JPH09267762A - Trailer wheel steering control method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the steering stability of a connected car and resistance to external disturbances, to simplify trailer wheel steering control and to improve its reliability. SOLUTION: A controller 105 for a trailer wheel steering control device calculates a target trailer wheel steering angle from trailer yawing rate data inputted from a yawing rate sensor 101 by using a transmission function indicating a relation between a trailer wheel steering angle and a trailer yawing rate and steers a trailer wheel 18 via a control valve 82 and a hydraulic cylinder device 30 such that an actual trailer wheel steering angle detected by a steering angle sensor 103 becomes equal to the target trailer wheel steering angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trailer wheel steering control method and device for improving the steering stability of a vehicle coupled with a tractor and a trailer.

[0002]

2. Related Art An articulated vehicle is provided with a tractor and a trailer that is detachably connected to the tractor through a connector provided on the tractor, and has high transportation efficiency. However, since the articulated vehicle has a joint point that allows the trailer and the tractor to rotate relative to each other, the steering stability is inferior to that of a single vehicle such as a passenger vehicle, and meandering motion may occur.

In a single vehicle, it is general to improve steering stability by four-wheel steering in which the rear wheels are steered when the front wheels are steered. On the other hand, there are few examples of application of four-wheel steering to a combined vehicle. As an example of four-wheel steering in a combined vehicle, Japanese Patent Laid-Open No. 1-15
No. 6180 discloses a "control method for a four-wheel steering device for a trailer towing vehicle" in which a rear wheel steering angle of a trailer towing vehicle (tractor) is increased when the trailer is towed compared to a state in which the trailer is not towed. Has been done. That is, this four-wheel steering method is basically the same as the one applied to a passenger car or the like, but the rear wheel steering control is applied to the tractor of the combined vehicle.

As described above, the low steering stability of the combined vehicle is due to the structure unique to the combined vehicle in which the tractor and the trailer are connected so as to be rotatable relative to each other. Therefore, it is difficult to significantly improve the steering stability of the combined vehicle, especially at high speeds, by applying the same four-wheel steering method as that applied to passenger cars to the combined vehicle. it is conceivable that.

Therefore, the present applicant has filed Japanese Patent Application No. 5-1625.
In No. 22, a trailer wheel steering control method and apparatus for steering the wheels of the trailer so that the direction of the trailer coincides with the direction of the velocity vector of the tractor was proposed.
In this proposal, the wheels of the trailer are steered based on the transfer function that represents the relationship between the steering angle of the trailer wheel and the relative yaw angle, and the relative yaw angle detected while the vehicle is running.

[0006]

SUMMARY OF THE INVENTION The present invention provides a wheel steering control method for a trailer and an apparatus therefor which have different operating principles from those of the above-mentioned proposed method and apparatus, thereby improving the steering stability of a combined vehicle. At the same time, it is an object of the present invention to improve the disturbance resistance of the combined vehicle, simplify the trailer wheel steering control, and improve the reliability.

[0007]

According to the present invention, there is provided a trailer wheel steering control method and apparatus for steering a trailer wheel so that the direction of the trailer matches the direction of the velocity vector of the tractor. . The control method according to claim 1, wherein a transfer function representing a relationship between a trailer wheel steering angle and a trailer yaw rate is derived in advance, a yaw rate of the trailer is obtained while the vehicle is traveling, and the trailer is obtained while the vehicle is traveling. The target trailer wheel steering angle is determined based on the yaw rate and the transfer function, and the wheels of the trailer are steered so that the actual trailer wheel steering angle becomes the target trailer wheel steering angle.

A control method according to a second aspect of the present invention is the control method according to the first aspect, which relates to the lateral speed of the tractor, the tractor yaw rate, the relative yaw angle between the tractor and the trailer, the tractor front wheel steering angle and the trailer wheel steering angle in the mathematical model of the combined vehicle. The transfer function is derived in advance from the equation of motion of ## EQU1 ## and an equation representing the relationship between the trailer yaw rate, the tractor yaw rate, and the relative yaw angle.

