JP3748547B2 - Vehicle steering system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering apparatus, and for example, relates to a steering apparatus including an auxiliary steering mechanism necessary for performing automatic steering to compensate a driver's steering wheel operation amount and steering for automatic driving. .
[0002]
[Prior art]
Conventionally, the steering direction of the vehicle, that is, the direction of the wheel is automatically controlled to be optimal so that the change in the actual vehicle traveling direction with respect to the operation amount of the steering wheel is optimized, or the traveling position of the vehicle maintains a predetermined lane. Thus, it has been proposed to automatically drive and control the steering system instead of the driver (see, for example, Patent Document 1).
[0003]
In addition, it has been proposed that the motor and the steering wheel are prevented from vibrating, the steering wheel is prevented from rotating suddenly when the control system is started, and the responsiveness is improved during steering (for example, patents). Reference 2).
[0004]
[Patent Document 1]
JP-A-6-206553 [Patent Document 2]
Japanese Patent Laid-Open No. 2002-145093
[Problems to be solved by the invention]
However, in the above-described conventional example, the steering wheel and the steering wheel are mechanically coupled. However, in the vehicle steering device that can operate independently, the ratio of the steering wheel angle to the pinion angle is low because the steering wheel has poor convergence. There is a problem that the handle oscillates and diverges when the wheel is changed.
[0006]
The present invention has been made in view of the above points, and can add a feedback control amount based on a deviation between a target rudder angle and an actual rudder angle to a reaction force control command value to suppress steering oscillation and divergence. An object of the present invention is to provide a vehicle steering apparatus.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a vehicle steering apparatus according to the present invention mechanically connects a steering wheel operated by a driver and a steering wheel steered by a steering wheel control mechanism, and is electrically controllable. In a vehicle steering apparatus that can be independently operated by a sub steering mechanism, a steering wheel angle detecting means that detects a steering angle of the steering wheel, and is installed between the steering wheel and the auxiliary steering mechanism and applied to the steering wheel. A reaction force torque detecting means for detecting a reaction force torque, a wheel rudder angle detecting means for detecting an angle corresponding to a wheel rudder angle of the steered wheel, installed between the auxiliary steering mechanism and the steering wheel, A target reaction force generating means for generating a target reaction force that is a target value of the reaction force torque applied to the handle, a target reaction force generated by the target reaction force generating means, and a reaction detected by the reaction force torque detecting means. Power Reaction force torque control means for driving and controlling the auxiliary steering mechanism so that the torques coincide with each other, target wheel steering angle generating means for generating a target steering angle of the steering wheel, and steering mechanism drive for controlling the steering wheel control mechanism Means, a wheel steering angle control means for driving the steering mechanism drive means so that a target vehicle steering angle generated by the target wheel steering angle generation means matches an output of the wheel steering angle detection means, and the target wheel Wheel steering angle compensation means for adding a feedback control amount based on a deviation between the target wheel steering angle generated by the steering angle generation means and the output of the wheel steering angle detection means to the output of the reaction force torque control means. It is characterized by.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a vehicle steering apparatus according to Embodiment 1 of the present invention. In the vehicle steering apparatus shown in FIG. 1, the handle 1 is steered by a driver to steer the steering wheels 7a and 7b. The first planetary gear mechanism 2 as an electrically controllable sub-steering mechanism includes a sun gear 201 coupled to the handle 1, planetary gears 202a and 202b supported by a carrier mechanism 203, a ring gear 204, A worm wheel 205 for rotating the ring gear 204 is formed.
[0009]
The second planetary gear mechanism 3 as a sub-steering mechanism that can be controlled electrically is composed of a sun gear 301 and a carrier mechanism 303 connected to the carrier mechanism 203 of the first planetary gear mechanism via a shaft 4. The planetary gears 302a and 302b are supported, and the ring gear 304 is fixed. The shaft 4 connects the carrier mechanism 203 of the first planetary gear mechanism 2 and the carrier mechanism 303 of the second planetary gear mechanism 3 to transmit power.
