JPH01229768A - Device for steering rear wheel of vehicle - Google Patents

Abstract

PURPOSE:To improve the reliability of rear wheel control in the captioned device which carries out the steering of a rear wheel by the power of a motor by providing a first rear wheel steering angle detecting means for detecting the rotating position of the motor and a second rear wheel steering angle detecting means for detecting the mechanical displacement of a rear wheel steering mechanism. CONSTITUTION:While a clutch 2 is in an engaged condition, a rear wheel steering mechanism B rotates knuckle arms 10R, 10L clockwise or counterclockwise via a relay rod 12, etc. by the rotation of a servomotor 20 as a driving source, thereby, steering rear wheels 2R, 2L. In this case, an encoder 32 for detecting the rotating position of the servomotor 20 is provided as a first rear wheel steering angle detecting means. Also, a rear wheel steering angle sensor 36 for detecting the mechanical displacement of members on the relay rod 12 side from the clutch 22 is provided as a second rear wheel steering angle detecting means. The output signals of these detecting means 32, 36 are inputted in a control unit U to carryout rear wheel steering control.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rear wheel steering device for a vehicle that steers the rear wheels.

(Prior Art) Some vehicles have so-called four-wheel steering (4WS) in which both the front wheels and the rear wheels are steered.

In this four-wheel steering, the steering mechanism for the rear wheels is
1); A mechanical type that mechanically connects the I-wheel steering mechanism and the rear wheel steering mechanism, and an electromagnetic type drive such as an electric motor for the rear wheel steering mechanism, as seen in Japanese Utility Model Application Publication No. 62-25275. It is broadly classified into an electric type in which the rear wheels are steered by the driving force of the drive means by linking means. In this electromagnetic type, it has also been proposed to interpose a speed reduction mechanism between the drive stage and the rear wheel steering mechanism in order to minimize the size of the drive means. 62-2
(See Publication No. 5277).

In the above-mentioned electric type, rear wheel steering is controlled exclusively electrically, so it is necessary to consider fail-safe measures such as failure of this control system. From this point of view, as seen in Japanese Unexamined Patent Publication No. 61-202977, it has been proposed to add a holding stage to the rear wheel steering mechanism that always biases the rear wheel steering mechanism in the neutral direction. ing. This proposal is based on the idea that when some kind of failure occurs in the control system, the rear wheel steering control is stopped and the rear wheels are forcibly returned to the neutral position using the 1γ holding means in F. be.

(Problem to be Solved by the Invention) By the way, when steering the rear wheels due to drought or dusk, it is common to perform feedback control to achieve the target rear wheel steering angle. A sensor is required to detect the steering angle of the vehicle.

In this case, if the sensor that detects the actual steering angle of the rear wheels fails, it will not be possible to accurately control the steering of the rear wheels.
In this regard, some countermeasures are desired.

Therefore, an object of the present invention is to provide sufficient safety in the event that a failure occurs in the rear wheel steering angle projection that detects the actual steering angle of the rear wheels in a device that steers the rear wheels using a motor as a drive source. Secure it? It is an object of [-1] to provide a rear wheel steering device with a middle white shape.

(Means and operations for solving the problems) In order to achieve the object described in n11, the present invention has the following configuration. That is, a rear wheel steering mechanism for steering the rear wheels, a motor as a drive source that is linked to the rear wheel steering mechanism and displaces the side of the rear wheel steering P9, and a first motor that detects the rotational position of the motor. Rear wheel steering angle detection means.

and second rear wheel steering angle detection means for detecting mechanical displacement of the rear wheel steering mechanism.

This is a configuration equipped with the following.

As described above, the present invention has two systems for detecting the actual steering angle of the rear wheels: the first rear wheel steering angle detection means and the second rear wheel steering angle detection stage. , so that the dependability of control can be improved, and failure detection can be easily performed by using the outputs of these two detection means.

(Example) An example of the present invention will now be described based on the attached drawings.

In Figure 1, IR is the 1111th wheel on the right, 1F is the left ni
+wheel, 2[or right rear wheel, 2L, is the left rear wheel, the left and right front wheels IR1IL are linked by the front wheel steering device Nl1A, and the left and right rear wheels 2R12L are linked by the rear wheel steering mechanism B. ing.

