JPH09207800A - Steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a course change with a natural feeling by providing an intention detecting means for detecting the steering intention of a driver added to a handle, and a steering angle changing means for changing the operating quantity of a driving means determined by a steering quantity calculating means according to the output of the intention detectingmeans. SOLUTION: The target value of displacing angle of a motor 11 for providing a steering quantity necessary for keeping the positional relation of one's own vehicle to a road lane is determined on the basis of the forward lane state in traveling detected by a CCD camera 20 and the operating state of the own vehicle detected by a steering angle sensor 17. The target value is changed by the detected value of a steering torque sensor 16 for detecting the steering intention of a driver added to a handle 1 and the intervened steering angle determined on the basis of the steering direction. The difference between the input steering angle by the driver and the determined steering angle of the system is transmitted to the handle 1 as steering force to deviate the vehicle from an intended course, but the deviation is strictly determined by the steering force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a relationship between a lane on a road and a vehicle using a sensor such as a camera while traveling on a road, and issues a command for traveling along the lane to drive the vehicle. The present invention relates to a steering device for a vehicle, which is adapted to allow a vehicle to continuously travel along a lane by being provided to a steering means.

[0002]

2. Description of the Related Art The present applicant has previously proposed a technique according to the above concept (Japanese Patent Laid-Open No. 5-197423).
This was to automatically drive the vehicle by the output of the system. However, while the vehicle is running, change lanes, change lanes at interchanges, avoid obstacles falling on the road surface, change work course on the shoulder of the road and slightly change lane course due to construction signs. Are often encountered, and automatic steering of such vehicles requires a high degree of intelligence, and it is impossible with the current technology to perform fully autonomous driving.

[0003]

Therefore, when changing the direction of the vehicle during the automatic driving of the vehicle along the lane, it is more preferable that the driver can intervene during the automatic driving. It is practical, and human beings will continue to be the main driver of driving until the road side mechanism maintenance progresses in the distant future and it becomes suitable for autonomous driving,
Nevertheless, it is desired to realize a system that provides information suitable for driving from the system side to the driver in an easy-to-understand format. For that purpose, the information necessary for the vehicle to travel along the lane is converted to the form of steering force and steering angle and transmitted to the driver, and the driver drives the vehicle on his own will while taking this information into consideration. It is necessary to build an excellent man-machine interface system so that it can be done. Especially when the driver is trying to steer in a direction different from the target set by the system while the system is following the lane, the vehicle will turn straight to the steering force applied to the steering wheel, and yet, It is necessary to realize a good man-machine interface by letting the driver know that the system is still functioning by transmitting the steering force to return to the original lane following course to the steering wheel. is there.

By the way, in calculating the output torque command value commanded by the system to the motor of the drive means for actuating the steering means, the amount obtained by multiplying the gain by the difference between the current steering angle and the target steering angle desired by the system. The applicant has previously proposed a method in which lane following is executed by setting the motor torque as a command value (Japanese Patent Application No. 7-310).
No. 070). Even in this method, if the gain is selected to be a relatively small amount, the motor torque also becomes small. Therefore, as long as the steering force applied to the steering wheel by the driver exceeds the motor torque, the course can be changed by the driver's intention, and the original The steering reaction force to return to the lane can still be secured. However,
This method also has the following drawbacks (1) to (3).

(1) Since the gain cannot be made large, the response of the system becomes low, and the target course may not be traced accurately.

(2) Since the reaction force depends on a single gain, only a reaction force that is simply proportional to the input steering angle of the driver can be obtained, and it is difficult for the driver to create an optimized reaction force.

(3) Normally, the motor provided in the driving means is connected to the steering system via the reduction gear without directly using the torque transmission to the steering system. There is a type that rejects the torque of. Even if you don't refuse, when the motor draws a little current and you're trying to execute a system command,
The steering torque applied by the driver loses,
In some cases, as a result, the driver's intention was not communicated. For example, when the gear ratio of the worm gear shown as an example in the specification of the present application is set to be large, the above-mentioned drawbacks appear. However, if you set a small gear ratio,
There is a dilemma that this time, unless a huge motor is prepared, the vehicle cannot be guided along the target course.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to change a course by a driver's intention without deteriorating the responsiveness of the system. It is possible to create the optimum steering reaction force for such a vehicle and increase the degree of freedom in design, so that the steering reaction force can be created freely and accurately regardless of the type of reduction gear and the reduction ratio. Another object of the present invention is to provide a vehicle steering system having a man-machine interface.

