Stray field cancellation for steering torque sensors

Abstract

Stray magnetic field cancellation for a steering torque sensor is disclosed. A method for stray magnetic field cancellation for a steering torque sensor, the method comprising receiving a detected magnetic field from at least one magnetic sensor disposed within a torque sensing region, the detected magnetic field corresponding to an angular displacement between an upper steering shaft and a lower steering shaft of an electric power steering system. The method further comprises generating a first torque signal based on the detected magnetic field, and receiving a detected stray magnetic field from at least one stray region sensor disposed outside of the torque sensing region. The method further comprises determining a torque signal error based on the detected stray magnetic field, and generating a second torque signal based on the first torque signal and the torque signal error. The method further comprises selectively controlling at least a portion of the electric power steering system using the second torque signal.

Description

[0001] This divisional application is a divisional application of the application filed on June 18, 2020, with application number 202010559807.4. Technical Field

[0002] This disclosure relates to electric power steering systems, and more particularly to stray magnetic field cancellation for steering torque sensors used in electric power steering systems. Background Technology

[0003] Vehicles such as cars, trucks, SUVs, crossovers, minivans, or other suitable vehicles typically include power steering features such as electric power steering (EPS) systems. EPS systems are generally configured to provide steering assistance to the operator of the corresponding vehicle. For example, an EPS system can be configured to apply auxiliary torque to an electric motor connected to the steering mechanism. When the operator interacts with the hand-held steering wheel or steering wheel associated with the steering mechanism, the amount of force or torque applied by the operator to the hand-held steering wheel or steering wheel is assisted by the electric motor (e.g., reducing the amount of force or torque required for the operator to perform the corresponding steering maneuver).

[0004] In such an EPS system, a torque sensor measures the input torque corresponding to the amount of torque applied by the operator to the steering wheel. Typically, the torque sensor detects the angular displacement between the upper and lower shafts in the EPS system. The upper and lower shafts are assembled with a torsion bar internally attached between them, resulting in a torsion angle linearly proportional to the torque applied by the operator to the steering wheel when torque is applied between the shafts. This torsion angle facilitates the flow of magnetic flux between the two rotors assembled to either shaft. The upper shaft rotor typically includes a permanent magnet serving as a magnetic source, while the lower shaft rotor typically includes a pair of ferromagnetic ring structures serving as a magnetic flux path. The ferromagnetic ring structures transmit magnetic flux through an air gap region, and the magnetic flux density generated in a given cross-sectional area of ​​the air gap region is linearly proportional to the displacement angle and the torque applied to the shaft. This magnetic flux density can be measured using a magnetic sensor (e.g., a Hall effect sensor) to generate an electrical signal proportional to the applied torque. Summary of the Invention

[0005] This disclosure generally relates to electric power steering systems.

[0006] One aspect of the disclosed embodiments includes a steering torque sensor system comprising at least one magnetic sensor disposed within a torque sensing region for detecting a magnetic field within the torque sensing region to determine angular displacement between an upper steering shaft and a lower steering shaft. The steering torque sensor system also includes at least one stray area sensor located outside the torque sensing region for detecting stray magnetic fields.

[0007] Another aspect of the disclosed embodiments includes a system for canceling stray magnetic fields in a steering torque sensor. The system includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive a detected magnetic field from at least one magnetic sensor disposed within a torque sensing region, the detected magnetic field corresponding to an angular displacement between an upper steering shaft and a lower steering shaft of an electric power steering system; generate a first torque signal based on the detected magnetic field; receive a detected stray magnetic field from at least one stray area sensor disposed outside the torque sensing region; determine a torque signal error based on the detected stray magnetic field; generate a second torque signal based on the first torque signal and the torque signal error; and use the second torque signal to selectively control at least a portion of the electric power steering system.

[0008] Another aspect of the disclosed embodiments includes a method for canceling stray magnetic fields in a steering torque sensor. The method includes: receiving a detected magnetic field from at least one magnetic sensor disposed within a torque sensing region, the detected magnetic field corresponding to an angular displacement between an upper steering axis and a lower steering axis of an electric power steering system. The method further includes: generating a first torque signal based on the detected magnetic field, and receiving the detected stray magnetic field from at least one stray area sensor disposed outside the torque sensing region. The method further includes: determining a torque signal error based on the detected stray magnetic field, and generating a second torque signal based on the first torque signal and the torque signal error. The method further includes: using the second torque signal to selectively control at least a portion of the assisted electric power steering system to reduce errors from the stray magnetic field.

