JPH09244743A - Automatic operation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a control system to be tolerant of noise and to execute stable steering control by detecting the real yaw rate of a vehicle, operating a deviation against a target yaw rate and correcting a target steering angle in a direction where physical quantity obtained by delaying the deviation is canceled. SOLUTION: A controller 20 reads a steering detection signal, a magnetic flux detection signal, a yaw rate detection signal and a vehicle speed detection signal from a steering sensor 14, a magnetic marker sensor 17, a yaw rate sensor 18 and a vehicle speed sensor 19 and operates the lateral displacement of the vehicle based on the magnetic flux detection signal. A gain for converting the lateral displacement into the target steering angle is set and the gain and a time constant are set based on the vehicle speed detection signal. The yaw rate deviation is operated and the target steering angles of front wheels 3L and 3R are operated. A steering control signal by which a difference between the target steering angle and the steering angle detection signal showing the actual steering angle becomes zero is operated and the steering control signal is outputted to an automatic steering mechanism 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic driving system for automatically controlling the steering angle of steered wheels of a vehicle, and more particularly, to a stable steering angle control that is strong against noise applied to a control system. It was done.

[0002]

2. Description of the Related Art As a conventional technique of this kind, for example, "Transactions of the Society of Instrument and Control Engineers, vol. 12, No. 4, (1976), 394"
"Optimal Design of Automatic Steering System Using Kalman Filter"
(Tsuboi, Harashima, Inaba). That is,
The conventional technique described in this paper relates to an automatic driving device called an induction cable system, in which an alternating current of several kHz is applied to a cable arranged along a traveling line to generate a magnetic field. , A sensor that detects the magnetic field is installed in the vehicle, the position of the vehicle with respect to the cable is recognized based on the output of the sensor, and the steered wheels are used so that the vehicle travels along the target travel line according to the recognition result. It is designed to generate a steering angle.

In addition to the induction cable system, there is a conventional technique called a magnetic marker system. This magnetic marker system uses a permanent magnet buried in the road surface at a predetermined interval (for example, 1 m) instead of the cable in the induction cable system. In other words, in the magnetic marker method,
By detecting the magnetic flux generated by the embedded permanent magnet on the vehicle side, the lateral position of the vehicle with respect to the target travel line is recognized and the steering angle of the steered wheels is controlled.

[0004]

Here, a block diagram of the control system in the conventional automatic driving apparatus as described above is shown in FIG. In FIG. 8, G ₁ is a transfer function of a controller that generates a steering angle control signal, and G _{2 is}
Is a transfer function from the mechanism that generates the steering angle according to the steering angle control signal to the vehicle trajectory.

The transfer function G ₂ (s) is calculated by
(S ² × quadratic equation) ”, the quadratic integral characteristic (type 2) is obtained. Therefore, the phase from the driving of the steering angle generation mechanism to the trajectory of the vehicle is There is a possibility that stable travel along the target travel line will not be possible because the delay will be 180 degrees or more.Therefore, in order to increase the stability of the control system, the transfer function G ₁ (s) has a differential element as a compensation element as a compensation element. Is required to advance the phase of the steering angle control signal generated by the controller.

However, as shown in FIG. 8, process noise (noise associated with the steering generation mechanism) and observation noise (noise superimposed on the detection signal of the sensor) are added to the control system. When the differential element is added to G ₁ (s), even the noise component is emphasized by the differential element, which adversely affects the stability improvement of the control system.

In particular, in the above-mentioned induction cable system, since the alternating current of several kHz is applied to generate the magnetic field, the observation noise is large and the noise enhancement effect by the differential element becomes a big problem. ing. Further, even in the magnetic marker method, if the deviation of the permanent magnet M _{1 from} the reference line L ₁ along the target traveling line is large as shown in FIG. As a result of M ₁ being buried at a predetermined interval, even if the actual lateral displacement (deviation of the lateral position of the vehicle with respect to the target travel line) changes like a curve as shown in FIG. Since the value (detected lateral displacement) becomes a discrete value like a straight line, there is a problem that the steering angle control signal when the discrete value is switched is emphasized as shown in FIG. 10 (b). is there.