In the embodiment, the front wheel steering mechanism A includes a pair of left and right knuckle arms 3R13L and a tie rod 4R14L, respectively.
and a relay rod 5 that connects the pair of left and right tie rods 4R14 [4]. A steering mechanism C is linked to this old wheel steering mechanism, and the steering mechanism C is of a rack and pinion type in the embodiment, and a pinion 6, which is a component thereof, is connected to a handle 8 via a shaft 7. connected. This results in
When the handle 8 is turned to the right, the relay rod 5 is displaced to the left in Figure 1, and the knuckle arm: 3
F<, 3 L is steered clockwise in the figure by an amount corresponding to the steering angle.Similarly, When the steering wheel 8 is operated to turn to the left, the left and right heavy wheels I RlIL are steered to the left in accordance with the amount of displacement of this operation.

Similarly to the front wheel steering mechanism Δ, the rear wheel steering mechanism B also includes a pair of left and right knuckle arms 10[(, I01, and tie rods 1117, II+-, and the tie rod I11
? , I I +, , and a relay rod 12 that connects the relay rods 12 and 3 in the middle 1j holding stage.
is attached. middle) γ holding means 1' 3 is the third
As shown in the figure, a casing 15 fixed to a small body 14
Inside the casing 15 are a pair of spring receivers 16a.
, 16b are loosely fitted, and these spring receivers 16a, 16h
A compression spring 17 is disposed between them. The relay rod 12 extends through the casing 15, and the relay rod 12 is formed with a pair of flanges 12a, 12b spaced apart from each other. The relay rod 12 is configured to receive it, and is always urged in the neutral direction by a compression spring 17. Of course, the compression spring 17 is provided with a spring force sufficient to overcome the side force during cornering.

] The wheel turning mechanism B is linked to a servo motor 20 as a drive source for steering the rear wheels 2F<, 2L. More specifically, the relay rod 12 and the servo motor 2
0, a reduction mechanism 21 including a gear train 21a and a ball screw 21b, a clutch 22, and a brake mechanism 23 are interposed in order from the relay rod 12 side. As a result, the clutch 22 is configured to mechanically disconnect the servo motor 20 and the rear wheel steering mechanism B as appropriate, and the rear wheel steering mechanism 23 grips the output shaft of the servo motor 20 and rotates the rear wheel steering mechanism B. The rotation of the output shaft can be locked.

With the above configuration, when the clutch 22 is in the connected state, the relay rod 12 is displaced to the left or right in FIG. 1 due to the forward or reverse rotation of the servo motor 20, and the knuckle arm! OR, IOL is the center of rotation 1
0R", 101' as the center, the servo motor 20
It will be steered clockwise or counterclockwise in the figure by an amount corresponding to the amount of rotation. On the other hand, when the clutch 22 is in the disengaged state, the rear wheels 21 (, 2L) are forcibly returned to the neutral position by the neutral holding means 13, and are held at the 1"1 position. That will happen.

In other words, when the clutch 22 is disengaged, the front wheel +1'
? , 1L are steered, so-called 2WS 11 (both).

Here, the rear wheel steering control is considered to be heavy speed sensitive, and an example of changing the steering ratio according to heavy speed is as shown in FIG. 33. When the control characteristics shown in FIG. 3 are applied, the rear wheel steering angle relative to the steering wheel steering angle changes in the same phase direction as the vehicle speed increases.

This situation is shown in FIG. In order to carry out such control, the control unit U basically receives signals from the steering wheel angle sensor 30, the speed sensors 31 and 417, and the encoder 32 that detects the rotational position of the servo motor 20. In the control unit 1, the rear wheel steering angle is determined based on the steering wheel steering angle and the vehicle speed, and a control signal corresponding to the required rear wheel steering is output to the servo controller 20. Ru. Then, the encoder 3 detects whether or not the servo controller 20 is operating properly.
2, the rear wheels 2R12[4 are steered while being constantly monitored, that is, under feedback control.

The above basic controls are for fail-safe purposes.

The control system has a two-way configuration. In other words, a front wheel steering angle sensor 34 is added to the steering wheel steering angle sensor 30, a second heavy speed sensor 35 is added to the vehicle speed sensor 31, and the encoder 32 is located closer to the relay rod 12 than the clutch 22. A rear wheel steering angle sensor 36 for detecting mechanical displacement of the members is added, and these sensors 30 to 36
In this system, rear wheel steering is performed only when both corresponding sensors detect the same value.

