JP5091809B2 - Steering angle detector - Google Patents

Description

  The present invention relates to a steering angle detection device, and more particularly to a steering angle detection device capable of correcting a steering middle point position.

In general, in order to detect the steering angle of a steering wheel of a vehicle such as an automobile, a steering angle sensor that generates a pulse signal at every predetermined steering angle and every rotation of the steering wheel is used, and the position of the steering wheel during straight traveling is set as a middle position. The steering angle is detected based on this position. In this case, it is complicated to detect the straight traveling state of the vehicle and detect the steering wheel midpoint position for each traveling to specify the steering angle. The offset amount between the point and the steering angle is stored, and when the vehicle travels thereafter, the midpoint is obtained by calculation using the stored offset value (see Patent Document 1).
JP 2001-4313 A

By the way, since the steering angle is stored when the engine is stopped, and the stored value is used at the next start, the information on the steering angle is inherited when the engine is restarted after the engine is stopped. When the passenger turns off the ignition after turning off the ignition and turns the handle by putting his hand on the handle, or when he notices that the wheel is bent after turning off the ignition after stopping the engine, he turns the handle. When it is moved and corrected straight, the offset stored value used until then is shifted by the amount of rotation of the steering wheel, and immediately after the next start, the stored steering is stored until the vehicle goes straight again. There is a problem that the corners cannot be used.
Therefore, the steering angle cannot be used when it is necessary to obtain the steering angle immediately after starting, and the steering angle cannot be used for assist control during extremely low speed traveling before entering normal traveling such as garage removal assistance. is there.

  Accordingly, an object of the present invention is to provide a steering angle detection device that can quickly obtain a steering angle after starting.

In order to achieve the above object, the invention described in claim 1 is a steering angle detection device for detecting a steering angle of a steering wheel that steers a wheel of a vehicle, wherein the steering wheel has a middle point position at which the steering angle is zero and every 360 degrees. Z-phase determination means (for example, the steering angle sensor 5 in the embodiment) that detects this when the Z-phase is reached, and wheel rotation amount detection means (for example, the wheel in the embodiment) that detects the rotation amount of the wheel A first speed sensor 8) for setting a steering angle based on a stop-time steering angle stored when the engine is stopped when the Z-phase of the steering wheel is detected on the basis of the Z-phase determination means after starting. Regardless of the correction means (for example, the level 1 correction in step S3 in the embodiment) and the correction result of the first correction means, based on the detection result of the wheel rotation amount detection means at an extremely low vehicle speed. The second correction means for correcting the steering angle of the steering wheel (for example, level 2A correction in step S9 in the embodiment, level 2B correction in step S21) and the detection result of the wheel rotation amount detection means during normal vehicle speed straight traveling. And a third correction means for correcting the steering angle of the steering wheel (for example, level 3 correction in step S12 in the embodiment).
By configuring in this way, the midpoint of the steering wheel steering angle can be corrected even by movement of a very short distance immediately after starting, so that the steering angle of the steering wheel can be accurately grasped at such an extremely low speed.
The invention described in claim 2 is characterized in that the second correction means and the third correction means are selected in accordance with the vehicle speed (for example, 10 km / h or less, 20 km / h or more in the embodiment).
By configuring in this way, the steering wheel steering angle can be grasped in all traveling situations of the vehicle by performing the optimum midpoint correction according to the vehicle speed.
According to a third aspect of the present invention, the steering angle setting by the first correction means is performed only once after start-up, and the steering angle correction by the second correction means is that the steering angle correction by the second correction means is completed. Alternatively, it is completed when the steering angle correction by the third correction unit is completed once, and the steering angle correction by the third correction unit is continuously performed during traveling.
With this configuration, it is not necessary to perform unnecessary processing when the vehicle starts to travel.
The invention described in claim 4 is characterized in that the steering angle correction by the third correction means sets a stricter criterion for determining the middle position of the steering wheel than the first correction means and the second correction means.
By comprising in this way, the precision of a midpoint position can be continuously maintained highly by making the criteria of the midpoint position performed continuously during driving | running | striction severe.
According to a fifth aspect of the invention, the steering angle correction by the third correction unit is performed regardless of the result of the steering angle correction by the second correction unit after completion of the steering angle setting by the first correction unit. It is characterized by.
With such a configuration, priority is given to the steering angle correction at the normal vehicle speed straight traveling, and the steering angle correction by the second correction means can be performed at an extremely low vehicle speed when necessary.
In the invention described in claim 6, the wheel rotation amount detecting means used for correcting the steering angle by the second correcting means uses the distance traveled by the left and right wheels or the number of pulses detected by the wheel speed sensor. It is characterized by.
By configuring in this way, it is possible to cope with extremely low vehicle speeds in which accuracy cannot be ensured by the difference in left and right speeds because the time with respect to the travel distance is long.
According to the seventh aspect of the present invention, when the steering angle correction is performed by the second correction unit, the Z-phase position detected by the Z-phase determination unit is the midpoint of the steering angle zero and the other Z phases. Then, the threshold of the number of pulses detected by the distance traveled by the left and right wheels or the wheel speed sensor, which is a reference for determination, is changed, for example, the determination of the midpoint position of the steering angle zero as in the invention described in claim 8 Compared to the threshold value, other Z-phase position determination threshold values can be set narrower by the distance traveled by the left and right wheels or the number of pulses.
With this configuration, the determination range at the left and right 360 degrees can be tightened by widening the determination range at the midpoint where the running stability can be ensured in the Z phase.