[0009] Another aspect of the disclosed embodiments includes an apparatus comprising at least one magnetic sensor that detects a magnetic field within a torque sensing region, the detected magnetic field corresponding to an amount of torque applied to a hand-held steering wheel associated with an electric power steering system. The apparatus also includes at least one stray area sensor that detects stray magnetic fields outside the torque sensing region, the stray magnetic fields corresponding to an amount of error that may affect the detected torque applied to the hand-held steering wheel. The apparatus further includes a controller configured to: generate a first torque signal based on the detected magnetic field; determine a torque signal error based on the detected stray magnetic field; generate a second torque signal based on the first torque signal and the torque signal error; and use the second torque signal to selectively control at least a portion of the electric power steering system.

[0010] These and other advantages and features will become more apparent from the following description taken in conjunction with the accompanying drawings. Attached Figure Description

[0011] The subject matter considered to be the invention is specifically pointed out and clearly stated in the claims at the end of the specification. The foregoing and other features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein: Figure 1 The vehicle based on the principles of this disclosure is shown in general.

[0012] Figure 2 A perspective view of a steering torque sensor subjected to a stray magnetic field, based on the principles of this disclosure, is shown in general.

[0013] Figure 3 A cross-sectional view of a steering torque sensor subjected to a stray magnetic field, based on the principles of this disclosure, is shown in general.

[0014] Figure 4 One aspect of a method for canceling stray magnetic fields according to the principles of this disclosure is generally shown.

[0015] Figure 5 This roughly illustrates another aspect of the method for canceling stray magnetic fields.

[0016] Figure 6 A block diagram of a stray magnetic field cancellation system based on the principles of this disclosure is shown in general.

[0017] Figure 7 This is a flowchart that generally illustrates a stray magnetic field cancellation method based on the principles of this disclosure. Detailed Implementation

[0018] The following discussion pertains to various embodiments of this disclosure. While one or more of these embodiments may be preferred, the disclosed embodiments should not be construed as or otherwise used to limit the scope of this disclosure, including the claims. Furthermore, those skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is intended only as an exemplary discussion of that embodiment and is not intended to imply that the scope of this disclosure, including the claims, is limited to that embodiment.

[0019] This paper discloses a system and method for compensating for torque sensor errors caused by stray magnetic fields originating from a composite of single fixed sources.

[0020] As described, vehicles such as cars, trucks, SUVs, crossovers, minivans, or other suitable vehicles typically include power steering features such as electric power steering (EPS) systems. EPS systems are generally configured to provide steering assistance to the operator of the corresponding vehicle. For example, an EPS system may be configured to apply auxiliary torque to an electric motor connected to the steering mechanism. When the operator interacts with the hand-held steering wheel or steering wheel associated with the steering mechanism, the amount of force or torque applied by the operator to the hand-held steering wheel or steering wheel is assisted by the electric motor (e.g., reducing the amount of force or torque required for the operator to perform the corresponding steering maneuver).

[0021] In such an EPS system, a torque sensor measures the input torque corresponding to the amount of torque applied by the operator to the steering wheel. Typically, the torque sensor detects the angular displacement between the upper and lower shafts in the EPS system. These shafts are assembled with a torsion bar internally attached between them, resulting in a torsion angle that is linearly proportional to the torque applied by the operator to the steering wheel when torque is applied between the shafts. This torsion angle facilitates the flow of magnetic flux between the two rotors assembled to either shaft. The upper shaft rotor typically includes a permanent magnet serving as a magnetic source, while the lower shaft rotor typically includes a pair of ferromagnetic ring structures serving as a magnetic flux path. These ferromagnetic ring structures transmit magnetic flux through an air gap region, and the magnetic flux density generated in a given cross-sectional area of ​​the air gap region is linearly proportional to the displacement angle and the torque applied to the shaft. This magnetic flux density can be measured using a magnetic sensor (e.g., a Hall effect sensor) to generate an electrical signal proportional to the applied torque. Magnetic sensors are typically housed on a printed circuit board (e.g., or a circuit card) and a plastic housing known as a probe housing assembly (PHA).

