JP2014149237A - Rotation angle detector, torque sensor, and electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor capable of high-accurately detecting a rotation angle of a rotation shaft provided on a vehicle.SOLUTION: A torque sensor 5 includes: a torsion bar 12c for coupling an input shaft 12a and an output shaft 12b to each other; and a magnetic circuit 57 for varying magnetism imparted to a Hall IC 56 in response to variations in a relative rotation angle of the output shaft 12b with respect to the input shaft 12a. The torque sensor 5 detects the relative rotation angle of the output shaft 12b with respect to the input shaft 12a on the basis of an output signal of the Hall IC 56, namely, an angle of torsion of the torsion bar 12c, and detects steering torque on the basis of the detected angle of torsion. In this case, the detected angle of torsion is corrected on the basis of an azimuth direction to which a vehicle is oriented.

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of a rotation shaft provided in a vehicle, and a torque sensor and an electric power steering device using the rotation angle detection device.

  The electric power steering apparatus is equipped with a torque sensor that detects a steering torque applied to a steering shaft of a vehicle when a driver performs a steering operation. Conventionally, a torque sensor described in Patent Literature 1 is known as this type of torque sensor. In the torque sensor described in Patent Document 1, the steering shaft has a structure in which an input shaft and an output shaft are connected to each other via a torsion bar. The torque sensor includes a magnetic circuit that changes the magnetism applied to the Hall IC in accordance with a change in the relative rotation angle of the output shaft with respect to the input shaft. In this torque sensor, when a steering torque is applied to the steering shaft in accordance with the steering operation by the driver, the torsion bar is twisted to cause a relative rotational displacement between the input shaft and the output shaft. As a result, the magnetic strength applied to the Hall IC changes, and the output signal of the Hall IC changes. That is, the output signal of the Hall IC changes according to the twist angle of the torsion bar. Using this, the torque sensor described in Patent Document 1 detects the torsion angle of the torsion bar based on the output signal of the Hall IC, and obtains the steering torque based on the detected torsion angle.

JP 2005-98821 A

  Incidentally, in such a torque sensor provided on the steering shaft, the magnetic detection direction of the Hall IC is usually inclined with respect to the horizontal direction. This is because the installation posture of the hall IC is inclined with respect to the horizontal direction when the torque sensor is attached along the steering shaft because the installation posture of the steering shaft in the vehicle is not horizontal. When the magnetic detection direction of the Hall IC is inclined with respect to the horizontal direction, the Hall IC detects geomagnetism depending on the direction of the vehicle. In such a situation, the Hall IC outputs a voltage signal corresponding to the strength of the magnetism obtained by combining the magnetism applied from the magnetic circuit and the geomagnetism. The direction of geomagnetism acting on the Hall IC changes according to the direction of the vehicle. Therefore, the magnitude of the geomagnetism detected by the Hall IC changes according to the direction of the vehicle, and it becomes difficult to accurately detect the torsion angle of the torsion bar. This is a factor that lowers the detection accuracy of the steering torque.

  Such a problem is not limited to a torque sensor, and is a problem common to a rotation angle detection device that detects a rotation angle of a rotation shaft provided in a vehicle using a magnetoelectric conversion element such as a Hall IC.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a rotation angle detection device, a torque sensor, and an electric power steering capable of detecting a rotation angle of a rotation shaft provided in a vehicle with high accuracy. To provide an apparatus.

  In order to solve the above-described problem, a magnetic circuit that changes magnetism applied to a magnetoelectric conversion element according to a change in a rotation angle of a rotation shaft mounted on a vehicle is provided, and based on an output signal of the magnetoelectric conversion element The rotation angle detection device that detects the rotation angle of the rotation shaft includes a vehicle direction detection unit that detects the direction of the vehicle with respect to geomagnetism, and corrects the detected rotation angle based on the direction of the vehicle.

  According to this configuration, even if the output signal of the magnetoelectric conversion element changes according to the direction of the vehicle due to the influence of geomagnetism, the rotation angle of the rotating shaft detected based on the output signal of the magnetoelectric conversion element Is corrected based on the direction of the vehicle. As a result, since the influence of geomagnetism can be eliminated from the detected rotation angle, the rotation angle of the rotation shaft can be detected with high accuracy.

