JP2005001667A - Steering angle correcting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely correct a neutral point of a steering angle and improve reliability in a steering angle correcting device for correcting the neutral point of the steering angle. <P>SOLUTION: An initial maximum steering angle and an initial minimum steering angle of steering are stored in advance. At the time of correcting a neutral point, the steering is operated, so as to find a maximum steering angle (steer) or a minimum steering angle (steer) (S504, S506). In this case, it is judged whether the maximum steering angle by the operation is beyond a dead zone area with an initial maximum steering angle (steering angle MAX) as a reference, or the minimum steering angle is beyond a dead zone area with the initial minimum steering angle (steering angle MIN) as a reference (S507, S512). By this judgment, when it is beyond the dead zone area, it is judged as displacement of the steering angle of the neutral point, so as to correct the steering angle of the neutral point (S508, S513). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rudder angle correction device that performs neutral point correction of a rudder angle, for example, in a vehicle or the like, obtains a relative rudder angle based on information from a rudder angle detector, detects a neutral point, The present invention relates to a steering angle correction device that corrects a relative steering angle with a neutral point to obtain an absolute steering angle.

  Conventionally, such a device is a parking assistance device that assists a beginner who is unfamiliar with parking such as parallel parking or garage parking at the time of parking operation, and displays a predicted traveling track of the vehicle according to the steering angle of the steering wheel at the time of parking operation. Applied. For example, in the parking assist device disclosed in Patent Document 1, in order to detect the steering amount of the driver's steering wheel, a steering travel sensor is used to obtain a predicted travel path of the vehicle based on the steering angle from the steering sensor and vehicle specifications. The predicted travel trajectory is displayed so as to be superimposed on a rear image captured by a camera provided at the rear. The predicted travel locus is variably displayed according to the steering angle from the camera steering sensor.

  In this case, it is necessary to determine the neutral point of the steering wheel in order to display the predicted backward trajectory. Here, the neutral point is determined based on information from wheel speed sensors provided on the left and right wheels, respectively. . Specifically, in the wheel speed pulses output from the wheel speed sensors provided on the left and right, when there is no difference between the left and right pulses, the counter value for obtaining the steering angle is considered that the vehicle is traveling straight. Is set to zero (the neutral position) in straight ahead, and the neutral point of the steering angle is determined.

In Patent Document 2, when a neutral position signal is output from a steering sensor using a steering angle sensor that outputs a neutral point signal of a steering wheel, a vehicle speed sensor that detects a vehicle speed, and a yaw rate sensor that detects a yaw rate of the vehicle, A neutral point is determined when the absolute value of the yaw rate is equal to or lower than the predetermined yaw rate value and the vehicle speed is equal to or higher than the predetermined vehicle speed.
JP 11-334470 A (first page) Japanese Utility Model Publication No. 1-170070 (first page)

  However, the method for correcting the neutral point of the rudder angle as described above requires information from the wheel speed sensors provided on the left and right wheels in addition to the steering sensor. If there is a difference, the number of pulses output from the left and right wheel speed sensors changes due to this air pressure difference, making it difficult to correct the neutral point of the steering angle.

  In addition, a steering sensor that outputs a neutral point signal is required in a device that performs neutral point correction of the steering angle using a steering angle sensor that outputs a neutral point signal of a steering wheel, a vehicle speed sensor, and a yaw rate sensor. In this case, when the vehicle is shipped from the factory, or when the steering wheel is removed and reattached, etc., if the steering wheel mounting accuracy is not sufficient, a position different from the true neutral point becomes the neutral point. Therefore, since the neutral point signal is output at a position that is not a true neutral point when the vehicle is traveling, the reliability of the neutral point correction is lowered.

  In addition, when the vehicle is running normally, if the vehicle is running on a large curve where the difference between the left and right wheels is not likely to occur, it is necessary to determine the neutral point in order to distinguish between straight running and turning. If the pulse difference threshold is increased, even if there is a certain difference between the left and right pulse differences during turning, the state is determined as the neutral position, so an error will occur when detecting the neutral point and accurate neutral point detection will occur. In some cases, it is impossible to correct the rudder angle.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to accurately correct the neutral point of the rudder angle and improve the reliability.

  The first technical means taken in order to solve the above-mentioned problems is the steering angle detection means (2) for detecting the steering angle and the initial maximum steering angle (steering angle MAX) of the steering (21) having a neutral point. And an initial steering angle storage means (11) for storing in advance an initial minimum steering angle (steering angle MIN), a limit steering angle storage means (11) for storing the maximum steering angle or the minimum steering angle by operating the steering, Neutral point correction that corrects the rudder angle at the neutral point when the maximum rudder angle is outside the dead band region based on the initial maximum rudder angle or the minimum rudder angle is outside the dead band region based on the initial minimum rudder angle And means (11).

  Further, the second technical means taken in order to solve the above-described problems includes a steering angle detection means (2) for detecting a steering angle of a steering provided in a vehicle, and an initial maximum steering angle (steering angle MAX). ) And an initial minimum steering angle (steering angle MIN), an initial steering angle storage means (11) that stores in advance, a limit steering angle storage means (11) that stores a maximum steering angle or a minimum steering angle, and a minimum steering angle And a minimum dead zone region (region from the steering angle MIN to a predetermined steering angle (for example, 10 °)) and a maximum dead zone region (based on the steering angle MAX to a predetermined steering angle (for example, 10 °)). 10 °) area), and after obtaining the neutral point rudder angle based on the initial minimum rudder angle and the initial maximum rudder angle, the steering is operated in one direction, and the dead zone region with the smallest rudder angle (steer) The deviation between the rudder angle and the minimum rudder angle Or, if the steering is operated in the reverse direction, the deviation between the steering angle and the maximum steering angle is obtained when the steering angle is outside the maximum dead zone, and the neutral point correction is performed to correct the neutral steering angle based on the deviation. Means (11).

