JP3275364B2 - Reverse traveling 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 reverse traveling control method for an automatic guided vehicle, which is devised so that the reverse traveling can be performed stably even at a high 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. 2 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. When the vehicle travels forward (direction A), the guide line 10 is detected by the front guide sensor 5f, and the steering is performed so that the center of the guide sensor 5f, that is, the center of the vehicle body 4 is located directly above the guide line 10. Drive while controlling. When the vehicle travels in the reverse direction (travels in the B direction), the guidance sensor 5b on the rear side is used.
The vehicle travels under steering control in the same manner as in the case of f.
Various controls for traveling, including steering control, are performed by commands from the control device 6.

In the automatic guided vehicle 1 described above, the guidance sensor 5
The guide line 10 is detected by f and 5b (5f is used when moving forward and 5b is used when moving backward), the distance (deviation) between the guidance line 10 and the center of the vehicle body 4 is sensed, and steering is performed according to the displacement. The corner is decided. The relationship between the deviation amount and the steering angle is set in the control device 6 in advance.

[0004] The set steering angle is made different between forward and reverse, even if the amount of deviation is the same. That is, for the same deviation amount, the steering angle set for the reverse travel is larger than the steering angle set for the forward travel. Therefore, when the vehicle is moving backward, the controlled steering angle is large and the front wheels 2 are largely steered even if the detected deviation amount is small.

[0005]

Therefore, in the case where the automatic guided vehicle 1 travels backward while detecting the guide line 10 laid in a straight line, if the traveling speed becomes high, the coarseness of the sensor resolution and the delay of the control system may increase. For example, the control may diverge due to such factors, and the automatic guided vehicle 1 may deviate from the guide line 10 and go out of course.

Conventionally, in order to prevent a course-out, a signal detected at a central portion of the induction sensor 5f is ignored and this portion is set as a dead zone so that steering control is not performed even if a minute change in sensing data occurs. However, this means cannot provide a sufficient effect, and when a deviation is detected beyond the dead zone, large steering must be performed sharply, and control performance may be degraded depending on the characteristics of the control system. .

The present invention has been made in view of the above-mentioned prior art, and provides a reverse traveling control method for an automatic guided vehicle that controls the vehicle so as to be able to travel stably without traveling out of course even when traveling backward at a high speed on a straight taxiway. is there.

[0008]

Means for Solving the Problems The present invention for solving the above problems, with respect 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, disposed symmetrically along the vehicle width direction The vehicle has two rear wheels and a front wheel for steering, and a guidance sensor provided along the vehicle width direction at the rear of the vehicle body detects a guidance line laid on the traveling path, and the center of the vehicle with respect to the guidance line is detected. determine the amount of deviation SY line C _2, the setting from the deviation amount SY calculates the steering angle theta, by the steering control as the steering angle of the front wheel is set steering angle theta, linearly AGV In the reverse traveling control method for traveling backward along the guide line, the set steering angle θ is determined based on the following equations (5) to (8), and the steering angle of the front wheels is adjusted so as to match the set steering angle θ. Reverse travel control method of the automatic guided vehicle, characterized by ring control. α = arc tan {SY / ( SX + DSX)} ··· (5) r s = {(SX + DSX) / 2} / sin α ··· (6) r c = r s cos α + (SY / 2) ·· · (7) θ = arc tan (L / r c) ··· (8) where, SY is shift amount, SX is the antenna length is the distance between the inductive sensor and the axle of the rear wheel Yes, DSX
Is a virtual antenna length which is an arbitrary length set in advance , and L is a wheelbase length.

[0009]

[Operation] By setting the virtual antenna length, the detection angle changes from α _o to α, and the set steering angle θ _o to θ
Becomes smaller. Therefore, gentle steering is performed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.
The same parts as those in the prior art are denoted by the same reference numerals, and overlapping description will be omitted. The reverse traveling control method according to the present invention is applied to the automatic guided vehicle 1 shown in FIG. In this method, when the automatic guided vehicle 1 travels backward along the guide line 10, a steering angle set according to the amount of displacement of the guide line 10 from the center of the guide sensor 5b is determined by a geometric control method (described later). ), And the set steering angle is reduced during high-speed running. The calculation for setting the steering angle is performed by the control device 6, and a specific example thereof will be described below.

