JPH05201349A - Control method for reach type fork-lift - Google Patents

Abstract

PURPOSE:To provide a reach type fork-lift which continuously changes a progress direction to all directions completely satisfies a theory of Ackerman Jeantaud, and besides corrects the posture of a car body to all progress directions. CONSTITUTION:A reach type fork-lift 1 is formed such that left and right road wheels 5 and 6 are steerably supported, a means for detecting the steering angle thereof is provided, a drive wheel 4 steerable by a handle and a means detectable of the steering angle thereof are provided, and a progress angle input means 15 capable of inputting a reference direction extending along the central line of a car body and an angle with the reference direction is provided. When a progress angle theta0 is on the right of the reference direction, the steering angle thetaR of the right road wheel 6 is caused to coincide with the progress angle theta0. The cornering center P of a car body determined by a geometric relation between the right road wheel 6 and the drive wheel 4 is computed and the right road wheel 5 is steered and controlled such that the extension line HL of the left road wheel 5 crosses the cornering center P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reach type forklift capable of steering a road wheel, and to a control method capable of correcting the posture in any traveling direction.

[0002]

2. Description of the Related Art Conventionally, a multi-directional traveling vehicle disclosed in Japanese Patent Publication No. 58-15342 has been proposed. This vehicle a
As shown in FIG. 14, when the traveling direction is A, the caster wheels c and f are fixed by turning, and the respective cylinders are hydraulically controlled so that the caster wheel d can be turned, so that the steering / driving wheel b is set. Ackerman can be steered by steering.

Further, as shown in FIG. 15, when the traveling direction is set to B, the caster wheels d and f are fixed along the turning direction and hydraulic control is performed on each cylinder so that the caster wheel c can be turned. However, the Ackermann steering can be performed in the same manner as above by steering the steering / driving wheel b.

[0004]

However, when switching the traveling direction between A and B, it is necessary to perform individual operations such as pushing a button switch after stopping the vehicle a, so-called mode switching, The direction of travel cannot be changed continuously. Further, the Ackerman steering and the attitude of the vehicle a are corrected only when the traveling direction is A or B.

The present invention has been devised in view of the above problems, and its purpose is to continuously change the traveling direction in all directions while maintaining the driving feeling of an ordinary reach type forklift as a basic tone, and The goal is to provide a reach-type forklift that fully satisfies Jeant's theory and can correct the posture of the vehicle body in all directions.

[0006]

According to the present invention, the left and right straddle arms each support a load wheel so as to be steerable, and a means for detecting the steering angle of the left and right road wheels is provided, and the steering wheel can be steered. A reach type forklift equipped with a drive wheel and means for detecting a steering angle of the drive wheel, wherein a reach angle between a reference direction along a center line of a vehicle body and an advancing direction which can be arbitrarily determined is advanced. And a traveling angle input means for indicating the traveling angle is provided, and when the traveling angle is on the right side with respect to the reference direction, the steering angle of the right road wheel is made to coincide with the traveling angle, and the right road The turning center of the vehicle body determined by the geometrical relationship between the wheel and the drive wheel is calculated, and the extension line of the center line of the rotation axis of the left road wheel intersects with the turning center. It is obtained by the basic to the steering control the cormorant left road wheel.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the reach type forklift (hereinafter,
A forklift 1) supports the main body 2 and the left and right straddle arms 20, 20 protruding from the main body 2 so that the load wheels 5, 6 can be steered, and the main body 2 is handled by a handle 3. A steerable drive wheel 4 is provided.

The drive wheel 4 is
A swingable swinging gear 17 mechanically linked to the handle 3
The turning gear 17 is attached to a potentiometer 18 capable of detecting the amount of rotation of the turning gear 17, so that the steering angle of the drive wheel 4 can be detected. Although not shown, caster wheels are arranged on the side of the drive wheel 4 to ensure traveling stability.

A cargo handling tool 7 is mounted between the straddle arms 20, 20 so that it can slide back and forth and can be moved up and down by a lift cylinder (not shown).

The road wheels 5 and 6 are rotatably supported by swivel brackets 8 and 9 which are swivelable with respect to the straddle arm 20, and the swivel brackets 8 and 9 are each provided with a conductive member 10 such as a chain or a belt. Steering motors 11 and 12 are mounted via 10 respectively. Therefore, by rotating the steering motors 11 and 12, the left and right road wheels 5 and 6 can be steered about the steering center points L and R, respectively. still,
In this example, the center of the road wheel serves as the steering center point, but a so-called kingpin offset may be provided in a predetermined amount.