  By the way, the strength of geomagnetism changes according to the latitude of the current position of the vehicle. Specifically, the geomagnetism becomes stronger as the current position of the vehicle is higher latitude, and the geomagnetism becomes weaker as the latitude is lower. Therefore, the offset voltage of the output signal of the magnetoelectric conversion element due to geomagnetism changes according to the latitude of the current position of the vehicle.

  Therefore, it is preferable that the rotation angle detection device further includes a latitude detection unit that detects the latitude of the current position of the vehicle, and further corrects the detected rotation angle based on the latitude of the current position of the vehicle.

  According to this configuration, since the rotation angle detected based on the output signal of the magnetoelectric transducer is further corrected according to the strength of the geomagnetism at the current position of the vehicle, the influence of geomagnetism can be more accurately eliminated. Can do. Therefore, the rotation angle of the rotation shaft can be detected with higher accuracy.

  In addition, a torque sensor that solves the above problem includes a torsion bar that connects a first rotating shaft and a second rotating shaft mounted on a vehicle, and a relative rotation of the second rotating shaft with respect to the first rotating shaft. As a rotation angle detection device for detecting an angle, the rotation angle detection device is provided, and the first rotation shaft or the second rotation shaft is provided on the basis of a relative rotation angle of the second rotation shaft with respect to the first rotation shaft. The applied torque is detected.

  According to this configuration, since the relative rotation angle of the second rotation shaft with respect to the first rotation shaft, in other words, the torsion angle of the torsion bar can be detected more accurately, the first rotation shaft or the second rotation The torque applied to the shaft can be detected with high accuracy.

  Furthermore, an electric power steering apparatus that solves the above-described problems includes a motor that includes the torque sensor as a torque sensor that detects a steering torque applied to a steering shaft of a vehicle during a steering operation, and that applies an assist torque to a steering mechanism of the vehicle. And a control unit that controls driving of the motor based on a steering torque detected by the torque sensor.

  According to this configuration, the steering torque applied to the steering mechanism during right steering and left steering can be detected more accurately. As a result, a situation in which the assist torque is different between right steering and left steering is less likely to occur, and the steering feeling of the driver can be improved.

  According to these rotation angle detection devices, torque sensors, and electric power steering devices, the rotation angle of the rotation shaft provided in the vehicle can be detected with high accuracy.

The block diagram which shows schematic structure of an electric power steering apparatus. The perspective view which shows the disassembled perspective structure about one Embodiment of a torque sensor. The developed view which expanded the 1st and 2nd yoke and the multipolar magnet on the plane about the torque sensor of an embodiment. The side view which shows the side surface structure of the Hall IC periphery about the torque sensor of embodiment. The graph which shows the relationship between the twist angle of a torsion bar, and the output signal of Hall IC about the torque sensor of embodiment. The flowchart which shows the procedure of the torque calculation process by the torque sensor of embodiment.

  Hereinafter, an embodiment of the torque sensor will be described. The torque sensor of this embodiment is used for an electric power steering apparatus. First, an outline of the electric power steering apparatus will be described.

  As shown in FIG. 1, the electric power steering apparatus includes a steering mechanism 1 for turning the steered wheels 3 based on an operation of the driver's steering wheel 10 and an assist mechanism 2 for assisting the driver's steering operation. Yes.

  The steering mechanism 1 includes a steering shaft 11 that serves as a rotating shaft of the steering wheel 10. The steering shaft 11 includes a column shaft 12 connected to the steering wheel 10, an intermediate shaft 13 connected to the lower end portion of the column shaft 12, and a pinion shaft 14 connected to the lower end portion of the intermediate shaft 13. A rack shaft 16 is connected to a lower end portion of the pinion shaft 14 via a rack and pinion mechanism 15. In the steering mechanism 1, when the steering shaft 11 rotates in response to the driver's operation of the steering wheel 10, the rotational motion is converted into a reciprocating linear motion in the axial direction of the rack shaft 16 via the rack and pinion mechanism 15. The reciprocating linear motion of the rack shaft 16 is transmitted to the steered wheels 3 via tie rods 17 connected to both ends thereof, whereby the steered angle of the steered wheels 3 is changed and the traveling direction of the vehicle is changed.

  The assist mechanism 2 includes a motor 20 that applies assist torque to the steering shaft 11. The motor 20 is a three-phase brushless motor. The rotation of the motor 20 is transmitted to the column shaft 12 via the speed reducer 21, whereby a motor torque is applied to the steering shaft 11 and the steering operation is assisted.