  In this case, either the maximum steering angle or the minimum steering angle may be corrected based on the deviation.

  Further, the correction of the neutral point rudder angle is preferably performed while the vehicle is stopped.

  According to the present invention, the initial maximum steering angle and the initial minimum steering angle of the steering are stored in advance (for example, stored in a vehicle at the time of factory shipment, for example), and the maximum steering angle is adjusted by operating the steering at the time of neutral point correction. Alternatively, the minimum rudder angle is obtained (S504, S506), and the maximum rudder angle by the operation is outside the dead zone region based on the initial maximum rudder angle (steering angle MAX), or the minimum rudder angle is the initial minimum rudder angle (steering angle MIN). It is determined whether it is outside the dead zone region with reference to (S507, S512). If the result of this determination is that the vehicle is outside the dead zone region, the neutral point rudder angle is corrected (S508, S513), assuming that the neutral point rudder angle has shifted. Therefore, even when the maximum steering angle or the minimum steering angle is deviated, neutral point correction based on the steering angle stored as the initial steering angle can be performed, and accurate neutral point correction can be performed.

  In this case, when the maximum steering angle is outside the dead zone region based on the initial maximum steering angle by the operation, the neutral point steering angle can be corrected by the deviation between the maximum steering angle and the initial maximum steering angle. Similarly, when the minimum rudder angle is outside the dead zone region based on the initial minimum rudder angle by operation, the neutral point rudder angle can be corrected by the deviation between the minimum rudder angle and the initial minimum rudder angle.

  In addition, in order to facilitate understanding of the present invention, the reference numerals used in the embodiments described below are added for reference in the parentheses shown above, but the reference numerals are not limited thereto.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram when the rudder angle correction device according to the first embodiment of the present invention is applied to a parking assistance device 1. In this figure, a controller 16 for controlling the parking assist device 1 includes a steering sensor for detecting a steering angle of a CCD camera (hereinafter referred to as a camera) 17 and a steering wheel (hereinafter referred to as a steering) 21 for photographing the rear of the vehicle. 2, a shift lever reverse switch 3 for detecting a reverse (reverse) state of a transmission shift lever, a parking switch 4 for operating a parking assist function at the time of a parking operation, and a vehicle speed sensor 5 provided on a transmission rotation shaft of the transmission Based on these signals, the controller 16 can display a rear image of the vehicle and a predicted traveling locus 20 described later on the display 13. Further, the voice synthesis circuit 7 can output a voice synthesis output from the speaker 8 to the driver.

  The signal from the vehicle speed sensor 5 input to the CPU 11 is a signal that generates a pulse signal corresponding to the rotation of the rotation shaft of the mission. However, the present invention is not limited to this, and anti-skid brake control or stability control is used. It is also possible to use a vehicle speed signal that is normally input to a controller (not shown) that performs the above. The vehicle speed at which the vehicle is running or stopped can be found from the pulse period of such a signal.

  Inside the controller 16 is a CPU 11 that controls the graphics, a graphics drawing circuit 12 that draws graphics on the display 13, a superimpose circuit 9 that superimposes the graphics signal and the rear image from the camera 17, and a synchronization signal from the camera image. A synchronous separation circuit 10 that extracts and supplies the graphics drawing circuit 12 and a parking section detection image recognition device 15 that receives a signal from the camera 17 and recognizes a parking section image are provided. Note that the image recognition device 15 may be provided separately from the controller 16.

  On the display 13, there is provided a steering angle state display (display marker) 14 whose lighting state changes depending on the steering angle state of the steering. Depending on the steering angle state, either the left or right or the center of the display marker 14 is lit. It is possible to know which side 21 is steered together with the rear image.

  FIG. 2 shows an attachment diagram when the parking assist device 1 is attached to the vehicle. A camera 17 that captures the rear is attached near the upper center of the license plate at the rear of the vehicle, and is installed with the optical axis facing downward. Specifically, as shown in FIG. 3, it is attached to the center of the rear of the vehicle facing downward (about 30 degrees), and the camera itself secures a field of view of 140 degrees to the left and right with a wide-angle lens. The area can be photographed.

  Further, a display 13 is provided on the panel surface of the center console in the vehicle interior, and a controller 16 is provided above the glove box. Furthermore, the parking switch 4 that issues a request to assist parking is provided in the vicinity of the center console that is easy for the driver to operate.

  Here, the steering sensor 2 will be described with reference to FIG. The steering sensor 2 is a commercially available sensor, and the steering angle of the steering 21 can be detected. The slit plate 2a is attached to rotate integrally with the steering column shaft 23, and two sets of photo interrupters 2c and 2b having a phase difference of 90 ° are attached. In this configuration, two signal pulses of A-phase and B-phase are generated by turning on / off the phototransistor by passing or blocking light by rotation of a plurality of slits provided circumferentially on the disk plate 2a. Output. This is because the phase of the B phase is delayed by 90 ° or advanced by the rotation direction of the steering wheel 21. In this embodiment, the steering angle is 1 ° / pulse. Something is used.

  Next, processing of the controller 16 will be described with reference to FIG. The controller 16 starts the program shown in FIG. 5 when the power is turned on (the accessory switch is turned on).