[0009]

In order to achieve the above-mentioned object, the invention according to claim 1 detects the movement state of the vehicle and the first detection means for detecting the front lane condition of the road on which the vehicle is running. The second detection means, the steering amount calculation means for calculating the steering amount necessary for maintaining the positional relationship of the vehicle with respect to the road lane from the outputs of the first and second detection means, and the steering wheel of the vehicle are operated. In a vehicle steering system including a steering means and a drive means for operating the steering means according to an output of the steering amount calculation means, a steering connected to the steering means to enable torque transmission to the steering means. Intention detecting means for detecting the steering intention of the driver applied to the steering wheel, and steering angle changing means for changing the operation amount of the driving means determined based on the output of the steering amount calculating means according to the output of the intention detecting means. Including And it features.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the intention detecting means is a force sensor arranged between the steering handle and the steering means. Characterize.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the invention, the rudder angle changing means includes:
It is characterized in that the operation amount of the drive means is changed according to the direction and magnitude of the output of the intention detection means.

According to a fourth aspect of the present invention, in addition to the configuration of the third aspect of the invention, the steering angle changing means sets the operating amount increase ratio of the drive means to at least 2 with respect to the increase of the output of the intention detecting means. It is characterized in that it can be switched to a stage.

According to a fifth aspect of the invention, in addition to the configuration of the first or second aspect of the invention, the rudder angle changing means includes:
When the absolute value of the output of the intention detecting means is less than the reference value, the operation amount of the driving means is changed in proportion to the output of the intention detecting means by a first ratio. When the absolute value of the magnitude of the output of is larger than or equal to the reference value, the actuation amount of the drive means should be changed in proportion to the magnitude of the output of the intention detecting means at a second rate larger than the first rate. It is characterized by being configured.

According to a sixth aspect of the invention, in addition to the configuration of the fifth aspect of the invention, the drive means is determined based on the first ratio when the output of the intention detecting means is at the reference value. The steering angle changing means is configured such that the operation amount of the drive means determined based on the second ratio is large or substantially equal to the operation amount.

According to a seventh aspect of the invention, in addition to the structure of the third aspect of the invention, within a predetermined range of the output of the intention detecting means, the driving means of the driving means is changed despite the change of the output of the intention detecting means. The steering angle changing means is configured so that the operation change amount becomes "0".

According to an eighth aspect of the invention, in addition to the structure of the seventh aspect of the invention, the steering amount calculation means is at least part of a predetermined range of the output of the intention detection means, and the own vehicle with respect to the road lane. Is configured to be changed according to the output of the intention detecting means.

Further, in addition to the structure of the invention described in any one of claims 1 to 8, a ninth aspect of the invention is a spring formed of software between the steering handle and the steering means, or It is characterized in that a mechanical spring is interposed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 7 show a first embodiment of the present invention. FIG. 1 is an overall configuration diagram of a vehicle steering system, FIG. 2 is a control block diagram, and FIG. 3 shows a part of a control algorithm. 4 is a flowchart showing the rest of the control algorithm, FIG. 5 is a diagram for explaining the processing in the flowchart of FIG. 3, FIG. 6 is a diagram showing the relationship between the steering force and the intervention steering angle, and FIG. 7 is a vehicle. It is a figure which shows the relationship of the input steering angle and steering force on a line.

First, referring to FIG. 1, this vehicle steering system includes a steering handle 1 that is rotated by a driver.
A steering shaft 2 which is rotated according to an operation of the steering handle 1; and a front wheel 5 as a steering wheel.
The steering means 3 for operating the steering means 3 and the driving means 4 for operating the steering means 3 are provided.

The steering shaft 2 is formed by connecting the other end of the transmission shaft 2a, one end of which is connected to the steering handle 1, and one end of the transmission shaft 2c, via a torsion bar 2b. The end is connected to the steering means 3. The steering means 3 is a rack-and-pinion type having a pinion 8 provided at the other end of the transmission shaft 2c and a rack 9 meshing with the pinion 8, and both ends of the rack 9 are tie rods. The left and right front wheels 5 are connected via 10 respectively. The rotation of the pinion 8 drives the rack 9 up and down in FIG.
The front wheels 5 are turned around their rotation axes in accordance with the operation of the above., Whereby a desired steering can be obtained.

The drive means 4 is connected to one end of the transmission shaft 2c of the steering shaft 2, and is for boosting the output of the motor 11 and the motor 11 to input it to the transmission shaft 2c of the steering shaft 2. The worm gear mechanism 12 includes a worm gear mechanism 12 and a screw gear 13 connected to the output of the motor 11 and a worm gear 14 provided on the transmission shaft portion 7 mesh with each other.

The operation of the motor 11 in the drive means 4 is
It is controlled by the CPU 15 ₁ , and the CPU 1
5 _1, a steering torque sensor 16 as intention detecting means for detecting a steering intention of the applied driver steering torque i.e. the steering wheel 1 be on the steering shaft 2, is an encoder for detecting the rotation angle of the motor 11 A steering angle sensor 17, a vehicle speed sensor 18 that electrically detects the speed of the vehicle, a yaw rate sensor 19 that electrically detects the rotational speed of the vehicle about a vertical axis, and a CCD camera 20 that images the road conditions ahead of the vehicle. The obtained information is entered. In addition, the SAS (S
teer Assist System) switch 21
And the indicator light 22 indicating that the lane follow-up control is being executed are respectively connected to the CPU 15 ₁ .

