JP3134551B2 - Travel control method for automatic guided vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling control method for an automatic guided vehicle, which is devised so that a steering control can be stably performed according to a vehicle speed.

[0002]

2. Description of the Related Art An automatic guided vehicle travels unmannedly at various factories, warehouses, offices, and the like, and transports parts, products, small articles, and the like. Here, an example of an automatic guided vehicle is shown in FIG.
This will be described with reference to FIG. The automatic guided vehicle 1 shown in FIG. 3 is of a tricycle type having one front wheel 2 that performs rotational driving and steering, and two rear wheels 3 that function as driven wheels. At the front and rear of the vehicle body 4, guidance sensors 5f,
5b is installed.

In order to set such a steering angle of the automatic guided vehicle 1, a geometric control method may be used. Here, the geometric control method will be described based on FIG. Each code defines the following. SX is the antenna length, and is the distance between the axles of the pair of rear wheels 3 and the guidance sensor 5b at the rear. L: Wheelbase length. P ₁ : a center point between the rear wheels, which is located at the center of the pair of rear wheels 3, 3. C ₁ : the axle line, a straight line along the axles of the rear wheels 3, 3. C ₂ : a vehicle center line extending in the vehicle length (front-back) direction at the center of the vehicle body 4 in the vehicle width direction. P ₂ : sensor center point, located at the center of the rear guidance sensor 5b. P ₃ : a sensing point, a position at which the guidance line 10 is detected by the guidance sensor 5b. P ₄ : a center point, which is located at the center of the line segments P ₁ and P ₃ . P ₅ : a turning center point, a point at which a line r _{so that} is orthogonal to the line segments P ₁ and P ₃ and extended from the point P ₄ intersects the axle line C ₁ . P ₆ is a steering point, and the front wheels 2 are steered around this point. r _so : a line segment connecting points P ₄ and P ₅ . r _fo : a line segment connecting points P ₅ and P ₆ . r _co : a line segment connecting points P ₅ and P ₁ . rθ _o: line perpendicular to the point P ₆ as the line segment r _fo. SY: The amount of deviation, the distance between points P ₂ and P ₃ ,
The vehicle center line C ₂ and the guide line 10 at the rear of the vehicle body 4
Distance between. α _o : detection angle, line segments P ₁ and P ₂ and line segments P ₁ and P ₃
And the angle made. θ _o : Set steering angle

[0004] From the geometric conditions shown in FIG.
(4) is obtained. α _o = arc tan (SY / SX) (1) r _so = (SX / 2) sin α _o (2) r _co = r _so cos α _o + (SY / 2) (3) θ _o = arc tan (L / r _co ) ... (4)

The control device 6 uses the relations of the above equations (1) to (4) to determine a steering angle θ ₀ to be set according to the detected deviation amount SY, and the steering angle of the front wheels 2 is θ _0.
The steering angle is controlled so that Such a method is called a geometric control method.

[0006]

In the above-described conventional geometrical control method, since the antenna length SX is fixed, the steering angle θ ₀ can be obtained regardless of whether the vehicle speed is high or low with the same shift amount SY. Is the same.

However, in order to perform smooth steering, it is preferable that the steering angle is large at a low speed and the steering angle is reduced at a high speed for the same shift amount SY. In order to change the steering angle according to the vehicle speed even with the same deviation amount as described above, it is conceivable to adjust the gain of the signal processing system. However, this makes signal calculation complicated. I will.

The present invention has been made in view of the above-mentioned prior art, and provides a traveling control method for an automatic guided vehicle in which an optimum steering angle can be easily obtained according to the vehicle speed even with the same deviation amount. .

[0009]

Means for Solving the Problems The present invention for solving the above problems, there to the vehicle body center line C ₂ extending the center in the vehicle width direction of the vehicle body in the vehicle length direction and arranged symmetrically along the vehicle width direction An axle line C ₁ having two rear wheels and a front wheel for steering and connecting the axles of the rear wheels of the vehicle body.
And detecting the induction lines laid on the traveling path by induction sensor provided along the vehicle width direction to the rear than the guided wheel between the center points P ₁ after the an intersection of the axle line C ₁ and the body center line C ₂ the following formula and a line segment connecting the sensing point of detecting the guide wire with a sensor, the detection angle formed between the vehicle body center line _{C 2 (i) (ii)} (iii)
In the traveling control method of the automatic guided vehicle, in which the set steering angle θ is obtained by applying the steering angle so that the steering angle of the front wheels coincides with the set steering angle θ, the rear part of the vehicle body with respect to the axle line C ₁ of
Within the predetermined range of the position, the guidance sensor is
It can slide forward and backward, and the vehicle speed is set in advance.
When the vehicle speed is lower than the set vehicle speed , slide the induction sensor.
Is slid to the frontmost position in the de-moving range, the vehicle speed Oh
When the vehicle speed is faster than the preset vehicle speed,
The guide sensor is slid rearward as it becomes smaller . r _SO = (distance / 2 between the inductive sensor and the point P ₁₎ sin (detection _{angle) ·· (i) r CO =} r SO cos ( detection angle) + (amount of deviation / 2) -----・ ・ ・ ・ ・ (Ii) θ = arctan (wheel base length / r _CO ) ・ ・ ・ ・ (iii )

[0010]

With the same deviation amount, when the vehicle speed is low, the guidance sensor is located on the front side and the detection angle and the set steering angle are large. When the vehicle speed is high, the guidance sensor is located on the rear side and the detection angle and the detection angle are set. The steering angle becomes smaller.
Therefore, stable steering can be performed even if the vehicle speed changes.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, the parts performing the same functions as those of the prior art are denoted by the same reference numerals, and overlapping description will be omitted.

