JP2014070939A - Steering angle arithmetic unit of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering angle arithmetic unit of a vehicle capable of improving arithmetic accuracy of a steering angle using signals detected from an acceleration sensor.SOLUTION: A first acceleration sensor 21 is attached to a steering wheel 12. Moreover, a second acceleration sensor 22 is attached to a vehicle body. Then, a control device 30 calculates a steering angle of the steering wheel 12 using travel acceleration and gravitational acceleration based on signals detected from the respective acceleration sensors 21 and 22.

Description

  The present invention relates to a vehicle steering angle calculation device that calculates a steering angle of a vehicle steering.

As vehicle control, control represented by a steering operation angle operated by a driver as one of parameters, as represented by skid suppression control, is known.
Patent Document 1 discloses an example of a steering angle sensor that detects the steering angle of the steering. The steering angle sensor includes a main rotating body that rotates integrally with the steering shaft, and two magnetic bodies provided on the vehicle body side. A vehicle control device including such a steering angle sensor acquires the steering angle of the steering based on a detection signal from the steering angle sensor, and performs vehicle control based on the steering angle.

  Further, as a method for detecting the steering angle of the steering, a method in which a biaxial orthogonal acceleration sensor is provided in the steering instead of the steering angle sensor as described above and a detection signal from the acceleration sensor is used. Such an acceleration sensor is a sensor capable of detecting an acceleration component in a first direction and an acceleration component in a second direction orthogonal to each other, and a vector sum of these acceleration components is referred to as a “sensor output value”.

  As shown in FIGS. 9A and 9B, the acceleration sensor 100 is provided on the steering 102 so that the first direction and the second direction are along a mounting plane orthogonal to the steering shaft 101. Gravity acceleration Gg acts on the acceleration sensor 100. Therefore, when the vehicle is stopped and the steering angle of the steering wheel 102 is “ω”, the gravity-equivalent acceleration Gv along the mounting plane is expressed by the following relational expression (Formula 1). Further, when the acceleration equivalent to gravity Gv is used, the acceleration component Gα in the first axis direction and the acceleration component Gβ in the second axis direction are expressed by the following relational expressions (Expression 2) and (Expression 3). .

Further, by converting the relational expressions (Expression 1) to (Expression 3), the steering angle θ of the steering wheel 102 can be expressed by the following relational expression (Expression 4). The vehicle control device calculates the steering angle θ of the steering 102 based on the detection signal from the acceleration sensor 100, and performs vehicle control based on the calculated steering angle θ.

JP 2004-271427 A

  By the way, while the vehicle is traveling, not only the gravitational acceleration Gg but also acceleration (hereinafter also referred to as “travel acceleration”) acts on the acceleration sensor 100 provided on the steering 102. . That is, the sensor output value is a value based on the gravitational acceleration Gg and the traveling acceleration. Therefore, the acceleration component Gα in the first direction and the acceleration component Gβ in the second direction based on the detection signal from the acceleration sensor 100 include the first direction component and the second direction component of the traveling acceleration. It becomes. Therefore, it is difficult to say that the calculation accuracy of the steering angle θ of the steering 102 is high while the vehicle is traveling.

  The present invention has been made in view of such circumstances. An object of the present invention is to provide a vehicle steering angle calculation device that can improve the calculation accuracy of the steering angle of a steering wheel using a detection signal from an acceleration sensor.

In the following, means for achieving the above object and its effects are described.
One aspect of the present invention is based on a detection signal output from a first acceleration sensor (21) attached to a steering (12) of a vehicle or a member (13) that rotates in conjunction with the steering (12). The first sensor output value (G1) including the acceleration components (G1α, G1β) in the first direction and the second direction orthogonal to the steering shaft (12) is acquired (S12, S22) and attached to the vehicle body. The second sensor output value (G2, G0) based on the detection signal output from the two-axis or three-axis orthogonal type second acceleration sensor (22, 43) is acquired (S13, S27). Based on the first and second sensor output values (G1, G2, G0) thus obtained, the steering angle (θ, θ (N)) of the steering (12) is calculated (S17, S30). The gist.