Referring now to the exemplary drive means 4, the worm gear mechanism 12 on the steering shaft 2.
The actuator provided with is mainly used for power steering of light-weight vehicles. In such a type of power steering, a steering torque sensor 16 for detecting a steering torque is provided near the worm gear mechanism 12 and on the steering handle 1 side. In this embodiment, the drive means 4 and the steering torque sensor are provided. Both 16 are shared with the lane-following control system. The principle of the steering torque sensor 16 is as follows.
The torsion bar 2b is twisted by receiving a steering force, which is converted into an axial linear displacement by a mechanism such as a cam, which is converted into an electric signal by a potentiometer or the like and taken out. Has been done.

By the way, in the power steering, the direction of the steering torque of the driver and the direction of the torque output from the system to the motor 11 always coincide with each other. Therefore, even if the worm gear mechanism 12 is used, the system and the driver do not conflict with each other. Absent. On the other hand, in the case of lane-following, the lane-following and the steering direction in which the driver intervenes generally do not match. Therefore, unless the gear ratio of the worm gear mechanism 12 is set low, the known method does Steering does not occur.

In FIG. 2, the image picked up by the CCD camera 20 is subjected to processing such as feature point extraction and Hough transform in the image processing section 23, and based on the image after the image processing in the image processing section 23. The drivable area recognition unit 24 searches for a drivable area, and based on the result, the target route setting unit 25 formulates a plan of a course to be traveled, and the plan is input to the CPU 15 ₁ . That is, CC
D camera 20, image processing unit 23, steerable region recognition unit 2
4 and the target route setting unit 25 constitute a first detecting unit in the claims, and the result of detecting the front lane condition of the road on which the vehicle is traveling is CP by the first detecting unit.
Input to U15 ₁ .

Steering angle sensor 17 in encoder form
The output of the directly input to the CPU 15 _1, steering the output of the torque sensor 16 is an analog signal A / D converter 2
6 is input to the CPU 15 _1, and the outputs of the vehicle speed sensor 18 and the yaw rate sensor 19 are also directly input to the CPU 15 ₁ . Thus, the steering angle sensor 17 and the vehicle speed sensor 1
8 and the yaw rate sensor 19, which constitutes the second detecting means in the claims, the motion state of the vehicle detected by the second detecting means is inputted to the CPU 15 _1.

CPU 15₁Is the first and second inspections described above.
Positional relationship of own vehicle to road lane based on detection result of intelligent means
Steering amount calculation hand that calculates the steering amount required to maintain
Depending on the function as a step and the output of the steering torque sensor 16,
Steering angle change for changing the calculated steering amount by the steering amount calculation means.
The CPU 15 functions as a further means. ₁
The digital signal corresponding to the calculation result of the operation amount of the motor 11 in
No. is converted into an analog signal by the D / A converter 27, and
The weak analog signal is the current value in the motor amplifier 28.
And is given to the motor 11.

[0029] Incidentally, CPU 15 _1, the memory device for storing various gains and constants necessary for computing (ROM) 2
9 is provided internally, and the information in the ROM 29 is read out if necessary.

In accordance with an algorithm to be described later, the CPU 15 ₁ generates a steering torque that follows the lane by operating the motor 11 to guide the driver, and responds to the steering force of the driver applied to the steering wheel 1. As a result, the front wheel 5 is deflected by an appropriate amount from the guidance course, and the driver receives the reaction force corresponding to the amount of deflection as road surface information.

FIG. 3 and FIG. 4 shows the control algorithm set in CPU 15 _1, after activation of the system due to the SAS switch 21 is pressed, various kinds of sensor information is read in step S001. From the next step S002 to step S009, the same processing as that described in detail in the previous application (Japanese Patent Application Laid-Open No. 5-197423) is performed, and the target value θd of the displacement angle of the motor 11 for following the lane. Is calculated. The details are described in this publication, so only a brief description will be given here.

That is, in the XY fixed coordinate system shown in FIG. 5, xy relative coordinates are set with the vehicle W as the origin, the longitudinal direction of the vehicle W as the x-axis, and the vehicle width direction of the vehicle W as the y-axis. , A CCD camera 20, an image processing unit 23, a steerable area recognition unit 24, and a target route setting unit 25.
The target route M based on the detection result of the detection means is set on the xy relative coordinate system, and in step S002, the vehicle W is detected.
The inclination angle Θ _W of the vehicle _W is determined, and in step S003, the current position of the vehicle W on the XY fixed coordinate system (X _W ,
Y _W ) is calculated, and the target point P on the target route M is set in step S004.