That is, in the conventional automatic driving device that differentiates the detected lateral displacement of the vehicle and uses it for control,
Since the noise component included in the detected value is also emphasized and taken into the steering angle control signal, there is an unsolved problem that the sensitivity of the steering angle to noise increases.

The present invention has been made by paying attention to the unsolved problems of the prior art as described above, and is an automatic driving apparatus that is strong against noise added to the control system and can perform stable steering angle control. Is intended to provide.

[0010]

In order to achieve the above object, the invention according to claim 1 is a lateral position detecting means for detecting a lateral position of a vehicle with respect to a target traveling line, and this lateral position detecting means. In a self-driving device comprising a target steering angle calculation means for calculating a target steering angle in accordance with the detection result of, and a steering angle generation means for generating a steering angle in the steered wheels of the vehicle based on the target steering angle, A yaw rate detecting means for detecting an actual yaw rate of the vehicle, and a deviation calculating means for calculating a deviation of the actual yaw rate from a target yaw rate are provided, and the target steering angle calculating means is arranged to cancel the physical quantity in which the deviation is delayed. The target steering angle is corrected.

According to a second aspect of the present invention, in the automatic driving apparatus according to the first aspect of the present invention, vehicle speed detecting means for detecting a vehicle speed is provided, and the target steering angle calculating means is
The physical quantity is reduced as the vehicle speed increases.

According to a third aspect of the present invention, in the automatic driving apparatus according to the second aspect of the invention, the target steering angle calculation means performs a delay process of a first order or more with respect to the deviation. The physical quantity is calculated, and the gain of the delay process is set to be small according to the increase in the vehicle speed.

On the other hand, the invention according to claim 4 is the automatic driving apparatus according to claim 1, further comprising a vehicle speed detecting means for detecting a vehicle speed, and the target steering angle calculating means is
The delay amount of the deviation is increased as the vehicle speed increases.

According to a fifth aspect of the present invention, in the automatic driving apparatus according to the fourth aspect of the invention, the target steering angle calculation means performs a delay process of a first order or more with respect to the deviation. The physical quantity is calculated, and the time constant of the delay process is set to be large according to the increase in the vehicle speed.

Here, in the invention according to claim 1,
When the lateral position detection means detects the lateral position of the vehicle with respect to the target travel line, the target steering angle calculation means causes the target steering angle calculation means to eliminate the deviation between the detected lateral position of the vehicle and the target travel line, for example. Calculate the angle. On the other hand, the yaw rate detecting means detects the actual yaw rate, and the deviation calculating means calculates the deviation of the actual yaw rate from the target yaw rate. Then, the target steering angle calculation means corrects and calculates the target steering angle so as to cancel the physical quantity that delays the deviation calculated by the deviation calculation means.

This is equivalent to correcting the target steering angle so as to cancel the yaw rate and the yaw angle displacement, so that the influence of the yaw movement on the lateral movement of the vehicle is canceled and the steering angle is reduced. To the lateral displacement of the vehicle becomes a linear integral type. As a result, the phase margin of the control system is secured, the differential compensation, which was required in the past, is unnecessary, and the control system is strong against noise.

Then, since the steering angle generating means generates the steering angle on the steered wheels in accordance with the corrected target steering angle, the traveling line of the vehicle stably approaches or coincides with the target traveling line.

The physical quantity with the deviation delayed may be a value obtained by delaying the deviation for a predetermined time, or the deviation may have a characteristic such that the transfer function has a first-order lag, a second-order lag, or a third-order lag. It may be a value processed by a filter or the like.

When the physical quantity obtained by delaying the deviation is divided into a yaw rate component and a yaw angle displacement component, the component corresponding to the yaw rate decreases as the vehicle speed increases, but the phase is 90 degrees with respect to the yaw rate. The component corresponding to the delayed yaw angle displacement is not affected by the vehicle speed. Therefore, in the correction amount of the target steering angle, the ratio of the yaw rate component gradually decreases as the vehicle speed increases. Therefore, claim 2
According to the invention of claim 4, the target steering angle calculation means decreases the physical quantity used for the correction calculation according to the increase of the vehicle speed, or the target steering angle calculation means increases the vehicle speed as in the invention of claim 4. If the delay amount of the deviation is increased in accordance with the above, or both of them are performed, an appropriate correction amount corresponding to the change of the vehicle speed can be obtained.