  The electric power steering apparatus is provided with various sensors for detecting the operation amount of the steering wheel 10 and the vehicle state amount. For example, the column shaft 12 is provided with a torque sensor 5 that detects torque (steering torque) Th applied to the steering shaft 11 when the driver performs a steering operation. The vehicle is provided with a vehicle speed sensor 6 that detects the traveling speed S thereof. The outputs of these sensors 5 and 6 are taken into the control device (control unit) 4. The control device 4 sets a target assist torque based on the steering torque Th and the vehicle speed S detected by the sensors 5 and 6 so that the assist torque applied from the motor 20 to the steering shaft 11 follows the target assist torque. The current supplied to the motor 20 is feedback controlled. Thus, assist control for applying motor torque to the steering shaft 11 is executed.

Next, the structure of the torque sensor 5 will be described in detail.
As shown in FIG. 2, the column shaft 12 has an input shaft 12a connected to the steering wheel 10 and an output shaft 12b connected to the intermediate shaft 13 connected on the same axis m via a torsion bar 12c. Have a structure. The axis m indicates the central axis of the column shaft 12 and extends in the front-rear direction of the vehicle and is inclined with respect to the horizontal direction.

  The torque sensor 5 includes a cylindrical holding member 50 and annular yokes 51 and 52 arranged around the holding member 50 with a predetermined gap therebetween. The holding member 50 is fitted on the lower end portion of the input shaft 12a and rotates integrally with the input shaft 12a. A multipolar magnet 53 in which N poles and S poles are alternately arranged in the circumferential direction is attached to the outer peripheral surface of the holding member 50. The yokes 51 and 52 are connected to the output shaft 12b via a connection structure (not shown), and rotate integrally with the output shaft 12b. On the inner peripheral surface of the first yoke 51 disposed on the input shaft 12a side, a plurality of claw portions 51a extending toward the output shaft 12b are formed at predetermined angular intervals. A plurality of claw portions 52a extending toward the input shaft 12a are formed at predetermined angular intervals on the inner peripheral surface of the second yoke 52 disposed on the output shaft 12b side. FIG. 3 is a development view in which the two yokes 51 and 52 and the holding member 50 are expanded on a plane. As shown in FIG. 3, the claw portions 51 a and 52 a of the yokes 51 and 52 are alternately arranged in the circumferential direction of the holding member 50, and face the multipolar magnet 53.

  As shown in FIG. 2, the torque sensor 5 has an annular first magnetic flux collecting ring 54 disposed around the first yoke 51 with a predetermined gap, and a predetermined gap with the second yoke 52. An annular second magnetic flux collecting ring 55 is provided around and spaced from the periphery. These magnetism collecting rings 54 and 55 are made of a magnetic member, and are fixed to a housing (not shown) that covers the periphery of the column shaft 12. As shown in the enlarged view in the drawing, the magnetism collecting rings 54 and 55 are respectively formed with magnetism collecting portions 54a and 55a arranged to face each other with a predetermined gap in the direction of the axis m. A Hall IC 56 is sandwiched between the magnetism collecting portions 54a and 55a. The Hall IC 56 is an integrated chip that is configured around a Hall element 56a that outputs a voltage signal corresponding to the strength of the applied magnetism (magnetic field). The magnetic detection surface 56b of the Hall element 56a is orthogonal to the axis m. Therefore, as shown in FIG. 4, the magnetic detection direction of the Hall IC 56 is inclined with respect to the horizontal direction. More specifically, the magnetic detection direction of the Hall IC 56 is a direction inclined with respect to the front-rear direction of the vehicle and a direction orthogonal to the left-right direction of the vehicle.

  As shown in FIG. 2, in the torque sensor 5, the magnetism formed by the multipolar magnet 53 is collected by the yokes 51 and 52 via the claw portions 51a and 52a. As a result, magnetism is generated in the magnetism collecting rings 54 and 55 arranged around the yokes 51 and 52, and a magnetic field is formed between the magnetism collecting portions 54a and 55a. Due to this magnetic field, magnetism along the magnetic detection direction is applied to the Hall IC 56, and the Hall IC 56 outputs a voltage signal V corresponding to the strength of the applied magnetism. Thus, in the torque sensor 5, the magnetic circuit 57 is configured by the yokes 51 and 52, the multipolar magnet 53, and the magnetism collecting rings 54 and 55. The output signal V of the Hall IC 56 is taken into the control device 4.