The control method according to claim 3 is the method according to claim 1 or 2.
In, the method further includes the step of previously obtaining a second transfer function having a second frequency response characteristic approximate to the frequency response characteristic corresponding to the transfer function, and the actual trailer wheel steering angle is
The wheels of the trailer are steered so that a target trailer wheel steering angle determined based on the detected yaw rate of the trailer and the second transfer function is obtained.

A control method according to claim 4 is the control method according to claim 3, wherein the second transfer function is 1 for a Laplace variable.
It is characterized by being expressed by a polynomial of degree. The control device according to claim 5 has a steering mechanism for steering the wheels of the trailer, a detector for detecting the yaw rate of the trailer, and a transfer function representing a relationship between the steering angle of the trailer wheel and the trailer yaw rate. And a calculation unit for determining the target trailer wheel steering angle based on the trailer yaw rate detected by the detector, and the actual trailer wheel steering angle is the target trailer wheel steering angle. And a drive unit for driving the steering mechanism.

A control device according to a sixth aspect of the present invention is the control device according to the fifth aspect, which relates to the lateral speed of the tractor, the tractor yaw rate, the relative yaw angle between the tractor and the trailer, the tractor front wheel steering angle, and the trailer wheel steering angle in the mathematical model of the combined vehicle. The arithmetic element is configured so as to have a transfer function derived in advance from the equation of motion of ## EQU1 ## and an equation representing the relationship between the trailer yaw rate, the tractor yaw rate, and the relative yaw angle.

The control device according to claim 7 is the control device according to claim 5 or 6.
In the above, in the second calculation method, the arithmetic element has a second frequency response characteristic approximate to the frequency response characteristic corresponding to the transfer function.
It has a transfer function of. Referring to FIG. 1, a tractor is shown on the right side and a trailer is shown on the left side. The direction of the velocity vector of the tractor at the joint point (hitch point) H where the tractor and trailer are connected is represented by the angle βh formed by the velocity vector and the center line of the tractor. In FIG. 1, when the tractor front wheel steering angle δ1, the trailer wheel steering angle δ5, and the relative yaw angle ψ between the tractor and the trailer are small, the angle βh is expressed by the following equation.

Βh = (vTC-1h · γTC) / uTC (1) where vTC, lh, γTC and uTC are lateral velocity of the tractor, distance between the hitch point H and the center of gravity of the tractor, and center of gravity of the tractor. The yaw rate of the tractor around the point and the longitudinal velocity of the tractor are shown. In the present invention, the transfer function G (s) representing the relationship between the trailer wheel steering angle δ5 and the trailer yaw rate γTR is derived. Preferably, the lateral velocity uTC of the tractor and the yaw rate γT of the tractor in a mathematical model (FIG. 2) of a vehicle with steerable trailer wheels.
C, the relative yaw angle ψ, the tractor front wheel steering angle δ1, and the trailer wheel steering angle δ5, and the formula expressing the relationship between the trailer yaw rate γTR, the tractor yaw rate γTC, and the relative yaw angle ψ from the trailer wheel steering. A transfer function G (s) representing the relationship between the angle δ5 and the trailer yaw rate γTR is derived.

More specifically, the mathematical model of FIG. 2 relates to a semi-trailer on which trailer wheels can be steered and is defined using a plane coordinate system XY. In FIG. 2, the tractor is shown on the right side and the trailer is shown on the left side. In this mathematical model, when the semi-trailer travels at a constant vehicle speed and the steering angle is small, the equation of motion can be expressed as a matrix as follows.