In the next step S005, the target yaw rate γm is calculated. In the calculation, the virtual route S until the vehicle W reaches the target point P is first calculated.
The target point yaw rate γp that occurs during traveling along p, the angular deviation Δθp between the vehicle W and the target route M at the target point P, and the yaw rate correction Δγp that eliminates the angular deviation Δθp are sequentially calculated. Then, the target yaw rate γm is calculated according to the following equation.

Γm = γp-KmΔγp In the above equation, Km is a correction coefficient, and this correction coefficient K
m is obtained by the interrupt processing of steps S006 and S007 in parallel with steps S002 to S005. That is, the curvature ρ and the road width D of the travelable route A are obtained in step S006, and the correction coefficient Km is calculated from the curvature ρ, the road width D and the vehicle speed V by fuzzy inference in step S007.
Is required. This is because it is difficult to smoothly converge on the target route M depending on the curvature of the traveling route and the like, so that the correction coefficient K is determined according to the state quantities such as the curvature ρ and the road width D.
It is designed to find m.

Subsequently, in step S008, the target steering angle δm of the front wheels necessary for producing the target yaw rate γm obtained in step S005 is obtained, and in step S009, the steering angle of the front wheels 5 is adjusted to the target steering angle δm. The target value θd of the displacement angle of the motor 11 for matching the angles is
It is calculated based on the gear ratio of the steering means 3 and the driving means 4.

In step S010 of FIG. 4 subsequent to step S009, how much the front wheels 5 should be deflected from the target steering angle δm is calculated from the steering force τs applied by the driver. That is, in step S010, the intervention steering angle β _IN, which is an amount obtained by multiplying the deflection amount by the gear ratio of the steering means 3 and the driving means 4, is determined.
While the absolute value of the steering force τs is smaller than the reference value τo, the amount obtained by multiplying the steering force τs by a relatively small gain K2 is used as the intervention steering angle β _IN, and the absolute value of the steering force τs is equal to or larger than the reference value. Is larger than K2, the gain K3 is larger than K2.
The amount obtained by multiplying the steering force τs by is defined as the intervention steering angle β _IN . At this time, the constant β _O is selected so that a step does not occur at the gain switching point. This will be described with reference to FIG. 6. When | τs | <τo, the proportional relationship between the steering force τs and the intervention steering angle β _IN is relatively gentle as shown by the straight line L1, and | τs | ≧ τo. At times, the proportional relationship between the two becomes relatively tight as shown by the straight lines L2 and L3. Moreover, the constant β 0 is selected as shown so that these relationships are smoothly switched at the points Q1 and Q2 where the steering force τ s is ± τ _o . According to this relationship, the steering force τs
Since the inclination of the straight line becomes large when is large, a large amount of deflection can be obtained by a slight increase in the steering force τs, and the vehicle can be deviated from the lane with a correspondingly small increase in steering force.

Next, in step S011, a process for performing feedback control is performed so that the new target value (θd + β _IN ) matches the amount θt obtained by converting the current steering angle on the motor shaft. That is, as is well known, the output torque T11 of the motor 11 is determined by multiplying the difference between the target value (θd + β _IN ) and θt by the control gain K4.

Then, in step S012, the output torque T11 of the motor 11 is output to the motor amplifier 28, and SA
Whether or not the S switch 21 is turned off is step S013.
The first step S0
Returning to 01, this is repeated thereafter.

Next, the operation of the first embodiment will be described. The front lane condition of the traveling road detected by the CCD camera 20, the image processing unit 23, the steerable area recognition unit 24 and the target route setting unit 25. And steering angle sensor 1
7. Based on the motion state of the vehicle detected by the vehicle speed sensor 18 and the yaw rate sensor 19, the displacement angle of the motor 11 for obtaining the steering amount necessary to maintain the positional relationship of the vehicle with respect to the road lane is determined. The target value θd is set, and the target value θd is determined by the detection value of the steering torque sensor 16 for detecting the steering intention of the driver applied to the steering wheel 1, that is, the intervention steering angle β _IN determined based on the steering force τs and the steering direction. Can be changed. That is, when the steering force τs is applied to the steering wheel 1 by the steering of the driver, the intervention steering angle β _IN is added to the target steering angle δm according to the steering amount,
The front wheels 5 are steered off the lane following course. This will be described with reference to FIG. 7. When the road lane is curved as shown, the steering force τ applied to the steering wheel 1
When s is 0, that is, when the input steering angle, which is the driver's intention, and the steering angle determined by the system match,
The vehicle runs on a target course indicated by the dotted line in the figure. However, if the input steering angle of the driver and the determined steering angle of the system are inconsistent, the difference is transmitted to the steering wheel 1 as a steering force and produces τs. The vehicle deviates from the course of the dotted line according to τs, but the amount of deviation is determined only by the steering force τs. In other words, the driver must continue to apply the steering force τs during the deviation. At this time, the driver perceives τs as a road reaction force. When trying to steer the steering wheel 1 from the straight ahead position when driving a normal vehicle, the road surface reaction force corresponding to the steered amount from the straight ahead position is received. Instead of "," a road surface reaction force proportional to the "steering amount from the target course" is received.