  According to the first aspect of the present invention, since the middle point of the steering angle of the steering wheel can be corrected even by movement of a very short distance immediately after starting, the steering angle of the steering wheel can be accurately grasped at such an extremely low speed. For example, in garage exit assistance, etc., there is an effect that can be effectively used for control for estimating the expected course based on the steering angle of the steering wheel.

  According to the second aspect of the present invention, the steering wheel steering angle can be grasped in all the driving situations of the vehicle by performing the optimum midpoint correction according to the vehicle speed. There is an effect that can.

  According to the third aspect of the present invention, there is no need to perform unnecessary processing when the vehicle starts to travel, so that the processing load can be reduced.

  According to the invention described in claim 4, the accuracy of the midpoint position can be continuously maintained high by tightening the criteria for determining the midpoint position that is continuously performed during traveling. This has the effect of increasing the accuracy of the position.

  According to the fifth aspect of the present invention, the steering angle correction at the normal vehicle speed straight traveling is prioritized, and the steering angle correction by the second correction means can be performed at the extremely low vehicle speed when necessary. The effect is that priority can be given.

  According to the sixth aspect of the present invention, since the time with respect to the travel distance is long, it is possible to cope with an extremely low vehicle speed in which the accuracy cannot be ensured by the difference between the left and right speeds, and therefore the steering angle can be corrected accurately. effective.

  According to the seventh and eighth aspects of the present invention, the determination range at the left and right 360 degrees can be tightened by widening the determination range at the midpoint in the Z phase. There is an effect that it is easy to find a range in which the situation can be determined.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram including a steering angle detection device of the present invention. An IG (ignition) switch 2 connected to the battery 1 is connected to an IG switch determination unit 3, and the IG switch determination unit 3 is connected to a handle angle midpoint correction processing unit 4. The value of the IG flag output from the IG switch determination unit 3 is sent to the handle angle midpoint correction processing unit 4. Here, the IG flag is “1” when the ignition is on.

  Reference numeral 5 denotes a rudder angle sensor. The rudder angle sensor 5 outputs three types of pulse signals. Specifically, as shown in FIG. 2, the A phase that outputs 90 pulses (High and Low are 2 degrees (deg) width) by one rotation of the steering wheel, and the 1/4 wavelength that outputs the same pulse as the A phase. It has a B phase with a deviation of (1 degree (deg)). In the clockwise rotation, the A phase rising pulse (High) is entered and then the B phase rising pulse enters after a ¼ wavelength delay. In the counterclockwise rotation, the B phase is delayed by a quarter wavelength after the B phase rising pulse is received. A rising pulse (High) is entered. By these A phase and B phase, it is possible to detect how many degrees the handle has been turned left and right (deg) from the current position.

Further, as shown in FIG. 3, the rudder angle sensor 5 has a Z phase that outputs one pulse with one rotation of the steering wheel. This Z-phase pulse outputs a high signal until then at the midpoint of the steering wheel steering angle zero, 360 degrees to the left, and 360 degrees to the right in a vehicle where the steering wheel rotates about one and a half turns to the left and right. The low signal is output in the range of 10 degrees (deg).
From this Z phase, it can be detected that the steering angle of the steering wheel is zero, which is the middle point, 360 degrees to the right, or 360 degrees to the left.