  According to the above configuration, the first sensor output value (G1) based on the detection signal from the first acceleration sensor (21) rotating in conjunction with the rotation of the steering (12), that is, the acceleration component in the first direction. The second sensor output value (G2, G0) based on the detection signal from the second acceleration sensor (22, 43) provided on the vehicle body as well as (G1α) and the acceleration component (G1β) in the second direction. ) Is also used to calculate the steering angle (θ, θ (N)) of the steering (12). As a result, the steering angle using the detection signal from the first acceleration sensor (21) is compared with the case where the steering angle (θ, θ (N)) is calculated using only the first sensor output value (G1). The calculation accuracy of (θ, θ (N)) can be improved.

The “vehicle body” here refers to a part whose position and orientation are not changed by a driver's vehicle operation.
The second acceleration sensor (22) is attached to a portion of the vehicle steering device (11) that is not displaced in conjunction with the rotation of the steering (12), and an acceleration component (G2y) in the vehicle width direction, It is preferable to detect at least an acceleration component (G2az) in a direction orthogonal to the direction in which the steering shaft (12) extends and the width direction of the vehicle.

  According to the above configuration, the second acceleration sensor (22) can be disposed relatively close to the steering (12). As a result, the second sensor output value (G2) based on the detection signal from the second acceleration sensor (22) is a value close to the force acting on the first acceleration sensor (21). Therefore, by performing the calculation process using the second sensor output value (G2), the steering angle (θ, θ (N)) of the steering (12) can be calculated with high accuracy.

  The second acceleration sensor (43) is disposed in the center of gravity region (40) including the center of gravity of the vehicle, and the longitudinal acceleration component (G0x), the lateral acceleration component (G0y), and the vertical direction of the vehicle. The acceleration component (G0z) may be detected. The center-of-gravity region (40) includes a yaw rate sensor (44) for detecting the yaw rate (Yr) of the vehicle, a roll rate sensor (45) for detecting the roll rate (Rr) of the vehicle, and the pitch rate (Pr) of the vehicle. A pitch rate sensor (46) for detection may be further provided.

  In this case, the steering angle calculation device is based on the detection signals from the sensors (43 to 46) provided in the center of gravity region (40) and acts on the first acceleration sensor (21) in the longitudinal direction of the vehicle. (G02x), an output correction value (G02) including an acceleration component (G02y) in the width direction of the vehicle and an acceleration component (G02z) in the vertical direction of the vehicle is calculated (S27), and the calculated output correction value (G02) and the first The steering angle (θ, θ (N)) of the steering (12) is preferably calculated based on the sensor output value (G1) of 1 (S30).

  As described above, the yaw rate sensor (44), the roll rate sensor (45), and the pitch rate sensor (46) are provided in the center of gravity area (40) of the vehicle in addition to the second acceleration sensor (43). An output correction value (G0) corresponding to the force acting on the acceleration sensor (21) can be estimated and calculated. The output correction value (G0) thus obtained, that is, the vehicle longitudinal acceleration component (G02x), the vehicle width acceleration component (G02y), and the vehicle vertical acceleration component (G02z), By using the first sensor output value (G1) including the acceleration components (G1α, G1β) in the first and second directions, the steering angle (θ, θ (N)) of the steering (12) can be accurately determined. It becomes possible to calculate.

  By the way, when the vehicle is freely falling, the acceleration in the direction of gravity acting on the vehicle is close to “0 (zero)”, and the first sensor output based on the detection signal from the first acceleration sensor (21). It becomes difficult to use the value (G1) for the calculation of the steering angle (θ, θ (N)) of the steering (12). Therefore, when a free fall of the vehicle is detected (S15, S28: NO), the steering angle (θ, θ (N)) of the steering (12) is set to a value (θ (N−1) before the free fall is detected. )) Is preferable (S16, S29).

  In order to explain the present invention in an easy-to-understand manner, it has been described in association with the reference numerals of the drawings showing the embodiments, but it goes without saying that the present invention is not limited to the embodiments.