  In step S101, various initial values are set in the memory necessary for this processing. Thereafter, the state of the shift reverse switch 3 is chucked in step S102, and if it is off (not reverse), the display on the display 13 is stopped in step S111, and the process returns to step S102. On the other hand, when the shift reverse switch 3 is turned on (reverse lever state), step S103 is performed. In step S103, the display 13 is switched to the camera image mode so that an image behind the vehicle can be displayed as a raw image. That is, it is a normal back monitor camera.

  Next, the parking switch 4 which assists parking at the time of parking operation is checked in step S104. If the parking switch 4 is off (no parking assistance is requested), the graphic screen of the display 13 is cleared in step S112, only the rear raw image is displayed on the display 13, and the process returns to step S102. . On the other hand, if the parking switch 4 is on (in a state where there is a parking assistance request) in step S104, the process proceeds to step S105, where a predetermined voice signal is output to the voice synthesis circuit 7 and voice output is performed from the speaker 8. . In other words, depending on the situation, “Parking assistance. Adjust the locus to the desired position, please back while paying attention to the surroundings.”, “The parking guide will start from now. Rotate the handle so that the tip of the (trajectory) display is toward the parking area. "Be careful of the right (left)." Give guidance.

  Next, in step S106, the steering sensor value N is read from the steering sensor 2, and the current turning radius R at the time of parking operation is calculated based on the value. Specifically, the reading of the steering sensor 2 is interrupted to the main program when the rising edge of the A phase signal is detected, and the interruption process shown in FIG. 6 is executed. That is, the state of the B phase signal is checked in step S201 in FIG. 6, and if the B phase signal is high (H: high potential), the steering count value N is incremented in step S202, and decremented if low (L: low potential). The value is stored in the memory. In this case, the steering count value N is θ = N because one pulse is 1 °.

  However, since the absolute steering angle of the steering wheel 21 becomes unstable only by counting the steering value N shown above, the neutral point of the steering angle is detected by the method shown in FIG. 7, and the neutral point is determined by setting N = 0. .

  Accordingly, neutral point determination (neutral point processing) will be described with reference to FIGS. This process is executed by a timer interrupt with a fixed period (for example, 5 ms).

  In FIG. 7, the neutral point process (long distance) is performed in step S302 after the neutral point process (short distance) in step S301. The neutral point process shown in steps S301 and S302 is basically performed in FIGS. The same processing as that shown in FIG. In this process, parameter settings are set independently for short distance and long distance. That is, when short-distance neutral point processing is performed in step S301, the short-distance parameters (distance constant maximum / minimum vehicle speed constant, intra-section steering angle change / steering angle data change allowable value constant, count constant) are set. When the neutral point is determined by this process, the short distance establishment flag indicating that the short distance is established is set. However, if the neutral point is not determined, the short distance establishment flag is changed to the state after initialization (clear state). maintain. Similarly, when long-distance neutral point processing is performed in step S302, long-distance parameters (distance constant maximum / minimum vehicle speed constant, intra-section steering angle change / steering angle data change allowable value constant, count constant) ) Is set, and when the neutral point is determined by this process, the long distance establishment flag indicating that the long distance is established is set. However, if the neutral point is not determined, the long distance establishment flag is set to the state after initialization (clear state). ) Is different in maintaining.

  The neutral point process in the first embodiment will be described with reference to FIGS. 8 and 9. In step S401, the vehicle speed is calculated based on the cycle of the pulse signal from the vehicle speed sensor 5, and the travel distance of the vehicle is calculated from the accumulated pulses of the vehicle speed pulses. In the next step S402, a change in the steering count value N of the steering sensor 2 (for example, the counter value is decremented by 1 when the right turning is 1 °, and the counter value is 1 when the left turning is 1 °. The rudder angle (in this case, the relative rudder angle) is calculated from the increment.

  Next, in step S403 and step S405, the vehicle speed is compared with the intra-section maximum vehicle speed and the intra-section minimum vehicle speed. In the present embodiment, the maximum / minimum vehicle speed within a section is the maximum vehicle speed within the section as an initial value for both the short distance / long distance when it is within a section (for example, 10 m for short distance determination and 100 m for long distance determination): 20 km / h and the minimum vehicle speed in the section: 300 km / h are set. Therefore, when the vehicle speed is compared with the maximum vehicle speed in the section in step S403, if the vehicle speed is faster than the maximum vehicle speed in the section, the vehicle speed at that time is set as the maximum vehicle speed in the section in step S404. In step S405, the vehicle speed is compared with the in-section minimum vehicle speed. If the vehicle speed is slower than the in-section minimum vehicle speed, the current vehicle speed is set as the in-section minimum vehicle speed in step S406.

  Similarly, in steps S407 and 409, the steering angle is compared with the maximum steering angle in the section and the minimum steering angle in the section of a predetermined section (10 m for short distance determination and 100 m for long distance determination). For the maximum / minimum rudder angle within the section, for example, different initial values are set for short distance / long distance, and the initial value before the determination is made is the maximum steering angle within the section (steering wheel angle: −630 °). ): Minimum steering angle value with an offset of zero (steering wheel angle: + 630 °), Minimum vehicle speed within the zone: Maximum steering angle value with an offset of zero. Therefore, in step S407, when the rudder angle (actual rudder angle) from the steering sensor 2 is compared with the maximum steering angle in the section, if the steering angle is larger than the maximum steering angle in the section, the section is determined in step S408. The rudder angle at that time is set as the inner maximum rudder angle. In step S409, the steering angle is compared with the minimum steering angle in the section. If the steering angle obtained from the steering sensor 2 is smaller than the minimum steering angle in the section, the minimum vehicle speed in the section is set in step S406. The rudder angle is set.