  The A-phase, B-phase, and Z-phase signals output from the steering angle sensor are output to the steering wheel angle calculation unit 6. Steering wheel steering angle information before correction and Z-phase flag information are input to the steering wheel angle midpoint correction processing unit 4 from the steering wheel angle calculation unit 6. The Z-phase flag is “1” when the Z-phase is detected.

Reference numeral 7 denotes a CAN transceiver. The CAN transceiver 7 receives various types of information from other units 9 provided on all wheels and wheel speed sensors 8 connected thereto via F-CAN which is an in-vehicle run. . Information received by the CAN transceiver 7, for example, information on the wheel speed for detecting the wheel speed from the wheel speed sensor 8, wheel speed pulse integrated value, and PKB (parking brake) flag information is input to the steering wheel angle midpoint correction processing unit 4. Is done. The steering wheel angle midpoint correction processing unit 4 outputs the corrected steering wheel steering angle.
The IG switch determination unit 3, the handle angle calculation unit 6, the CAN transceiver 7, and the handle angle midpoint correction processing unit 4 constitute a control unit 10.

Next, the steering angle detection process will be described based on the flowcharts of FIGS.
This flowchart roughly shows a procedure for detecting the current steering angle while the vehicle is stopped until the vehicle stops running with the ignition on. This process is mainly performed by the handle angle midpoint correction processing unit 4.
In step S1 of FIG. 4, it is determined whether or not the Z phase has been detected after the ignition switch is turned on. This determination is performed until the Z phase is detected. When the Z-phase is detected, it is determined in step S2 whether or not it coincides with the midpoint position when the IG (ignition switch) is off.

  For example, since the steering angle of the steering wheel is 60 degrees (plus counterclockwise) when the IG is off, it is assumed that 60 degrees is stored as a stored value. Next, when the IG is on, the steering angle of the steering wheel starts from zero (zero is the initial steering wheel angle before correction). Therefore, the Z-phase is not applied until the steering wheel steering angle starting from zero degrees is turned -60 degrees (60 degrees to the right). Will be detected. In this case, the zero point position (position cut 60 degrees to the right) derived from the stored value is equal to the rotation angle (position 60 degrees to the right) up to the Z phase that has been detected. Therefore, it coincides with the midpoint position when the IG is off.

If the result of determination in step S2 is the same (“YES”), level 1 correction is performed in step S3. This level 1 correction is a correction process for replacing the steering angle with zero. Here, the replacement processing is “−60” when the value of “0” stored when the IG is turned on is turned to 60 degrees to the right. However, since the Z phase is detected here, this “−” This means that the value “60” is replaced with the value “0” when it passes through the Z phase. After this processing, “1” is set to the level 1 correction completion flag in step S4, and the process proceeds to step S5. On the other hand, if the result of determination in step S2 is not the same (“NO”), the process proceeds to step S17. The range of the number of pulses at the zero point, which is a criterion for determining whether or not they match, is set to about ± 10 pulses (20 pulse width).
Therefore, level correction 2A (step S9) and level 2B correction (step S21), which will be described later, are performed even if level 1 correction is performed ("YES" in step S2) or "NO" in step S2. That is, the correction is performed regardless of the correction result of the level 1 correction (steps S4 and S17).

  In step S5, it is determined whether or not the wheel speed detected by the wheel speed sensor is 20 km / h or more for all wheels. If the determination result is 20 km / h or more, the process proceeds to step S12. That is, even if the level 2A correction is not performed, the process shifts to the level 3 correction. As a result of the determination in step S5, if even one wheel is less than 20 km / h, the process proceeds to step S6. In step S6, it is determined whether the left and right rear wheel speeds are 10 km / h or less. As a result of the determination, if the left and right rear wheels are 10 km / h or less, the process proceeds to step S7 on the assumption that the Z phase has been detected. When the determination result in step S6 is either 10 km / h or more, the process returns to step S5. In other words, if any of the left and right rear wheels exceeds 10 km / h and is less than 20 km / h, the vehicle waits until the other range is reached. Whether the level 2A correction or the level 3 correction is selected by the determination in step S5 or step S6.