That is, in the sensors 30 to 36, for example, the first
When the heavy speed detected by the second 11th speed sensor 31 differs from the vehicle speed detected by the second 11th speed sensor 35, it means that a failure has occurred, and the rear wheels 2R12L are maintained in the middle q state by control during fail mode, which will be described later. It is supposed to be done.

Further, in order to detect various failures, on/off signals from switches 37 to 40 are manually input to the control unit U, and the alternator's L terminal 4! A signal indicating whether or not power is being generated is manually input from the station. Here, [marked switch 3
7 is a neutral clutch switch, switch 38 is an inhibitor switch, switch 39 is a brake switch, and switch 40 is an engine switch. Here, the neutral switch 37 outputs an off signal when the shift position of the manual transmission is neutral or the clutch pedal is depressed in light rain when the manual transmission is equipped, and an on signal is output otherwise. It looks like this. In a vehicle equipped with an automatic transmission, the inhibitor switch 38 outputs an on signal when the range is in neutral (N) or parking (P), and outputs an off signal when the range is in the drive range. ing. The brake switch 39 outputs an on signal when the brake pedal is depressed, and the engine switch 40 outputs an on signal when the engine is in operation.

1", if the control system is shown in a block diagram, it will be as shown in FIG. Switches 37 to 40 as well as the alternator, 4:";"j from terminal 41 are input via buffer 51, and sensors 30 and 34
．． 36 is manually inputted via the △/1) converter 52, and the signal from the encoder 32 is input to the interface 5:
3. On the other hand, the signals generated in the microprocessor 50 are sent to the servo motor 29 via the drive circuit 54, and to the motor brake 23 via the brake drive circuit 55, or to the brake motor 29 via the brake drive circuit 55.
4 sent to the clutch 22 via the notch drive circuit 56
This rear wheel steering control is started on the condition that the signal from the alternator terminal 41 becomes high (Hi). In the same figure, reference numeral 57 is a battery, 58 is an ignition key switch, and 59 is a relay.If some kind of failure occurs in the four-wheel steering control system, the relay drive circuit 60 operates to stop the coil 61 from being energized. The vehicle is stopped, and as a result, the I3 contact of the relay 59 is closed and the blue lamp 62 is turned on.

Next, failures and their treatment will be explained.Here, a treatment corresponding to the location where the failure occurs is taken, and there are two modes of treatment as follows.

Control of the rear wheels 2R and 2L during the process 3L deaf+, ￥iA(th) fail mode and their positions '1.l+' This is the mode when the tiJ function is still possible. In other words, the motor 2
When it is possible to return to medium to γ by 0,
The middle η recovery is performed by this dry spell 20. Specifically, the contents of the one-wheel treatment are as follows: ■ After the warning lamp 62 lights up, ■ The rear wheels 217, 21 are returned to the neutral position by the drive of the servo motor 20; ■ After that, - The brake 23 is then engaged.

Treatment mode! 3 (2nd fail mode α Kai 1st rear wheel 2R
This is a situation when control of 12F and determination of its position become impossible. The details of this procedure are as follows.

■After the warning lamp 62 lights up, ■The flag 22 is turned off, and the connection between the servo motor 20 and the rear wheel steering mechanism 13 is cut off. After waiting for the clutch 214 to return to the middle ☆- position, the clutch 22 is connected.

Preferably, the motor brake 23 is engaged after the clutch 22 is disengaged. As a result, the rear wheel 2 [<
, 2F, will be physically recorded. After that, the supply of power to the motor 20 is cut off.

Below, the failure modes and their setting conditions will be explained for each system, and the corresponding treatment methods will be explained.

This trace progress "r" 41* When it is determined that a failure has occurred in this system, 11;
The treatment of aspect Δ of item I is performed.

(1) Change in the first vehicle speed sensor 31 [j(error~,.

This judgment is that the brake switch is 39 years old) (OF TO')
, and one first vehicle speed sensor 31 has a voltage of 1 (1V + /
Check the deceleration of r, i *-l > a (constant)11
The condition is that the Here, ■1 represents the vehicle speed detected by the first medium speed sensor 31. That is, when the vehicle shows a deceleration of 1- or more than a predetermined value even though the heavy vehicle is not braked, it is determined that the first vehicle speed sensor 31 is malfunctioning.

(2) Error in change of second vehicle speed sensor 35.

This determination is made as in the case of the first vehicle speed sensor 31,
The brake switch 39 is off (OFF), and the second vehicle speed sensor 35 is 1 dVt/d and l>a (constant Fi).
) has been detected. Here■2
represents the vehicle speed detected by the first vehicle speed sensor 3+.