  From the above, in the processing from step S403 to step S406, the maximum / minimum vehicle speed in the section within a predetermined section of the vehicle speed (10 m for the short distance neutral point processing and 100 m for the long distance neutral point processing) is obtained. In the processing from step S407 to step S410, the maximum / minimum steering angle within the section of the steering angle within the predetermined section is obtained.

  In the next step S411, it is compared whether the vehicle speed pulse cumulative value calculated in step S401 is greater than or equal to the distance constant. As the distance constant, a short distance predetermined value (10 m) is set in advance for a short distance, and a long distance predetermined value (100 m) is set in advance for a long distance. That is, here, the determination is made in the unit section, and the comparison is made according to the steering angle state including the vehicle speed state every 10 m in the determination of the short distance and the distance of 10 m in the determination of the long distance. If it is determined in step S411 that the accumulated vehicle speed pulse value is greater than or equal to the distance constant described above, step S412 is performed. Otherwise, the neutral point process is terminated.

  In step S412, the maximum vehicle speed in the section is lower than the maximum vehicle speed constant (for example, 300 Km / h), and the minimum vehicle speed in the section is higher than the minimum vehicle speed constant (for example, 20 Km / h) (that is, a certain vehicle speed is maintained during vehicle travel). The deviation between the maximum steering angle in the section and the minimum steering angle in the section is considered to be traveling in the straight traveling state, the steering angle change allowable value constant in the section (for example, 10 ° in the steering angle) Or less (condition 1). Therefore, if the above condition 1 is not satisfied, it is considered that the steering angle change has not yet converged to the neutral position, and this process is terminated without performing neutral point correction. Step S413 is performed.

  In step S413, the steering angle value (steering angle data) detected in a predetermined memory (steering angle data MAX, steering angle data MIN, steering angle data MEAN) in the CPU provided continuously for several bytes is used as a steering angle candidate value. Remember as. Here, the cumulative rudder angle count (the value of the cumulative rudder angle counter) is used as a storage pointer (index), and the maximum rudder angle in the section is sequentially switched from the upper address memory to the lower address memory according to the steering angle data MAX. The minimum steering angle in the section is stored in the steering angle data MIN in the same manner. These data are stored, and the average of the maximum steering angle in the section and the minimum steering angle in the section is stored in a predetermined area using the cumulative steering angle count as a pointer in the steering angle data MEAN, and then the cumulative steering is moved in order. Increment the value of the corner counter.

  Thereafter, it is determined whether the value of the cumulative steering angle counter has reached a predetermined count constant (predetermined number of times). This count constant differs between the short distance processing shown in step S301 and the long distance processing shown in step S302. The count constant (20) is set for the short distance, and the count constant (10) is set to the predetermined number for the long distance. It is set in advance. In this step S414, it is determined whether the steering angle value is stored every predetermined distance (for example, every 200 m for short distance processing and every 1 Km for long distance processing), and the cumulative steering angle count is equal to or less than the above-described count constant. In this case, the neutral point processing after step S415 is not performed. However, when the count value becomes larger than the count constant, in step S415, the steering angle data MAX for each pointer (N: 19 for short distance, 9 for long distance). The steering angle candidate value stored in the steering angle data and the steering angle candidate value stored in the steering angle data MIN can be regarded as being in a straight traveling state. Or less) (condition 2). Therefore, if the above condition 2 is not satisfied, it is determined that the steering angle data is not stable, and it is determined that accurate steering angle correction cannot be performed, and the cumulative steering angle count that has been accumulated in step S418 is calculated. clear.

  On the other hand, when the condition 2 is satisfied, in step S416, the sum of the steering angle data MEAN stored as a pointer in the accumulated steering angle count within a predetermined section is calculated and divided by a count constant, that is, a predetermined value. The average steering angle of the steering angle data obtained for each section is set as the neutral point of the steering sensor in the short distance / long distance processing, and the cumulative steering angle counter is cleared. Thereafter, the establishment flag is set in step S417. Here, when the short distance neutral point is determined in the process of step S301, the short distance establishment flag is set, and in the process of step S302, the long distance neutral point is set. Is determined, a long distance establishment flag is set.

  Thereafter, returning to FIG. 7, in step S303, whether the short-point and long-distance neutral points are both obtained (the establishment flag is set) based on the flags set in the neutral point processing shown in steps S301 and S302. Is determined. If both neutral points are found and established, in step S304, the neutral point at which the rudder angle value determined by the long-distance neutral point process is extremely stable is determined as the neutral point of the steering rudder angle. To do.

  On the other hand, when the condition of step S303 is not satisfied, when the short distance is not established in step S305 and only the long distance is established, the long distance neutral point processing is similarly determined in step S306. Let the neutral point be the neutral point of the steering angle. If the condition in step S305 is not satisfied, the determination in step S307 is performed this time. Here, when the short distance neutral point is determined five times (200 m data × 5), the long distance neutral point (1 km data) is determined for the first time, so the short distance neutral point is the first. However, if the neutral point of the long distance has not yet been determined, the first neutral point determined by the neutral point process at the short distance in step S308 is set as the neutral point of the steering angle correction. Further, when the neutral point is determined 2 to 4 times in the neutral point processing at the short distance, that is, as shown in step S309, the neutral point is determined at the second time onward after the short distance. If the neutral point has not been determined, the average value of the neutral point at the short distance previously determined in step S310 and the neutral point at the short distance determined this time is set as the neutral point of the steering angle correction. That is, in the processing from step S307 to step S310, the steering angle is corrected at the short-point neutral point at an early stage for each short-distance section until the stable long-point neutral point is obtained, and the error is gradually increased. In the end, it is going to be a stable true neutral point.