[0022] However, due to the nature of the type of magnetic sensor used to detect the magnetic field, torque measurements (e.g., corresponding to the magnetic field amplitude) can be susceptible to stray magnetic fields that may be incident on the EPS system. When stray fields are superimposed on the desired field measured within the torque sensor assembly, these stray fields can introduce measurement errors into the torque measurement, potentially leading to unacceptable system performance.

[0023] With the increasing electrification of systems in vehicles, especially where conductors carrying high currents are used, sources of stray magnetic fields may exist near torque sensors. This can cause measurement errors (e.g., when these fields are present). Currently, sensor designs do not consider reducing or eliminating errors caused by these stray fields.

[0024] Therefore, systems and methods such as those described herein are desirable for compensating for torque sensor errors caused by stray magnetic fields originating from a monolithic fixed source. In some embodiments, the systems and methods described herein can be configured to provide a non-contact torque sensor using magnetic sensing techniques. The systems and methods described herein can be configured to use one or more magnetic sensors within the torque sensing device to measure magnetic flux density proportional to steering torque (e.g., the amount of torque applied by the operator to a hand-held steering wheel). The systems and methods described herein can be configured to use one or more magnetic sensors outside the sensing area as stray field sensors, in addition to using one or more magnetic sensors within the torque sensing device. In some embodiments, the stray field sensors can be positioned at a distance and orientation such that the stray field sensors are not affected by the inherent magnetic components of the torque sensing device.

[0025] In some embodiments, sensors capable of measuring along one or more axes of magnetic field detection (e.g., depending on the sensing application) may be utilized. In some embodiments, the systems and methods described herein may be configured to characterize stray magnetic field sources at locations corresponding to the steering mechanism of torque sensing devices and EPS systems. The systems and methods described herein may be configured to measure the outputs of magnetic sensors and stray field sensors (e.g., torque sensing devices) across the operating range of stray field sources.

[0026] In some embodiments, the systems and methods described herein can be configured to determine the baseline performance of an EPS system (e.g., and a torque sensing device). The systems and methods described herein can be configured to measure a magnetic field in a static, neutral hand-held steering wheel position, where no torque is applied to the hand-held steering wheel and there is no response from the EPS system that could cause physical movement of the EPS system (e.g., no stray magnetic field).

[0027] In some embodiments, the systems and methods described herein can be configured to measure the magnetic field at the level of change of the incident stray magnetic field present in the EPS system. The systems and methods described herein can be configured to measure and record the magnetic field and stray magnetic field at this level of change.

[0028] In some embodiments, the systems and methods described herein can be configured to establish a mathematical relationship between a signal measured by a stray field sensor and the amount of error sensed on a torque sensor (e.g., a magnetic sensor for measuring a magnetic field corresponding to torque applied to a hand-held steering wheel). The systems and methods described herein can be configured to use this mathematical relationship to calculate a mathematical cancellation factor. The systems and methods described herein can be configured to adjust the torque signal corresponding to the detected magnetic field (e.g., the torque signal for a given detected magnetic field) by subtracting the corresponding cancellation factor. The systems and methods described herein can be configured to dynamically remove the error applied to the torque sensor from the stray magnetic field by generating an estimate of the torque error using the stray field measurement results and removing the estimated torque error from the torque signal.

[0029] In some embodiments, the systems and methods described herein can be configured to generate a torque error model based on the relationship between detected magnetic fields and detected stray magnetic fields at different operating levels for a stray field source. The systems and methods described herein can store the torque error model in associated memory. The systems and methods described herein can be configured to access the torque error model to determine an estimated error associated with the detected stray field. The systems and methods described herein can be configured to adjust the torque signal based on the estimated error.

[0030] In some embodiments, a stray field sensor may include a stray field probe. The stray field probe may provide a digital or analog output. In some embodiments, the stray field probe may include a digital output having a dedicated input and / or output (I / O) interface to the controller of the EPS system. In some embodiments, the digital output may share existing torque signal lines and I / O, which can reduce the number of wires used in the systems described herein. In some embodiments, the stray field probe may share a common power supply with a torque sensing device (e.g., including a magnetic field sensor). In some embodiments, the stray field probe may receive power from an isolated power supply. In some embodiments, the systems and methods described herein may be configured to use stray field cancellation to derive any suitable mechanization of the torque sensor.