It is to be noted that, as in the invention according to claim 2, to reduce the physical quantity used for the correction calculation in accordance with the increase of the vehicle speed, for example, as in the invention according to claim 3, the first or more order with respect to the deviation is set. When the physical quantity is calculated by performing the delay processing, it is realized by setting the gain of the delay processing to be small according to the increase in the vehicle speed. Further, increasing the delay amount of the deviation in accordance with the increase of the vehicle speed as in the invention according to claim 4 performs, for example, the delay process of the first order or more for the deviation as in the invention according to claim 5. Therefore, when the physical quantity is calculated, it is realized by setting the time constant of the delay processing to be large according to the increase of the vehicle speed.

[0021]

According to the present invention, the target steering angle is corrected so as to cancel the physical quantity in which the deviation of the actual yaw rate from the target yaw rate is delayed, and the steered angle is generated on the steered wheels based on the corrected target steering angle. Since this is done, the differential compensation, which was necessary in the past, is not required, so there is an effect that the control system is strong against noise, stable steering angle control can be performed, and the cost is low.

Particularly, in the inventions according to claims 2, 3, 4, and 5, the correction amount of the target steering angle becomes an appropriate amount according to the vehicle speed, so that there is an effect that more stable steering angle control can be performed. is there.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are views showing an embodiment of the present invention, and FIG. 1 is a plan view showing a schematic configuration of a vehicle 1 equipped with an automatic driving device.

First, the structure will be described. Even in the vehicle 1, basically, as in a normal vehicle, the driver steers the steering wheel 2 so that the front wheels 3L and 3R as steered wheels are steered. Is to occur. That is, as shown in an enlarged view in FIG. 2, the upper end of an upper steering shaft 4U is integrally connected to the steering wheel 2 in the rotational direction, and the lower steering is connected to the lower end of the upper steering shaft 4U via the universal joint 5. A shaft 4L is connected, and a pinion shaft is integrally formed at a lower end (not shown) inserted into the steering gear box 6 of the lower steering shaft 4L, and the pinion shaft moves forward and backward in the vehicle in the steering gear box 6. And mesh with the rack shaft 7. Although not shown in FIG. 2, the steering mechanism includes, for example, a torque sensor disposed at the lower end of the upper steering shaft 4U for detecting a torque generated in the steering system, and a steering torque detected by the torque sensor. A known hydraulic power steering device including a hydraulic actuator for applying a steering assist torque to the rack shaft 7 so as to reduce the power is provided.

Tie rods are connected to both ends (not shown) of the rack shaft 7, and the outer end sides of these tie rods are connected to knuckles that rotatably support the front wheels 3L, 3R. Therefore, when the driver steers the steering wheel 2, the steering force is transmitted to the lower steering shaft 4L via the upper steering shaft 4U and the universal joint 5, and the rotational force of the lower steering shaft 4L is transmitted to the steering gear box 6. Since the force is converted into the forward / backward force of the rack shaft 7, the steering force is input to both tie rods, and a steering angle is generated at the front wheels 3L and 3R. In addition, since the steering assist torque is generated by the hydraulic power steering device so as to reduce the steering torque generated in the steering system, the burden on the driver is reduced.

Further, the upper steering shaft 4U
Is provided with an automatic steering mechanism 10 that can automatically generate a steering angle for the front wheels 3L and 3R. That is, the automatic steering mechanism 10 includes an electric motor 11 and a transmission mechanism 12 that transmits the rotational force of the electric motor 11 to the upper steering shaft 4U while reducing the rotational force. In this embodiment, the transmission mechanism is used. 12, an input gear 12a rotating integrally with the output shaft of the electric motor 11, an output gear 12b rotating coaxially with the upper steering shaft 4U, and an endless belt 12c stretched between the input gear 12a and the output gear 12b. And an electromagnetic clutch 12d capable of intermittent connection between the output gear 12b and the upper steering shaft 4U. Electromagnetic clutch 12
When the driver selects manual steering, d is in a disconnected state so that the electric motor 11 does not become a load of the steering system.