The output shafts of the steering motors 11 and 12 are potentiometers 1 capable of detecting the amount of rotation thereof.
3, 14 are attached, and are configured to detect the steering angles of the left and right road wheels 5, 6.

A control unit 16 and a traveling angle input unit 15 are provided on the main body 2. The traveling angle input device 15
Is composed of a rotary potentiometer or the like, and is preferably arranged near the driver's seat (not shown) so that the driver can arbitrarily set it.

The traveling angle input device 15 is exemplified by an arrow on the surface of the operating portion as shown in the figure. The arrow indicates the direction of travel, and the driver
The current traveling direction of is shown so that it can be easily known which direction it will be described in detail later.

Next, the basic concept of the present invention will be described together with the operation based on FIGS. 4 to 11. In FIG.
Let D be the steering center of the drive wheel 4 and G be the axis lined with the turning centers connecting the steering centers L and R of the left and right road wheels 5 and 6 (hereinafter simply referred to as axis G).
Let C be the center line of the vehicle body.

The direction in which the forklift 1 advances is called the direction of travel, and when the steering angles of the left and right road wheels 5, 6 are zero (the state shown in FIG. 4), the vehicle body center line C It coincides with the traveling direction S. The traveling direction S
Is a reference direction when steering the forklift 1. Normally, the driver faces the front in that direction and steers the steering wheel from the neutral position to the left or right to the traveling direction S. Change the attitude angle of the car body. Therefore, when the traveling direction S is considered as the reference, if the steering angle of the drive wheel is zero, the forklift 1 travels straight.

Next, the traveling angle means an angle formed by the vehicle body center line C and the traveling direction S. Therefore, in the state illustrated in FIG. 4, the vehicle body center line C and the traveling direction S coincide with each other, and thus become zero.

Further, in the present invention, the traveling direction S can be arbitrarily set and can be set by operating the traveling angle input device 15. In other words, the forklift 1 can be steered regardless of the actual orientation of the vehicle body, assuming that the vehicle body centerline C is in a direction that coincides with an arbitrarily determined traveling direction. Therefore, the driver can steer the forklift with reference to the direction of the arrow shown on the traveling angle input device 15.

Next, the steering angles θL and θR of the left and right road wheels 5 and 6 are calculated from the axis G and the steering centers L and R of the road wheels 5 and 6, respectively, from the center line of the rotation axis of each road wheel. Extension lines HL, HR (hereinafter, simply extension line HL
, HR).

The steering angle θ1 of the drive wheel 4 is an angle formed by an extension line F of the center line of the rotation axis of the drive wheel 4 (hereinafter simply referred to as extension line F) and an axis perpendicular to the vehicle body center line C. , For each angle, think counterclockwise as positive.

In FIG. 5, the traveling angle of the forklift 1 is zero,
The moment when the steering angle of the drive wheel 4 is θ1 is shown. In this case, since the traveling direction S coincides with the vehicle body center line C, the steering angles of the left and right road wheels are both set to zero. The turning center P of the forklift 1 is geometrically determined by the axis G and the steering angle θ1 of the drive wheel 4, and the forklift 1 is turning about this point.

FIG. 6 shows the moment when the traveling angle of the forklift 1 is instructed by the traveling angle input device 15 by θ0 and the steering angle of the drive wheel 4 is θ1. In this case, the steering angle θL of the left road wheel 5 is made equal to the traveling angle θ0, and the intersection of the extension line HL of the left road wheel 5 and the extension line F of the drive wheel 4 in that state is defined as the turning center P. To do.

An extension line HR of the right road wheel 6
The right road wheel is steered so that can coincide with the turning center P.

FIG. 7 shows a moment when the traveling angle of the forklift 1 is indicated by θ0 by the traveling angle input device 15 and the steering angle θ1 of the drive wheel 4 is equal to the traveling angle θ0. Therefore, as described above, the steering angle θL of the left road wheel 5 is steered equal to the traveling angle θ0, and the intersection of the extension line HL of the left road wheel 5 and the extension line F of the drive wheel 4 is determined as the turning center P. However, in such a state, the extension lines HL and F are parallel to each other, and the turning center P is located at infinity of the axis G where the turning centers are lined up.