The schematic diagram which shows the steering device of 1st Embodiment. The schematic diagram explaining the arrangement | positioning aspect of a 1st acceleration sensor. The schematic diagram explaining the arrangement | positioning aspect of a 2nd acceleration sensor. The flowchart explaining the processing routine performed when calculating the steering angle of a steering wheel in 1st Embodiment. The schematic diagram which shows the vehicle of 2nd Embodiment. The graph which shows the installation position of the steering wheel centering on a gravity center area | region. The flowchart explaining the processing routine performed when calculating the steering angle of a steering wheel in 2nd Embodiment. The schematic diagram explaining the steering device of another embodiment. (A) is a schematic diagram which shows the conventional steering apparatus, (b) is a schematic diagram explaining the arrangement | positioning aspect of the acceleration sensor in a steering wheel.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the following description in the present specification, the longitudinal direction of the vehicle is referred to as “X-axis direction”, the width direction of the vehicle is referred to as “Y-axis direction”, and the vertical direction of the vehicle is referred to as “Z-axis direction”. ".

  As shown in FIG. 1, the vehicle steering apparatus 11 includes a steering wheel 12 that is operated by a driver, and a steering shaft 13 that extends obliquely downward and forward from the rotation center of the steering wheel 12. A part of the steering shaft 13 is included in a steering column 14 attached to the vehicle body. The steering column 14 is not displaced in conjunction with the rotation of the steering wheel 12.

  In the steering device 11 of the present embodiment, it is assumed that the tilt angle of the steering wheel 12 is constant. Therefore, the mounting angle ω of the steering wheel 12 with respect to the Z-axis direction is stored in advance in the memory of the control device 30 as the steering angle calculation device.

  A biaxial orthogonal first acceleration sensor 21 is built in the center of the steering wheel 12. The first acceleration sensor 21 is disposed at the rotation center of the steering wheel 12. Further, the steering column 14 is provided with a second acceleration sensor 22 of a two-axis orthogonal type. In other words, in the present embodiment, the second acceleration sensor 22 is disposed at a position close to the first acceleration sensor 21. The control device 30 calculates the steering angle of the steering wheel 12 based on the detection signals output from the acceleration sensors 21 and 22.

  As shown in FIGS. 1 and 2, the first acceleration sensor 21 is a sensor that detects α-axis and β-axis acceleration components along a virtual plane 15 </ b> A orthogonal to the direction in which the steering shaft 13 extends. In the present embodiment, the acceleration component in the α-axis direction corresponds to the “acceleration component in the first direction”, and this acceleration component is referred to as “α-axis acceleration component G1α”. Further, the acceleration component in the β-axis direction corresponds to “acceleration component in the second direction”, and this acceleration component is referred to as “β-axis acceleration component G1β”. The vector sum of the α-axis acceleration component G1α and the β-axis acceleration component G1β is referred to as “first sensor output value G1”.

  Incidentally, in addition to the gravitational acceleration “Gg” acting on the first acceleration sensor 21, a traveling acceleration which is an acceleration accompanying the traveling of the vehicle is acting. Therefore, the first sensor output value G1 is the total acceleration Gt obtained by combining the gravitational acceleration Gg and the traveling acceleration.

  As shown in FIGS. 1 and 3, the second acceleration sensor 22 is a sensor that detects biaxial acceleration components that are along a virtual plane 15 </ b> B orthogonal to the direction in which the steering shaft 13 extends and are orthogonal to each other. The two axes orthogonal to each other are an axis extending in the direction in which the Y axis and the Z axis are rotated clockwise in FIG. 1 by the attachment angle ω (hereinafter also referred to as “pseudo Z axis”). The virtual plane 15B is parallel to the virtual plane 15A.

  In the present embodiment, since the second acceleration sensor 22 is disposed at a position close to the first acceleration sensor 21, the sum of accelerations acting on the second acceleration sensor 22 acts on the first acceleration sensor 21. It almost coincides with the total acceleration Gt. Therefore, the second sensor output value G2 based on the detection signal output from the second acceleration sensor 22 substantially matches the first sensor output value G1. The acceleration component in the Y-axis direction of the second sensor output value G2 is referred to as “Y-axis acceleration component G2y”, and the acceleration component in the pseudo Z-axis direction is referred to as “pseudo Z-axis acceleration component G2az”.