[0031] In some embodiments, the systems and methods described herein can be configured to receive a detected magnetic field from at least one magnetic sensor disposed within a torque sensing region, the detected magnetic field corresponding to an angular displacement between the upper and lower steering axes of the electric power steering system. The systems and methods described herein can be configured to generate a first torque signal based on the detected magnetic field. The systems and methods described herein can be configured to receive a detected stray magnetic field from at least one stray region sensor disposed outside the torque sensing region.

[0032] The systems and methods described herein can be configured to determine torque signal errors based on detected stray magnetic fields. The systems and methods described herein can be configured to generate a second torque signal based on a first torque signal and a torque signal error estimate. The systems and methods described herein can be configured to selectively control at least a portion of an electric power steering system using the second torque signal. In some embodiments, the systems and methods described herein can be configured to estimate torque signal errors using a torque error model configured to estimate torque signal errors using detected stray magnetic fields.

[0033] In some embodiments, at least one stray area sensor includes a probe. In some embodiments, the probe provides a digital output. In some embodiments, the probe provides an analog output. In some embodiments, at least one magnetic sensor and at least one stray area sensor are disposed on a printed circuit board. In some embodiments, at least one stray area sensor shares a common power supply with at least one magnetic sensor. In some embodiments, at least one stray area sensor receives power from an isolated power supply, which is different from the power supply that provides power to at least one magnetic sensor. In some embodiments, a first torque signal represents the amount of torque applied to a hand-held steering wheel associated with the electric power steering system. In some embodiments, the detected magnetic field is affected by a detected stray magnetic field.

[0034] Figure 1 Vehicle 10, generally illustrated according to the principles of this disclosure, is shown. Vehicle 10 may include any suitable vehicle, such as a car, truck, SUV, minivan, crossover, any other passenger vehicle, any suitable commercial vehicle, or any other suitable vehicle. Although vehicle 10 is illustrated as a passenger vehicle with wheels and used on a road, the principles of this disclosure can be applied to other means of transportation, such as airplanes, ships, trains, drones, or other suitable vehicles.

[0035] Vehicle 10 includes a body 12 and an engine hood 14. A passenger compartment 18 is defined at least partially by the body 12. Another portion of the body 12 defines an engine compartment 20. The engine hood 14 is movably attached to a portion of the body 12 such that when the engine hood 14 is in a first position or open position, the engine hood 14 provides access to the engine compartment 20, and when the engine hood 14 is in a second position or closed position, the engine hood 14 covers the engine compartment 20. In some embodiments, the engine compartment 20 may be located in the rear portion of the vehicle 10 (compared to what is typically shown).

[0036] The passenger compartment 18 may be located behind the engine compartment 20, but in embodiments where the engine compartment 20 is located in the rear portion of the vehicle 10, the passenger compartment 18 may be located in front of the engine compartment 20. The vehicle 10 may include any suitable propulsion system, including an internal combustion engine, one or more electric motors (e.g., an electric vehicle), one or more fuel cells, a hybrid propulsion system including a combination of an internal combustion engine and one or more electric motors (e.g., a hybrid vehicle), and / or any other suitable propulsion system.

[0037] In some embodiments, vehicle 10 may include a gasoline-powered engine, such as a spark-ignition engine. In some embodiments, vehicle 10 may include a diesel-powered engine, such as a compression-ignition engine. Engine compartment 20 houses and / or surrounds at least some components of the propulsion system of vehicle 10. Additionally or optionally, propulsion control devices (e.g., accelerator actuators, brake actuators, steering wheel, and other such components) are arranged in passenger compartment 18 of vehicle 10. The propulsion control devices may be actuated or controlled by the driver of vehicle 10 and may be directly connected to corresponding components of the propulsion system, such as throttle, brakes, axles, and vehicle transmission. In some embodiments, the propulsion control devices may transmit signals to a vehicle computer (e.g., drive-by-wire), which in turn may control the corresponding propulsion components of the propulsion system. Thus, in some embodiments, vehicle 10 may be an autonomous vehicle.

[0038] In some embodiments, vehicle 10 includes a transmission that communicates with the crankshaft via a flywheel, clutch, or hydraulic coupling. In some embodiments, the transmission includes a manual transmission. In some embodiments, the transmission includes an automatic transmission. In the case of an internal combustion engine or hybrid vehicle, vehicle 10 may include one or more pistons that cooperate with the crankshaft to generate force, which is transmitted through the transmission to one or more shafts to rotate wheels 22. When vehicle 10 includes one or more electric motors, a vehicle battery and / or fuel cell provides energy to the electric motors to rotate wheels 22.