  In this case, when one neutral point at a short distance is obtained, the short-point neutral point determined there is processed in time series until a neutral point at a long distance is obtained for each short-distance processing. The data is updated as new data, previous data, last time data,... And stored in a predetermined memory.

  In this way, if the neutral point is obtained in parallel in the short distance section and the long distance section, even if a very stable neutral point in the long distance section is not determined, the neutral point error in the short distance section is calculated by moving average. Since it is possible to determine the accurate neutral point by gradually approaching the true neutral point while decreasing in steps, more accurate steering angle correction can be performed.

  Returning to the main routine of FIG. 5 again, the parameter calculation of the predicted traveling locus 20 is performed in step S107, and the predicted traveling locus 20 obtained by the method described later is overlapped with the rear image on the display 13 in step S108. Draw a graphic. In step S109, the parking switch 4 is checked again. If the parking switch 4 is off (no parking assistance request), the process returns to step S102 and the same processing from step S102 is repeated, but on (with parking assistance request). In this case, in step S110, the shift reverse switch 3 is checked this time. If it is not reverse (reverse), the process returns to step S102, but in the reverse state, the same processing from step S106 to step S110 is repeated. . That is, if a request for assisting parking is issued by the parking switch 4, the predicted traveling track 20 is repeatedly calculated, and the predicted traveling track 20 is variably displayed on the rear screen in real time according to the steering angle (see FIG. 15). .

  Next, how to obtain the predicted traveling locus 20 will be described. This is because, as shown in FIG. 10, the turning center O at low speed (here, 10 km / h or less) exists on the extension line of the rear axle of the vehicle, and the steering angle (steering angle) due to the geometrical relationship. ) From θ and the wheel base L, the turning radius R is derived by the relational expression R = L / tan θ. In this case, when the steering angle θ = 0, the vehicle is traveling straight and R = ∞.

  FIG. 12 shows the graphics display coordinates (x, y) on the camera, and the coordinate conversion method using the illustrated coordinate system is shown in FIG. As shown in FIG. 13, the camera 17 is mounted at a height of Hc above the road surface with the optical axis inclined downward from the horizontal state by θ, and the lens of the camera 17 has a wide angle and a deep depth of focus. It is configured to draw an image of the road surface on the CCD device. Therefore, the following mapping relationship is established between the road surface coordinate system (X, Z) and the coordinate system (x, y) on the display.

Specifically, (X, Y, Z): road surface coordinates, (x, y): camera coordinates on the CCD element surface, f: camera lens focal length, (x ′, y ′, z ′): lens coordinates , Θ: camera mounting angle, Hc: mounting height from the road surface,
x = f · x ′ / z ′, y = f · y ′ / z ′ (1)
x ′ = X
y ′ = Zsin θ + (Y−Hc) cos θ} (2)
z ′ = Z cos θ− (Y−Hc) sin θ (3)
The following relational expression holds. Here, if it is limited only to the coordinates on the road surface, Y = 0, and if x and y are obtained by the above relational expressions,
x = f · X / (Zcos θ + Hc · sin θ) (4)
y = f · (Zsinθ + Hc · cosθ) / (Zcosθ + Hc · sinθ)
... (5)
It becomes. That is, the coordinates (x, y) on the graphics screen on the display when the point (X, Z) on the road surface is photographed by the camera 17 can be obtained from the relational expressions (4) and (5). it can.

  When displaying the predicted travel path 20 of (x, y) obtained by the above method on the display, various display methods are conceivable as shown in FIG. In other words, (a) is a method for displaying by the expected saddle through which the left and right wheels of the vehicle pass, (b) is a method for displaying a traveling area in which the vehicle travels when parked, and (3) is a fixed distance interval (ladder interval: 50 cm). ) Is displayed in a ladder-like manner, and here, a method is used in which the sense of distance and the angle of the vehicle body at each position are easily understood using (c). In this case, the length l of the predicted vehicle trajectory 20 is set to a fixed length (for example, 3 m), or a fixed angle, and the color is changed between a turning state (green) and a straight traveling state (blue). In addition, it is also possible to take a method that makes it easy to distinguish only the predicted trajectory tip.

  FIG. 15 is an example of a display screen on the display 13 and shows a state in which the predicted travel locus changes depending on the steering angle, which is the parking switch 4 in the real image behind the vehicle. Only in the case of a state where there is a parking assistance request, the scheduled traveling trajectory 20 having a ladder shape corresponding to the steering angle is displayed in an overlapping manner. In this case, by displaying the predicted traveling locus in the rear image, a display marker 14 for displaying the steering angle state can be displayed together with a part of the display 13 so that it can be understood how much the steering angle is steered. You can see how much you actually steer.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. This second embodiment is a configuration in which a yaw rate sensor 6 is added to the configuration of the first embodiment shown in FIG. 1, and the neutral point of the steering angle is determined by information from the steering sensor 2, the vehicle speed sensor 5, and the yaw rate sensor 6. Correction is performed. For this reason, the same part as 1st Embodiment is described easily, and a different part is mainly demonstrated in detail.