  Next, a processing routine executed by the control device 30 when calculating the steering angle of the steering wheel 12 will be described with reference to a flowchart shown in FIG. This processing routine is executed at every preset calculation cycle.

  In the processing routine shown in FIG. 4, the control device 30 increments the count number N by “1” (step S11). Subsequently, the control device 30 acquires the first sensor output value G1, that is, the α-axis acceleration component G1α and the β-axis acceleration component G1β based on the detection signal from the first acceleration sensor 21 (step S12).

  Then, the control device 30 acquires the second sensor output value G2, that is, the Y-axis acceleration component G2y and the pseudo Z-axis acceleration component G2az, based on the detection signal from the second acceleration sensor 22 (step S13). Subsequently, the control device 30 substitutes the obtained pseudo Z-axis acceleration component G2az into the following relational expression (formula 5), and calculates the vertical acceleration Gz (step S14).

Then, the control device 30 determines whether or not the calculated absolute value of the vertical acceleration Gz is larger than a predetermined determination value GTh (step S15). This determination value GTh is a determination value for determining whether or not the vehicle is free-falling, and is set in advance by experiments or simulations. When the absolute value of the vertical acceleration Gz is equal to or smaller than the determination value GTh (step S15: NO), the control device 30 proceeds to the next step S16 because it can be estimated that the vehicle is falling freely.

  In step S <b> 16, the control device 30 sets the steering angle θ (N−1) calculated at the previous timing as the current steering angle θ (N). That is, when it is detected that the vehicle is falling freely, the steering angle θ is held at a value before detection. Thereafter, the control device 30 once ends this processing routine.

  On the other hand, when the absolute value of the vertical acceleration Gz is larger than the determination value GTh (step S15: YES), the control device 30 calculates the current steering angle θ (N) using the values acquired in steps S12 and S13. (Step S17). That is, the control device 30 calculates the current steering angle θ (N) using the following relational expressions (formula 6) to (formula 11). First, the α-axis acceleration component G1α is expressed as a relational expression (Expression 6), and the β-axis acceleration component G1β is expressed as a relational expression (Expression 7).

Further, when the relational expression (formula 7) is modified, the above-mentioned “cos θ” is expressed as the relational expression (formula 8). When the right side of the relational expression (formula 8) is substituted into “cos θ” of the relational expression (formula 6), the relational expression (formula 6) is converted into the relational expression (formula 9). When such a relational expression (formula 9) is modified, “sin θ” is expressed as a relational expression (formula 10). When this relational expression (formula 10) is further modified, the steering angle θ is expressed as the relational expression (formula 11). This steering angle θ is the current steering angle θ (N). Thereafter, the control device 30 once ends this processing routine.

As described above, in the present embodiment, the following effects can be obtained.

  (1) Not only the first sensor output value G1 (G1α, G1β) based on the detection signal from the first acceleration sensor 21, but also the first sensor signal based on the detection signal from the second acceleration sensor 22 provided on the vehicle body. The current steering angle θ (N) of the steering wheel 12 is calculated using the sensor output value G2 (G2y, G2az) of 2. As a result, the calculation accuracy of the current steering angle θ (N) can be improved as compared with the case where the current steering angle θ (N) is calculated only by the first sensor output value G1 (G1α, G1β). become able to.

  (2) The second acceleration sensor 22 is disposed relatively close to the steering wheel 12. As a result, the second sensor output value G2 (G2y, G2az) based on the detection signal from the second acceleration sensor 22 becomes a value close to the total acceleration Gt acting on the first acceleration sensor 21. Therefore, the current steering angle θ (N) of the steering wheel 12 can be accurately calculated by performing the calculation process using the second sensor output value G2 (G2y, G2az).

  (3) In this embodiment, when a free fall of the vehicle is detected, the current steering angle θ (N) is held at the value before the detection of the free fall, that is, the previous steering angle θ (N−1). Thereby, compared with the case where only the first sensor output value G1 (G1α, G1β) based on the detection signal output from the first acceleration sensor 21 at the time of free fall is used for the calculation of the current steering angle θ (N). Thus, the estimation accuracy of the current steering angle θ (N) is increased.