  In step S7, it is determined whether or not the level 2 correction completion flag is “1”. When the level 2 correction completion flag is “1”, the process proceeds to step S11. Here, since the level 2A and 2B correction has not been performed once, the flag value is “0” and the determination result is “NO”, so the flow proceeds to step S8. Here, if the level 2A and 2B correction has been performed even once, the level 2 correction completion flag becomes “1”, and thereafter the level 2A and 2B correction is not performed (“YES” in steps S7 and S20). If there is, the process proceeds to step S12 via step S11).

In step S8, it is determined whether or not the Z phase detected again matches the level 1 correction result. In other words, in the level 1 correction, the Z phase detected first is not necessarily the midpoint of zero, but merely detects the Z phase, so whether the Z phase is zero, 360 degrees to the right, Whether it is 360 degrees to the left cannot be determined. For example, when the steering wheel is rotated 360 degrees to either the left or right after IG is turned off, processing is performed as if it is a midpoint although it is not originally a midpoint.
Therefore, in step S8, the difference between the left and right rear wheel speeds is detected from the detected value of the wheel speed sensor, and it is determined whether the detected Z-phase steering angle is 360 degrees left, 360 degrees right, or zero. It is detected and it is determined whether or not there is an error in the determination that the Z phase in the level 1 correction is zero. When the left wheel speed is greater than the right, the Z phase is 360 degrees to the right (one turn to the right), and when the right wheel speed is greater than the left, the Z phase is 360 degrees to the left (the Z phase is one turn to the left) If the Z phase and the left and right wheel speeds are equal, it can be determined that the position is the midpoint position.

  If the determination result in step S8 is “YES” and the Z phase matches the result of the level 1 correction, the process proceeds to step S9, the determination result in step S8 is “NO”, and the Z phase is level 1. If it does not coincide with the result of the correction, the process proceeds to step S21.

  In step S9, level 2A correction is performed. Here, this level 2A correction corrects the steering angle based on the difference between the integrated values of the number of pulses read from the left and right rear wheel speed sensors, that is, the difference in distance. This is because the measurement time becomes longer at extremely low speeds, so that the result is not accurately obtained by the amount of time when the speed is used as a reference. As a result of measuring the integrated value of the number of pulses, if it is confirmed that the stored value of the level 1 correction is correctly the midpoint of the steering angle zero in the level 1 correction, the midpoint of the steering wheel steering angle is corrected to zero. . If it is incorrect, correct it with the correct value. That is, correction is performed regardless of the level 1 correction result.

Level 2A correction is performed according to the following procedure, which shows processing until the steering wheel steering angle value is corrected (step S9) on the premise of the processing in step S8.
As a first step, the steering wheel steering angle and the wheel speed pulse integrated value at the time of detecting the Z phase are stored in the memory. As a second step, the wheel speed pulse integrated value is stored again, and the difference between the increase amounts of the left and right wheel speed pulses is calculated. In the third stage, the Z-phase position is determined. The conditions for storing the steering wheel steering angle and the wheel speed pulse integrated value at the time of the first phase Z phase detection in the memory are that the rear wheel speed, which is the condition of step S6, is 10 km / h or less for both left and right, and the PKB flag Is “0”, that is, the parking brake is not applied and the wheel is not locked, and the level 2 correction completion flag that is the condition of step S7 is “0”, that is, level 2 correction (including 2A and 2B) is performed once. It is a condition that the Z phase, which is the condition of step S1, is detected once. When such a condition is satisfied, the value of the current steering wheel steering angle is set as the steering wheel steering angle when passing through the Z phase, and the current wheel pulse is set as the wheel speed pulse values of the left and right rear wheels.

  As a condition for storing the second wheel speed pulse integrated value in the second stage in the memory, the condition in the first stage is satisfied, and the detected Z phase is limited to the vicinity of the detected Z phase. The steering angle of the steering wheel is within a range of ± 100 degrees across the vehicle, and there was a certain distance, for example, traveling more than 50 pulses at the wheel speed pulse, in order to calculate the difference between the left and right wheel speed pulses. Is a condition. When such a condition is satisfied, the current wheel pulse is set to the wheel speed pulse value of the left and right rear wheels.