[0039] Vehicle 10 may include an autonomous vehicle propulsion system, such as cruise control, adaptive cruise control, automatic braking control, other autonomous vehicle propulsion systems, or combinations thereof. Vehicle 10 may be an autonomous or semi-autonomous vehicle, or other suitable type of vehicle. Vehicle 10 may include additional or fewer features compared to those generally shown and / or disclosed herein.

[0040] In some embodiments, vehicle 10 may include an Ethernet component 24, a controller area network (CAN) bus 26, a media-oriented system transport component (MOST) 28, a FlexRay component 30 (e.g., a brake-by-wire system), and a local interconnect network component (LIN) 32. Vehicle 10 may use the CAN bus 26, MOST 28, FlexRay component 30, LIN 32, other suitable network or communication systems, or combinations thereof, to transmit various information from, for example, sensors inside or outside the vehicle, to, for example, various processors or controllers inside or outside the vehicle. Vehicle 10 may include additional or fewer features compared to those generally shown and / or disclosed herein.

[0041] Vehicle 10 may include an electric power steering (EPS) system. The EPS system may include an EPS controller area network (CAN) bus. The EPS CAN bus can communicate with the vehicle CAN bus of vehicle 10. The vehicle CAN bus may include features similar to CAN bus 26 or other suitable features. The vehicle CAN bus can communicate with various sensors within vehicle 10 and receive various measurements from these sensors. For example, one or more sensors of vehicle 10 may measure vehicle speed, vehicle yaw rate, steering wheel angle, wheel angle, other suitable measurements, or combinations thereof. The vehicle CAN bus can receive one or more signals indicating various measurements from the controller of vehicle 10. For example, the vehicle CAN bus can receive a vehicle speed signal indicating a measured vehicle speed of vehicle 10. The vehicle CAN bus can transmit one or more signals to the EPS CAN bus. The EPS CAN bus can transmit one or more signals to the EPS controller.

[0042] The EPS system can be configured to assist and / or control the steering of vehicle 10. The EPS system may include or communicate with various sensors configured to measure various aspects of the steering system of vehicle 10. For example, in Figure 6As generally illustrated herein, an EPS system may include one or more controllers, such as an EPS microcontroller unit (MCU), hereinafter referred to as controller 102. Controller 102 may include processor 104 and associated memory 106. Processor 104 may include any suitable processor, such as those described herein. Memory 106 may include a single disk or multiple disks (e.g., a hard disk drive) and includes a storage management module that manages one or more partitions within memory 106. In some embodiments, memory 106 may include flash memory, semiconductor (solid-state) memory, etc. Memory 106 may include random access memory (RAM), read-only memory (ROM), or a combination thereof. Memory 106 may include instructions that, when executed by processor 104, cause processor 104 to detect at least an input torque corresponding to the torque applied by an operator to the hand-held steering wheel of vehicle 10. In addition to the processors and / or memory described herein, controller 102 may also include any suitable number of processors and / or memory. It should be understood that an EPS system may include any suitable number of controllers, processors, and memory.

[0043] Controller 102 can determine various values ​​corresponding to one or more signals. For example, controller 102 can receive a vehicle speed signal (e.g., a first vehicle speed signal) and can determine a vehicle speed value (e.g., a first vehicle speed) based on that vehicle speed signal. Controller 102 can determine one or more auxiliary torque values ​​based on various values ​​determined from one or more signals. The one or more auxiliary torque values ​​can correspond to the amount of torque to be supplied to the EPS motor. Controller 102 can use one or more auxiliary torque values ​​to selectively control the EPS motor. The EPS motor can communicate with a steering system, such as the steer-by-wire system of vehicle 10 or other suitable steering system. When the EPS motor is controlled according to one or more auxiliary torque values, the EPS motor provides steering assistance to the steering components of the steering system of vehicle 10. The steering assistance can reduce the amount of torque or force required for the operator of vehicle 10 to perform the corresponding steering maneuver.

[0044] In some embodiments, the controller 102 may communicate with the torque sensing device 200, such as Figure 2 As generally shown in the diagram. Device 200 may include one or more magnetic sensors 202 (e.g., which may be referred to as torque sensors), said one or more magnetic sensors 202 being disposed in the torque sensing region 204 of device 200, such as... Figure 3 As generally shown. Sensor 202 may include any suitable sensor, probe or other suitable mechanism configured to detect the magnetic field in torque sensing region 204.

