Mitigation of an effect of capacitively coupled current while driving a sensor component over an unshielded twisted pair wire configuration

Patent metadata

Field	Value
Publication number	US-11977134-B2
Application number	US-202117161840-A
Country	US
Kind code	B2
Filing date	Jan 29, 2021
Priority date	Feb 24, 2020
Publication date	May 7, 2024
Grant date	May 7, 2024

Abstract

An illustrative system includes a sensor component and a controller conductively coupled by way of a first wire and a second wire in a twisted pair configuration. The controller includes a driver configured to drive the sensor component by way of the first and second wires with a drive current in accordance with a gain parameter and a control loop circuit. The control loop circuit is configured to receive a control signal representative of a target current value for the drive current, adjust the gain parameter based on a difference between the target current value and an actual current value of current that is actually being driven through the sensor component, and abstain from adjusting the gain parameter based on current capacitively coupled onto the first and second wires by an external electric field.

First claim

What is claimed is:

1. A system comprising:
a sensor component; and
a controller conductively coupled to the sensor component by way of a first wire and a second wire in a twisted pair configuration, the controller comprising:
a driver configured to drive the sensor component by way of the first and second wires with a drive current in accordance with a gain parameter specified by an error signal output by a summing circuit, and
a control loop circuit configured to
receive a control signal representative of a target current value for the drive current,
adjust the gain parameter based on a difference between the target current value and an actual current value of current that is actually being driven through the sensor component, the adjusting configured to reduce the difference between the target current value and the actual current value, and
abstain from adjusting the gain parameter based on current capacitively coupled onto the first and second wires by an external electric field;

wherein the control loop circuit comprises:
a first current sensor configured to
measure a first actual current value of current that is actually on the first wire while the sensor component is being driven with the drive current, and
output a first feedback signal representative of the first actual current value;

a second current sensor configured to
measure a second actual current value of current that is actually on the second wire while the sensor component is being driven with the drive current, and
output a second feedback signal representative of the second actual current value; and

wherein the summing circuit is configured to subtract the first and second feedback signals from the control signal to output the error signal that specifies the gain parameter.

2. The system of claim 1 , wherein an orientation of the first current sensor with respect to the first wire is opposite an orientation of the second current sensor with respect to the second wire such that:
a drive current component of the first actual current value and a drive current component of the second actual current value are either both positive or both negative, the drive current components caused by the drive current output by the driver; and
an injected current component of the first actual current value has a first sign and an injected current component of the second actual current value has a second sign opposite the first sign, the injected current components caused by the current capacitively coupled onto the first and second wires by the external electric field.

3. The system of claim 1 , wherein the control signal, the first feedback signal, and the second feedback signal are voltage signals.

4. The system of claim 1 , further comprising:
a wearable sensor unit configured to be worn by a user, the wearable sensor unit including a magnetometer configured to detect a magnetic field generated within the user;
wherein the sensor component is included in the wearable sensor unit and associated with the magnetometer.

5. The system of claim 4 , wherein the sensor component comprises a light source included in the magnetometer.

6. The system of claim 5 , wherein the sensor component comprises a thermistor configured to detect an operating temperature of the light source.

7. The system of claim 6 , wherein the sensor component comprises a heater for the light source.

8. The system of claim 4 , wherein the sensor component comprises a heater for a vapor cell of the magnetometer.

9. The system of claim 4 , wherein:
the wearable sensor unit further includes a magnetic field generator configured to generate a compensation magnetic field configured to actively shield the magnetometer from ambient background magnetic fields; and
the sensor component comprises one or more coils included in the magnetic field generator.

10. The system of claim 4 , wherein the controller is implemented by a computing device not configured to be worn by the user.

11. The system of claim 4 , wherein the controller is included in a wearable device configured to be worn by the user and separate from the wearable sensor unit.

12. The system of claim 1 , wherein the controller further comprises a drive current management circuit configured to generate the control signal and output the control signal to the control loop circuit.

13. The system of claim 1 , wherein the first and second wires in the twisted pair configuration are included in an unshielded cable.

14. A system comprising:
a sensor component;
a controller; and
an unshielded cable comprising a first wire and a second wire in a twisted pair configuration that conductively couple the controller to the sensor component;
wherein the controller comprises:
a driver configured to drive the sensor component by way of the first and second wires with a drive current in accordance with a gain parameter specified by an error signal output by a summing circuit, and
a control loop circuit configured to
receive a control signal representative of a target current value for the drive current,
adjust the gain parameter based on a difference between the target current value and an actual current value of current that is actually being driven through the sensor component, the adjusting configured to reduce the difference between the target current value and the actual current value, and
abstain from adjusting the gain parameter based on current capacitively coupled onto the first and second wires by an external electric field;

wherein the control loop circuit comprises:
a first current sensor configured to
measure a first actual current value of current that is actually on the first wire while the sensor component is being driven with the drive current, and
output a first feedback signal representative of the first actual current value;

a second current sensor configured to
measure a second actual current value of current that is actually on the second wire while the sensor component is being driven with the drive current, and
output a second feedback signal representative of the second actual current value; and

wherein the summing circuit is configured to subtract the first and second feedback signals from the control signal to output the error signal that specifies the gain parameter.

15. The system of claim 14 , wherein an orientation of the first current sensor with respect to the first wire is opposite an orientation of the second current sensor with respect to the second wire such that:
a drive current component of the first actual current value and a drive current component of the second actual current value are either both positive or both negative, the drive current components caused by the drive current output by the driver; and
an injected current component of the first actual current value has a first sign and an injected current component of the second actual current value has a second sign opposite the first sign, the injected current components caused by the current capacitively coupled onto the first and second wires by the external electric field.

16. A magnetic field measurement system comprising:
a wearable sensor unit configured to be worn by a user and used to detect a magnetic field generated within the user;
a sensor component included in the wearable sensor unit; and
a controller remote from the wearable sensor unit and conductively coupled to the sensor component by way of a first wire and a second wire in a twisted pair configuration, the controller comprising:
a driver configured to drive the sensor component by way of the first and second wires

Assignees

• Hi Llc

Inventors

• Garber Stephen
• Mohseni Hooman

Classifications

• A61B5/242

  Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents · CPC title

• G01R33/0076 Primary

  Protection, e.g. with housings against stray fields · CPC title

• H01B11/04

  with pairs or quads mutually positioned to reduce cross-talk · CPC title

• A61B5/245

  specially adapted for magnetoencephalographic [MEG] signals · CPC title

• A61B2562/0223

  Magnetic field sensors · CPC title