[0015]

[Equation 1]

Where a13 = -WTR.l'f a23 =-(WTR.l'f2 + ITR) a33 = -WTR.l'f.lh b11 = WTC + WTR b12 = -WTR (lh + l'f) b13 = -2K5 L '/ uTC b21 = WTR l'f b22 =-{WTR l'f (lh + l'f) + ITR} b23 = -2K5 l'2 / uTC, b31 = WTR lh b32 =-{WTR lh (lh + l'f) + ITC} b33 = -2K5.lh.l '/ uTC c11 = 2 (K1 + K3 + K5) / uTC c12 = -2 [{K3.lf-K1.lf + K5 (lh + l')
/ UTC] + (WTC + WTR) uTC c13 = -2K5 c21 = 2K5.l '/ uTC c22 = -2 {K5.l' (lh + l ') / uTC} + WTR.
l'f.uTC c23 = -2K5.l'c31 = 2 (K3.lf-K1.lf + K5.lh) / uTC c32 = -2 [{K1.lf2 + K3.lf2 + K5.lh (lh
+ L ′)} / uTC] + WTR · lh · uTC c33 = −2K5 · lh Note that WTC and WTR represent tractor mass and trailer mass, respectively, and ITC and ITR represent tractor inertial ratio and trailer inertial ratio. Further, if, lr, lh, l'f, lr and l'are tractor center of gravity point-front axle distance, tractor center of gravity point-rear axle distance, tractor center of gravity point-hitch point distance, trailer center of gravity point-hitch. The distance between points, the distance between the center of gravity of the trailer and the axle, and the distance between the trailer axle and the point of hitch are shown. Further, K1, K3 and K5 represent the tractor front wheel cornering stiffness (per wheel), the tractor rear wheel cornering stiffness (per wheel) and the trailer wheel cornering stiffness (per wheel), respectively.

The tractor lateral velocity vT corresponding to the front wheel steering input δ1 of the tractor and the trailer wheel steering angle δ5.
C, tractor yaw rate γ TC and relative yaw angle ψ
Can be obtained from the above equation of motion. In order for the centerline of the trailer to coincide with the direction of the velocity vector of the tractor at the hitch point H, the relative yaw angle ψ between the tractor and the trailer must coincide with the angle βh expressed by the equation (1). In other words, the following formula must hold.

Βh = (vTC-1h · γTC) / uTC = ψ (3) Further, the trailer yaw rate γTR is expressed by the following equation. γTR = γTC + ψs (4) Next, the tractor lateral velocity vTC obtained from the equation (2),
By substituting the yaw rate γTC and the relative yaw angle ψ into the equations (3) and (4) to eliminate δ1, the trailer yaw rate γTR and the trailer wheel steering that match the angle βh and the relative yaw angle ψ. The transfer function G (s) representing the relationship with the angle δ5 is obtained as follows.

G (s) = δ5 (s) / γTR (s) = (H7s7 + H6s6 + ... + H1s + H0) / (E6s6 + E5s5 + E4s4 + ... + E1s + E) ... (5) Then, while the connected vehicle is running, the trailer yaw rate γTR Is detected, and thus the detected yaw rate γTR and transfer function G
The target trailer wheel steering angle is determined based on (s). Alternatively, instead of detecting the trailer yaw rate γTR directly, the tractor's yaw rate γTC and relative yaw angle ψ
The trailer yaw rate γTR according to the equation (4).
May be calculated.

Further, the wheels of the trailer are steered so that the actual trailer wheel steering angle becomes the target trailer wheel steering angle. In other words, the trailer wheel steering angle δ5 is controlled so that the angle βh and the relative yaw angle ψ match. That is, when both the angles βh and ψ have a counterclockwise sign as shown in FIG. 1, if the angle ψ is smaller than the angle βh, the steering angle δ5 is increased in the counterclockwise direction while the angle ψ is increased. Is larger than the angle βh, the steering angle δ5 is decreased.

When the angle βh (the direction of the velocity vector of the tractor) and the relative yaw angle ψ (the direction of the trailer) match, the trailer is towed straight in the direction toward the center line of the vehicle. The driving stability of the combined vehicle is improved. In a specific aspect of the present invention, in order to simplify the trailer wheel steering control, instead of the transfer function G (s),
An approximate second transfer function G ′ (s) is used for this.
Therefore, the frequency response characteristic corresponding to the transfer function G (s) is obtained. Next, there is a second frequency response characteristic (shown by a chain of circles in FIG. 3) approximate to this frequency response characteristic, and for the Laplace variable, for example, a first-order polynomial (K1s + K0)
The second transfer function G ′ (s) represented by The reason for using the second transfer function represented by the first-order polynomial in this way is that the numerator polynomial and the denominator polynomial in the above-mentioned transfer function G (s) have orders 7 and 6, respectively. . As shown in FIG. 4, the coefficients K1 and K0 of the differential term and the proportional term of the second transfer function G '(s) are obtained as a function of the vehicle speed u, whereby the second transfer function G' (s ) Is required.