[0010]
The rack and pinion type steering wheel control mechanism 5 as a steering mechanism for turning the steering wheel has a rack and pinion 501 mechanically connected to the sun gear 301 of the second planetary gear mechanism 3 and is used for steering. A steering mechanism driving means 9 used as an actuator and a reversible worm wheel 502 for rotating the rack and pinion 501 are connected. Further, the steering wheels 7a and 7b are connected to the rack and pinion 501 through knuckle arms 6a and 6b.
[0011]
The reaction force torque generating means 8 gives reaction force torque to the handle 1 and is constituted by a reaction force motor 801 and a worm gear 802 that meshes with the worm wheel 205 of the first planetary gear mechanism 2. Here, the worm gear 802 can be self-locked so that the worm gear 802 does not rotate even when the worm wheel 205 is operated.
[0012]
The steering mechanism drive unit 9 drives the steering wheel control mechanism 5 and includes a steering motor 901 and a worm gear 902 that meshes with the worm wheel 502 of the steering wheel control mechanism 5. However, the combination of the worm wheel 502 and the worm gear 902 can be rotated from the worm wheel 502 side, that is, can be reversed.
[0013]
The reaction force torque detection means 10 detects the reaction force torque generated in the handle 1, the actual steering angle detection means 11 detects the steering angle of the steering wheels 7a and 7b, and the handle angle detection means 12 The steering angle of the steering wheel 1 is detected.
[0014]
The target wheel rudder angle generating means 13 is based on, for example, an output 1201 of the steering wheel angle detecting means 12, a steering request signal 20 from another system (for example, a lane keeping device), a vehicle state signal (for example, vehicle speed / yaw rate, etc.) 20 or the like. The target steering angle 1301 is generated by calculating the necessary steering angle. The wheel steering angle control means 14 controls the steering angle of the steering wheels 7a and 7b by driving the steering mechanism drive means 9 so that the target wheel steering angle 1301 and the wheel steering angle detection means output 1101 are equal.
[0015]
The target reaction force generation means 15 sets a reaction torque target value to be given to the driver via the steering wheel 1, for example, an output 1201 of the steering wheel angle detection means 12, a vehicle state signal (for example, vehicle speed / yaw rate, etc.) 21, etc. From this, an appropriate reaction force is calculated and a target reaction force torque 1501 is generated.
[0016]
The reaction torque control means 16 controls the reaction torque applied to the handle 1 by controlling the drive torque of the reaction force motor 8 so that the target reaction torque 1501 and the output 1001 of the reaction torque detection means 10 coincide. Is controlled by the PID controller or the like based on the deviation between the target reaction torque 1501 and the output 1001 of the reaction torque detector 10 to the reaction force electric motor 801 of the reaction torque generator 8. The reaction force torque is controlled by controlling the drive current.
[0017]
The wheel rudder angle compensation means 17 inputs the target wheel rudder angle 1301 that is the output of the target wheel rudder angle generation means 13 and the output 1101 of the wheel rudder angle detection means, and a feedback control amount 1701 that has been subjected to a predetermined calculation. Is output. The feedback control amount 1701 is added to the output of the reaction force torque control means 16 to drive the reaction force electric motor 801.
[0018]
FIG. 2 is a diagram for explaining the operation of the reaction force torque control means 16 and the wheel steering angle compensation means 17. As shown in FIG. 2, the reaction force torque control means 16 receives the output 1501 of the target reaction force generation means 15 and the output 1001 of the reaction force torque detection means 10, calculates the deviation, and sets the detected torque as the target. The coefficient K1 that follows the reaction force is multiplied and output. The wheel steering angle compensation means 17 receives the output 1301 of the target wheel steering angle generation means 13 and the output 1101 of the wheel steering angle detection means 11 and calculates a deviation. This deviation is multiplied by a coefficient K2 that does not cause the handle to oscillate or diverge. This calculation result is the feedback control amount 1701 of the wheel steering angle compensation means 17. The feedback control amount 1701 is added to the output 1601 of the reaction force torque control means 16 to drive the reaction force electric motor 801.
[0019]
Next, the operation will be described. The reaction torque in the apparatus having the auxiliary steering mechanism shown in FIG.
