JP2007248151A - Absolute angle information output apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absolute angle information output apparatus which reduces a calculation burden on the part using output values. <P>SOLUTION: The absolute angle information output apparatus 1 for outputting the absolute angle of a rotating body comprises an absolute angle acquisition means for detecting the absolute angle of the rotating body and an output angle determination means 64 for determining an output angle to be output on the basis of the absolute angle of the rotating body acquired by the absolute angle acquisition means. The output angle determination means 64 determines the output angle so that it falls within a range predetermined on the basis of the movable range of the rotating body. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to an absolute angle information output device that outputs information related to the absolute angle of a rotating body.

  2. Description of the Related Art Conventionally, a control system that reduces engine output and performs wheel brake control in order to suppress side slip of a wheel when the vehicle is turning is known by a name such as VSC (Vehicle Stability Control). In this VSC, the skid of the front wheels is determined based on the difference between the target yaw rate calculated from the steering angle and the vehicle speed and the detected value of the yaw rate sensor, and the engine output is reduced or decreased depending on the determination result. Since control is performed such as applying brakes to the wheels, sensors for detecting the steering angle are required. In addition to this VSC, various scenes that require a steering angle are also assumed in other vehicle controls.

  By the way, there are sensors that detect the steering angle, one that outputs an absolute angle (angle from a neutral position where the vehicle goes straight) and one that outputs a relative angle change. From the viewpoint of the calculation burden of the control device or the like in the VSC), it is more preferable to output an absolute angle.

  As an example of a steering rudder angle sensor that outputs an absolute angle, one described in Patent Document 1 is known. In this apparatus, the absolute angle is calculated based on the period difference between the resolver of the steering torque sensor and the rotation angle sensor of the assist motor.

Another example of a steering rudder angle sensor that outputs an absolute angle is disclosed in Patent Document 2. In this apparatus, two gears having different numbers of gears are meshed with a gear that rotates with the steering wheel, and an absolute angle is calculated based on the rotation angle of the two gears.
JP 2003-75109 A Japanese National Patent Publication No. 11-500828

  The steering wheel is usually operated to rotate beyond the range of 360 °. Therefore, a rotation angle sensor such as a simple potentiometer is not sufficient. Therefore, the steering rudder angle sensor that outputs the absolute angle is not limited to the devices described in Patent Document 1 and Patent Document 2, and calculates the absolute angle by synthesizing the rotation angles of the rotating bodies having different periods. In general, the absolute angle is calculated after transmitting the rotation to a rotating body having a longer cycle (for example, four times the rotation cycle of the steering wheel). In this case, it has the periodicity expanded to 360 ° or more by any method described above.

  This expanded period is usually determined so as to coincide with the movable region of the steering wheel (for example, ± 720 ° from the reference position (neutral position) with the clockwise direction being positive and the counterclockwise direction being negative). . This is because if the period is increased, there is a margin in the detectable angle, but at the same time, the resolution of the sensor becomes rough and the communication load increases. Also, on the side where the steering angle is used, it is usually designed to perform control in conformity with this movable region.

  However, in reality, an absolute angle exceeding the original movable region of the steering wheel may be detected due to a deviation or the like when the sensor is attached. As a result, for example, when ± 720 ° is defined as one cycle, when it reaches + 725 ° beyond + 720 ° from + 720 ° or less, −715 ° is output.

  If this is done, the continuity of control will be lost on the side using the steering angle, so error handling and correction calculations will need to be performed, and the significance of selecting an absolute angle output from the viewpoint of reducing the calculation burden Is killed.

  Such a problem is not limited to the detection target of the steering wheel, but occurs in common in devices that detect and output the absolute angle of the rotating body. The same problem occurs in a rotating object having a movable range of 360 ° or less.

  The present invention has been made to solve such problems, and it is a main object of the present invention to provide an absolute angle information output device capable of reducing the calculation burden on the side using the output value.