[0045] The device 200 may include one or more stray magnetic field sensors 206 configured to detect stray magnetic fields that affect the magnetic field detected by sensor 202. Sensor 206 may include any suitable sensor, probe, or other suitable mechanism configured to detect stray magnetic fields near the device 200. Sensor 206 may be positioned on the device 200, outside the torque sensing region 204, such that sensor 206 is unaffected by magnetic fields within the torque sensing region 204.

[0046] In some embodiments, sensor 202 and / or sensor 204 may operate along one or more axes of magnetic field detection.

[0047] The controller 102 can receive a detected magnetic field (e.g., a value representing the detected magnetic field) within the torque sensing region 204 from the sensor 202. The detected magnetic field may correspond to the angular displacement between the upper and lower steering shafts of the EPS system. The controller 102 can generate a first torque signal based on the detected magnetic field. The first torque signal may represent the amount of torque applied by the operator to the hand-held steering wheel of the vehicle 10. The first torque signal (e.g., and the detected magnetic field) may be affected by one or more stray magnetic fields adjacent to the torque sensing device 200. It should be understood that the controller 102 can receive multiple detected magnetic fields from the sensor 206 and can generate corresponding torque signals.

[0048] The controller 102 can receive detected stray magnetic fields (e.g., or values ​​representing the detected stray magnetic fields) from the sensor 206. The controller 102 can determine torque signal errors based on the detected stray magnetic fields. For example, the controller 102 can access a torque error model and identify the estimation error corresponding to the detected stray magnetic field (e.g., the amount of influence of the detected stray magnetic field on the magnetic field within the torque sensing region 204).

[0049] Controller 102 can determine the torque signal error based on the estimated error. Controller 102 can generate a second torque signal based on the first torque signal and the torque signal error. Controller 102 can then provide the second torque signal to the EPS system (e.g., the EPS motor or other suitable component). As described, the EPS system can use the second torque signal as an input torque signal.

[0050] In some embodiments, controller 102 may perform the methods described herein. However, the methods described herein, as performed by controller 102, are not intended to be limiting, and any type of software executing on the controller may perform the methods described herein without departing from the scope of this disclosure. For example, a controller such as a processor executing software within a computing device may perform the methods described herein.

[0051] Figure 7 This is a flowchart generally illustrating a stray magnetic field cancellation method 300 according to the principles of this disclosure. At 302, method 300 receives a detected magnetic field corresponding to the angular deployment between the upper and lower steering axes of the electric power steering system. For example, controller 102 receives the detected magnetic field from sensor 202.

[0052] At 304, method 300 generates a first torque signal based on the detected magnetic field. For example, controller 102 generates the first torque signal.

[0053] At 306, method 300 receives the detected stray magnetic field. For example, controller 102 receives the detected stray magnetic field from sensor 206.

[0054] At 308, method 300 determines the torque signal error based on the detected stray magnetic field. For example, controller 102 uses a torque error model to determine the torque signal error.

[0055] At 310, method 300 generates a second torque signal based on a first torque signal and a torque signal error. For example, controller 102 generates the second torque signal based on the first torque signal and the torque signal error.

[0056] At 312, method 300 uses a second torque signal to selectively control at least a portion of the electric power steering system. For example, controller 102 uses the second torque signal to selectively control at least a portion of the EPS system.

[0057] In some embodiments, a system for canceling stray magnetic fields from a steering torque sensor includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive a detected magnetic field from at least one magnetic sensor disposed within a torque sensing region, the detected magnetic field corresponding to an angular displacement between an upper steering shaft and a lower steering shaft of an electric power steering system; generate a first torque signal based on the detected magnetic field; receive a detected stray magnetic field from at least one stray region sensor disposed outside the torque sensing region; determine a torque signal error based on the detected stray magnetic field; generate a second torque signal based on the first torque signal and the torque signal error; and selectively control at least a portion of the electric power steering system using the second torque signal.