That is, when automatic steering is selected,
When the electromagnetic clutch 12d is in the connected state, the electric motor 11
Is transmitted to the upper steering shaft 4U via the transmission mechanism 12, so that the steering angles are generated at the front wheels 3L and 3R as in the case of manual steering. In this embodiment, the position of the rack shaft 7 is larger than the position at which the transmission mechanism 12 of the upper steering shaft 4U is connected.
Since the torque sensor of the hydraulic power steering device is disposed on the side closer to, the steering angle can be generated at the front wheels 3L and 3R even if the rotational force of the electric motor 11 is small. .

Then, the steering angle control signal δ _c is supplied to the automatic steering mechanism 10 from the controller 20 mounted on the vehicle 1, and the direction and size corresponding to the steering angle control signal δ are supplied. Is generated in the electric motor 11,
As a result, the front wheels 3L and 3R are automatically steered.

Further, the upper steering shaft 4U is provided with a steering angle sensor 14 for measuring the rotational displacement of the upper steering shaft 4U and detecting the actual steering angle of the front wheels 3L, 3R. The steering angle sensor 14 includes a rotary encoder 15 and a transmission mechanism 16 that transmits the rotation of the upper steering shaft 4U to the rotation shaft of the rotary encoder 15. In this embodiment, the transmission mechanism 16 Input gear 1 that rotates coaxially with upper steering shaft 4U
6a, an output gear 16b that rotates integrally with the rotary shaft of the rotary encoder 15, and an endless belt 16c stretched between the input gear 16a and the output gear 16b. Then, the output of the rotary encoder 15 of the steering angle sensor 14 is supplied to the controller 20 as a steering angle detection signal δ _f .

Further, a magnetic marker sensor 17 is arranged at a central position below the front end of the vehicle body of the vehicle 1. The magnetic marker sensor 17 is a magnetic sensor similar to that used in the above-described magnetic marker system, and detects magnetic flux generated by permanent magnets embedded at a predetermined interval on the road surface along the target travel line. Has become. Then, the magnetic flux detection signal m ₀ detected by the magnetic marker sensor 17 is supplied to the controller 20, and the controller 20 uses the magnetic flux detection signal m ₀ to embed the permanent magnet embedded in the road surface. The lateral position between the vehicle 1 and the vehicle 1 is detected as the lateral displacement of the vehicle 1.

A yaw rate sensor 18 is disposed at the center of gravity of the vehicle 1, and the yaw rate sensor 1
The yaw rate detection signal φ ′ detected by 8 is also the controller 2
0 is supplied. The vehicle 1 is provided with a vehicle speed sensor 19 for detecting the vehicle speed by detecting the number of rotations on the output side of the transmission, and the vehicle speed detection signal V detected by the vehicle speed sensor 19 is also sent to the controller 20. It is being supplied.

Although not shown, the controller 20 is A /
Interface circuits such as D converter and D / A converter, RO
Each of the detection signals δ _f and m supplied includes a memory device such as M and RAM and a microcomputer.
_{Based on 0} , φ ′ and V, the vehicle 1
Determines a target steering angle for traveling along a target traveling line on the traveling road surface, and supplies a steering angle control signal δ to the automatic steering mechanism 10 such that the target steering angle is generated in the front wheels 3L, 3R. ing.

That is, the outline of the processing executed in the controller 20 is as shown in FIG. The process shown in FIG. 3 is executed in synchronization with a predetermined sampling clock. First, in step 101, the steering angle sensor 14, the magnetic marker sensor 17, the yaw rate sensor 18 and the vehicle speed sensor 19 are used. The supplied steering angle detection signal δ _f , magnetic flux detection signal m ₀ , yaw rate detection signal φ ′ and vehicle speed detection signal V are read, and then the process proceeds to step 102, where the lateral direction of the vehicle 1 is determined based on the magnetic flux detection signal m _0. The displacement (lateral position of the vehicle 1 with respect to the target travel line) η is calculated.