Th = Ts × (θh−θs) (1)
Th: reaction torque Ts: spring constant of reaction force detection means 10 h: handle angle θs: angle of sun gear 203
[0020]
Further, the angle θs of the sun gear 203 is constrained by the angle θc of the carrier 203 of the first planetary gear mechanism 2 and the angle θr of the ring gear 204. Here, assuming that the carrier-sun gear reduction ratio is Gc and the ring gear-sun gear reduction ratio is Gr, which is determined by the geometry of the gear constituting the first planetary gear mechanism 2,
θs = Gc × θc−Gr × θr (2)
The relationship holds.
[0021]
On the other hand, the pinion angle θp corresponding to the wheel steering angle is controlled to the target wheel steering angle generated from the steering wheel angle θh. Moreover, since the structure of the 2nd planetary gear mechanism 3 is equivalent to the 1st planetary gear mechanism 2,
θc = 1 / Gc × θp (3)
It becomes. From formulas (1) to (3),
Th = Ts × {(θh−θp) + Gr × θr} (4)
Is established.
[0022]
Here, assuming that the target reaction force torque is Tr, the reaction force torque control means 16 controls the rotation angle θr of the ring gear 204 so that Tr−Th = 0. Therefore,
Tr−Th = Tr−Ts × {(θh−θp) + Gr × θr} = 0
And changing this formula,
θr = Tr / (Ts × Gr) − (θh−θp) / Gr
Thus, the reaction force torque control means 16 controls the rotation angle θr of the ring gear 204.
[0023]
While the driver is steering the steering wheel 1, a deviation occurs between the steering wheel angle θh and the angle θs of the sun gear 203, and the reaction torque control is established because Expression (1) is established. The rotation transmitted from the steering wheels 7a, 7b to the handle 1 is canceled by the rotation angle θr of the ring gear 204 of the first planetary gear mechanism 2 because the reaction torque control is established. Therefore, there is no deviation between the output 1301 of the target wheel steering angle generation means 13 generated from the steering wheel angle θh and the output 1101 of the wheel steering angle detection means 11, so the output 1701 of the wheel steering angle compensation means 17 becomes 0, It is not added to the output 1601 of the force torque control means 16. In other words, the wheel rudder angle compensation means 17 is effective when the reaction torque control, which is a state where the driver has released his hand from the handle 1, is not established, and when the driver is steering the handle 1. Does not affect the wheel rudder angle compensation.
[0024]
If the driver releases his hand from the handle 1 during steering, the worm gear 802 and the worm wheel 205 of the first planetary gear mechanism 2 are self-locked because the formula (1) is not established and the reaction force control is not established. The turning angle of the steered wheel 7 due to the force is transmitted to the handle 1.
[0025]
When the steering ratio is 1, the turn-back angle of the pinion angle θp is equal to the return angle of the steering wheel 1, and as shown in FIG. 3A, the output 1301 of the target wheel steering angle generated from the steering wheel angle θh. And the output 1101 of the wheel rudder angle detecting means coincide with each other, and no deviation occurs. Therefore, even if the reaction force torque control is not established, the handle 1 converges as shown in FIG.
[0026]
Further, since the deviation between the output 1301 of the target wheel rudder angle generation means and the output 1101 of the wheel rudder angle detection means is 0, as shown in FIG. 3C, the output 1701 of the wheel rudder angle compensation means becomes 0, and the reaction force electric motor The drive current of 8 is only the output 1601 of the reaction force torque control means.
[0027]
When the turning ratio is 1 or more, if the driver releases his hand from the steering wheel 1 during steering, the formula (1) is not established and the reaction force control is not established, so the worm gear 802 of the first planetary gear mechanism 2 The worm wheel 205 is self-locking, and the turning-back angle of the steered wheel 7 due to the reaction force is transmitted to the handle 1, and the handle 1 moves by the wheel rudder angle of the steered wheel 7, that is, the pinion angle θp.