Then, the actual trailer wheel steering angle is the second
The wheels of the trailer are steered so that the target trailer wheel steering angle obtained based on the transfer function G ′ (s) of

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION A combination vehicle equipped with a wheel steering control device for a trailer according to an embodiment of the present invention will be described below with reference to FIGS. Referring to FIG.
The connecting vehicle comprises a tractor 1 and a trailer 2, and the trailer 2 is detachably connected to the tractor 1 via a connecting device. The coupling device is a tractor 1.
The coupler 3 is provided on the upper surface of the chassis frame 6 at the rear of the cabin 5, and the king pin 4 is provided so as to project from the lower surface of the chassis frame (FIG. 6) of the trailer 2. The coupler 3 has a pair of jaws (not shown) that can be opened and closed,
Engagement recesses are formed on opposite edges of the jaws. Then, the king pin 4 is engaged between the engaging recesses by closing the pair of jaws while the king pin 4 is inserted between the engaging recesses. Furthermore, the jaws are locked in a closed state by press-fitting a lock plunger (not shown) into the gap between the opposed edges of the pair of closed jaws.

In FIG. 5, reference numeral 7 indicates support legs provided on both sides of the front part of the chassis frame of the trailer 2, and the front part of the trailer 2 is supported by the support legs 7 when the tractor 1 and the trailer 2 are connected. I try to support it. Referring to FIG. 6, the chassis frame 10 of the trailer 2 has left and right side rails 12 and a plurality of cross members 14 having both ends fixed to the side rails 12. The left and right side frames 12 support the front end portion and the rear end portion of the main leaf spring 20 via shackle links (not shown). Reference numeral 16 indicates an axle housing that rotatably supports wheels (only the left wheel is shown in FIG. 6) 18 of the trailer 2.

The axle housing 16 is rotated about a center of rotation on the trailer longitudinal centerline by a trailer wheel steering mechanism, which will be described later, whereby the wheels 18 of the trailer 2 are steered. And in connection with the trailer wheel steering, the main leaf spring 20 and
Both ends of the axle housing 16 are supported via rubber pad members (not shown) by the helper leaf spring 22 arranged above the main leaf spring 20, and the main leaf spring 20 and the axle housing 16 can be displaced relative to each other. It has become.

The trailer wheel steering mechanism includes a hydraulic cylinder device 30 as a wheel steering actuator, an upper radius rod 40 having a V-shaped apex portion as a rotation center of the axle housing 16 and having a V-shaped top view, and a hydraulic cylinder device 30. And a mechanism for converting displacement of the piston shaft 32 into rotation of the axle housing 16. Specifically, in the trailer wheel steering mechanism, the upper radius rod 40 is disposed between the left and right side frames 12,
The V-shaped vertex is pivotally attached to the axle housing 16 via a ball joint, and the left and right free ends are pivotally attached to the side frames 12 via ball joints. Further, the left and right lower radius rods 60, which form a main part of the conversion mechanism together with the L-shaped lever 50, have one ends pivotally attached to brackets provided at the lower ends of both ends of the axle housing 16 via ball joints. The other end is pivotally attached to the tip of the lateral arm of the L-shaped lever 50 via a ball joint. The bent portion of the lever 50 is pivotally supported by a bracket fixed to the side frame 12. The end of the connecting rod 70 is pivotally attached to the rear end of the vertical arm of the L-shaped lever 50 via a ball joint.

Piston shaft 32 of hydraulic cylinder device 30
Is connected to the middle portion of the vertical arm of the left L-shaped lever 50, for example, via a ball joint. The cylinder 34 of the cylinder device 30 is supported by the bracket of the chassis frame 10 via a ball joint. The trailer wheel steering mechanism further includes a hydraulic pump 80 and a control valve 82 shown in FIG. 7, and the control valve 82 controls the hydraulic pressure supply between the hydraulic pump 80 and each of the left and right cylinder chambers of the cylinder 34. ing.

