein the first multi-turn magnetic sensor and the second multi-turn magnetic sensor are each configured to count a same number of turns in opposite directions, and the turn count for the reset state is a midpoint between the first value and the second value.
4 . The multi-turn magnetic sensing system of claim 2 , wherein the first multi-turn magnetic sensor and the second multi-turn magnetic sensor are each filled with domain walls in the reset state.
5 . The multi-turn magnetic sensing system of claim 1 , further comprising a magnetic reset configured to magnetically reset the first and second multi-turn magnetic sensors to the reset state, wherein the decoder is configured to determine the turn count in a range from a first value to a second value relative to the reset state, and wherein the turn count for the reset state has a value in between the first value and the second value.
6 . The multi-turn magnetic sensing system of claim 5 , wherein the magnetic reset comprises a coil configured to apply a reset magnetic field to reset the first and second multi-turn magnetic sensors to the reset state.
7 . The multi-turn magnetic sensing system of claim 5 , further comprising memory configured to store an index value, wherein the multi-turn magnetic sensing system is configured to update the index value in association with magnetically resetting the first and second multi-turn magnetic sensors, and wherein the decoder is configured to generate the turn count based on the index value and the output signals from the first multi-turn magnetic sensor and the second multi-turn magnetic sensor.
8 . The multi-turn magnetic sensing system of claim 1 , wherein the multi-turn magnetic sensing system operates in a subset of valid states of the first and second multi-turn magnetic sensors when operating in equilibrium.
9 . The multi-turn magnetic sensing system of claim 1 , wherein the first and second multi-turn magnetic sensors have a state that corresponds to a same number of turns as the reset state, and the first and second multi-turn magnetic sensors are not configured to move from the state to the reset state by rotation of the magnetic field.
10 . The multi-turn magnetic sensing system of claim 1 , wherein the turn count has a same value for at least two different of states of the first and second multi-turn magnetic sensors.
11 . The multi-turn magnetic sensing system of claim 1 , further comprising an angle sensor and processing circuitry configured to output a position measurement, wherein the position measurement is based on the turn count and an angle, and wherein the angle is based on an output signal of the angle sensor.
12 . A multi-turn magnetic sensing system with mid-range reset, the multi-turn magnetic sensing system comprising:
a first multi-turn magnetic sensor;
a second multi-turn magnetic sensor, wherein domain walls propagate in opposite directions in the second multi-turn magnetic sensor and the first multi-turn magnetic sensor in response to a magnetic field; and
a decoder configured to output a turn count associated with states of the first multi-turn magnetic sensor and the second multi-turn magnetic sensor, wherein the turn count is in a range from a first value to a second value relative to a reset state, and wherein the turn count for the reset state is between the first value and the second value.
13 . The multi-turn magnetic sensing system of claim 12 , further comprising a magnetic reset configured to magnetically reset the first and second multi-turn magnetic sensors to the reset state.
14 . The multi-turn magnetic sensing system of claim 12 , wherein the turn count has a same value for at least two different of states of the first and second multi-turn magnetic sensors.
15 . The multi-turn magnetic sensing system of claim 12 , wherein the first and second multi-turn magnetic sensors have a state that corresponds to a same number of turns as the reset state, and the first and second multi-turn magnetic sensors are not configured to move from the state to the reset state by rotation of the magnetic field.
16 . A method of multi-turn magnetic sensing with mid-range reset, the method comprising:
resetting a first multi-turn sensor and a second multi-turn sensor to a reset state, wherein domain walls propagate in opposite directions in the first multi-turn sensor and the second multi-turn sensor in response to rotation of a magnetic field;
detecting a first non-zero number of turns of the magnetic field from the reset state based on reading out first values from the first multi-turn sensor and the second multi-turn sensor, the first non-zero number of turns representing that a cumulative rotation of the magnetic field is in a clockwise direction from the reset state; and
detecting a second non-zero number of turns of the magnetic field relative to the reset state based on reading out second values from the first multi-turn sensor and the second multi-turn sensor, the second non-zero number of turns representing that the cumulative rotation of the magnetic field is in a counterclockwise direction from the reset state.
17 . The method of claim 16 , wherein the first multi-turn sensor and the second multi-turn sensor are each comprise magnetic spirals having a same number of turns.
18 . The method of claim 16 , wherein the first multi-turn sensor and the second multi-turn sensor are each filled with domain walls in the reset state.
19 . The method of claim 16 , further comprising:
magnetically resetting the first multi-turn sensor in response to the magnetic field rotating a certain number of turns;
updating an index value stored in memory in association with the magnetically resetting; and
after the updating and additional rotation of the magnetic field, determining a turn count based on the index value and reading out third values from the first multi-turn sensor and the second multi-turn sensor.
20 . The method of claim 16 , further comprising generating a position measurement based on a turn count and angle information associated with the magnetic field.