Then, the routine proceeds from step 102 to 103, in which the gain K ₁ used for converting the lateral displacement η into the target steering angle is set, and the gain K ₂ and the time constant τ are set based on the vehicle speed detection signal V. It is set. Here, the gain K ₂ and the time constant τ are used when the first-order delay processing is performed on the deviation of the yaw rate detection signal φ ′ from the target value, as will be described later in detail, and the gain K ₂ is The vehicle speed detection signal V is set to decrease as it increases, and the time constant τ is set to increase as the vehicle speed detection signal V increases. The relationship between the gain K ₂ and the time constant τ and the vehicle speed detection signal V is set as appropriate by performing a simulation based on the specifications of the vehicle 1.

Next, the routine proceeds from step 103 to 104, where the yaw rate detection signal φ'which is the actual yaw rate,
'Yaw rate deviation which is a deviation of the ₀ φ' target yaw rate φ ₁
(= Φ′−φ ′ ₀ ) is calculated. Here, the target yaw rate φ ′ ₀ is obtained from, for example, the vehicle speed detection signal V, the radius of curvature of the target traveling line, and the like, φ ′ ₀ = 0 when traveling straight, and the vehicle speed detection signal V and the curve when traveling on a curve. The value will depend on the radius of curvature of the road. That is, the target yaw rate φ ′ ₀ is the yaw rate that should naturally occur in the vehicle 1. This target yaw rate φ ′ ₀ may be obtained based on map data given in advance, or may be calculated by, for example, capturing an image in front of the vehicle and detecting the road curvature.

When the processing up to step 104 is completed, the process proceeds to step 105, and the target steering angle δ of the front wheels 3L, 3R is calculated according to the following equation (1).

Δ = −K ₁ η− {K ₂ / (1 + τs)} φ ′ ₁ (1) Note that s is a Laplace operator. This step 105
When the target steering angle δ is obtained with, the process proceeds to step 106, and the steering angle detection signal δ representing the target steering angle δ and the actual steering angle δ.
Calculate the steering angle control signal δ _c so that the difference from _f becomes zero,
The steering angle control signal δ _c is output to the automatic steering mechanism 10. When the process of step 106 is finished, the process this time is finished. After that, after waiting until the predetermined sampling clock has elapsed, step 1
Returning to 01, the above-mentioned processing is repeatedly executed.

Next, the operation of this embodiment will be described. Here, the vehicle 1 is represented by a two-wheel model as shown in FIG. However, the meaning of each symbol in FIG. 4 is as follows.

Φ '... yaw rate y' ... lateral velocity β
... Slip angle (β = y '/ V) C _f ... Cornering power of front wheel C _r ... Cornering power of rear wheel m ... Vehicle mass I ... Vehicle yaw moment of inertia δ _f
… Steering angle of front wheel V… Vehicle speed a… Distance between front wheel and center of gravity point b… Distance between rear wheel and center of gravity point F _f … Cornering force of front wheel F _r … Cornering force of rear wheel And the equation of motion of the vehicle at this time is , (2) below
Expression, Expression (3) is obtained.

[0040]

[Equation 1]

(2)

[0042]

[Equation 2]

(3) Further, regarding the lateral displacement η of the vehicle, η '= V (φ + β) (4) Therefore, from these equations (2) to (4), the vehicle state equation becomes the following equation (5).

[0044]

(Equation 3)

(5) However, D ₁ = − (C _f + C _r ) / mV D ₂ = (bC _r −aC _f ) / mV ² −1 D ₃ = (bC _r −aC _f ) / ID ₄ = - a ^{_{(a 2 C f + b 2}} C r) / IV E 1 = C f / mV E 2 = aC f / I.

FIG. 5 is a block diagram of the control system drawn on the basis of the equation (5). That is, as is apparent from the block diagram of FIG. 5, the steering angles δ _f of the front wheels 3L and 3R are such that the lateral movement of the vehicle (lateral slip angle β, lateral displacement η, etc.) and yaw direction (yaw rate). φ ', yaw angle displacement φ, etc.), but at the same time, the yaw rate φ'and the yaw angle displacement φ interfere with the lateral slip angle β and the lateral displacement η as shown in the lines and. I also understand that.

Therefore, assuming that the yaw rate φ'and the yaw angle displacement φ do not interfere with the lateral slip angle β and the lateral displacement η, the transfer function between the steering angle δ _f and the lateral displacement η is as follows. It becomes like the formula (6).