[0058] In some embodiments, at least one stray area sensor includes a probe. In some embodiments, the probe provides a digital output. In some embodiments, the probe provides an analog output. In some embodiments, at least one magnetic sensor and at least one stray area sensor are disposed on a printed circuit board. In some embodiments, at least one stray area sensor shares a common power supply with at least one magnetic sensor. In some embodiments, at least one stray area sensor receives power from an isolated power supply, which is different from the power supply that provides power to at least one magnetic sensor. In some embodiments, a first torque signal represents the amount of torque applied to a hand-held steering wheel associated with an electric power steering system. In some embodiments, the detected magnetic field is affected by a detected stray magnetic field. In some embodiments, the instruction also prompts the processor to use a torque error model to determine a torque signal error, the torque error model being configured to estimate the torque signal error using the detected stray magnetic field.

[0059] In some embodiments, a method for canceling stray magnetic fields in a steering torque sensor includes: receiving a detected magnetic field from at least one magnetic sensor disposed within a torque sensing region, the detected magnetic field corresponding to an angular displacement between an upper steering axis and a lower steering axis of an electric power steering system. The method further includes: generating a first torque signal based on the detected magnetic field, and receiving the detected stray magnetic field from at least one stray region sensor disposed outside the torque sensing region. The method further includes: determining a torque signal error based on the detected stray magnetic field, and generating a second torque signal based on the first torque signal and the torque signal error. The method further includes: selectively controlling at least a portion of the electric power steering system using the second torque signal.

[0060] In some embodiments, at least one stray area sensor includes a probe. In some embodiments, the probe provides a digital output. In some embodiments, the probe provides an analog output. In some embodiments, at least one magnetic sensor and at least one stray area sensor are disposed on a printed circuit board. In some embodiments, a first torque signal represents the amount of torque applied to a hand-held steering wheel associated with an electric power steering system. In some embodiments, the detected magnetic field is affected by a detected stray magnetic field. In some embodiments, the method further includes using a torque error model to determine a torque signal error, the torque error model being configured to estimate the torque signal error using the detected stray magnetic field.

[0061] In some embodiments, an apparatus includes at least one magnetic sensor that detects a magnetic field within a torque sensing region, the detected magnetic field corresponding to the amount of torque applied to a hand-held steering wheel associated with an electric power steering system. The apparatus also includes at least one stray area sensor that detects stray magnetic fields outside the torque sensing region, the detected magnetic field being influenced by the detected stray magnetic field. The apparatus further includes a controller configured to: generate a first torque signal based on the detected magnetic field; determine a torque signal error based on the detected stray magnetic field; generate a second torque signal based on the first torque signal and the torque signal error; and use the second torque signal to selectively control at least a portion of the electric power steering system.

[0062] In some embodiments, the controller is also configured to use a torque error model to determine the torque signal error, the torque error model being configured to estimate the torque signal error using detected stray magnetic fields.

[0063] The foregoing discussion is intended to illustrate the principles and various embodiments of this disclosure. Once the foregoing disclosure is fully understood, many variations and modifications will become apparent to those skilled in the art. The following claims are intended to be construed as encompassing all such variations and modifications.

[0064] The word “example” is used herein to mean used as an example, illustration, or description. Any aspect or design described herein as an “example” is not necessarily to be construed as being more preferred or advantageous than other aspects or designs. Rather, the use of the word “example” is intended to present a concept in a specific manner. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise stated or clearly apparent from the context, “X comprises A or B” is intended to mean any natural inclusion. That is, if X comprises A; X comprises B; or X comprises A and B, then “X comprises A or B” is satisfied in any of the foregoing cases. Additionally, the article “a / an” used in this application and the appended claims should generally be interpreted as meaning “one or more” unless otherwise stated or clearly apparent from the context to the singular form. Furthermore, unless so described, the use of the terms “an embodiment” or “one embodiment” throughout the document is not intended to refer to the same embodiment or implementation.

[0065] The systems, algorithms, methods, and instructions described herein can be implemented in hardware, software, or any combination thereof. Hardware may include, for example, a computer, intellectual property (IP) core, application-specific integrated circuit (ASIC), programmable logic array, optical processor, programmable logic controller, microcode, microcontroller, server, microprocessor, digital signal processor, or any other suitable circuit. In the claims, the term "processor" should be understood to include any of the foregoing hardware, individually or in combination. The terms "signal" and "data" are used interchangeably.

[0066] As used herein, the term "module" can include a packaged functional hardware unit designed for use with other components, a set of instructions executable by a controller (e.g., a processor executing software or firmware), processing circuitry configured to perform a specific function, and a separate hardware or software component that interfaces with a larger system. For example, a module can include an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), circuitry, digital logic circuitry, analog circuitry, a combination of discrete circuitry, gate circuits, and other types of hardware or combinations thereof. In other embodiments, a module can include memory storing instructions executable by a controller to implement the features of the module.