  One aspect of the present invention for achieving the above object is an absolute angle information output device for outputting an absolute angle of a rotating body, comprising: an absolute angle acquiring means for acquiring an absolute angle of the rotating body; and an absolute angle acquiring means. Output angle determining means for determining an output angle output from the apparatus based on the acquired absolute angle of the rotating body, and the output angle determining means is a predetermined range determined in advance based on the movable range of the rotating body. The output angle is determined so as to be a value within the range. Here, the absolute angle acquisition means may be a means for deriving the absolute angle of the rotating body by calculation, or a means for directly detecting the absolute angle of the rotating body.

  According to this aspect of the present invention, the output angle can be determined so as to be a value within a predetermined range determined in advance based on the movable range of the rotating body.

  Moreover, in one aspect of the present invention, the output angle determination means, for example, when the absolute angle of the rotating body acquired by the absolute angle acquisition means is outside the predetermined range, the limit value of the predetermined range is set as the output angle. It is characterized by this.

  Moreover, in one aspect of the present invention, the output angle determination unit outputs, for example, a limit value of the exceeded predetermined range when the absolute angle of the rotating body acquired by the absolute angle acquisition unit exceeds a predetermined range. It is characterized by an angle. In this case, the absolute angle acquisition unit is a unit that detects the absolute angle of the rotating body with a predetermined cycle determined in advance based on the movable range of the rotating body, for example. In these cases, the output angle determination means includes, for example, storage means for storing the detection result of the absolute angle acquisition means, and based on the history of detection results of the absolute angle acquisition means stored in the storage means, the absolute angle acquisition means This is means for determining whether or not the absolute angle of the rotating body acquired by the above exceeds a predetermined range.

  In one embodiment of the present invention, the rotating body is, for example, a steering wheel.

  ADVANTAGE OF THE INVENTION According to this invention, the absolute angle information output device which can reduce the calculation burden in the side which utilizes an output value can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.

  Hereinafter, an embodiment of an absolute angle information output device according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating an example of an overall configuration of an absolute angle information output device 1 that is mounted on a vehicle and outputs a steering angle to other devices in the vehicle according to an embodiment of the present invention. The absolute angle information output device 1 includes gears 10, 20, and 30, angle sensors 40 and 50, and an output calculation device 60 as main components.

  The gear 10 is fixed to a steering wheel shaft that rotates integrally with the steering wheel, and thus rotates integrally with the steering wheel. For example, the gear 10 has X as its number of teeth.

  In this embodiment, the movable range of the steering wheel is assumed to be ± 720 ° from the reference position (neutral position) with the clockwise direction being positive and the counterclockwise direction being negative. Here, the reference position refers to the position of the steering wheel where the vehicle goes straight. Further, the steering wheel is restricted by a lock mechanism so as not to rotate beyond the movable range.

  The gears 20 and 30 are rotatably held, for example, on the same plane as the gear 10, and the rotation of the gear 10 is transmitted. For example, the gears 20 and 30 have Y and Z as the number of teeth, respectively (X ≠ Y, Y ≠ Z, X ≠ Z). Accordingly, the gears 10 rotate at different periods. Magnets 20A and 20B are attached to the gears 20 and 30, respectively.

  The angle sensors 40 and 50 are sensors that detect the absolute angle of the rotating body using, for example, an anisotropic magnetoresistive element (AMR element). In the case of the present embodiment, the angle sensor 40 detects the magnetic field generated by the magnet 20A and detects the absolute angle α of the gear 20 with a period of 0 ° to 360 °. Similarly, the angle sensor 50 detects the magnetic field generated by the magnet 30A and detects the absolute angle β of the gear 30 with a period of 0 ° to 360 °.

  The output arithmetic unit 60 is, for example, a computer unit centered on a CPU, and includes a ROM storing a program executed by the CPU, a readable / writable RAM, a timer, a counter, and the like. The output calculation device 60 includes an absolute angle acquisition unit 62 and an output angle determination unit 64 as functional blocks realized using such a hardware device.