  In the configuration diagram shown in FIG. 16, in order to detect the turning state of the vehicle, information from the yaw rate sensor 6 is input to the CPU 11, and the controller 16 also takes in information from the yaw rate sensor 6 to correct the neutral point of the steering angle. It can be configured. The yaw rate sensor 6 may be attached at an arbitrary position in the vehicle compartment, but the display 13 for displaying the predicted traveling locus 20 is also used as the display screen of the navigation device even if it is not newly provided in recent vehicles. In this case, it is built in the navigation device body. For this reason, the signal from the yaw rate sensor 6 provided in the navigation device can be directly or indirectly taken into the controller via a communication line and processed. In the present embodiment, the signal from the yaw rate sensor 6 is one that outputs 0.5 V at -60 ° / sec, and that outputs 4.5 V at + 60 ° / sec, and one whose output changes linearly. However, it is not limited to this.

  In the second embodiment, the angle is calculated based on the information from the yaw rate sensor 6 in the neutral point processing (implemented at a constant cycle of 5 ms) shown in FIGS. 8 and 9 of the first embodiment (step S402a), A point for obtaining a neutral point (step S412a) is added. In FIG. 17 and FIG. 18, the same step numbers are assigned in the second embodiment in order to facilitate understanding of the parts processed with the same contents as in the first embodiment.

  In FIG. 17, the processing in steps S401 and S402 is the same as that in FIG. Here, the travel distance of the vehicle is calculated from the signal from the vehicle speed sensor 5, and the steering angle is calculated from the signal from the steering sensor 2. In step S402a, the angular velocity generated in the vehicle by the signal from the yaw rate sensor 6 or the angle is calculated by time integration of the angular velocity. Thereafter, in the same processes from step S403 to step S410 as in FIG. 8, the maximum / minimum vehicle speed in the section within a predetermined section of the vehicle speed (10 m for the short-distance neutral point process and 100 m for the long-distance neutral point process). Is obtained, and the maximum / minimum steering angle in the section of the steering angle in the predetermined section is determined by the processing from step S407 to step S410.

  In the next step S411, it is compared whether the vehicle speed pulse cumulative value calculated in step S401 is greater than or equal to the distance constant. Similarly to FIG. 8, the distance constant is preset with a short distance predetermined value (10 m) for a short distance and a long distance predetermined value (100 m) for a long distance. The determination is performed in the section, and the comparison is made according to the steering angle state including the vehicle speed state every 10 m in the determination of the short distance and in the determination of the long distance. If it is determined in step S411 that the accumulated vehicle speed pulse value is greater than or equal to the distance constant described above, step S412a is performed. Otherwise, this neutral point process is terminated.

  In the next step S412a, the maximum vehicle speed in the section is lower than the maximum vehicle speed constant (for example, 300 Km / h), and the minimum vehicle speed in the section is higher than the minimum vehicle speed constant (for example, 20 Km / h) (ie When the vehicle speed is high), the deviation between the maximum steering angle within the section and the minimum steering angle within the section is considered to be a steering angle change allowable value constant within the section that is considered to be traveling straight (for example, a steering steering angle of 10 (Condition 1) is determined. However, in the second embodiment, the yaw rate value (maximum in the section) from the yaw rate sensor 6 in the section (every 10 m) is a characteristic part in the second embodiment. It is determined whether (yaw) is smaller than a predetermined value that can be regarded as a straight traveling state, that is, a maximum yaw constant (for example, 1 ° / sec) (condition 2). Here, if the above condition 2 is not satisfied, it is considered that the change in the steering angle has not yet converged to the neutral position, and this process is terminated without performing the neutral point correction. As in FIG. 9, the process from step S413 to step S417 is performed to determine the neutral point of the steering angle.

  In the second embodiment, the signal from the yaw rate sensor 6 is combined with the configuration of the first embodiment, the maximum yaw rate value in the section is obtained, and the value is within a predetermined value (for example, 1 ° / sec) that can be regarded as a substantially straight traveling state. In this case, an accurate neutral point of the steering angle is determined based on a change in the state of the vehicle when the vehicle is traveling. Therefore, in this case, the determination of the neutral position does not require the steering sensor 2 that outputs a neutral point signal as in the prior art, and the neutral point can be determined more accurately. Since the point can be determined, the reliability is improved.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG. The third embodiment is a configuration in which the vehicle speed sensor 5 is eliminated in the configuration of the first embodiment shown in FIG. 1, and the neutral point correction of the steering angle is performed using information from only the steering sensor 2. For this reason, description of the same part as 1st Embodiment is abbreviate | omitted, and a different part is demonstrated.

  FIG. 20 shows a flowchart of the neutral point rudder angle in the third embodiment, and the process will be described below. FIG. 20 is performed by a timer interruption of the CPU 11. In step S501, based on information from the steering sensor 2, a change in the steering count value N of the steering sensor 2 (for example, when the right turning is 1 °). The counter value is decremented by 1 and the counter value is incremented by 1 when the left turn is 1 °) to calculate the steering angle (in this case, indicates the relative steering angle). In step S502, the absolute steering angle (steering angle) steer obtained based on the input steering angle (relative steering angle) calculated in step S501 and the neutral steering angle (neutral steering angle) stored at the initial stage is stored.

  Here, the neutral rudder angle memorized first will be briefly described. In the vehicle, the neutral point rudder angle is stored and set first at the time of factory shipment. Specifically, at the time of shipment from the factory, the vehicle is first stopped at a predetermined place such as the factory, and the operator turns the steering wheel 21 to the right and left to the maximum, and the steering value from the steering sensor 2 at that time is stored in the controller. Store in the memory. Thereafter, the steering wheel 21 is returned to a substantially neutral position, the vehicle is placed on a drum tester that forcibly rotates the wheel, and the rotating drum of the drum tester is rotated to rotate the vehicle tire at a predetermined speed for several seconds. Based on the state, a method of calculating a neutral point rudder angle by creating a pseudo straight traveling state by the neutral point correction method shown in the first embodiment is employed.