  (4) As described above, the steering angle θ can be calculated with relatively high accuracy without using the detection signal from the steering angle sensor that detects the rotation angle of the steering wheel 12. For this reason, it is possible to suppress a decrease in the accuracy of vehicle control using the steering angle θ as a parameter, such as side slip suppression control.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment is different from the first embodiment in that the second acceleration sensor is provided in the center of gravity region including the center of gravity of the vehicle, the calculation method of the steering angle, and the like. Accordingly, in the following description, parts different from those of the first embodiment will be mainly described, and members having the same configurations as those of the first embodiment are denoted by the same reference numerals, and redundant description will be omitted. To do.

  As shown in FIG. 5, a triaxial orthogonal second acceleration sensor 43 is provided in the center of gravity region 40 including the center of gravity of the vehicle. The second acceleration sensor 43 is arranged in a manner capable of detecting an acceleration component in the X-axis direction, an acceleration component in the Y-axis direction, and an acceleration component in the Z-axis direction. The “center of gravity” in the present embodiment indicates the center of gravity of the vehicle when the vehicle is stopped on a flat road surface.

  In the present embodiment, the acceleration component in the X-axis direction is referred to as “X-axis acceleration component G0x”, the acceleration component in the Y-axis direction is referred to as “Y-axis acceleration component G0y”, and the acceleration component in the Z-axis direction is referred to as “Z-axis acceleration component G0x”. This is referred to as “axial acceleration component G0z”. The vector sum of the X-axis acceleration component G0x, the Y-axis acceleration component G0y, and the Z-axis acceleration component G0z is referred to as “second sensor output value G0”.

  In the center of gravity region 40 of the vehicle, a yaw rate sensor 44 that detects the yaw rate of the vehicle, a roll rate sensor 45 that detects the roll rate of the vehicle, and a pitch rate sensor 46 that detects the pitch rate of the vehicle are arranged. And each sensor 43-46 located in the gravity center area | region 40 is electrically connected to the control apparatus 30 as a steering angle calculating device.

  Here, as shown in FIGS. 5 and 6, the steering wheel 12 to which the first acceleration sensor 21 is attached is provided at a position away from the center of gravity region 40. That is, the steering wheel 12 is separated from the center of gravity region 40 by the first distance Lx in the X-axis direction, separated from the center of gravity region 40 by the second distance Ly in the Y-axis direction, and further from the center of gravity region 40 in the Z-axis direction. It is separated by a third distance Lz. Therefore, the second sensor output value G0 calculated based on the detection signal from the second acceleration sensor 43 deviates from the total acceleration Gt acting on the steering wheel 12 (first acceleration sensor 21) when the vehicle travels. It is a value.

  Therefore, in the present embodiment, the second sensor output value G0 is corrected using the yaw rate Yr, roll rate Rr, and pitch rate Pr, and an output correction value G02 is obtained. The steering angle θ of the steering wheel 12 is calculated by using the output correction value G02 and the first sensor output value G1 based on the detection signal from the first acceleration sensor 21.

  Next, a processing routine executed by the control device 30 to calculate the steering angle of the steering wheel 12 will be described with reference to a flowchart shown in FIG. This processing routine is executed at every preset calculation cycle.

  In the processing routine shown in FIG. 7, the control device 30 increments the count number N by “1” (step S21), and the first sensor output value G1 (G1α based on the detection signal from the first acceleration sensor 21). , G1β) is acquired (step S22). Subsequently, the control device 30 acquires the second sensor output value G0, that is, the X-axis acceleration component G0x, the Y-axis acceleration component G0y, and the Z-axis acceleration component G0z, based on the detection signal from the second acceleration sensor 43. (Step S23).

  Then, the control device 30 acquires the vehicle yaw rate Yr based on the detection signal from the yaw rate sensor 44 (step S24), and acquires the vehicle pitch rate Pr based on the detection signal from the pitch rate sensor 46 (step S24). S25). Subsequently, the control device 30 acquires the roll rate Rr of the vehicle based on the detection signal from the roll rate sensor 45 (step S26).