As shown in FIG. 7, in addition to the trailer wheel steering mechanism having the above-described configuration, the trailer wheel steering control device includes a yaw rate sensor 101 for detecting the yaw rate of the trailer 2, a vehicle speed sensor 102, and a trailer wheel steering mechanism. The angle sensor 103 is provided. The steering angle sensor 103 is
For example, a rotating member (not shown) fixed to a shaft member penetrating a ball joint at the V-shaped apex of the upper radius rod 40 and rotatably provided integrally with the axle housing 16 and fixed to the chassis frame 10 of the trailer 2. And a conversion mechanism (not shown) for converting the rotation of the rotary member into the displacement of the stroke sensor.

The control device further includes a controller 105 including a processor, a memory, an input / output circuit and the like (not shown). The controller 105 has a sensor 1 on the input side.
01, 102 and 103, the control valve 8 on the output side
2 are connected. When the control valve 82 is driven, the high pressure hydraulic oil discharged from the hydraulic pump 80 is transferred to the cylinder 34.
Is supplied to the corresponding one of the left and right cylinder chambers, and the hydraulic oil in the other cylinder chamber is discharged to the oil tank.
Alternatively, the hydraulic pressures supplied to the left and right cylinder chambers are controlled to different values. As a result, a differential pressure is generated between both cylinder chambers, and the piston shaft 32 projects from the cylinder 34 or retracts into the cylinder 34. That is, the cylinder device 30 expands or contracts. As a result, the trailer wheel 1
So that the steering angle δ5 (Fig. 1) of 8 decreases or increases,
The wheels 18 are steered.

More specifically, for example, when the cylinder device 30 is extended, the left L-shaped lever 50 rotates clockwise in FIG. 6, and the left lower radius rod 60 is pulled behind the trailer 2. At the same time, the right L-shaped lever 50, which is connected to the left L-shaped lever 50 via the connecting rod 70, rotates clockwise and the lower right radius rod 60 is pulled forward of the trailer 2. As a result, the axle housing 16 rotates around a ball joint provided at the V-shaped apex of the upper radius rod 40, and the trailer wheel 18 is steered by this.

The processor of controller 15 is derived from the mathematical model of FIG. 2 and is a first-order polynomial of the Laplace variable (K
1 s + K 0) is provided with a function as a calculation unit including a calculation element having an approximate transfer function G ′ (s), and the target value δ5T of the trailer wheel steering angle δ5 is determined based on the trailer yaw rate γTR. ing. That is, as shown in FIG. 8, the processor functionally has a proportional gain calculator 11 for calculating a proportional gain K0 according to the vehicle speed u.
1, a differential gain calculation unit 112 for calculating a differential gain K1 according to the vehicle speed u, a proportional calculation unit 113 for multiplying the yaw rate γTR by a proportional gain K0, and a differential value obtained by differentiating the yaw rate γTR. It has a differential operation section 114 for multiplying the differential gain K1 and an adder section 115 for adding the output of the proportional operation section and the output of the differential operation section.

Further, the processor has a function as a drive unit for driving the trailer wheel steering mechanism (FIG. 7) so that the actual trailer wheel steering angle becomes a target value. The operation of the trailer wheel steering control device will be described below. While the connected vehicle is traveling, the processor of the controller 15 repeatedly executes the trailer wheel steering control processing shown in FIG. 9 at a predetermined cycle.

In each control processing cycle, the processor reads the detection outputs from the yaw rate sensor 101, the vehicle speed sensor 102 and the steering angle sensor 103 (step S11). Next, the processor obtains the target value δ5T of the trailer wheel steering angle δ5 based on the yaw rate data γTR from the yaw rate sensor 101 (step S1).
2). Therefore, the processor obtains the proportional gain K0 and the differential gain K1 corresponding to the vehicle speed u by referring to the map previously stored in the memory and corresponding to FIG.
Is multiplied by a proportional gain K0 to obtain a value K0 · γTR. Then, the processor differentiates the yaw rate γTR to obtain a differential value d
γTR / dt is obtained, and this differential value is multiplied by the differential gain K1 to obtain the value K1 · (dγTR / dt), and further the value K0 · γTR
And the value K1 · (dγTR / dt) are added to obtain the target steering angle δ5
Ask for T.