  In the next step S503, the steering angle steer when operated to the limit steering angle is compared with the maximum steering angle value (steering angle MAX) stored in advance in the memory of the CPU 11 at the initial time (factory shipment, etc.). Is done. Here, when the steering angle steer is larger than the steering angle MAX, the steering angle is regarded as the maximum steering angle and is substituted into the steering angle MAX to obtain the maximum value of the steering angle. Similarly, the steering angle steer by operation is compared with the minimum steering angle value (steering angle MIN) stored in the memory in advance at the initial time (factory shipment, etc.), and the steering angle steer is smaller than the steering angle MIN. In this case, the steering angle is regarded as the minimum steering angle, and the steering angle MIN is substituted to obtain the minimum value of the steering angle. That is, in steps S503 to S506, the steering 21 is operated to obtain the maximum value and the minimum value of the steering angle.

  In the next step S507, whether or not the steering angle steer is within a dead zone (for example, when the steering angle rotates ± 630 °, the dead zone steering angle is set to 10 °) based on the steering angle minimum value R MIN. It is determined whether it is out of the area. As a direction in which the neutral point rudder angle deviates, there may be a case in which it deviates in the direction of the rudder angle MAX and a case in which it deviates in the rudder angle MIN direction. However, in FIG. 21, as an example, the neutral point rudder angle has shifted in the MIN direction. Shows the case. In the flowchart of FIG. 20, the steering angle steer when the steering wheel 21 is turned to the limit is in the dead zone region based on the minimum steering angle value RMIN (the minimum steering angle is shifted by 10 ° or more from the stored initial steering angle). ), The processing after step S512 is performed, but when it is outside the dead zone region, the processing after step S512 is performed.

  In step S508, since the steering angle steer is smaller than the dead zone region based on the first stored steering angle minimum value RMIN, the neutral point of the steering angle is regarded as being shifted in the MIN direction. The neutral point is corrected by adding the actual deviation (steering angle initial value R MIN−steering angle steer) to the currently stored neutral point rudder angle as a new neutral point rudder angle. Thereafter, in steps S509 to S511, a correction by a deviation (steering angle initial value R MIN−steering angle steer) is performed, and (steering angle initial value R MIN−steering angle steer) added to the steering angle MAX is a new rudder. In addition to the angle MAX, the value of R MIN is substituted into the steering angle MIN, and the value of R MIN is determined as the steering angle steer.

  Similarly, in step S512, it is determined whether the rudder angle steer when steered to the limit is outside the dead zone region based on the rudder angle maximum value L MAX stored first. When the rudder angle steer is within the dead zone region (less than + 10 °) based on the maximum stored rudder angle maximum L MAX, the neutral point is not corrected, but outside the dead zone region (+ 10 ° or more). In this case, it is determined that the neutral point is deviated, and the neutral point is obtained by adding the actual deviation (steering angle initial value L MAX -steering angle steer) to the current neutral point rudder angle. Perform point correction. In steps S514 to S516, the value of L MAX is set as the steering angle MAX, and the difference (steering angle initial value L MAX−steering angle steer) is added to the current steering angle MIN to obtain new steering angles MIN, L The value of MIN is corrected as the steering angle steer.

  That is, in this correction method, the steering angle maximum value and the steering angle minimum value are stored in advance in the memory as initial values, and then the steering operation is performed, with the minimum or maximum steering angle stored as a reference. The correct absolute rudder angle is obtained by correcting the neutral rudder angle from the deviation of the maximum rudder angle and the minimum rudder angle when it is outside the dead zone area. Even when the rudder angle or the minimum rudder angle is deviated, correction based on the initial value of the rudder angle can be performed, and accurate neutral point correction can be performed. In this case, once the neutral point rudder angle is first stored and set in the memory, it can be corrected only by the steering operation.For example, even when the vehicle is stopped, an accurate neutral point rudder angle can be obtained. Correction can be made.

  In the present embodiment, the vehicle speed detection means is the vehicle speed sensor 5, but the present invention is not limited to this, and the vehicle speed may be detected by information from wheel speed sensors provided on the left and right wheels of the vehicle. Further, although the direction change detecting means is the yaw rate sensor 6, the present invention is not limited to this, and the direction of change of the vehicle may be detected from the left and right wheel speed difference and the steering angle based on the vehicle characteristics.

  According to this embodiment, by adopting the steering angle value as the steering angle candidate value only when the vehicle speed is within the predetermined vehicle speed range and the change in the steering angle is within the predetermined steering angle, the maximum steering angle within the predetermined steering angle and Based on the rudder angle information in the rudder angle that detects the minimum rudder angle and can be regarded as a straight traveling state, the rudder angle candidate value is stored in the memory for a predetermined number of times for each predetermined distance, and the rudder angle candidate value stored in the memory Since the neutral point for which the steering angle correction is performed can be determined for each predetermined distance based on the sum of the steering angle candidate values and the number of the steering angle candidate values, the neutral point correction can be accurately performed for each predetermined distance.

  In this case, if the neutral point is determined when the deviation between the maximum rudder angle and the minimum rudder angle of the rudder angle candidate value is within a predetermined deviation, an accurate neutral point of the rudder angle is determined in a region where the rudder angle deviation is stable. it can.

  By performing correction when the turning angle of the vehicle is within a predetermined value that can be regarded as a substantially straight traveling state, the accurate neutral point of the steering angle based on the change in the state of the vehicle can be corrected and determined when the vehicle is traveling.