  Then, the output correction value G02 is calculated as an estimated value of the sum of accelerations acting on the steering wheel 12 using the values acquired in steps S23 to S26 (step S27). In the present embodiment, the acceleration component in the X-axis direction of the output correction value G02 is referred to as “X-axis correction acceleration component G02x”, and the acceleration component in the Y-axis direction of the output correction value G02 is referred to as “Y-axis correction acceleration component G02y”. Further, the acceleration component in the Z-axis direction of the output correction value G02 is referred to as “Z-axis corrected acceleration component G02z”.

  In the present embodiment, the X-axis corrected acceleration component G02x, the Y-axis corrected acceleration component G02y, and the Z-axis corrected acceleration component G02z are expressed as the following relational expressions (Expression 12), (Expression 13), and (Expression 14). The

Then, the control device 30 determines whether or not the absolute value of the Z-axis acceleration component G0z acquired in step S23 is larger than a predetermined determination value GTh (step S28). When the absolute value of the Z-axis acceleration component G0z is equal to or smaller than the determination value GTh (step S28: NO), the control device 30 can estimate that the vehicle is free-falling. Therefore, the control device 30 calculates the steering angle calculated at the previous timing. Let θ (N−1) be the current steering angle θ (N) (step S29). Thereafter, the control device 30 once ends this processing routine.

  On the other hand, when the absolute value of the Z-axis acceleration component G0z is larger than the determination value GTh (step S28: YES), the control device 30 uses the value acquired in the above steps S22 and S27 and uses the current steering angle θ (N). Is calculated (step S30). That is, the control device 30 substitutes the attachment angle ω, the X-axis corrected acceleration component G02x, and the Z-axis corrected acceleration component G02z into the following relational expression (Expression 15), and calculates the pseudo Z-axis acceleration component G2az.

The control device 30 substitutes the Y-axis corrected acceleration component G02y, the α-axis acceleration component G1α, and the β-axis acceleration component G1β into the relational expression (formula 11) in addition to the pseudo Z-axis acceleration component G2az thus determined. The current steering angle θ (N) is obtained. At this time, “G02y” is substituted for “G2y” in the relational expression (Formula 11). Thereafter, the control device 30 once ends this processing routine.

As explained above, in this embodiment, in addition to the effects (3) and (4) in the first embodiment, the following effects can be further obtained.
(5) Values that can be acquired not only from the first sensor output value G1 (G1α, G1β) based on the detection signal from the first acceleration sensor 21, but also from detection signals from various sensors 43 to 46 provided in the center of gravity region 40 Is also used to calculate the current steering angle θ (N) of the steering wheel 12. As a result, the calculation accuracy of the current steering angle θ (N) can be improved as compared with the case where the current steering angle θ (N) is calculated only by the first sensor output value G1 (G1α, G1β). become able to.

  (6) The yaw rate, roll rate, and pitch rate are values that can be estimated and calculated using a detection signal from the second acceleration sensor 43 and the like. Therefore, it is possible to calculate the current steering angle θ (N) without using detection signals from the yaw rate sensor 44, the roll rate sensor 45, and the pitch rate sensor 46. However, in this case, it takes time to estimate and calculate the yaw rate, roll rate, and pitch rate, and the calculated value of the steering angle may be somewhat delayed from the actual steering angle. In this regard, in the present embodiment, the steering angle θ is calculated using sensor values (Yr, Rr, Pr) based on detection signals from the yaw rate sensor 44, the roll rate sensor 45, and the pitch rate sensor 46. By performing the calculation process using the actual measurement value in this way, the calculation accuracy of the current steering angle θ (N) can be improved.

In addition, you may change said each embodiment into another embodiment as follows.
In each embodiment, the first acceleration sensor 21 may not be a sensor provided in advance in the vehicle. For example, the first acceleration sensor 21 may be a two-axis orthogonal type or three-axis orthogonal type acceleration sensor provided in a portable communication device owned by a vehicle occupant. In this case, as shown in FIG. 8, it is preferable to provide an attachment portion 16 for attaching the communication device 50 incorporating the first acceleration sensor 21 at the center of the steering wheel 12.