Further, an extension line HR of the right road wheel 6
When trying to match the turning center P with the extension line HR,
Becomes parallel to both extension lines HL and F, and forklift 1
Indicates that the vehicle travels along the traveling direction S without changing the orientation of the vehicle body. This is because the steering angle of the drive wheel 4 becomes zero when the traveling direction S is considered as a reference for steering the forklift 1.

Next, FIG. 8 shows the moment when the forklift 1 travel angle θ0 = π / 2 is instructed by the travel angle input device 15 and the steering angle of the drive wheel 4 is θ1. . Therefore, as described above, the steering angle θL of the left road wheel 5 is π / 2, the intersection of the extension line HL of the left road wheel 5 and the extension line F of the drive wheel 4 is the turning center P, and the right road wheel is The right road wheel is steered so that the extension line HR of 6 can coincide with the turning center P.

In such a state, the actual wheelbase becomes very short, that is, L1, so that the attitude of the forklift 1 can be changed extremely severely.

When the drive wheel 4 is further cut from the state shown in FIG. 8 and the steering angle θ1 of the drive wheel is + π / 2, the forklift 1 moves along the traveling direction S as described with reference to FIG. Traverse without changing the posture of the vehicle. Moreover, the posture can be corrected by steering the drive wheel 4 in the traveling direction S.

Further, in FIG. 9, the traveling angle −θ in the minus direction is shown.
The case where 0 is designated is illustrated. In this case, the steering angle θL of the right road wheel 6 is made equal to the traveling angle −θ0, and the extension line HR and the extension line F of the right road wheel 6 are set.
Let the intersection point with and be the turning center P. Then, the left road wheel 5 is steered so that the extension line HL of the left road wheel 5 can coincide with the turning center P.

FIG. 10 shows the case where the advancing angle θ 0 = −π / 2. In this case, the wheel base is L2, which can be set slightly longer than in the case of FIG. 8 described above.

Further, FIG. 11 exemplifies a case where the traveling angle θ 0 and the steering angle of the drive wheel are both −π / 2.

The above is the basic concept of the present invention, but by carrying out the control as described above, the Ackermann-Junt theory can be satisfied in all traveling directions.
Further, by giving an instruction of the traveling angle, for example, in the state shown in FIG. 6, the vehicle body center line C of the forklift 1 is vertical in the figure, but it is as if the vehicle body center line C reaches the instructed traveling angle θ0. The posture of the forklift truck 1 can be corrected on the assumption that the forklift truck 1 exists in the traveling direction S along the direction.

Therefore, regardless of the actual direction of the center line C of the vehicle body of the forklift 1, an arbitrary traveling direction S can be given, and the attitude of the forklift 1 can be corrected with reference to this traveling direction S.

Means for embodying the above concept will be described in detail with reference to the control block diagram shown in FIG.

The controller 16 is an A / D converter, a ROM for storing programs and the like, and a working memory RA.
M, a microprocessor MPU, a D / A converter, and a motor controller 19, which are connected by a bus line or I / O.

The A / D converter includes a traveling angle input device 1
The traveling angle is input from 5, and the steering angles θD, θR, and θL are input from the potentiometers 18, 14, and 13, respectively.
The A / D converter converts the input signal from an analog signal into a digital signal.

Based on these signals, the MPU calculates the steering angles θL and θR of the left and right road wheels 5 and 6. The arithmetic processing procedure is stored in the ROM, which will be described later.

The steering angles θL and θR of the left and right road wheels 5 and 6 calculated by the MPU are calculated based on the deviation between the calculation result and the current detected value of the steering angle. The turning speed of No. 6 is determined, converted into an analog signal by the D / A converter 58, and then output to the left and right steering motors 11 and 12 via the motor controller 19.

The motor controller 19 includes an MPU.
From the I / O, a control signal is input to control the steering motors 11 and 12 such as forward rotation, reverse rotation, and forcible lock when an abnormality occurs.

Next, the processing procedure of the MPU will be described based on the flowchart shown in FIG. First, memory and I / O
Are initialized (S1, S2), and initialization is performed to set the traveling angle θ0 of the forklift 1 to zero (S3).