[0067] Furthermore, in one respect, for example, the system described herein may be implemented using a general-purpose computer or general-purpose processor with a computer program that, when executed, performs any of the corresponding methods, algorithms, and / or instructions described herein. Additionally or alternatively, for example, a special-purpose computer / processor may be utilized, which may contain additional hardware for performing any of the methods, algorithms, or instructions described herein.

[0068] Furthermore, all or part of the embodiments of this disclosure may take the form of a computer program product accessible from, for example, a computer-usable or computer-readable medium. A computer-usable or computer-readable medium may be, for example, any means that can tangibly contain, store, communicate, or transmit a program for use by or in connection with any processor. The medium may be, for example, an electrical, magnetic, optical, electromagnetic, or semiconductor device. Other suitable media may also be used.

[0069] The above embodiments, implementations, and aspects have been described to allow for easy understanding of this disclosure and do not limit it. Rather, this disclosure is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which should be interpreted in the broadest possible sense to cover all such modifications and equivalent structures permitted by law.

Claims

1. A system for canceling stray magnetic fields in a steering torque sensor, the system comprising: processor; as well as Memory containing instructions that, when executed by a processor, cause the processor to: The detected magnetic field is received from at least one magnetic sensor located within the torque sensing area, the detected magnetic field corresponding to the angular displacement between the upper and lower steering shafts of the electric power steering system; The first torque signal is generated based on the detected magnetic field; The detected stray magnetic field is received from at least one stray region sensor located outside the torque sensing region; The torque signal error is determined using a torque error model based on the detected stray magnetic field. The torque error model is generated based on the relationship between at least one other detected stray magnetic field associated with the incident stray field source at the corresponding level and at least one other detected magnetic field. The torque error model is configured to model the amount of influence of the detected stray magnetic field on the detected magnetic field in the torque sensing region. A second torque signal is generated based on the first torque signal and the torque signal error; and A second torque signal is used to selectively control at least a portion of the electric power steering system.

2. The system of claim 1, wherein, The at least one stray area sensor includes a probe.

3. The system of claim 2, wherein, The probe provides digital output.

4. The system of claim 2, wherein, The probe provides analog output.

5. The system of claim 1, wherein, The at least one magnetic sensor and the at least one stray area sensor are mounted on a printed circuit board.

6. The system of claim 1, wherein, The at least one stray area sensor shares a common power supply with the at least one magnetic sensor.

7. The system according to claim 1, wherein, The at least one stray area sensor receives power from an isolated power source, which is different from the power source that supplies power to the at least one magnetic sensor.

8. The system according to claim 1, wherein, The first torque signal represents the amount of torque applied to the hand-held steering wheel associated with the electric power steering system.

9. The system according to claim 1, wherein, The detected magnetic field is affected by the detected stray magnetic field.

10. A method for canceling stray magnetic fields in a steering torque sensor, the method comprising: The detected magnetic field is received from at least one magnetic sensor located within the torque sensing area, the detected magnetic field corresponding to the angular displacement between the upper and lower steering shafts of the electric power steering system; The first torque signal is generated based on the detected magnetic field; The detected stray magnetic field is received from at least one stray region sensor located outside the torque sensing region; The torque signal error is determined using a torque error model based on the detected stray magnetic field. The torque error model is generated based on the relationship between at least one other detected stray magnetic field associated with the incident stray field source at the corresponding level and at least one other detected magnetic field. The torque error model is configured to model the amount of influence of the detected stray magnetic field on the detected magnetic field in the torque sensing region. A second torque signal is generated based on the first torque signal and the torque signal error; and A second torque signal is used to selectively control at least a portion of the electric power steering system.

11. The method according to claim 10, wherein, The at least one stray area sensor includes a probe.

12. The method according to claim 11, wherein, The probe provides digital output.

13. The method according to claim 11, wherein, The probe provides analog output.

14. The method of claim 10, wherein, The at least one magnetic sensor and the at least one stray area sensor are mounted on a printed circuit board.

15. The method according to claim 10, wherein, The first torque signal represents the amount of torque applied to the hand-held steering wheel associated with the electric power steering system.

16. The method of claim 10, wherein, The detected magnetic field is affected by the detected stray magnetic field.

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