  Next, in the second stage, the left-right difference in the increase amount of the wheel speed pulse is obtained. For example, the wheel speed pulse in the first stage is 10 pulses for the left rear wheel, 20 pulses for the right rear wheel, and the second wheel speed pulse in the second stage is 30 pulses for the left rear wheel and 41 pulses for the right rear wheel. In this case, the increase amount of the left rear wheel is 20 pulses, and the increase amount of the right rear wheel is 21 pulses. Therefore, the difference between the increase amounts of the wheel speed pulses of the left and right rear wheels is 1 pulse, that is, this is the left and right rear wheels. It becomes the distance difference of the ring.

  In the third stage, it is determined whether the Z phase is at the midpoint position, 360 degrees to the left, or 360 degrees to the right based on the difference in the increase amount. Specifically, the left-right difference of the increase amount is in the Z phase of 360 degrees to the left within the range of -14 to -9 pulses, and the midpoint position is within the range of the left-right difference of the increase amount of -4 to +4 pulses. The Z phase is determined to be 360 degrees to the right if the left-right difference in the increase amount is within the range of +9 pulse to +14 pulse. In the above example, since the difference was 1 pulse, it became clear that the stored Z phase was the midpoint. Therefore, the steering angle is corrected with the position where the Z phase is detected as the midpoint. Here, when the Z phase is 360 degrees to the left and right, the range is 5 pulses, the midpoint determination range is 8 pulses, and so on, compared to the determination threshold value of the midpoint position of the Z phase at zero steering angle. The reason why the difference is set by narrowing the determination threshold of the Z-phase position by the number of pulses of the left and right rear wheels is because the range near the midpoint is more stable as a car because it is more stable and easier to find It is. This process corresponds to step S9, and if there is an error in the determination result being determined as the midpoint at the time of level 1 correction, the process proceeds to level 2B correction in step S21.

Then, in the next step S10, “1” is set to the level 2 correction completion flag, and the process proceeds to step S11.
In step S11, it is determined whether or not the wheel speed detected by the wheel speed sensor is 20 km / h or more for all wheels. If the determination result is 20 km / h or more, the process proceeds to step S12. If the determination result in step S11 is less than 20 km / h, the process proceeds to step S6. Note that, after this, either the left or right rear wheel speed becomes 10 km / h or less, and even if the process returns to step S6, “YES” in step S7, the level 2A correction in step S9 is not performed twice.

  In step S12, level 3 correction is performed. This level 3 correction is performed under the condition that the wheel speed is 20 km / h or more for all wheels (step S11), and the steering angle is obtained by the wheel speed sensor, and the steering angle corrected in the level 1 correction or the level 2A or 2B correction is obtained. to correct. Here, this level 3 correction corrects the midpoint of the steering angle zero based on the speed difference (value obtained by dividing the distance obtained from the number of pulses by time) read from the wheel speed sensors of the left and right rear wheels. This is because when the vehicle is traveling straight at a normal vehicle speed of 20 km / h or higher, the steering angle is calculated more accurately by using the speed difference.

  As specific conditions for level 3 correction, the PKB flag is “0”, that is, the parking brake is not applied and the wheel is not locked, there is no acceleration / deceleration, within a certain range after the Z-phase detection. Thus, there is no deviation between the left and right wheel speeds, and the steering angle at this time is corrected with the steering angle at this time as a midpoint, and output.

  Here, in the level 3 correction, the correction is performed under stricter conditions than the level 1 correction and the level 2 correction. This is a correction performed during normal traveling at a normal vehicle speed, so that it can be limited to the vicinity of the midpoint by the higher vehicle speed, and the accuracy of level 3 correction performed continuously is increased. The target of this determination is the midpoint, but the number of pulses used as the determination reference for the midpoint position is smaller than the number of pulses for midpoint determination of level 1 correction, level 2A, and 2B correction (less than 6 pulses). ) Is set strictly.

  In step S13, “1” is set in the level 3 correction completion flag and “1” is set in the level 2 correction completion flag, and the process proceeds to step S15. That is, when the level 3 correction completion flag is “1”, the level 2 correction completion flag is also “1”. Therefore, once the level 3 correction is performed, the level 2A and 2B corrections are performed. Even if the 2A and 2B correction is not performed (“YES” in steps S5 and S18), the level 2A and 2B correction is not performed thereafter.

  In step S15, the steering angle is obtained by the wheel speed sensor under the condition that the wheel speed detected by the wheel speed sensor is 20 km / h or more for all the wheels, and the value of the steering angle corrected in the previous level 3 correction is obtained. The process is continuously performed during traveling while updating, and is continued until the traveling is finished (terminated).