Moreover, in this first embodiment, since two gains K2 and K3 are prepared in the process of determining the reaction force, the road surface reaction force bends as shown in FIG. If it increases, the increase rate of the road surface reaction force will be kept low. This is because the driver clearly wants to deviate from the lane to turn the steering angle to such an extent, so it is easier to change lanes by suppressing the increase in reaction force. While the steering angle is small, the reaction force increases sensitively to a slight increase in the steering angle, so stable lane following can be performed. This is because a vehicle with a normal power steering determines the characteristics around straight ahead with emphasis on straightness and sensitively increases the reaction force even with a slight increase in the steering amount, but power assist is effective when the steering angle becomes large. Then, it aims at the same effect as reducing the increase rate of the reaction force thereafter.

Further, even if the internal resistance of the worm gear mechanism 12 in the drive means 4 is large, the motor 11 is operated by β _IN in accordance with the steering torque τ s previously applied, so that there is room to oppose the command from the driver. There is no. There is no restriction on the setting of the control gain K4 for reaching the determined target steering angle (θd + β _IN ),
It is possible to increase the responsiveness by setting a sufficiently large value.

8 to 12 show a second embodiment of the present invention, and FIG. 8 is an overall structural view of a vehicle steering system,
9 is a control block diagram, FIG. 10 is a flowchart showing a part of the control algorithm, FIG. 11 is a flowchart showing the rest of the control algorithm, and FIG. 12 is a diagram showing the relationship between the steering force and the intervention steering angle.

In FIG. 8, the steering wheel 1 and the steering shaft 2 are rotatably coupled to each other via a worm gear type steering angle correction device 32 interposed between the steering wheel 1 and the steering shaft 2. Thus, the steering angle correction device 32
Is composed of, for example, a worm gear 33 connected to the steering shaft 2 side, a screw gear 34 meshing with the worm gear 33, and a motor 35 fixed to the steering handle 1 side and connected to the screw gear 34. Further, a potentiometer-type correction angle sensor 36 is attached to the steering angle correction device 32.

The second embodiment is basically different from the first embodiment in that the steering angle correction device 32 is housed inside the steering wheel 1. The steering angle correction device 32 and the correction angle are different from each other. The parts other than the sensor 36 are configured similarly to the first embodiment.

In the control block diagram shown in FIG. 9, RO
The CPU 15 ₂ provided inside the the M29, an output of the first detecting means comprising a CCD camera 20, the image processing section 23, steerable area recognition unit 24 and the target course setting section 25, the output of the steering angle sensor 17, A The output of the steering torque sensor 16, the output of the vehicle speed sensor 18, the yaw rate sensor 19 and the SA which are converted into digital signals via the / D converter 26.
The output of the S switch 21 is input similarly to the first embodiment shown in FIG. 2, and the output of the correction angle sensor 36 is converted into a digital signal by the A / D converter 37 and input. Further, the output of the CPU 15 ₂ is given to the motor 11 via the D / A converter 27 and the motor amplifier 28 as well as to the indicator light 22. Further, the motor 35 in the steering angle correction device 32 is supplied with a current value from the motor amplifier 39, and the open motor amplifier 39 receives the digital signal output from the CPU 15 ₂ as D / A.
It is converted into an analog signal by the converter 38 and input.

In accordance with an algorithm described later, the CPU 15 ₂ generates a steering torque that follows the lane by driving the motor 11 to guide the driver, and the interior of the lane according to the steering force of the driver applied to the steering wheel 1. Even if there is a slight discrepancy between the steering angle of the driver and the output angle of the system, the steering angle correction device 32 absorbs the difference even if the target course is slightly changed. It is possible to follow the lane without making detailed operations. Also in this case, when the driver inputs a large steering force, it is intended to change the lane, and in addition to the lane-following function, the front wheels 5 are deflected to easily deviate from the course. A reaction force corresponding to the amount of deflection can be received as road surface information.

Next, the control algorithm will be described with reference to FIGS. 10 and 11. Steps S101 to S104 in FIGS. 11 and 12 are basically the same as steps S001 to S004 in FIGS. 3 and 4 in the first embodiment. The same processing is executed, and step S10 is performed.
7 to S111 are steps S005 to S005 of FIGS. 3 and 4.
Since the processing basically the same as that of S009 is executed, the description thereof is omitted, and only steps S105, S106, S112 to S117 different from the first embodiment will be described below.

In step S105 after the target point P is set in step S104, the course change amount ΔX is calculated. Here, ΔX is obtained by multiplying the steering force τs by the proportional constant K1, but it does not make sense to change the target course beyond the width of the lane, so 30% of the width L of the lane (if left and right are considered, If it is less than 60%, the calculation result will be set as ΔX and the calculation result ( When τs × K1) exceeds 30%, it is fixed at 30%.