[0028]
The steering wheel 1 is further moved by subtracting the steering wheel angle θh from the pinion angle θp from the neutral point of the steering wheel 1, and as shown in FIG. 4A, the target steering wheel angle generated from the steering wheel angle θh. Deviation occurs between the output 1301 and the output 1101 of the wheel steering angle detection means. This deviation is multiplied by a coefficient K2 that does not cause the steering wheel 1 to oscillate or diverge, and a feedback amount 1701 as shown in FIG. 4C is added to the output 1601 of the reaction force torque control means, thereby The output 1301 coincides with the output 1101 of the wheel steering angle detection means, and as shown in FIG. 4B, the oscillation and divergence of the handle 1 are suppressed and the handle convergence is improved.
[0029]
In the embodiment, the feedback control amount 1701 by the wheel rudder angle compensation means 17 suppresses the divergence / oscillation of the steering wheel 1 by adding the feedback amount by the proportional control to the output of the reaction force torque control means 16. However, the present invention is not limited to this configuration. For example, the output 1301 of the target wheel rudder angle and the wheel such as the feedback amount by differential control, the feedback amount by proportional control and differential control, or the feedback amount by phase compensation control with a delay filter included Any feedback amount that eliminates the deviation from the output 1101 of the rudder angle detection means 11 may be used.
[0030]
【The invention's effect】
As described above, according to the present invention, the feedback control amount based on the deviation between the output of the target wheel steering angle generation means and the output of the wheel steering angle detection means is added to the output of the reaction force torque control means. When deviation occurs between the target wheel rudder angle and the output of the wheel rudder angle detection means, by matching the target wheel rudder angle with the wheel rudder angle, the handle can suppress oscillation and divergence, and the handle convergence can be improved. Thus, it is possible to provide a vehicle steering apparatus that does not feel uncomfortable.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a vehicle steering apparatus according to Embodiment 1 of the present invention.
2 is a block diagram showing the operation of the reaction force control means and wheel steering angle compensation means of FIG. 1. FIG.
3 is a diagram showing a steering wheel angle, a target wheel rudder angle / wheel rudder angle, and an output of the wheel rudder angle compensating means in FIG. 1 when the steering ratio is 1. FIG.
4 is a diagram showing the effect of the wheel steering angle compensation means of FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Handle, 1st planetary gear mechanism which comprises sub-steering mechanism which can be electrically controlled, 3 Second planetary gear mechanism which comprises substeering mechanism that can be electrically controlled, 5 Steering for steering steered wheels Wheel control mechanism, 6a, 6b knuckle arm, 7a, 7b steering wheel, 8 reaction force torque generating means, 9 steering mechanism driving means, 10 reaction force torque detecting means, 11 wheel steering angle detecting means, 12 steering wheel angle detecting means, 13 Target wheel steering angle generation means, 14 wheel steering angle control means, 15 target reaction force generation means, 16 reaction force torque control means, 17 wheel steering angle compensation means, 20 steering request signal from other system, 21 vehicle state signal.

Claims (1)

In a vehicle steering apparatus in which a steering wheel operated by a driver and a steering wheel steered by a steering wheel control mechanism are mechanically coupled, and can be independently operated by a sub-steer mechanism that is electrically controllable,
A handle angle detecting means for detecting a steering angle of the handle;
Reaction force torque detecting means installed between the handle and the auxiliary steering mechanism for detecting reaction force torque applied to the handle;
Wheel steering angle detection means installed between the auxiliary steering mechanism and the steering wheel and detecting an angle corresponding to the wheel steering angle of the steering wheel;
A target reaction force generating means for generating a target reaction force that is a target value of a reaction force torque applied to the handle;
Reaction force torque control means for driving and controlling the auxiliary steering mechanism such that the target reaction force generated by the target reaction force generation means and the reaction force torque detected by the reaction force torque detection means coincide with each other;
Target wheel rudder angle generating means for generating a target steering angle of the steering wheel;
Steering mechanism driving means for controlling the steering wheel control mechanism;
Wheel steering angle control means for driving the steering mechanism driving means so that the target vehicle steering angle generated by the target wheel steering angle generation means matches the output of the wheel steering angle detection means;
Wheel steering angle compensation means for adding a feedback control amount based on a deviation between the target wheel steering angle generated by the target wheel steering angle generation means and the output of the wheel steering angle detection means to the output of the reaction force torque control means; A vehicle steering apparatus comprising:

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