In step S17, the level 1 correction completion flag is set to “0” and the process proceeds to step S18. This flag is set to “1” when level 1 correction is performed. That is, in this state, the steering wheel steering angle when IG is off and the steering wheel angle before correction are stored.
In step S18, it is determined whether or not the wheel speed detected by the wheel speed sensor is 20 km / h or more for all the wheels. If the determination result is 20 km / h or more, the process proceeds to step S12. That is, even if the level 2B correction is not performed, the process shifts to the level 3 correction.
As a result of the determination in step S18, if even one wheel is less than 20 km / h, the process proceeds to step S19. In step S19, it is determined whether the left and right rear wheel speeds are 10 km / h or less. As a result of the determination, if the left and right rear wheels are 10 km / h or less, the process proceeds to step S20 on the assumption that the Z phase has been detected. When the determination result in step S19 is that either left or right exceeds 10 km / h, the process returns to step S18. In other words, if any of the left and right rear wheels exceeds 10 km / h and is less than 20 km / h, the vehicle waits until the other range is reached. Whether the level 2B correction or the level 3 correction is selected is determined by the determination in step S18 or step S19.

  In step S20, it is determined whether or not the level 2 correction completion flag is “1”. When the level 2 correction completion flag is “1”, the process proceeds to step S11. Here, since the level 2 correction has not been performed once, the flag value is “0” and the determination result is “NO”, so the flow proceeds to step S21.

In step S21, level 2B correction is performed. The level 2B correction is the same as the level 2A correction in terms of content, and thus description thereof is omitted.
In step 21, when level 1 correction is not performed (step S 17), a midpoint that gives an accurate steering angle is corrected so that the steering angle can be output. Although the correction is completed, there is a case where the midpoint at which the steering wheel steering angle is zero actually deviates by 360 degrees × n (n = integer) (“NO” in step S8). In any case, accurate midpoint correction can be performed from the Z-phase position detected the second time.
Then, in the next step S22, “1” is set to the level 2 correction completion flag, and the process proceeds to step S11.

  Therefore, according to this embodiment, since the middle point of the steering angle of the steering wheel can be corrected even by movement of a very short distance immediately after starting, the steering angle of the steering wheel can be accurately grasped at an extremely low speed of 10 km / h or less. For example, it can be effectively used for control for estimating the expected course based on the steering angle of the steering wheel, for example, in garage exit assistance. In other words, when performing control to display the trajectory of the wheels on the monitor for garage removal support, it is necessary to accurately grasp the steering angle of the steering wheel immediately after starting. The steering angle of the steering wheel can be grasped quickly.

  Also, by selecting level 1 correction, level 2A, 2B correction, and level 3 correction with thresholds of extremely low speeds of 10 km / h or less and straight travels of 20 km / h or more, an optimal midpoint correction according to the vehicle speed is selected. It can be performed. Therefore, it is possible to accurately grasp the steering angle of the steering wheel in all the driving situations of the vehicle and use it for various controls.

Level 1 correction is performed only once after start-up, and Level 2A correction is completed when Level 2A and 2B correction is completed once or Level 3 correction is completed even once. Level 3 correction is performed while driving. Since it is continuously performed, it is not necessary to perform unnecessary processing once it starts to travel at 20 km / h or more, so that the processing load can be reduced.
Furthermore, since the level 3 correction is performed regardless of the result of the steering angle correction by the level 2A and 2B correction means after the completion of the level 1 correction, the steering angle correction during straight traveling at 20 km / h or higher is prioritized. However, since it is possible to perform the steering angle correction at an extremely low speed of 10 km / h or less by the level 2A and 2B correction when necessary, the correction with high accuracy can be prioritized.

  The level 3 correction is made stricter by setting the determination point of the midpoint position of the steering wheel to be smaller than 14 pulses in the pulse width than the level 1 correction, the level 2A, and the 2B correction, and the midpoint position continuously performed during the traveling. By tightening the determination criteria, the accuracy of the midpoint position can be kept high continuously.