FIG. 1 shows an automatic guided vehicle 1 to which the present invention is applied. The speed sensor 11 detects a vehicle speed, and the guidance sensor 5b.
Is provided with a slide mechanism 12 which slides the front and rear in the front-rear direction. The control device 6 controls the sliding mechanism 12 based on the vehicle speed detected by the speed sensor 11 such that the guide sensor 5b is located on the front side when the vehicle speed is low and the guide sensor 5b moves rearward as the vehicle speed increases. Perform control. Note that the slide length by which the guidance sensor 5b moves from the foremost position to the last position is SSX.

Next, the method of the present invention will be described with reference to FIG.
In FIG. 2, the state in which the guidance sensor 5b is at the forefront position is indicated by a solid line, and the state at the last position is indicated by a dotted line. Further, each code is defined as follows. P ₇ : a sensing point, a position at which the guidance line 10 is detected by the guidance sensor 5 located at the last position. P ₈ : a center point, which is located at the center of the line segments P ₁ and P ₇ . P _9: turning a central point, that the line segment P _1, a line r _s which extends from the point P ₈ and perpendicular to P ₇ intersects the axle line C _1. r _s : a line segment connecting points P ₈ and P ₉ . r _f : a line segment connecting points P ₉ and P ₆ . r _c : a line segment connecting points P ₉ and P ₁ . rθ: line perpendicular to the point P ₆ as the line segment r _f. α: detection angle, which is an angle formed between the line segments P ₁ and P ₂ and the line segments P ₁ and P ₇ .

From the geometric conditions shown in FIG. 2, the following equations (5) to (8) are obtained including the slide length SSX. α = arc tan {SY / ( SX + SSX)} ... (5) r s = {(SX + SSX) / 2)} sin α ... (6) r c = r s cos α + (SY / 2) ... (7) θ _{= arc tan (L / r c} ) ... (8)

When the vehicle speed is low, the guidance sensor 5b is at the position shown by the solid line, and the control device 6 obtains the steering angle θ ₀ in the same manner as in the prior art (see FIG. 4).

When the vehicle speed increases, the guidance sensor 5b gradually moves backward, and reaches the position shown by the dotted line at the maximum speed. At the highest speed, the control device 6 uses the above equation (5).
The steering angle θ to be set in accordance with the detected shift amount SY is obtained using the relationship of (8). The steering angle θ is the same as the steering angle θ even if the shift amount SY is the same.
_Less than ₀ . Therefore, when traveling at high speed, if steering control is performed using the steering angle θ, gentle steering operation is performed, and traveling is performed stably.

After all, according to the present invention, even if the displacement amount SY is the same, as the vehicle speed increases, the sliding mechanism 1
2, the guide sensor 5b moves backward, the slide length SSX increases, and the steering angle θ decreases. Therefore, stable steering can be performed according to the vehicle speed.

In the above embodiment, the guide sensor 5b is continuously slid according to the vehicle speed. However, a plurality of mounting positions of the guide sensor 5b are set in steps along the front-rear direction, and the unmanned transport is performed. The guidance sensor 5b may be positioned at an arbitrary mounting position according to the traveling mode of the vehicle.

[0019]

As described above in detail with the embodiment, according to the present invention, when the steering angle is set from the deviation amount using the geometric control method, the position of the guidance sensor is changed according to the vehicle speed. Since the shift is performed in the front-rear direction, the steering angle is large at a low speed and the steering angle is reduced as the vehicle speed is increased even at the same deviation amount, so that stable steering traveling can be performed.
Moreover, since the position of the guidance sensor is merely moved according to the vehicle speed, there is no need to change the signal processing system, and the present invention can be easily realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an automatic guided vehicle to which the present invention is applied.

FIG. 2 is an explanatory diagram for explaining the present invention.

FIG. 3 is a perspective view showing an automatic guided vehicle.

FIG. 4 is an explanatory diagram showing a conventional geometric control method.

[Explanation of symbols]

1 AGV 2 front wheel 3 rear wheel 4 car body 5f, 5b inductive sensor 6 control device 10 guiding line 11 velocity sensor 12 sliding mechanism C ₁ axle line C ₂ body centerline alpha _0, alpha detection angle theta _0, theta set steering Corner

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05D 1/02

Claims (1)

(57) [Claims] And 1. A two rear wheels relative to the vehicle body center line C ₂ extending the center in the vehicle width direction in the vehicle length direction are disposed symmetrically along the vehicle width direction of the vehicle body, and a front wheel for steering A vehicle that has the rear axles of the vehicle body
Of the axis C ₁ and detecting the induction lines laid on the traveling path by induction sensor provided along the rear in the vehicle width direction, the axle line C
The following formula and a line segment connecting _one and the sensing point of detecting the guide line by wheel between the center points P ₁ and inductive sensor after an intersection of the body center line C _2, the detection angle formed between the vehicle body center line C ₂ (i) (i
i) (iii) determine the set steering angle theta by applying, in the travel control method of the automatic guided vehicle to the steering control such front wheel steering angle is coincident with the set steering angle theta, the axle line of the vehicle body Oh the rear position than C ₁
Move the guidance sensor forward and backward within the predetermined range.
The slide sensor can be slid, and when the vehicle speed is lower than the preset vehicle speed , the guidance sensor slides to the forefront position within the slide movement range.
When the vehicle speed is higher than the preset vehicle speed , the guidance sensor is moved rearward as the vehicle speed increases .
A traveling control method for an automatic guided vehicle, wherein the traveling control is performed on a ride . r _SO = (distance / 2 between the inductive sensor and the point P ₁₎ sin (detection _{angle) ·· (i) r CO =} r SO cos ( detection angle) + (amount of deviation / 2) ----- ···· (ii) θ = arctan (wheel base length / r _CO ) ··· (iii)