  On the other hand, when the driver applies a steering torque Th to the steering wheel 10, the steering torque Th is transmitted from the input shaft 12a to the output shaft 12b via the torsion bar 12c. At that time, torsional deformation corresponding to the steering torque Th occurs in the torsion bar 12c, and relative rotational displacement occurs between the input shaft 12a and the output shaft 12b. Therefore, the relative positional relationship between the multipolar magnet 53 and the claw portions 51a and 52a of the yokes 51 and 52 changes, and the magnetism collected by the yokes 51 and 52 changes. As a result, the magnetic strength applied to the Hall IC 56 changes, and the output signal of the Hall IC 56 changes. That is, in the torque sensor 5, when the relative rotation angle of the output shaft 12b with respect to the input shaft 12a, in other words, the torsion angle of the torsion bar 12c changes, the output signal of the Hall IC 56 changes. FIG. 5 shows the relationship between the torsion angle of the torsion bar 12c and the output signal of the Hall IC 56 by a solid line ma. In FIG. 5, the twist angle θt generated in the torsion bar 12 c when the steering wheel 10 is steered to the right is shown as a positive value, and the twist angle θt generated in the torsion bar 12 c when the steering wheel 10 is steered to the left is shown as a negative value. As shown in FIG. 5, the output signal V of the Hall IC 56 is set to be proportional to the twist angle θt of the torsion bar 12c. In FIG. 5, the output signal V of the Hall IC 56 when the twist angle θt is “0” is indicated by “V0”. In the memory 4a of the control device 4, a map indicated by a solid line ma in FIG. The control device 4 calculates the torsion angle θt of the torsion bar 12c from the output signal V of the Hall IC 56 using this map, and obtains the steering torque Th by multiplying the calculated torsion angle θt by the spring constant of the torsion bar 12c. .

  When the Hall IC 56 is installed in the posture shown in FIG. 4, the Hall IC 56 may detect the geomagnetism depending on the direction of the vehicle with respect to the geomagnetism (the direction of the traveling direction of the vehicle). For example, when the vehicle is facing north, the direction of geomagnetism is the direction from the front of the vehicle to the rear of the vehicle, as indicated by the two-dot chain arrow in the figure. At this time, geomagnetism is input to the magnetic detection surface 56b of the Hall IC 56. In such a situation, since the Hall IC 56 detects geomagnetism, the output signal V of the Hall IC 56 is offset by the amount of detected geomagnetism, and the correspondence between the output signal V of the Hall IC 56 and the twist angle θt changes. To do. For example, as shown in FIG. 5, when the offset voltage due to geomagnetism is “ΔV”, the correspondence between the output signal V of the Hall IC 56 and the twist angle θt changes from the solid line ma in the figure to the two-dot chain line mb. . Therefore, when the output signal V of the Hall IC 56 is “V0”, the control device 4 detects that the actual twist angle of the torsion bar 12c (hereinafter referred to as “actual twist angle”) is the predetermined value θt1. The twist angle (hereinafter referred to as “detected twist angle”) θt becomes “0”. That is, a deviation Δθt occurs between the detected twist angle θt and the actual twist angle. In such a situation, for example, when the deviation Δθt is a positive value, the absolute value of the detected torsion angle θt is calculated to be smaller by a predetermined value Δθt than normal during right steering, and by a predetermined value Δθt than normal during left steering. Calculated greatly. Therefore, a deviation occurs in the absolute value | Th | of the detected steering torque between the right steering and the left steering, and this causes a deviation between the assist torque during the right steering and the assist torque during the left steering. This makes the driver feel uncomfortable.

  On the other hand, the strength of the geomagnetism detected by the Hall IC 56 is determined by the magnitude of the magnetic detection direction component of the Hall IC 56 in the geomagnetism. Therefore, when the attitude of the Hall IC 56 with respect to the horizontal direction is as shown in FIG. 4, the absolute value of the strength of the geomagnetism detected by the Hall IC 56 increases as the direction of the vehicle approaches the north or the south. The vehicle becomes smaller as the vehicle approaches east or west. Therefore, the offset voltage ΔV of the Hall IC 56 caused by geomagnetism has a correlation with the direction in which the vehicle is facing. In other words, the deviation Δθt between the detected twist angle θt and the actual twist angle has a correlation with the direction in which the vehicle is facing. Using this, in the present embodiment, the detected steering torque Th is detected with high accuracy by correcting the detected torsion angle θt based on the direction in which the vehicle is facing. The configuration will be described in detail below.