  The absolute angle acquisition unit 62 calculates the number of teeth X, Y, Z of the gears 10, 20, 30 stored in advance in the ROM and the absolute angles α, β of the gears 20, 30 detected by the angle sensors 40, 50. Using this, the absolute angle θ of the gear 10 is derived. There is no particular limitation on the specific method relating to this derivation, and for example, the method described in Patent Document 2 (Japanese Patent Publication No. 11-500828) may be used.

  However, in this embodiment, since the movable range of the steering wheel is ± 720 ° as described above, the absolute angle θ derived using the detection results of the angle sensors 40 and 50 and the number of teeth X, Y, and Z is, for example, It is desired to be derived with a deriving period substantially matching 1440 °. That is, the number of teeth X, Y, and Z is set to a combination that can be derived with a derivation period that substantially matches 1440 °, and a derivation method that matches this is used.

  As described above, if the derivation period is greater than 1440 °, there is a margin in the detectable angle, but at the same time, problems such as coarse resolution of the sensor and increased communication load occur. Further, if the derivation period is smaller than 1440 °, an undetectable steering wheel movable range is generated, which is not preferable. Hereinafter, in the present embodiment, it is assumed that the output arithmetic device 60 uses a combination of the number of teeth with a derivation period of 1440 ° and a derivation method.

  As described above, in the absolute angle information output device 1 according to the present embodiment, the absolute angle acquisition unit 62 derives the absolute angle θ with a derivation cycle that matches the movable range of the steering wheel. Specifically, first, the absolute angle information output device 1 recognizes the reference position of the steering wheel when the device is attached, and then when the steering wheel is at the reference position, 720 ° is clockwise and 720 ° (two rotations). ) 1440 ° is derived when the steering wheel is operated, and 0 ° is derived when the steering wheel is operated 720 ° (two rotations) counterclockwise. It should be noted that expressing these as 0 ° to 1440 ° is for convenience only, and adding ± 720 ° with a sign or a direction flag is equivalent in terms of content.

  However, the steering wheel rotates beyond the derivation cycle of the absolute angle information output device 1 for some reason (such as misalignment of the reference position at the time of device installation or the above-described locking mechanism does not function properly), that is, There may be a scene where the absolute angle information output apparatus 1 rotates more than 720 ° from the reference position recognized. In this case, as shown in FIG. 2, a value near 0 ° is suddenly derived from the vicinity of 1440 °, or a value near 1440 ° is suddenly derived from the vicinity of 0 °. Here, FIG. 2 is a diagram showing a change in the absolute angle θ derived according to the rotation of the steering wheel. If this is output as the steering angle as it is, the continuity of control is lost in the device that performs vehicle control using the output steering angle, so that it becomes necessary to perform error processing and correction calculation in the device, The calculation burden increases.

  Therefore, in the absolute angle information output device 1 according to the present embodiment, the output angle determination unit 64 stores, for example, the steering wheel absolute angle θ derived every predetermined time in the RAM or the like, and the result of referring to this history. When it is determined that the steering wheel has rotated more than 720 ° in any direction from the reference position, the output angle is output so that the limit value of the derivation cycle (0 ° or 1440 ° in this embodiment) is output. That is, the steering rudder angle that is finally output is determined.

  Hereinafter, the operation when the output calculation device 60 determines and outputs the steering angle will be described. FIG. 3 is a flowchart showing a flow of characteristic processing executed by the CPU of the output calculation device 60. This flow is executed, for example, every predetermined time (for example, several [msec] to several tens [msec]).

  First, the output calculation device 60 has the number of teeth X, Y, Z of the gears 10, 20, 30 stored in advance in the ROM or the like as described above, and the absolute angle of the gears 20, 30 detected by the angle sensors 40, 50. Using α and β, the absolute angle θ is derived and stored in the predetermined area of the RAM (S100).