Next, the processor compares the actual trailer wheel steering angle δ5A represented by the steering angle sensor output with the target steering angle δ5T, and sends a control output corresponding to the comparison result to the control valve 82 (step). S13). When the control valve 82 is driven in this manner, the cylinder device 30 of the trailer wheel steering mechanism expands or contracts, and the actual steering angle δ5A is steered to be equal to the target value δ5T.

As described above, the trailer wheels 18 are steered so that the direction of the velocity vector of the tractor 1 and the direction of the trailer 2 always coincide with each other. For this reason, the trailer 2 is towed straight in the direction of the vehicle center line, and the steering stability of the combined vehicle is improved. The results of the simulation for evaluating the stability of the combined vehicle will be described below. The simulation was conducted for lane change and disturbance input.

10 and 11 show simulation results for lane change, FIG. 10 shows a case where the trailer wheels 18 are not steered, and FIG. 11 shows a case where the trailer wheels 18 are steered as described in the above embodiment. Show. The upper part of FIGS. 10 and 11 shows the input waveform of the tractor front wheel steering angle δ1. This input waveform shows that δ1 = a · {1-cosπ (t / t
c)} / 2, and from the time tc to the time 2tc, δ1 =
It is represented by a · sin {π- (t-0.5tc) / tc}. Here, a represents the steering angle amplitude, and tc represents the steering half cycle.
The input waveform is δ1 = from 2tc to 3tc.
a · {1-cos (t / tc) / tc} / 2, 3tc
After the time point, it is represented by δ1 = 0. Further, in the upper part of FIG. 11, a waveform of the trailer wheel steering angle δ5 is shown. The tractor yaw rate and the trailer yaw rate are shown in the center of FIGS. 10 and 11, and the error between the yaw angle ψ and the angle βh is shown at the bottom of FIGS. 10 and 11.

As is apparent from FIG. 11, the trailer wheel steering described in the above embodiment improves the stability of the trailer and the stability of the tractor, and the relationship of ψ-βh = 0 is almost achieved. 12, FIG. 13 and FIG. 14 show simulation results for disturbance input, FIG. 12 shows a case where the trailer wheels 18 are not steered, and FIG.
FIG. 14 shows a case where the trailer wheels 18 are steered as proposed in Japanese Patent No. 156180, and FIG. 14 shows a case where the trailer wheels 18 are steered as described in the above embodiment.

Waveforms of the disturbance input are shown in the upper portions of FIGS. 12, 13 and 14. Also, FIG. 13 and FIG.
A waveform of the trailer wheel steering angle δ5 is shown in the upper part of. This steering angle waveform indicates that the trailer wheels are steered even when the tractor front wheels are not steered even when the tractor velocity vector direction and the trailer direction do not match due to disturbance such as cross winds on the connected vehicle even when the vehicle is running straight. ing.
The tractor yaw rate and the trailer yaw rate are shown in the central portions of FIGS. 12, 13 and 14, and the error between the yaw angle ψ and the angle βh is shown in the lower portions of FIGS. 12, 13 and 14. .

As is apparent from FIGS. 12, 13 and 14, according to the trailer wheel steering described in the above embodiment,
When the trailer wheels are not steered and JP-A-1-1561
The error between the yaw angle ψ and the angle βh caused by the disturbance input is eliminated more quickly than in the case of steering the trailer wheels as proposed in No. 80. That is, the disturbance resistance of the combined vehicle is improved.