  As shown in FIG. 1, the control device 4 is connected to a car navigation device (car navigation device) 8 via an in-vehicle network 7 such as a CAN (Controller Area Network). The car navigation device 8 detects the current vehicle position using GPS (Global Positioning System), and performs route guidance to the destination based on the detected current position of the vehicle. The control device 4 acquires information on the current position of the vehicle from the car navigation device 8 via the in-vehicle network 7. The information on the current position of the vehicle includes the latitude and longitude of the current position of the vehicle, the direction in which the vehicle is facing, and the like. When the control device 4 detects the torsion angle θt of the torsion bar 12c based on the output signal of the Hall IC 56, the control device 4 corrects the detected torsion angle θt based on the direction in which the vehicle faces, and the corrected detected torsion angle. A steering torque Th is calculated based on θt. Next, the calculation procedure will be described with reference to FIG. The control device 4 repeatedly executes the process shown in FIG. 6 in accordance with the control period of the assist control.

  First, the control device 4 detects the output signal V of the Hall IC 56 (Step S1), and calculates the detected twist angle θt from the detected output signal V based on the map of the solid line ma illustrated in FIG. 5 (Step S2). ). Further, the control device 4 acquires information on the current position of the vehicle from the car navigation device 8 (step S3), and calculates a correction value θc based on the direction in which the vehicle is included (step S4). The relationship between the direction in which the vehicle is facing and the correction value θc is obtained in advance by experiments or the like, and a map indicating the relationship is stored in the memory 4a of the control device 4. In this map, basically, the absolute value | θc | of the correction value increases as the direction of the vehicle approaches north or south, and the absolute value of the correction value increases as the vehicle direction approaches east or west. θc | is set to be small. The control device 4 calculates the correction value θc from the direction in which the vehicle is facing based on the map stored in the memory 4a. Subsequently, the control device 4 subtracts the correction value θc from the detected twist angle θt, and sets the subtracted value (θt−θc) as a new detected twist angle θt (step S5). Then, the control device 4 calculates the steering torque Th by multiplying the new detected torsion angle θt by the spring constant of the torsion bar 12c (step S6), and ends the series of processes.

  If the control device 4 executes the process shown in FIG. 6, the detected torsion angle θt is corrected based on the direction of the vehicle, even when the output signal V of the Hall IC 56 changes according to the direction of the vehicle due to the influence of geomagnetism. The As a result, since the influence of geomagnetism can be eliminated from the detected twist angle θt, the actual twist angle of the torsion bar 12c can be detected with higher accuracy. Thereby, since the control apparatus 4 can detect the steering torque Th with higher accuracy, the deviation between the assist torque during the right steering and the assist torque during the left steering is reduced. That is, since it is difficult for a situation where the assist torque differs between right steering and left steering, the driver's steering feeling can be improved.

As described above, according to the torque sensor 5 of the present embodiment, the following effects can be obtained.
(1) The control device 4 acquires information on the direction of the vehicle from the car navigation device 8. Then, the control device 4 detects the twist angle θt of the torsion bar 12c based on the output signal V of the Hall IC 56, and corrects the detected twist angle θt based on the direction of the vehicle. Further, the control device 4 obtains the steering torque Th based on the corrected detected twist angle θt, and controls the driving of the motor 20 based on the steering torque Th. As a result, the influence of geomagnetism can be eliminated from the detected torsion angle θt, so that the actual torsion angle of the torsion bar 12c and the steering torque Th can be detected with higher accuracy, thereby improving the driver's steering feeling. Can do.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
・ The strength of geomagnetism changes according to the latitude of the current position of the vehicle. Specifically, the geomagnetism becomes stronger as the current position of the vehicle is higher latitude, and the geomagnetism becomes weaker as the latitude is lower. Therefore, the offset voltage of the output signal of the Hall IC 56 caused by geomagnetism changes according to the latitude of the current position of the vehicle. Therefore, the control device 4 may further correct the detected twist angle θt based on the latitude of the current position of the vehicle that can be acquired from the car navigation device 8. As a result, the influence of geomagnetism can be more accurately excluded from the detected torsion angle θt, so that the actual torsion angle and steering torque Th of the torsion bar 12c can be detected with higher accuracy. In this case, the car navigation device serves as a latitude detection unit.