  Next, it is determined whether or not a limit value was output as the steering angle when one routine of this flow was executed last time (S110).

  If the limit value is not output as the steering angle when one routine of this flow was executed last time, the absolute value θ is output by referring to the history of the absolute angle θ stored in the RAM. It is determined whether or not the rotation has exceeded 720 ° in any direction from the reference position recognized in 1 (S120). Specifically, for example, the absolute angle θ derived and stored when one routine of this flow was executed last time is in a first predetermined range (for example, 1420 ° to 1440 °) near 1440 °, When the absolute angle θ derived and stored this time is in the second predetermined range near 0 ° (for example, 0 ° to 20 °, etc.), conversely, the previous absolute angle θ is in the second predetermined range. When the current absolute angle θ is in the first predetermined range, it is determined that the steering wheel has rotated more than 720 ° in any direction from the reference position recognized by the absolute angle information output device 1. can do.

  If it is determined that the vehicle does not rotate in any direction beyond 720 °, the derived absolute angle θ is output as it is as the steering angle (S130), and one routine of this flow is terminated.

  On the other hand, if it is determined that the vehicle has rotated more than 720 ° in any direction, the exceeded limit value is output as the steering angle, and a numerical value is output to the predetermined flag indicating that the limit value has been output. The setting is stored in the RAM (S150), and one routine of this flow is completed. Here, the limit value in the present embodiment is 1440 ° when the previous absolute angle θ is in the first predetermined range and the current absolute angle θ is in the second predetermined range, and the previous absolute angle When θ is in the second predetermined range and the current absolute angle θ is in the first predetermined range, it is 0 °. That is, this corresponds to the limit value of the exceeded movable range when it is determined that the rotation of the steering wheel has exceeded the movable range. The determination in S110 is made with reference to the flag set in this step.

  If it is determined in S110 that a limit value has been output as the steering angle when one routine of this flow was executed last time, the position of the steering wheel is the reference position recognized by the absolute angle information output device 1 It is determined whether or not it has returned to the range of 720 ° in any direction (S140). Similar to the determination in S120, this determination is performed when the previous absolute angle θ is in the first predetermined range and the current absolute angle θ is in the second predetermined range, or when the previous absolute angle θ is the second predetermined range. When it is within the predetermined range and the current absolute angle θ is within the first predetermined range, it can be determined that it has returned to the range.

  If it is determined that the position of the steering wheel has been returned within the range, the absolute angle θ derived in S100 is output as it is as the steering angle, and one routine of this flow is terminated. At this time, although not shown, the flag relating to the output of the limit value is reset.

  If it is determined that the position of the steering wheel has not returned within the range, the same limit value as the previous time is output as the steering angle (S150), and one routine of this flow is terminated.

  Thus, in the absolute angle information output device 1 according to one embodiment of the present invention, the steering wheel exceeds the range of 720 ° in either direction from the reference position recognized by the absolute angle information output device 1. In the case of rotation, the exceeded limit value is output as the steering angle. FIG. 4 is a diagram illustrating a change in the steering angle according to the rotation of the steering wheel, which is determined using the above flow. When this is compared with the change in the absolute angle θ in FIG. 2, a sudden change due to exceeding the range of ± 720 ° is suppressed. Accordingly, it is possible to suppress the necessity of performing error processing and correction processing in a device (such as a brake ECU or an engine ECU in this embodiment) that uses the output steering rudder angle, and reduce the calculation burden. it can.

  Note that the processing of S100 in the flowchart is performed by the absolute angle acquisition unit 62, and the processing after S110 is performed by the output angle determination unit 64.

  As mentioned above, although the best mode for carrying out the present invention has been described using one embodiment, the present invention is not limited to such one embodiment, and within the scope not departing from the gist of the present invention, Various modifications and substitutions can be made to the above-described embodiment.