Next, in step S106, a process is performed to consider that the current position of the vehicle is intentionally deviated by −ΔX in the lateral direction in order to slightly change the target course in the lane according to the steering force τs. . By doing so, the CPU 15 ₂ causes the target point to move laterally by ΔX in the subsequent processing.
It is illusion that the target steering angle is deviated, and the necessary steering angle is calculated. As a result, the target course can be moved laterally by ΔX.

Step S following step S106
Steps S112 and S after 107 to S111 have passed
At 113, the front wheel 5 is calculated from the steering force τs applied by the driver.
Is calculated from the target steering angle δm, and a process for performing feedback control by adding the deflection amount to the target value θd of the displacement angle of the motor 11 is performed.
That is, in step S112, the intervention steering angle β _IN, which is an amount obtained by multiplying the deflection amount by the gear ratio of the steering means 3 and the driving means 4, is determined, but the absolute value of the steering force τs is a reference value. When it is smaller than τ15, β _IN = 0 is set, and when the steering force τs is τ15 or more, (τ
s-τ15) multiplied by gain K5 is the intervention steering angle β _IN
When the steering force τs is −τ15 or less, the intervention steering angle β _IN is set to an amount obtained by multiplying (τs + τ15) by the gain K5. This will be explained with reference to FIG.
When τs | is smaller than τ15, β _IN is 0 regardless of the increase of τs, and when | τs | is τ15 or more, β _IN also increases in proportion to τs. Further, in step S113, the amount θt obtained by converting the current steering angle onto the motor shaft is set with (θd + β _IN ) as a new target value.
The feedback control is performed so that the value of s matches the target value. That is, the amount obtained by multiplying the difference between the target value (θd + β _IN ) and θt by the control gain K6 is the output torque T1 of the motor 11.
It is defined as 1.

In the next steps S114 and S115, the motor torque T of the motor 35 in the steering angle correction device 32 is set.
35 is calculated. That is, in step S114, the amount obtained by multiplying the steering force τs by the proportional constant K7 is calculated as the target angle αad of the motor 35. If the calculated value of αad is, for example, within 15 °, the calculated value is used as it is.
If the calculated value exceeds 15 °, αad is fixed at 15 °. Here, as shown in FIG. 8, since the output of the motor 35 is boosted by the gear mechanism including the worm gear 33 and the screw gear 34, the worm gear is fixed even if the torque for fixing the motor 35 at 15 ° is small. Due to the irreversible power transmission characteristic of 33, the angle is 15 even if the steering force applied to the steering wheel 1 exceeds the output of the motor 35.
It will be fixed at °. Subsequently, in step S115, a motor torque T35 for performing follow-up control so that the actual angle matches the target angle αad is obtained in a known feedback control form.

Since the output values to the two motors 11 and 35 are determined in this manner, the command values are given to the motor amplifiers 28 and 39 in step S116. Subsequently, in step 117, it is confirmed whether or not the SAS switch 21 is turned off. If it is not turned off, the first step S
Returning to 111, this is repeated thereafter.

According to the second embodiment, when the absolute value of the steering force applied to the steering wheel 1 is smaller than a certain reference value τ15, the inside of the lane depends on the direction and magnitude of the steering force. The target course is off, and the vehicle runs along this misaligned target course, so there are things that you do not want to step on the road because you are falling on the road, or construction vehicles are working on the shoulders and pylons are lined up. In this case, the vehicle can move to one side inside the lane. Moreover, since the driver senses a reaction force having a magnitude proportional to the steering angle input by the driver as a road surface reaction force, the steering angle correction device 32 behaves as if a virtual spring were present inside the steering wheel 1.

The difference from the first embodiment is that the steering force τs is τ1.
If the range is smaller than 5, the target steering course is maintained because the intervention steering angle β _IN does not occur. However, the target course is appropriately deviated according to the direction and magnitude of the applied steering force τs, and as a result, Will change the course according to the driver's intention. However, since the changed course is parallel to the lane, it does not depart from the lane. On the other hand, in the case of the first embodiment, the intervention steering angle β _IN is generated in accordance with the direction and the magnitude of the applied steering force τs, and if left alone, the vehicle deviates from the lane.

When a steering force τs of τ15 or more is applied,
This time, the intervention steering angle β is added to the target value θd of the displacement angle of the motor 11.
_{With IN} added, the vehicle can change lanes. In this case, the road reaction force felt by the driver is proportional to the steering amount at a rate determined by the gain K5.

Further, in the second embodiment, the upper limit value τs of the steering force used for changing the target lane in the lane and the steering force τs at which the lane change starts to coincide with each other are set to τ15. When passing through the area, the connection will be smoother. However, matching the two steering forces is not an essential condition. However, if the steering force at which the lane change starts to occur is set to be larger than the upper limit value, there is an advantage that the system can be constructed without considering the interference between the two.