[0048]

(Equation 4)

(6) In other words, if the interference of the yaw rate φ ′ and the yaw angle displacement φ with the lateral slip angle β and the lateral displacement η can be eliminated, the transfer function between the steering angle δ _f and the lateral displacement η can be calculated. First-order integral type (1
Type). This means that the phase margin of the control system becomes 180 degrees even in the worst case, so that it is not necessary to load a differential element for phase compensation as in the conventional case, and a control system that is strong against noise can be realized. become.

Then, in order to obtain the transfer function as in the above equation (6), it suffices to add appropriate feedback to the steering angle δ _f , and such appropriate feedback δ _FB is given by the following (7). It becomes like a formula.

[0051]

(Equation 5)

(7) Here, a> 0, V> 0, and in the case of a general understeer vehicle, bC _r / aC _f > 1. The first term becomes the yaw rate feedback component δ _FB1 with the polarity of the yaw rate _φ'reversed . Since C _f > 0 and C _r > 0, the second term on the right side of the equation (7) becomes a yaw angle displacement feedback component δ _{FB2 in} which the polarity of the yaw angle displacement φ is inverted.

That is, the yaw rate φ'and the yaw angle displacement φ
If the yaw rate φ ′ and the yaw angle displacement φ are cancelled, the transfer function as shown in (6) above can be realized by giving feedback to the steering angle. In order to make the description easy to understand, the target yaw rate φ ′ ₀ and the target yaw angle φ ₀ are zero in straight running, but the target yaw rate φ ′ ₀ and the target yaw angle φ ₀ are Since it is not zero, the yaw rate φ ′ in the above equation (7) is replaced with the deviation (yaw rate deviation φ ′ ₁ ) between the actual yaw rate φ ′ and the target yaw rate φ ′ _0, and the yaw angular displacement φ in the above equation (7) is replaced. Is the deviation between the actual yaw angle displacement φ and the target yaw angle displacement φ ₀ (yaw angle deviation φ ₁ )
If replaced with, the above equation (7) represents the feedback δ _FB that takes into consideration the curve traveling as well.

Then, the feedback δ in the above equation (7)
_In order to obtain _FB , both the yaw rate deviation φ ′ ₁ and the yaw angle deviation φ ₁ need to be detected. Therefore, for example, the yaw rate deviation δ ′ ₁ is obtained based on the output of the yaw rate sensor 18, and the yaw rate sensor It is conceivable to obtain the yaw angle deviation φ ₁ based on a value obtained by integrating the output of 18 but the noise component included in the output of the yaw rate sensor 18 is large, and since the yaw angle deviation φ 1 is particularly required, the yaw angle deviation φ 1 There is a drawback that ₁ cannot be obtained with high precision. Further, the magnetic marker sensor 17 as shown in FIG. 1 is also provided in the rear part of the vehicle, and if the yaw angle displacement is detected from the outputs of these two magnetic marker sensors, the yaw angle displacement can be obtained with high accuracy. Not a good idea because the sensors are relatively expensive.

On the other hand, in the present embodiment, the feedback given to the target steering angle is fed back to the second side on the right side of the equation (1).
As indicated in Section, although the processed values delayed the yaw rate deviation phi _'1, according lag processing values can be easily obtained, moreover feedback [delta] _FB represented by substantially above (7) Therefore, it is possible to give appropriate feedback to the target steering angle with relatively high accuracy without increasing the cost.

[0056] Accordingly, to prove that the process value delayed the yaw rate deviation phi _'1 is equivalent to feedback [delta] _FB. That is, the feedback δ _FB , the yaw rate feedback component δ _FB1, and the yaw angle displacement feedback component δ
_{When FB2} is drawn on the phase plane with the yaw rate as the reference, it becomes as shown in FIG. That is, a vector in which the feedback [delta] _FB to negative phase, 'because the same direction as the vector obtained by delaying _one appropriate, such yaw rate deviation phi' yaw rate deviation phi inverts the polarity predetermined multiple of the value delayed ₁ By feeding back to the target steering angle, the same result as in the case of feeding back the value represented by the above equation (7) can be obtained.