  For example, when an absolute angle θ acquisition means having no periodicity (for example, a simple potentiometer for a rotating body having a movable range within 360 °) is provided, or a means for acquiring the absolute angle θ with a sufficiently large period ( For example, in the above embodiment, when the derivation period is set to 1800 ° or the like, the same effect can be obtained by simpler control. FIG. 5 is a diagram showing an example of a flowchart applicable in such a case. In this case, the absolute angle θ of the rotating body is acquired (S200), it is determined whether or not the acquired absolute angle θ exceeds a predetermined range (S210), and is acquired when the predetermined range is exceeded. The value may be output as it is (S220), and if it does not exceed the predetermined range, a limit value may be output (S230). The determination as to whether or not the absolute angle θ of the rotating body in this flow exceeds a predetermined range does not have to consider the circularity of the absolute angle θ based on the derivation period, so simply calculate the absolute angle θ and the limit value. This can be done by comparison.

  In addition, the specific modes of the gears 10, 20, and 30, the magnets 20A and 30A, the angle sensors 40 and 50, and the output calculation device 60 exemplified as the hardware configuration are merely examples, and there are no restrictions. For example, a belt, a pulley, a planetary gear, or the like may be used instead of the gear, and the angle sensors 40 and 50 are not limited to those using anisotropic magnetoresistive elements (AMR elements).

  The present invention can be used for an apparatus for detecting an absolute angle of a rotating body, such as at least a steering angle sensor. When mounted on a vehicle, the appearance, weight, size, running performance, etc. of the mounted vehicle are not limited.

It is a figure which shows an example of the whole structure of the absolute angle information output device 1 which concerns on one Example of this invention. It is a figure which shows the change of absolute angle (theta) derived | led-out according to rotation of a steering wheel. 6 is a flowchart showing a flow of characteristic processing executed by the CPU of the output arithmetic device 60. It is a figure which shows the change of the steering angle according to rotation of a steering wheel at the time of using the flowchart which shows the flow of the characteristic process of this invention. It is a figure which shows an example of the flowchart applicable to the apparatus which performs derivation | leading-out or detection which does not have periodicity, and the apparatus which derive | lead-out or detects with a sufficiently large period.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Absolute angle information output device 10, 20, 30 Gear 20A, 30A Magnet 40, 50 Angle sensor 60 Output calculating device 62 Absolute angle acquisition part 64 Output angle determination part

Claims (6)

An absolute angle information output device that outputs information on the absolute angle of a rotating body,
Absolute angle acquisition means for acquiring the absolute angle of the rotating body;
Output angle determination means for determining an output angle output from the absolute angle information output device based on the absolute angle of the rotating body acquired by the absolute angle acquisition means,
The output angle determining means determines the output angle so that the output angle is within a predetermined range based on a movable range of the rotating body.
An absolute angle information output device. The absolute angle information output device according to claim 1,
When the absolute angle of the rotating body acquired by the absolute angle acquisition unit is outside the predetermined range, the output angle determination unit sets the limit value of the predetermined range as an output angle.
An absolute angle information output device. The absolute angle information output device according to claim 1,
When the absolute angle of the rotating body acquired by the absolute angle acquisition unit exceeds the predetermined range, the output angle determination unit sets a limit value of the exceeded predetermined range as an output angle.
An absolute angle information output device. The absolute angle information output device according to claim 3,
The absolute angle acquisition means is means for acquiring the absolute angle of the rotating body at a predetermined cycle that is predetermined based on a movable range of the rotating body.
Absolute angle information output device. The absolute angle information output device according to claim 3 or 4,
The output angle determining means includes
Storage means for storing the absolute angle of the rotating body acquired by the absolute angle acquisition means;
A means for determining whether or not the absolute angle of the rotating body acquired by the absolute angle acquiring means exceeds the predetermined range based on a history of the absolute angle of the rotating body stored in the storage means; ,
Absolute angle information output device. An absolute angle information output device according to any one of claims 1 to 5,
The rotating body is a steering wheel;
Absolute angle information output device.

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