(3) Vehicle speed mismatch error The condition for this judgment is that the detected values of the first and second heavy speed sensors 31.35 do not match, as expressed by, for example, l■+V21>b (constant). .

In this case, it is considered that an abnormality has occurred in at least one of the heavy speed sensors, so regardless of which sensor 31. Then, processing is performed on the aspect.

(4) Simultaneous failure of both 1j speed sensors 31 and 35.

This judgment is about the alternator! , the signal from the terminal 41 is high (Hi), and the output of the first and second (1) speed sensors 31.35 is zero (V+=Vt=0). For vehicles with automatic transmissions, the condition is that the neutral switch 37 remains on for a certain period of time, while for heavy vehicles with automatic transmissions, the inhibitor switch 38 is turned off, the engine switch 40 is turned on, and Simultaneous failure of both sensors 31 and 35 is determined on the condition that the brake switch 39 remains off for a certain period of time.

In other words, even though the engine speed is sufficient to drive based on the power generation t1: and it can be considered that the vehicle is running from the 11 shift position, the fact that the middle speed is zero means that the sensor 31.35
There is no other way than that some kind of abnormality has occurred.

After 31U (machine M) [When it is determined that a failure has occurred in the main system, the action of aspect I3 is taken.

(1) Control deviation (part 1) This judgment is based on the mismatch between the output (E, N) of the encoder 32 and the output of the sensor 36, that is, the rear wheel steering angle (OR), for example, l f tEN) - G (θRH>c (constant).

(2) Control deviation (part 2) This judgment is based on the mismatch between the 1st rear wheel steering angle (or) and the actual rear wheel steering angle (OR) set by the control unit [J, for example, 1θr-OR1>c (constant).

(3) Rear wheel reference position error The main condition is that the rear wheel center reference cannot be found at the time of control start (initialization). here,
Initialization is performed on the condition that the engine key is turned on.

1) When f, +1 is determined to indicate that a failure has occurred in the C servo motor system. The treatment of aspect B is performed.

(1) Tachometer error The condition for this determination is that the control-1 and the rotation of the spindle 20 (detected value of the encoder 32) do not match.

(2) Motor monitor error This judgment is made in the following cases.

■Disconnection or short circuit of the 1,000-meter coil.

■Harness disconnection, short circuit 3 ■Failure of motor drive circuit 52.

Rear rudder 1 sensor system.

If a failure occurs in this system and 1 degree occurs, 1', 11 is determined, then the action in Aspect] 3 is taken.

(1) Rotary encoder error The condition for this determination is that an abnormality is recognized in the code output from the encoder 32. .

(2) Rear wheel steering angle sensor sensor error This determination is made on the condition that the output of the rear wheel steering angle sensor 36 exceeds the set range.

When it is determined that a failure has occurred in the main system, the treatment of mode A is performed.

(1) Steering wheel angle sensor/rear angle error This determination is made under the condition that the output of the steering wheel angle sensor 30 exceeds a limit of 1.

(2) Front wheel steering angle sensor monitor error The condition for this determination is that the output of the +Ff wheel steering angle sensor 36 exceeds the set range.

(: Jl +ii7 steering angle mismatch error This determination is made on the condition that the difference in output between the steering wheel angle sensor 30 and the 11?7 wheel rudder frs sensor 34 is less than a certain value l·).

Disconnecting the electromagnetic clutch - When it is determined that the disengaging operation of the clutch 22 is defective, the action of mode A is taken.

This determination is made on the condition that the output of the rear wheel steering angle sensor 36 fluctuates beyond a certain value when an off signal is output to the clutch 22 and the servo controller 20 is operated.

When it is determined that a failure has occurred in the main control unit system, the action of aspect B is taken.

(The condition for this IIRAM error judgment is that an abnormality is recognized in the fortune-telling check of [7ΔM.

(21ROM error status 111 is set on condition that an abnormality is recognized in the ll0M dam sum check.

(3) [♂RC error This judgment is made on condition that an abnormality is recognized in the initial check of the self-running counter.

(41A/I) Error The main judgment is based on the condition that - is always recognized in the I10 check of the converter 52. The condition is that the calculation results of the microprocessor 11 and the calculation results of the microprocessor 11 do not match.

(2) Communication error This judgment is based on the phase I between microprocessors I and 11.
jThe condition is that communication has become impossible.