[0057] FIGS. 7 (a) and (b), the above (1) when steering the front wheels 3L, 3R is fed back to the target steering angle values obtained by delaying the yaw rate deviation phi _'1 on the basis of the vehicle characteristics ( It is a frequency characteristic diagram showing the lateral displacement η / steering angle δ _f ), and since the phase characteristic starts from −180 degrees, the phase margin becomes zero when no feedback is applied, but the delay amount is large. It can be seen that the characteristics change as shown by the arrow and the phase margin increases as the time increases (the time constant τ increases). That is, if the time constant τ is appropriately set and the target steering angle δ is calculated according to the equation (1), the phase margin can be increased, and the differential compensation in the controller 20 becomes unnecessary or only a small differential is required. Therefore, it is possible to avoid the noise component from being emphasized, and an automatic steering system resistant to noise can be obtained.

In particular, in this embodiment, as shown in the second term on the right side of the above equation (1), the feedback amount is obtained by performing the first-order lag processing, so that it is included in the yaw rate detection signal φ '. Since the high frequency components that are generated are removed, the control system is more resistant to noise than when a simple delay process is performed on the time axis.

From the above, the processing shown in FIG. 3 is executed in the controller 20, the target steering angle δ which is appropriately corrected in accordance with the above equation (1) is calculated in step 105, and the steering angle which matches the target steering angle δ is calculated. Step 1 so that δ _f
If the steering angle control signal δ _c is output at 06, the vehicle 1 will stably travel along the target travel line drawn by the magnet embedded in the road surface.

Further, with respect to the problems relating to the magnetic marker method as described above, the differential compensation in the controller 20 becomes unnecessary or only a small differential is required, and the yaw rate φ confidence necessary for feedback is continuously detected. Therefore, the present embodiment is sufficiently solved.

Further, in the present embodiment, since the gain K ₂ and the time constant τ are set based on the vehicle speed detection signal V in step 103 of the processing in the controller 20, the steering angle with higher accuracy is obtained. It has the advantage that it can be controlled.

That is, as can be seen from (7) and FIG. 6, among the components of the feedback δ _FB , the yaw angle displacement feedback component δ _FB2 is not affected by the vehicle speed,
The yaw rate feedback component δ _FB1 changes with the vehicle speed. Specifically, the yaw rate feedback component Δ _FB1 tends to decrease as the vehicle speed increases.

Then, the feedback δ _FB tends to decrease in size as the vehicle speed increases, and the yaw angle displacement feedback component δ as the vehicle speed increases.
_FB2 tends to be dominant (in other words, the phase θ shown in FIG. 6 increases as the vehicle speed increases). Therefore, even if the vehicle speed changes, if the gain K ₂ is set to decrease as the vehicle speed detection signal V increases, and the time constant τ is set to increase as the vehicle speed detection signal V increases, the yaw rate deviation is set. Since it becomes possible to match the target steering angle correction amount (second term on the right side of the above equation (1)) obtained by delaying φ ′ ₁ with the appropriate feedback δ _FB obtained by the above equation (7). is there.

Here, in the present embodiment, the magnetic marker sensor 17 and the processing of step 102 correspond to the lateral position detecting means, the processing of step 105 corresponds to the target steering angle calculating means, and automatic steering is performed. The mechanism 10, the upper steering shaft 4U, the universal joint 5, the lower steering shaft 4L, the pinion shaft (not shown), the rack shaft 7, and the tie rods and knuckles (not shown) correspond to the steering angle generating means, and the yaw rate sensor 18 corresponds to the yaw rate detecting means. The processing of step 104 corresponds to the deviation calculating means, and the vehicle speed sensor 19 corresponds to the vehicle speed detecting means.

[0065] Incidentally, in the above embodiment, so that determining the correction amount of the target steering angle by the yaw rate deviation phi _'1 the first-order lag processing, delay processing, such as the 1
The present invention is not limited to the following delay processing, and for example, a dead time that increases as the vehicle speed detection signal V increases is set, and a physical quantity obtained by delaying the yaw rate deviation φ ′ ₁ according to the dead time is set. The second term on the right side of the above equation (1) may be replaced, or the yaw rate deviation φ ′ ₁ may be set to 2
The physical quantity that is stunned by the delay processing of the higher order than the order may be replaced with the second term on the right side of the expression (1).