Next, the advancing angle θ 0 of the forklift 1 and the drive wheel 4 input from the advancing angle input device 15.
The steering angle θ1 of the vehicle is stored in the RAM (S4, S
5).

Next, the reference coordinate axis, which will be described later, is coordinate-converted by the traveling angle θ0 (S6). If the traveling angle is zero (Y in S7), both steering angles θL and θR of the left and right road wheels 5 and 6 are set to zero (S8 and S9) and output (S8).
10).

On the other hand, if the traveling angle θ0 is not zero (N in S7), it is determined whether the traveling angle θ0 is positive (S11).
If the traveling angle θ0 is positive (Y in S11), the steering angle θL of the left road wheel 5 is made equal to the traveling angle θ0 (S1
2) The steering angle θR of the right road wheel 6 is calculated and output (S13, S10).

Further, if the traveling angle θ0 is negative (S11)
N), the steering angle θR of the right road wheel 6 is changed to the traveling angle θ0.
(S14), the steering angle θ of the left road wheel 5
L is calculated and output (S15, S10).

Next, of the processing procedure of the MPU, the procedure of the subroutine of the coordinate conversion performed in step S6 and the steering angle calculation in step S13 and step S15 will be described.
Details will be described with reference to FIGS. 12 and 13.

Now, as shown in FIG. 12, the advancing angle of the forklift 1 is + θ 0 (that is, Y in step S11 of the flowchart of FIG. 3), and the steering angle of the drive wheel 4 is +.
Set to θ1.

Now, consider a Cartesian coordinate axis (xy) whose origin is a representative point E arbitrarily defined on the vehicle body center line and whose y axis coincides with the vehicle body center line. The steering center points L, R, of the left and right road wheels 5, 6 on the orthogonal coordinate axes (xy)
And the coordinates of the steering center point D of the drive wheel 4 (xL
, YL), (xR, yR) and (xD, yD).

First, consider a transformed coordinate axis (XY) obtained by rotating and moving the above-mentioned orthogonal coordinate axis (xy) by a traveling angle θ0, and the respective steering center points L and R on this transformed coordinate axis (XY). And the coordinates (XL, YL), (XR, YR) and (XD, YD) of D are obtained. These coordinates are from number 1 to number 3
Can be found at.

[Equation 1]

[Equation 2]

[Equation 3]

Next, the coordinates (XP, YP) of the turning center P on the converted coordinate axis (XY) are calculated. Therefore, the intersection of the extension line HL of the left road wheel 5 and the extension line F of the drive wheel 4 is obtained.

The extension line HL of the left road wheel 5 is expressed by the equation 4 on the conversion coordinate axis (XY).

[Equation 4]

The extension line F of the drive wheel is expressed by the equation 5 on the conversion coordinate axis (XY).

[Equation 5]

When the intersection of both straight lines is obtained, it is clear that Y = YL for the Y coordinate, and the X coordinate X
P can be expressed by Equation 6.

[Equation 6]

Here, the steering angle θR of the right road wheel 5
And the tangent of the difference between the advancing angle θ0 and the traveling angle θ0 is given by Equation 7.

[Equation 7]

From Equation 7, the steering angle θ of the right road wheel 6
R can be calculated by Equation 8.

[Equation 8]

Similarly, in FIG. 13, the traveling angle of the forklift 1 is −θ 0 (that is, N in step S11 of the flowchart of FIG. 3), and the steering angle of the drive wheel 4 is +.
Shows the state of θ1. In this case, the extension line HR of the right road wheel 5 is represented by the equation 9 on the conversion coordinate axis (XY).

[Equation 9]

Further, the extension line F of the drive wheel is expressed by the above equation 5 on the conversion coordinate axis (XY).

When the intersection of both straight lines is obtained, it is clear that Y = YR for the Y coordinate, and the X coordinate is expressed by the formula 10
Can be expressed as

[Equation 10]

Here, the steering angle θL of the difference road wheel 5
Then, the tangent of the difference between the traveling angle θ0 and the traveling angle θ0 is obtained as shown in Formula 11.

[Equation 11]

From Equation 11, the steering angle θL of the left road wheel 5 can be obtained by Equation 12.

[Equation 12]

The steering angles θL and θR of the left and right road wheels 5 and 6 obtained by the above calculation are output, and the respective road wheels are steered.