  -The direction of geomagnetism applied to the Hall IC 56 also changes depending on the inclination of the vehicle with respect to the vertical direction. That is, the direction of the geomagnetism applied to the Hall IC 56 changes between when the vehicle is traveling on a flat ground and when traveling on a slope. Therefore, the inclination of the vehicle with respect to the vertical direction also causes the output signal of the Hall IC 56 to change. In order to suppress this, the inclination of the vehicle with respect to the vertical direction may be detected by, for example, an acceleration sensor, and the detected torsion angle θt may be further corrected based on the detected inclination of the vehicle. As a result, the influence of geomagnetism can be more accurately excluded from the detected torsion angle θt, so that the actual torsion angle and steering torque Th of the torsion bar 12c can be detected with higher accuracy.

  In the above embodiment, the torque sensor 5 using the Hall element 56a is illustrated, but the torque sensor 5 may be various magnetoelectric conversion elements such as a magnetoresistive effect element that outputs a voltage signal according to the direction of magnetism applied. May be used.

  In the above embodiment, the car navigation device 8 is used as the vehicle direction detection unit that detects the direction in which the vehicle is facing, in other words, the direction of the vehicle with respect to the geomagnetism. For example, a yaw rate sensor or an electronic compass mounted on the vehicle is used. Etc. may be used.

  In the above embodiment, the torque sensor 5 used in the electric power steering apparatus is illustrated, but the torque sensor 5 can be used in various in-vehicle devices other than the electric power steering apparatus.

  In the above embodiment, the case where the present invention is applied to the torque sensor 5 is illustrated, but the application target of the present invention is not limited to the torque sensor 5. For example, the present invention can be applied to a rotation angle detection device that detects an absolute rotation angle of a rotation shaft mounted on a vehicle, such as a rotation angle sensor (not shown) that detects the rotation angle of the motor 20. . In short, a rotating shaft mounted on the vehicle and a magnetic circuit that changes the magnetism applied to the magnetoelectric conversion element according to a change in the rotation angle of the rotating shaft, and based on the output signal of the magnetoelectric conversion element, The rotation angle detection device that detects the rotation angle may include a vehicle direction detection unit that detects the direction of the vehicle with respect to geomagnetism and corrects the detected rotation angle based on the direction of the vehicle. The magnetoelectric conversion element used in the magnetic circuit is not limited to the Hall element, and a magnetoelectric conversion element such as a magnetoresistance effect element can be used as appropriate.

  In the above embodiment, the present invention is applied to an electric power steering device that applies assist torque to the column shaft 12. Instead, for example, the present invention may be applied to an electric power steering device that applies assist torque to the pinion shaft 14 or applies assist torque to the rack shaft 16.

  DESCRIPTION OF SYMBOLS 1 ... Steering mechanism, 4 ... Control apparatus (control part), 5 ... Torque sensor, 8 ... Car navigation apparatus (vehicle direction detection part, latitude detection part), 11 ... Steering shaft, 12a ... Input shaft (1st rotating shaft) , 12b ... output shaft (second rotating shaft), 12c ... torsion bar, 20 ... motor, 56a ... Hall element (magnetoelectric conversion element), 57 ... magnetic circuit.

Claims (4)

A magnetic circuit that changes the magnetism applied to the magnetoelectric conversion element according to the change in the rotation angle of the rotation shaft mounted on the vehicle,
In the rotation angle detection device that detects the rotation angle of the rotation shaft based on the output signal of the magnetoelectric conversion element,
A vehicle orientation detector for detecting the orientation of the vehicle relative to geomagnetism,
A rotation angle detection device that corrects the detected rotation angle based on a direction of the vehicle. The rotation angle detection device according to claim 1,
A latitude detector for detecting the latitude of the current position of the vehicle;
The rotation angle detection device further corrects the detected rotation angle based on the latitude of the current position of the vehicle. A torsion bar for connecting the first rotating shaft and the second rotating shaft mounted on the vehicle to each other;
The rotation angle detection device according to claim 1 or 2, comprising a rotation angle detection device that detects a relative rotation angle of the second rotation shaft with respect to the first rotation shaft.
A torque sensor that detects torque applied to the first rotation shaft or the second rotation shaft based on a relative rotation angle of the second rotation shaft with respect to the first rotation shaft. As a torque sensor for detecting a steering torque applied to a steering shaft of a vehicle during a steering operation, the torque sensor according to claim 3 is provided,
A motor for applying assist torque to a steering mechanism of the vehicle;
An electric power steering apparatus comprising: a control unit configured to control driving of the motor based on a steering torque detected by the torque sensor.