Brake When the brake 23 fails, the treatment of aspect 13 is performed. This failure determination of the brake 23 may be performed, for example, as follows.

(1) In the case where the brake 23 keeps the air conditioner 20 locked.

When the motor 20 is controlled to rotate with the brake 23 inactive (unlocked) and there is no output from the encoder 32 and sensor 36 at this time (rear wheel 2R12L
is not steered).

(2) When the motor 20 cannot be locked by the brake 23.

When there is an output from the encoder 32 and sensor 36 when the brake 23 is controlled to lock and the motor 20 is rotated while braking is performed (the rear wheels 2R12L are steered).

Next, the mode of failure as described above and the corresponding fail-safe control will be explained with reference to the flowcharts of FIGS. 7 to 1O. Incidentally, in the following explanation, P, Q, 1st or S indicates step.

(The following is a blank space) Overall 1' Figure 9 First, system initialization is performed at the PO in Figure 9. At this time, a failure that can be known at the time of initialization is detected (for example, rear wheel reference position;
Check for errors, control unit ROM,
(Error checking of RAM, etc.)

In addition, in this Pl, as shown in FIG. 10, the reference positioning of the encoder 70, the encoder 32, and the sensor 36 is performed, and an abnormality in the encoder 32 is particularly detected. To explain this point sequentially, first, at Ql in FIG. , rear wheel 2R1
Initialize to the value (zero) when 2L is in the neutral position. Next, the target rear wheel steering angle O' is set by motor 2, for example.
0! The motor 20 is changed to a predetermined value O3 in the direction of 80° [F rotation, and accordingly, in Q3, the motor 20 is driven by a value corresponding to the θ angle.

After Q3, in Q4, it is determined whether the output EN of the encoder 32 has become a value corresponding to the above-mentioned θ (i.e., 10 within the allowable error range). When the determination in Q5 is YES, it is determined in Q5 whether the output θR of the sensor 36 and the output EN of the encoder 30 match.

When the determination in Q5 is YES, it means that changes in EN and θR are being made normally in response to changes in or, so in this case, the processing after PI in FIG. 9, which will be described later, is continued.

If the determination in Q4 above is No, in Q6, FEN
It is determined whether or not the rate of change of θR matches the rate of change of θR. When the determination in Q6 is YES, it is determined in Q7 whether a predetermined period of time has elapsed since the motor 20 was started to be driven in the 03 direction. If the determination in Q7 is NO, there is a possibility that EN and 01 do not match due to the control delay, so the process returns to Q4 and the above-described control is repeated. On the other hand, if the determination in Q7 is No, it means that EN due to the control delay does not match θ, that is, there is an abnormality in the encoder 32 or sensor 36. Control for safety (12 in FIG. 9, corresponding to FIG. 8) is performed.

Note that if the judgment in Q5 is NO, it is possible that the clutch 20 is worn out and slipping, so it is recommended to memorize the information to check the clutch 20 (by writing to RAM). ).

11 After initial failure detection of encoder tacho (2) and sensor 36 as shown in Fig. 1O described above is performed, the process moves to Pl of Fig. 9. Signals from each P1 sensor or switch are input manually. In other words, if there is an abnormality in the medium speed signal state (YES in P2), or if there is an abnormality in the front steering angle sensor system (P3's 'I If the clutch 22 is abnormal (1) 4 is determined as YES.
ES), if any one of the following applies, P5
Then, in principle, treatment mode A (braking in the first fail mode), which will be described later, is performed.

If all of the determinations from P2 to P4 in V are No, P6 to pH
A failure determination is made. If the judgment in P6 to P11 indicates that there is an abnormality in the rear wheel steering mechanism system (YES in the judgment in P6)
), if there is an abnormality in the motor 2o (when the determination in P7 is YES), if there is an abnormality in the rear steering angle sensor system (when the determination in P8 is YES), if there is an abnormality in the control unit system (When the determination in P9 is YES), if there is a failure in the microprocessor system (PIO
Judgment of Y l-: S (7)), brake 23
If there is an abnormality (when YES in the pH determination), if any one of the following applies, proceed to 1] 12. In this case, the following processing mode (second fail mode control) is performed.

1Jr2P 2~F' 4o, J:HiP 6~P 11
(7) When all the determination tests are NO, it means that there is no abnormality, and in this case, IF normal control is performed at P l 3. That is, control is performed to realize the steering ratio characteristics shown in FIG. 4.