Further, in the above-described embodiment, the lateral position of the vehicle 1 with respect to the target traveling line is detected by the magnetic marker method, but the invention is not limited to this. The lateral position may be detected by a method, or
As disclosed in Japanese Patent Application Laid-Open No. 3-288212 proposed by the applicant of the present application, the guide line drawn along the traveling path is recognized by the television camera, and the target traveling line is determined from the relative position between the guide line and the vehicle. The lateral position of the vehicle with respect to the vehicle may be detected, and the present applicant previously proposed JP-A-3-29.
As disclosed in Japanese Patent No. 3411, the distance between a vehicle and a guardrail installed along a road is measured using ultrasonic waves, and the lateral position of the vehicle with respect to a target travel line is detected from the distance. Good.

Further, in the above embodiment, the gain K _{2 is set} in the processing of step 103 in the controller 20.
While the vehicle speed detection signal V is set to decrease as the vehicle speed detection signal V increases, and the time constant τ is set to increase as the vehicle speed detection signal V increases, one of them is fixed and the other is set to the vehicle speed. Even if it is set based on the detection signal V, some effects can be obtained.
However, in order to perform the control with higher accuracy, it is desirable to appropriately set both the gain K ₂ and the time constant τ based on the vehicle speed detection signal V as in the above embodiment.

Further, in the above embodiment, only the steering angle can be automatically controlled. For example, an actuator for controlling the brake state and the accelerator state is provided, and the state of the actuator is supplied from the controller 20. By making it controllable by the control signal
The vehicle may also be capable of automatically controlling the vehicle speed.

[Brief description of drawings]

FIG. 1 is a plan view of a vehicle according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a part of a steering system.

FIG. 3 is a flowchart showing an outline of processing executed in a controller.

FIG. 4 is a two-wheel model diagram of a vehicle.

FIG. 5 is a block diagram showing a transfer function from a steering angle to a vehicle lateral displacement.

FIG. 6 is a vector diagram showing feedback for each component.

FIG. 7 is a frequency characteristic diagram showing vehicle characteristics in the embodiment.

FIG. 8 is a block diagram illustrating a conventional problem.

FIG. 9 is an explanatory diagram of a problem of the magnetic marker method.

FIG. 10 is a waveform diagram illustrating a problem of the magnetic marker method.

[Explanation of symbols]

 1 Vehicle 2 Steering Wheel 3L, 3R Front Wheel (Steering Wheel) 10 Automatic Steering Mechanism 14 Steering Angle Sensor 17 Magnetic Marker Sensor 18 Yaw Rate Sensor 19 Vehicle Speed Sensor 20 Controller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B62D 137: 00

Claims (5)

[Claims] 1. A lateral position detecting means for detecting a lateral position of a vehicle with respect to a target travel line, a target steering angle calculating means for calculating a target steering angle according to a detection result of the lateral position detecting means, In an automatic driving device provided with a steering angle generating means for generating a steering angle on a steered wheel of a vehicle based on a target steering angle, a yaw rate detecting means for detecting an actual yaw rate of the vehicle,
Deviation calculating means for calculating a deviation of the actual yaw rate from the target yaw rate is provided, and the target steering angle calculating means corrects the target steering angle in a direction of canceling the physical quantity in which the deviation is delayed. Automatic driving device characterized by. 2. The automatic driving apparatus according to claim 1, further comprising a vehicle speed detecting means for detecting a vehicle speed, wherein the target steering angle calculating means reduces the physical quantity in accordance with an increase in the vehicle speed. 3. The target steering angle calculation means calculates the physical quantity by performing delay processing of a first order or more with respect to the deviation, and sets a small gain of the delay processing in accordance with an increase in the vehicle speed. The automatic driving apparatus according to claim 2, wherein the automatic driving apparatus is configured to operate. 4. The automatic driving according to claim 1, further comprising vehicle speed detecting means for detecting a vehicle speed, wherein the target steering angle calculating means increases the delay amount of the deviation as the vehicle speed increases. apparatus. 5. The target steering angle calculation means calculates the physical quantity by performing a delay process of a first order or more with respect to the deviation, and increases the time constant of the delay process in accordance with an increase in the vehicle speed. The automatic driving device according to claim 4, wherein the automatic driving device is set.