  However, the communication device 50 is preferably a device that can communicate with the in-vehicle communication device 51 such as the in-vehicle navigation device wirelessly or by wire. In this case, the control device 30 acquires the first sensor output value G1 (G1α, G1β) based on the detection signal from the first acceleration sensor 21 via the in-vehicle communication device 51. Even if such a configuration is adopted, the same operations and effects as those of the above embodiments can be obtained.

  In the first embodiment, the second acceleration sensor 22 may not be a sensor provided in advance in the vehicle. For example, the second acceleration sensor 22 may be a two-axis orthogonal type or three-axis orthogonal type acceleration sensor provided in a portable communication device owned by a vehicle occupant. In this case, it is preferable to provide an attachment portion for attaching a communication device to a member (for example, a combination switch) other than the steering column 14 in the steering device 11.

  In the first embodiment, the second acceleration sensor 22 may be a three-axis orthogonal acceleration sensor. In this case, it is preferable to arrange the second acceleration sensor 22 so as to detect an acceleration component in the longitudinal direction, an acceleration component in the width direction, and an acceleration component in the vertical direction of the vehicle. In this case, the pseudo Z-axis acceleration component G2az is obtained using the longitudinal acceleration component, the vertical acceleration component, and the mounting angle ω, and the current steering angle θ (N) is calculated using the pseudo Z-axis acceleration component G2az. May be.

  In the second embodiment, if the vehicle yaw rate can be calculated using the detection signal from the second acceleration sensor 43, the yaw rate sensor 44 may not be provided in the center of gravity region 40. Even if the yaw rate sensor 44 is provided in the center of gravity region 40, the current steering angle θ (N) may be calculated without using the detection signal from the yaw rate sensor 44.

  In the second embodiment, the roll rate sensor 45 may not be provided in the center of gravity region 40 as long as the vehicle roll rate can be calculated using a detection signal from the second acceleration sensor 43 or the like. Even if the roll rate sensor 45 is provided in the center of gravity region 40, the current steering angle θ (N) may be calculated without using the detection signal from the roll rate sensor 45.

  In the second embodiment, the pitch rate sensor 46 may not be provided in the center of gravity region 40 as long as the vehicle pitch rate can be calculated using a detection signal from the second acceleration sensor 43 or the like. Even if the pitch rate sensor 46 is provided in the center of gravity region 40, the current steering angle θ (N) may be calculated without using the detection signal from the pitch rate sensor 46.

  -In each embodiment, you may attach the 1st acceleration sensor 21 to the member (for example, steering shaft 13) rotated in response to operation of the steering wheel 12 by a driver instead of the steering wheel 12.

  In each embodiment, the steering device 11 may be capable of adjusting the tilt angle of the steering wheel 12. In this case, the steering device 11 may be provided with a sensor that detects the mounting angle ω. In addition, in an apparatus that can adjust the tilt angle electrically, the change amount of the tilt angle based on the drive of the actuator may be estimated and calculated, and the attachment angle ω may be calculated based on the estimation result.

  The vehicle may be embodied as a vehicle equipped with a steering angle sensor that detects the steering angle of the steering wheel 12. In this case, the steering angle calculation process using the detection signal from the first acceleration sensor 21 may be performed as a fail-safe function such as when the steering angle sensor fails.

Next, technical ideas that can be grasped from the above embodiments and other embodiments will be added below.
(A) The second acceleration sensor (43) is arranged in the center of gravity region (40) including the center of gravity of the vehicle.
The steering angle calculation device
Using the detection signal from the second acceleration sensor (43), the yaw rate (Yr), pitch rate (Pr) and roll rate (Rr) of the vehicle are calculated,
Output correction including the longitudinal acceleration component (G02x), the lateral acceleration component (G02y), and the vertical acceleration component (G02z) acting on the first acceleration sensor (21) as the vehicle travels. Get the value (G02)
Based on the acquired output correction value (G02) and first sensor output value (G1), and the calculated yaw rate (Yr), pitch rate (Pr), and roll rate (Rr), the steering angle of the steering (12). It is preferable to calculate (θ, θ (N)).