Naoto J, L to 2A1 The details of the control in 1) 5 above are shown in FIG.

First, at Sl, the warning lamp 62 is turned on to notify the driver that an abnormality has occurred. Next, to check whether rear wheel control and position determination are always performed on the 1st floor,
A determination in S2.33 is made. That is, if the rear steering sensor 36 is normal (when the determination in S2 is YES) and the encoder 32 is normal (when the determination in S3 is YES), the motor 20 is controlled in S4 to steer the rear wheels. 2
Gradually return R22L to the neutral position. After this,
In S5, confirm that the motor 20 itself is normal (if the determination in S5 is YES), continue to drive the rear wheel 2R.
After confirming that 12L is actually in the neutral position (S
If the determination in step 6 is YES), the brake is operated in step S7 to lock the operation of the windshield 20 with the reverse rotations 2R and 2L in the neutral position. Of course, at this time, the clutch 22 remains connected, and therefore, the backward rotation 2 R12 [, Due to the locking action, it firmly ranks 9th place in the middle 1st place.
It is held at rt.

On the other hand, the previous IC! 8'2, S3 or S5, if NO, the motor 20 will drive the rear wheel 2R12.
This is a case where it is impossible to accurately return L to the neutral position. In this case, the process moves to Sll in processing mode B in FIG. 8, which will be described later.

41 Rule B (Fig. 8) First, after lighting the warning lamp 62 at SIO, S11
At this point, the clutch 22 is disengaged. As a result, the reverse rotation 211°2L is forcibly returned to the middle position l\ by the neutral holding means 13. After that, in S12, the brake 23 is activated to lock the motor 20, and then S1
Cut the power supply to the motor 20 in Step 3 (FUJIBO 14 of the motor 20).Wait for a predetermined time to pass in Step 6S14, that is, the time required for the reverse rotation 2R12L to return to the neutral position. This time has elapsed considering A-
Waiting for this, the clutch 20 is fully connected in S15 ([11Xγ position is firmly held)].

Here, when both the encoder 32 and the sensor 36 are in the IL state, feedback control at Pl:3 is performed by preferentially using the output EN of the encoder 32, and when this encoder 32 fails, the sensor Feedback control may be performed using the output θR of 36. An example of carrying out such control is shown in the flowchart of FIG. That is, if it is determined that the encoder 32 is 11: normal in the RI of FIG. 20 feedback control.When NO in the above RI control,
l? Assuming that the sensor 36 is confirmed to be normal in step 3, the sensor 36 is checked in R4.
Feed pump control is performed so that the output OR and the target rear wheel turning angle Or match. Note that when the determination in 1. [<3 is No, it is impossible to determine the position of the rear wheels 21≧, 2[, and so the fail-safe control shown in FIG. 8) is performed.

Of course, when performing the small control shown in FIG. 11, R8 shown in FIG. 9 becomes unnecessary.

(Effect of the invention) Below 1. As is clear from the above description, according to the present invention, in a vehicle in which the rear wheels are steered using the sun-sun as a drive source, there are two systems for detecting the actual rear wheel steering angle. The reliability of the system is improved, and failures can be detected using the outputs of the two parentheses, which is a desirable safety measure.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. Figure 2 is a configuration diagram of the rear wheel steering mechanism. FIG. 3 is an enlarged sectional view of the neutral holding means. FIG. 4 is a control characteristic diagram of a vehicle speed sensitive type which is an example of rear wheel steering. FIG. 5 is a characteristic diagram showing changes in rear wheel steering angle according to vehicle speed. FIG. 6 is a block diagram of a control system according to the embodiment. 7 to 11 are flowcharts showing control examples of the present invention. 1: +iif wheel 2: Rear wheel 20: Servo motor 32: Encoder (first rear wheel steering angle detection means) 36: Sensor (second rear wheel steering angle detection two-stage) [J: Control unit 13: Rear wheel steering mechanism

Claims (1)

[Claims] (1) a rear wheel steering mechanism for steering the rear wheels; a motor that is linked to the rear wheel steering mechanism and serves as a drive source for displacing the rear wheel steering mechanism; and a first motor that detects the rotational position of the motor. A rear wheel steering device for a vehicle, comprising: a rear wheel steering angle detection means; and a second rear wheel steering angle detection means for detecting mechanical displacement of the rear wheel steering mechanism.