The steering angle correction device 32 exemplified in the second embodiment.
Is the steering shaft 2 and steering wheel 1
It merely realizes a relative rotational motion between and and generates a torque proportional to the relative rotational amount between the two.
As a result of providing such a virtual spring in between, even if the motor 11 drives the steering means 3, the driver does not need to operate the steering handle 1 in accordance with the movement. Therefore, it will be understood that a mechanical spring may be inserted instead of the virtual spring created by this software. The present applicant has made another application (Japanese Patent Application No. 7-3219).
No. 17) shows that these mechanical spring structures are substitutable and discloses some structural examples, and these mechanical spring structures can be used as they are for realizing the present invention. Is.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

For example, the provision of the drive means 4 on the steering shaft 2 may not be a limitation and it is known to arrange the motor concentrically with the steering means 3, for example on the rack 9.

The method of changing the target course is not limited to the method illustrated here, and the same effect can be obtained by shifting the target point P to the left or right according to the steering force τs.

Further, as the steering angle correcting device 32, a sector gear system in which the worm gear 33 does not have a circular shape but a partial circle shape is also effective, as filed by the applicant of the present invention. As shown in the second embodiment, ± 15 °
In addition to deciding the value by software, a method of providing a mechanical stopper is also disclosed in the above application. It will be apparent to those skilled in the art that these methods can be applied to this embodiment. Furthermore, in the speed reducer using the worm gear 33 illustrated here, the steering angle correction device 32 can be fixed even if the current supplied to the motor 35 is stopped due to its irreversibility, and the displacement of the worm gear 33 is electrically changed. Even if the current to the motor 35 is stopped by detecting that it has reached ± 15 °, the same effect as that provided by the above mechanical stopper can be obtained, and the current can be changed in such a manner. When using the stopping method, the effect of energy saving comes out.

The characteristics shown in FIGS. 6 and 12 are expressed by a straight line and can be calculated by a linear expression. However, the characteristics are not limited to this and may be expressed by a quadratic expression. The present invention can be applied even to a curve that cannot be expressed by. In that case, the characteristic diagram may be stored in the CPU in the form of a map, and β _IN may be read while referring to this map.

[0063]

As described above, according to the first aspect of the present invention, the intention detecting means for detecting the steering intention of the driver applied to the steering handle connected to the steering means by enabling the torque transmission to the steering means. Since the operation amount of the drive means, which is determined based on the output of the steering amount calculation means, is changed according to the output of the intention detection means, a large gain can be obtained and the responsiveness of the system can be increased. It is possible to obtain a reaction force optimized for the driver by changing the gain while increasing the steering force, and freely and accurately generate the steering reaction force regardless of the type of reduction gear and the reduction ratio. By doing so, an excellent man-machine interface can be realized.

According to the second aspect of the present invention, the intention detecting means is a force sensor arranged between the steering handle and the steering means, and the steering intention of the driver can be accurately detected. .

According to the third aspect of the present invention, the steering angle changing means is configured to change the operation amount of the driving means in accordance with the direction and magnitude of the output of the intention detecting means. The traveling course of the vehicle can be changed in accordance with the steering intention.

According to the fourth aspect of the present invention, the steering angle changing means can switch the operating amount increase ratio of the driving means with respect to the increase of the output of the intention detecting means in at least two stages. It is possible to give the driver a reaction force according to the lane change demand.

According to the fifth aspect of the invention, the rudder angle changing means sets the output of the intention detecting means to the first output when the absolute value of the output of the intention detecting means is less than the reference value.
When the absolute value of the magnitude of the output of the intention detecting means is equal to or larger than the reference value, the output of the intention detecting means is changed from the first proportion. Is configured to change the actuation amount of the drive means in proportion to a large second ratio, so that the rate of increase of the road surface reaction force when the steering angle increases can be kept low, and the lane change can be performed more easily. Is possible.

According to the sixth aspect of the invention, when the output of the intention detecting means is at the reference value, the second ratio is set with respect to the operation amount of the driving means which is determined based on the first ratio. Since the steering angle changing means is configured so that the operation amount of the driving means determined based on the driving force is large or substantially equal, it is possible to avoid a great change in the road reaction force acting on the driver and to obtain a good steering feeling. Can be obtained.

According to the invention described in claim 7, in the predetermined range of the output of the intention detecting means, the operation change amount of the drive means becomes "0" despite the change of the output of the intention detecting means. Since the angle changing means is configured, it is possible to prevent the steering angle from immediately changing in a range where the steering amount of the driver is small.

According to the eighth aspect of the present invention, the steering amount calculation means outputs the positional relationship of the own vehicle to the road lane to the output of the intention detection means in at least a part of the predetermined range of the output of the intention detection means. Since it is configured to be changed accordingly, it is possible to change the running course within the lane within a range where the driver's steering amount is small.

Further, according to the invention described in claim 9, since a spring made of software or a mechanical spring is interposed between the steering handle and the steering means, the steering operated by the driving means is operated. The driver does not need to operate the steering wheel in the range in which the operation amount of the steering means slightly changes.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a vehicle steering system according to a first embodiment.