  Furthermore, in order to perform level 2A and 2B correction, the distance traveled by the left and right wheels or the number of pulses detected by the wheel speed sensor is used, so that the time with respect to the travel distance is long, so the difference in speed between the left and right It is possible to deal with extremely low vehicle speeds where accuracy cannot be ensured. As a result, steering angle correction can be performed accurately even at extremely low vehicle speeds.

  When level 2A and 2B correction is performed, the determination range at the middle point that can ensure the stability of traveling in the Z phase is widened (8 pulse width), so that the determination range of 360 degrees to the left and right (5 (Pulse width) can be tightened, so that it is easy to find a range in which it is possible to determine a more stable straight traveling situation.

  Therefore, by using the level 2A and 2B correction at the extremely low vehicle speed in this way, it is possible to quickly correct the midpoint and grasp the accurate steering angle. As a result, in the garage entry garage exit support, it is possible to cope with control that cannot be realized unless the steering angle of the steering wheel is detected promptly from the ignition-off state as in the case of garage exit.

  The present invention is not limited to the above embodiment, and can be set to other than vehicle speed thresholds of 10 km / h and 20 km / h, which are conditions for level 2A and 2B correction, for example. Further, the number of pulses for determining the midpoint is an example, and it is possible to adopt a mode such as changing according to the vehicle speed. Further, although the wheel speed sensor is taken as an example of the wheel rotation amount detection means, other sensors may be used.

1 is a block diagram of an embodiment of the present invention. It is a graph which shows the output waveform of A and B phase of the rudder angle sensor of this invention. It is a graph which shows the output waveform of the Z phase of the rudder angle sensor of this invention. It is a flowchart figure of embodiment of this invention. It is a flowchart figure of embodiment of this invention.

Explanation of symbols

5 Rudder angle sensor (Z-phase determination means)
8 Wheel speed sensor (wheel rotation amount detection means)
S2 Level 1 correction (first correction means)
S9 Level 2A correction (second correction means)
S12 Level 3 correction (third correction means)
S21 Level 2B correction (second correction means)

Claims (8)

  In a steering angle detection device for detecting a steering angle of a steering wheel that steers a wheel of a vehicle, when a steering wheel reaches a Z-phase at a middle point position of every steering angle and every 360 degrees, a Z-phase determination is detected. And a wheel rotation amount detection means for detecting the rotation amount of the wheel. When the Z phase of the steering wheel is detected on the basis of the Z phase determination means after starting, the steering at the stop stored when the engine is stopped First steering means for setting the steering angle based on the angle, and regardless of the correction result of the first correction means, the steering angle of the steering wheel is corrected based on the detection result of the wheel rotation amount detection means at an extremely low vehicle speed. A steering angle detection device comprising: second correction means; and third correction means for correcting the steering angle of the steering wheel based on the detection result of the wheel rotation amount detection means during normal vehicle speed straight traveling.   The steering angle detection device according to claim 1, wherein the second correction means and the third correction means are selected in accordance with a vehicle speed.   The steering angle setting by the first correction means is performed only once after starting, and the steering angle correction by the second correction means is performed when the steering angle correction by the second correction means is once completed, or the steering angle by the third correction means. 3. The steering angle detection device according to claim 2, wherein the correction is completed when the correction is completed even once, and the steering angle correction by the third correction means is continuously performed during traveling.   4. The steering angle correction by the third correction unit sets a criterion for determining the midpoint position of the steering wheel more strictly than the first correction unit and the second correction unit. 5. The steering angle detection device according to item.   The steering angle correction by the third correction unit is performed regardless of the result of the steering angle correction by the second correction unit after completion of the steering angle setting by the first correction unit. 5. The steering angle detection device according to any one of items 4.   The wheel rotation amount detection means used for performing the steering angle correction by the second correction means uses a distance traveled by left and right wheels or a pulse number detected by a wheel speed sensor. The steering angle detection device according to any one of claims 1 to 5.   When the steering angle correction is performed by the second correction means, the position of the Z phase detected by the Z phase determination means is determined by the middle point of the zero steering angle and the other Z phases as the determination reference. The steering angle detection device according to any one of claims 1 to 6, wherein a threshold of the distance traveled by the vehicle or a pulse number detected by a wheel speed sensor is changed.   8. The steering according to claim 7, wherein the determination threshold value for the other Z-phase position is set to be narrower by the distance traveled by the left and right wheels or the number of pulses as compared to the determination threshold value for the midpoint position at which the steering angle is zero. Angle detection device.

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