FIG. 15 shows a traveling locus of the semi-trailer when making a circular turn at an extremely low speed when the trailer wheels are not steered, and FIG. 16 is the same when the trailer wheels are steered as described in the above embodiment. The running locus of is shown. FIG.
5 and FIG. 16, symbols RTCf, RTCr and Rh
Indicates the turning radius of the front wheel axis of the tractor, the turning radius of the rear wheel axis of the tractor, and the turning radius of the hitch point.
And RTR respectively indicate a trailer wheel shaft center turning radius when the trailer wheel is not steered and a similar turning radius when the trailer wheel is steered.

As is apparent from FIGS. 15 and 16, the trailer wheel steering can reduce the rudder difference during turning in the low speed range. The present invention is not limited to the above embodiment, but can be variously modified. For example, in the embodiment, the steering angle is feedback-controlled according to the comparison result between the actual value and the target value of the trailer wheel steering angle, but the steering angle may be open-loop controlled.

[0042]

As described above, according to the present invention, since the wheels of the trailer are steered so that the direction of the trailer matches the direction of the velocity vector of the tractor, the steering stability of the combined vehicle can be improved. Further, since the target trailer wheel steering angle is determined based on the transfer function derived from the equation of motion in the mathematical model of the combined vehicle and the trailer yaw rate detected during the traveling of the combined vehicle, the trailer wheel steering control tolerance is determined. Disturbance is improved. That is, the traveling stability of the combined vehicle is significantly improved when the lane is changed or when a disturbance such as a side wind is received.

Further, the sensor system for the trailer wheel steering control can be simplified. In the present invention, the trailer yaw rate can be calculated from the tractor yaw rate sensor output and the relative yaw angle sensor output, but the trailer yaw rate sensor is preferably used for yaw rate detection.
In this case, the reliability of the trailer wheel steering control can be improved, and the device configuration can be simplified. This is because the relative yaw angle sensor is arranged at the connecting portion between the tractor and the trailer, whereas the trailer yaw rate sensor can be installed on the trailer side and has a large number of uses.

According to a particular aspect of the invention, instead of the transfer function, a second trailing function having a second frequency response characteristic approximating the frequency response characteristic corresponding to this transfer function is used. The wheel steering angle can be simply calculated. Further, the target trailer wheel steering angle can be easily determined by using the second transfer function represented by the first-order polynomial for the Laplace variable. Moreover, even when the second transfer function is represented by a first-order polynomial, the accuracy of approximation of the second transfer function with respect to the transfer function derived from the mathematical model is high. Therefore, even if a device having a relatively simple structure is used,
The trailer wheel steering control that can ensure the steering stability of the combined vehicle can be performed quickly.

[Brief description of drawings]

FIG. 1 is a diagram showing an angle βh formed by a tractor velocity vector and a tractor centerline, and a relative yaw angle ψ between a tractor and a trailer together with related parameters of a combination vehicle.

FIG. 2 is a diagram showing a mathematical model of an articulated vehicle.

3 is a frequency response corresponding to a transfer function G (s) derived from the equation of motion in the mathematical model of FIG. 2 and a frequency corresponding to an approximate transfer function G '(s) approximated to the transfer function G (s). It is a graph which shows a response.

FIG. 4 is a graph showing a relationship between coefficients K1 and K0 of an approximate transfer function G ′ (s) and a vehicle speed u.

FIG. 5 is a schematic side view showing the combined vehicle with the tractor and the trailer separated from each other.

FIG. 6 is a schematic partial plan view showing a trailer wheel steering mechanism mounted on a chassis frame of a trailer together with peripheral elements.

FIG. 7 is a schematic diagram showing a trailer wheel steering control device according to an embodiment of the present invention.

8 is a functional block diagram showing a target trailer wheel steering angle calculation function of a controller in the trailer wheel steering control device shown in FIG. 7. FIG.

9 is a flowchart showing a trailer wheel steering control process executed by the controller shown in FIG.

FIG. 10 is a graph showing a result of a simulation about a lane change for evaluating the stability of a combined vehicle having no trailer wheel steering function.

FIG. 11 is a graph showing a result of a simulation about a lane change for evaluating stability of a combined vehicle equipped with the device shown in FIG. 7.

FIG. 12 is a graph showing a simulation result of a disturbance input for evaluating the disturbance resistance of a combined vehicle having no trailer wheel steering function.