FIG. 2 is a control block diagram.

FIG. 3 is a flowchart showing a part of a control algorithm.

FIG. 4 is a flowchart showing the rest of the control algorithm.

FIG. 5 is a diagram for explaining the process in the flowchart of FIG.

FIG. 6 is a diagram showing a relationship between a steering force and an intervention steering angle.

FIG. 7 is a diagram showing a relationship between an input steering angle and a steering force on a lane.

FIG. 8 is an overall configuration diagram of a vehicle steering system according to a second embodiment.

FIG. 9 is a control block diagram.

FIG. 10 is a flowchart showing a part of a control algorithm.

FIG. 11 is a flowchart showing the rest of the control algorithm.

FIG. 12 is a diagram showing a relationship between a steering force and an intervention steering angle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steering handle 3 ... Steering means 4 ... Driving means 5 ... Front wheels as running wheels 15 ₁ , 15 ₂ ... CPU having functions of steering amount calculation means and steering angle changing means 16 ... Steering torque sensor as intention detecting means 17 ... Steering angle sensor which is a constituent element of second detecting means 18 ... Vehicle speed sensor which is a constituent element of second detecting means 19 ... A yaw rate sensor 20 which is a constituent element ... A CCD camera which is a constituent element of the first detection means 23 ... An image processing section which is a constituent element of the first detection means 24 ... A travelable area recognition which is a constituent element of the first detection means Part 25: Target route setting part which is a component of the first detection means

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

Claims (9)

[Claims] 1. A first detecting means (20, 23, 24, 25) for detecting a front lane condition of a road on which the vehicle is running and a second detecting means (17, 18, 19) for detecting a motion condition of the own vehicle.
And the first and second detection means (20, 23 to 25; 17)
To 19), the steering amount calculation means (15 ₁ , 15 ₂ ) for calculating the steering amount necessary for maintaining the positional relationship of the vehicle with respect to the road lane and the steering wheel (5) of the vehicle are operated. Steering means (3) and steering amount calculation means (15 ₁ , 1
The vehicular steering device and a driving means for actuating (4) the steering means (3) in accordance with the output of 5 _2), steering means as possible the transmission of torque to the steering means (3) (3 ) Connected to the steering handle (1) for detecting the driver's steering intention (16), and drive means (4) determined based on the outputs of the steering amount calculation means (15 ₁ , 15 ₂ ). ), The steering angle changing means (15 ₁ , 15 ₂ ) for changing the operation amount according to the output of the intention detecting means (16). 2. The vehicle according to claim 1, wherein the intention detecting means (16) is a force sensor arranged between the steering handle (1) and the steering means (3). Steering device. 3. The rudder angle changing means (15 ₁ , 15 ₂ )
However, the operation amount of the driving means (4) is determined by the intention detecting means (1
3. The vehicle steering system according to claim 1, wherein the steering system for a vehicle is configured to be changed according to the direction and magnitude of the output of 6). 4. The rudder angle changing means (15 ₁ , 15 ₂ )
4. The vehicle steering system according to claim 3, wherein the operation amount increasing ratio of the driving means (4) with respect to the increase of the output of the intention detecting means (16) is switchable in at least two stages. 5. The rudder angle changing means (15 ₁ , 15 ₂ )
However, when the absolute value of the magnitude of the output of the intention detecting means (16) is less than the reference value, the driving means (4) is proportional to the magnitude of the output of the intention detecting means (16) at a first ratio. When the absolute value of the magnitude of the output of the intention detecting means (16) is greater than or equal to the reference value, the magnitude of the output of the intention detecting means (16) is larger than the first ratio. 3. A device according to claim 1 or 2, characterized in that it is arranged to vary the actuation amount of the drive means (4) in proportion to the second ratio.
The vehicle steering system described. 6. The operation amount of the drive means (4), which is determined based on the first ratio when the output of the intention detecting means (16) is at the reference value, is based on the second ratio. The steering angle changing means (15 ₁ , 1) so that the operation amount of the driving means (4) determined by
The vehicle steering system according to claim 5, characterized in that 5 ₂ ) is configured. 7. In a predetermined range of the output of the intention detecting means (16), the operation change amount of the driving means (4) becomes “0” despite the change of the output of the intention detecting means (16). The vehicle steering system according to claim 3, wherein the steering angle changing means (15 ₂ ) is configured in the steering wheel. 8. steering amount calculating means (15 _2), the intention of at least a portion of the predetermined range of the output of the detecting means (16), the intention detecting means the positional relationship of the vehicle relative to the road lane (16) The vehicle steering system according to claim 7, wherein the steering system is configured to be changed according to the output. 9. A spring made of software or a mechanical spring is interposed between the steering handle (1) and the steering means (3). The vehicle steering system according to any one of the claims.