  Thereby, even if the vehicle is not equipped with a sensor for detecting the yaw rate (Yr), pitch rate (Pr), and roll rate (Rr), the steering angle (θ, θ (N)) can be calculated. It becomes like this.

  (B) The steering (12) is preferably provided with an attachment portion (16) to which a portable communication terminal (50) incorporating the first acceleration sensor (21) can be attached.

  DESCRIPTION OF SYMBOLS 11 ... Steering device, 12 ... Steering wheel, 13 ... Steering shaft, 14 ... Steering column, 21 ... First acceleration sensor, 22, 43 ... Second acceleration sensor, 40 ... Center of gravity, 44 ... Yaw rate sensor, 45 ... Roll rate sensor, 46 ... Pitch rate sensor, G0 ... Second sensor output value, G0x ... X-axis acceleration component, G0y ... Y-axis acceleration component, G0z ... Z-axis acceleration component, G02 ... Output correction value, G02x ... Vehicle X-axis acceleration component as a longitudinal acceleration component, G02y ... Y-axis acceleration component as an acceleration component in the vehicle width direction, G02z ... Running acceleration Z-axis component as an acceleration component in the vehicle vertical direction, G1 ... first Sensor output value, G1α, α-axis acceleration component as an acceleration component in the first direction, G1β, acceleration component in the second direction Β-axis acceleration component, G2 ... second sensor output value, G2y ... Y-axis acceleration component as an acceleration component in the width direction, G2az ... pseudo Z-axis acceleration component, Pr ... pitch rate, Rr ... roll rate, Yr ... Yaw rate, θ ... steering angle.

Claims (4)

Based on the detection signal output from the first acceleration sensor (21) attached to the vehicle steering (12) or the member (13) that rotates in conjunction with the steering (12), the steering shaft (12) A first sensor output value (G1) including acceleration components (G1α, G1β) in the first direction and the second direction orthogonal to each other is acquired (S12, S22),
A second sensor output value (G2, G0) based on a detection signal output from a second acceleration sensor (22, 43) of a two-axis or three-axis orthogonal type attached to the vehicle body is acquired (S13, S27),
Based on the acquired first and second sensor output values (G1, G2, G0), the steering angle (θ, θ (N)) of the steering (12) is calculated (S17, S30).
A steering angle calculation device for a vehicle. The second acceleration sensor (22)
In the vehicle steering device (11), it is attached to a portion that is not displaced in conjunction with the rotation of the steering (12),
The vehicle steering according to claim 1, wherein at least an acceleration component (G2y) in a vehicle width direction and an acceleration component (G2az) in a direction perpendicular to the direction in which the steering shaft (12) extends and the vehicle width direction are detected. Angular arithmetic unit. The second acceleration sensor (43) is disposed in the center of gravity region (40) including the center of gravity of the vehicle, and the acceleration component (G0x) in the longitudinal direction of the vehicle, the acceleration component (G0y) in the width direction, and the vertical direction Acceleration component (G0z) is detected,
In the center of gravity region (40), a yaw rate sensor (44) for detecting the yaw rate (Yr) of the vehicle, a roll rate sensor (45) for detecting the roll rate (Rr) of the vehicle, and a pitch rate (Pr) of the vehicle are detected. A pitch rate sensor (46) is further provided,
The steering angle calculation device
Based on detection signals from the sensors (43 to 46) provided in the center of gravity region (40), the acceleration component (G02x) in the longitudinal direction of the vehicle acting on the first acceleration sensor (21), the width of the vehicle An output correction value (G02) including a direction acceleration component (G02y) and a vehicle vertical acceleration component (G02z) is calculated (S27);
Based on the calculated output correction value (G02) and the first sensor output value (G1), the steering angle (θ, θ (N)) of the steering (12) is calculated (S30).
The vehicle steering angle calculation device according to claim 1. When a free fall of the vehicle is detected (S15, S28: NO), the steering angle (θ, θ (N)) of the steering (12) is a value (θ (N−1)) before the free fall is detected. ) (S16, S29)
The vehicle steering angle calculation device according to any one of claims 1 to 3.