The coordinates of the steering center points L and R of the road wheels 5 and 6 and the steering center point D of the drive wheel 4 are (xL, yL), (xR, yR) and (xD, y).
D) and the like are stored in advance in the ROM.

Although described in detail above, the present invention is not limited to the above embodiment, and for example, a steering mechanism for a road wheel is configured by using transmission means such as various gears and links other than a belt. It may be one.

Further, the origin E of the Cartesian coordinate system (xy) may be variously used other than the one shown in this example, and may be other than on the vehicle body center line.

[0063]

As a result of adopting the above method, the present invention provides
In all driving conditions, the Ackermann-Junt theory is satisfied, so the slipping of the road wheels can be prevented as much as possible, and smooth steering is possible.

In addition, since there is no discontinuous operation such as mode switching and the traveling direction can be continuously changed in all directions, no matter which direction the vehicle body of the forklift is actually facing, the traveling direction is arbitrary. The attitude of the vehicle body of the forklift can be corrected with reference to. Therefore, the required traveling area can be minimized, and the passage space required for traveling can be saved as much as possible even in the warehouse.

[Brief description of drawings]

FIG. 1 is a plan view of a reach type forklift used in the present invention.

FIG. 2 is a control block diagram of the present invention.

FIG. 3 is a flowchart of the present invention.

FIG. 4 is a plan view illustrating the operation of the present invention.

FIG. 5 is a plan view illustrating the operation of the present invention.

FIG. 6 is a plan view illustrating the operation of the present invention.

FIG. 7 is a plan view illustrating the operation of the present invention.

FIG. 8 is a plan view illustrating the operation of the present invention.

FIG. 9 is a plan view illustrating the operation of the present invention.

FIG. 10 is a plan view illustrating the operation of the present invention.

FIG. 11 is a plan view illustrating the operation of the present invention.

FIG. 12 is a plan view illustrating the control content of the present invention.

FIG. 13 is a plan view illustrating the control content of the present invention.

FIG. 14 is a plan view for explaining a conventional multidirectional traveling vehicle.

FIG. 15 is a plan view for explaining a conventional multidirectional vehicle.

[Explanation of symbols]

 1 Reach type forklift 2 Main body 3 Handle 4 Drive wheel 5 Left road wheel 6 Right road wheel 11 Steering motor 12 Steering motor 13 Potentiometer 14 Potentiometer 15 Travel angle input device 16 Control device 18 Potentiometer 20 Straddle arm

Front page continuation (72) Inventor Shinobu Tanaka 2-1-1, Higashijinzou, Nagaokakyo-shi, Kyoto

Claims (3)

[Claims] 1. A drive wheel steerable by a steering wheel, and a steering wheel supported on each of the left and right straddle arms so that the road wheel can be steerably supported and the steering angle of the left and right road wheels is detected. A reach type forklift having a means for detecting an angle, wherein a reference direction along a center line of a vehicle body and an angle formed by the reference direction and a traveling direction that can be arbitrarily set are defined as a traveling angle,
Advancing angle input means for indicating the advancing angle is provided, and when the advancing angle is on the right side with respect to the reference direction, the steering angle of the right road wheel is made to match the advancing angle, and the right road wheel and the The reach is characterized in that the turning center of the vehicle body determined by the geometrical relationship with the drive wheel is calculated, and the left road wheel is steered so that the extension line of the center line of the rotation axis of the left road wheel intersects with the turning center. Type forklift control method. 2. The reach-type forklift according to claim 1, wherein an angle formed by a reference direction along the center line of the vehicle body and an advancing direction that can be arbitrarily set with the reference direction is defined as an advancing angle, and the advancing angle is set. When a traveling angle input means capable of indicating is provided and the traveling angle is on the left side with respect to the reference direction, the steering angle of the left road wheel is matched with the traveling angle, and the left road wheel and the drive wheel are separated from each other. Reach-type forklift control characterized by calculating the turning center of the vehicle body determined by the geometrical relationship and steering-controlling the right road wheel so that the extension line of the center line of the rotation axis of the right road wheel intersects with the turning center. Method. 3. The method of controlling a reach type forklift according to claim 1, wherein when the traveling angle is zero, the steering angles of the left and right road wheels are set to zero.