FIG. 13 is a graph showing a simulation result of disturbance input for evaluating disturbance resistance of a combined vehicle equipped with the device proposed in JP-A-1-156180.

FIG. 14 is a graph showing a simulation result of disturbance input for evaluation of disturbance resistance of a combined vehicle equipped with the device shown in FIG. 7.

FIG. 15 is a diagram showing a traveling locus of an articulated vehicle during a circular turn at an extremely low speed when the trailer wheels are not steered.

FIG. 16 is a diagram showing a traveling locus of the combined vehicle when the trailer wheels are steered.

[Explanation of symbols]

1 tractor 2 trailer 3 coupler 4 kingpin 16 trailer axle housing 18 trailer wheel 30 hydraulic cylinder device (wheel steering actuator) 40 V-shaped upper radius rod 50 L-shaped lever 60 lower radius rod 70 connecting rod 80 hydraulic pump 82 control valve 101 Yaw rate sensor 102 Vehicle speed sensor 103 Trailer wheel steering angle sensor 105 Controller δ1 Tractor front wheel steering angle δ5 Trailer wheel steering angle H Hitch point βh Angle between tractor speed vector and tractor centerline ψ Relative yaw angle between tractor and trailer lh Hitch point Between the center of gravity of the tractor and the center of gravity of the tractor.

Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B62D 113: 00 137: 00

Claims (7)

[Claims] 1. A trailer wheel steering control method for steering a wheel of a trailer such that a trailer direction matches a direction of a velocity vector of a tractor, wherein a transfer function representing a relationship between a trailer wheel steering angle and a trailer yaw rate is set. Derived in advance, the yaw rate of the trailer is obtained while the vehicle is running, and the target trailer wheel steering angle is determined based on the yaw rate of the trailer and the transfer function obtained while the vehicle is running. A wheel steering control method for a trailer, wherein the wheels of the trailer are steered so that the steering angle becomes the target trailer wheel steering angle. 2. The equations of motion for the tractor lateral velocity, the tractor yaw rate, the relative yaw angle between the tractor and the trailer, the tractor front wheel steering angle and the trailer wheel steering angle in the mathematical model of the combination vehicle, and the trailer yaw rate and the tractor. The wheel steering control method for a trailer according to claim 1, wherein the transfer function is derived in advance from an equation representing a relationship between a yaw rate and the relative yaw angle. 3. The method further includes a step of previously determining a second transfer function having a second frequency response characteristic approximate to a frequency response characteristic corresponding to the transfer function, and an actual trailer wheel steering angle is detected by the detected trailing wheel steering angle. 3. The trailer wheel according to claim 1, wherein the trailer wheel is steered so as to reach a target trailer wheel steering angle determined based on the trailer yaw rate and the second transfer function. Steering control method. 4. The wheel steering control method for a trailer according to claim 3, wherein the second transfer function is represented by a first-order polynomial with respect to a Laplace variable. 5. A wheel steering control device for a trailer, which steers the wheels of the trailer so that the direction of the trailer matches the direction of the velocity vector of the tractor, the steering mechanism for steering the wheels of the trailer, and the trailer. A detector for detecting the yaw rate of the trailer, and a calculation element having a transfer function representing the relationship between the trailer wheel steering angle and the trailer yaw rate, based on the trailer yaw rate detected by the detector. And a drive unit for driving the steering mechanism such that the actual trailer wheel steering angle becomes the target trailer wheel steering angle. Wheel steering control device. 6. A tractor lateral velocity, a tractor yaw rate, a relative yaw angle between the tractor and the trailer, a tractor front wheel steering angle and a trailer wheel steering angle in a mathematical model of the combined vehicle, and a trailer yaw rate and a tractor yaw rate. The wheel steering control device for a trailer according to claim 5, wherein the arithmetic element is configured to have a transfer function derived in advance from an expression representing a relationship with a relative yaw angle. 7. The calculation element according to claim 5, wherein the calculation element has a second transfer function having a second frequency response characteristic approximate to the frequency response characteristic corresponding to the transfer function. Wheel steering control device for trailer.