  The vehicle further comprises a distance calculating means for calculating a travel distance based on information from the vehicle speed detecting means, storing steering angle candidate values for each of the short distance section and the long distance section, and the maximum steering angle in the short distance section and the long distance section. By detecting the minimum rudder angle and determining neutral points in the short-distance section and long-distance section, it is possible to determine and determine multiple neutral points in the short-distance section and long-distance section. Corner neutral point correction is possible.

  Furthermore, when the neutral point in both the short distance section and the long distance section is determined, the neutral point can be corrected with a more stable steering angle in the long distance section by adopting the neutral point in the long distance section.

  Furthermore, until the neutral point in the long distance section is determined, if the neutral point in the short distance section is adopted, the neutral point correction of the steering angle can be performed early in the short distance section.

  Further, according to the present embodiment, the initial maximum steering angle and the initial minimum steering angle of the steering are stored in advance, and when the neutral point is corrected, the maximum steering angle or the minimum steering angle is obtained by operating the steering. If the steering angle is outside the dead zone area based on the initial maximum steering angle or if the minimum steering angle is outside the dead zone area based on the initial minimum steering angle, Since the neutral rudder angle is corrected as if the rudder angle is deviated, the neutral point correction based on the rudder angle stored in the initial rudder angle is corrected even if the maximum rudder angle or the minimum rudder angle is deviated. It is possible to correct the neutral point of the steering angle accurately.

It is a system configuration figure at the time of applying a rudder angle correction device in a 1st embodiment of the present invention to a parking auxiliary device. It is an attachment figure at the time of attaching the parking assistance apparatus shown in FIG. 1 to a vehicle. It is the figure which showed the detection range of the CCD camera shown in FIG. 1 shows a configuration of the steering sensor shown in FIG. 1, (a) is a plan view of a steering sensor attached to a steering column shaft, (b) is a perspective view showing an outline of a slit plate and a photo interrupter of the steering sensor, and (c). These are figures which show the output of the A phase and B phase of a steering sensor. It is a flowchart which shows the process of the controller shown in FIG. It is a flowchart which shows the steering sensor signal processing of the controller shown in FIG. It is a flowchart which shows the neutral point process of the steering sensor of the controller shown in FIG. It is a flowchart which shows the neutral point process by the short distance / long distance shown in FIG. FIG. 9 is a flowchart continued from FIG. 8. FIG. It is explanatory drawing used for calculation of the driving | running | working estimated locus | trajectory shown in FIG. It is the figure which showed the example of a display of the driving | running | working prediction locus | trajectory shown in FIG. 1, (a) is a display by an expected bag, (b) is a driving area belt display for a vehicle width, (c) is a figure which shows a ladder-like display. is there. FIG. 2 is a graphics display coordinate of the CCD camera and display shown in FIG. 1. It is the figure which showed the attachment state at the time of attaching the CCD camera shown in FIG. 1 to a vehicle. It is explanatory drawing explaining the coordinate transformation method of the camera coordinate system imaged with a three-dimensional coordinate system and a camera. It is an example of a display screen of the display shown in FIG. It is a system block diagram at the time of applying the steering angle correction apparatus in 2nd Embodiment of this invention to a parking assistance apparatus. It is a flowchart which shows the process of the controller shown in FIG. FIG. 18 is a flowchart continued from FIG. 17. It is a system block diagram at the time of applying the rudder angle correction apparatus in 3rd Embodiment of this invention to a parking assistance apparatus. It is a flowchart which shows the process of the controller shown in FIG. It is explanatory drawing in the case of correct | amending the neutral point steering angle shown in FIG.

Explanation of symbols

1 Parking assistance device (steering angle correction device)
2 Steering sensor (steering angle detection means)
5 Vehicle speed sensor (vehicle speed detection means)
6 Yaw rate sensor (direction change detection means)
11 CPU (steering angle candidate value storage means, neutral point determination means, distance calculation means)
13 Display 17 CCD camera (camera)
20 Expected trajectory

Claims (4)

Rudder angle detecting means for detecting the rudder angle;
Initial steering angle storage means for storing in advance an initial maximum steering angle and an initial minimum steering angle of a steering wheel having a neutral point;
Limit steering angle storage means for storing the maximum steering angle or the minimum steering angle by operating the steering;
Neutral point that corrects the rudder angle of the neutral point when the maximum rudder angle is outside the dead zone region with the initial maximum rudder angle as a reference, or when the minimum rudder angle is outside the dead zone region with the initial minimum rudder angle as a reference. Correction means;
A rudder angle correction device comprising: Steering angle detection means for detecting the steering angle of the steering provided in the vehicle;
Initial steering angle storage means for storing in advance the initial maximum steering angle and the initial minimum steering angle of the steering;
Limit steering angle storage means for storing the maximum steering angle or the minimum steering angle of the steering;
A minimum dead zone set with reference to the minimum steering angle; a maximum dead zone set with reference to the maximum steering angle;
After obtaining a neutral point rudder angle based on the initial minimum rudder angle and the initial maximum rudder angle, when the steering is operated in one direction and the rudder angle is out of the minimum dead zone region, Deviation from the minimum steering angle, or when the steering is operated in the reverse direction, and the steering angle deviates from the maximum dead zone, obtain the deviation between the steering angle and the maximum steering angle, and based on the deviation Neutral point correcting means for correcting the neutral point rudder angle,
A rudder angle correction device comprising: The steering angle correction device according to claim 2, wherein either the maximum steering angle or the minimum steering angle is corrected based on the deviation. The rudder angle correction device according to claim 2, wherein the neutral point rudder angle is corrected while the vehicle is stopped.

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