A general geometric control method will be described with reference to FIG. 1, and subsequently, an improved geometric control method according to the present invention will be described.

First, a general geometric control method will be described with reference to FIG.
You. Each code defines the following. SX: antenna length, axle of a pair of rear wheels 3 and rear
Distance between the guidance sensor 5b. L: Wheelbase length. P₁: Center point between rear wheels, at the center of a pair of rear wheels 3
To position. C₁: A straight line along the axle of the rear wheels 3, 3 which is an axle line. C_Two: The center line of the vehicle body and the center of the vehicle body 4 in the vehicle width direction
A line that extends in the vehicle length (front-back) direction. P_Two: At the center of the sensor, inside the guidance sensor 5b at the rear
Centrally located. P_Three: Sensing point, guided by guidance sensor 5b
Position where line 10 was detected. P_Four: Central point, line segment P₁, P_ThreeLocated in the center of
You. P_Five: The turning center point, line segment P₁, P_ThreePoint perpendicular to
P_FourLine r extended from _soIs axle line C₁Intersection with. P₆: Steering point, front wheel 2 is steered around this point
You. r_so: Point P_Four, P_FiveA line segment connecting. r_fo: Point P_Five, P₆A line segment connecting. r_co: Point P_Five, P₁A line segment connecting. rθ_o: Point P₆Through the line segment r_foLine perpendicular to. SY: deviation amount, point P_Two, P_ThreeThe distance between, that is,
Vehicle center line C at the rear of vehicle body 4_TwoAnd guide wire 10
Distance between. α_o: Detection angle, line segment P₁, P_TwoAnd line segment P₁, P_Three
And the angle made. θ_o: Set steering angle.

From the geometric conditions shown in FIG.
Α _o = arc tan (SY / SX) to obtain (4) (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 unit 6, using the relationship of the above equation (1) to (4), determine the steering angle theta _o should be set in accordance with the detected deviation amount SY, steering angle of the front wheels 2 theta _o
The steering angle is controlled so that Such a method is called a geometric control method.

In the general geometric control method described above, the shift amount SY
However, if this control method is used as it is, when the vehicle is traveling in reverse at a high speed in a straight line, the control may diverge and the vehicle may go out of course as described above.

Therefore, in the present invention, as shown in FIG.
A virtual antenna that extends the antenna length by adding to the tenor length SX
Long DSX and virtual guidance sensor 5 were introduced, and
Defined as follows. Note that the virtual guidance sensor 5 is
Assume that an inductive sensor is present at this position, not a sensor
This is used in the arithmetic processing. P₇: Sensing point by virtual guidance sensor 5
The position calculated and estimated when the guide line 10 is detected. P₈: Central point, line segment P₁, P₇Located in the center of
You. P₉: The turning center point, line segment P₁, P₇Point perpendicular to
P₈Line r extended from _sIs axle line C₁Intersection with. r_s: Point P₈, P₉A line segment connecting. r_f: Point P₉, P₆A line segment connecting. r_c: Point P₉, P₁A line segment connecting. rθ: Point P₆Through the line segment r_fLine perpendicular to. α: detection angle, line segment P₁, P_TwoAnd line segment P₁, P₇When
The corner to make.

From the geometric conditions shown in FIG. 1, the following equations (5) to (8) are obtained including the virtual antenna length DSX. α = arc tan {SY / ( SX + DSX)} ··· (5) r s = {(SX + DSX) / 2} / sin α ··· (6) r c = r s cos α + (SY / 2) ·· · (7) θ = arc tan (L / r c) ··· (8)

The control device 6 obtains a steering angle θ to be set according to the detected deviation amount SY using the relations of the above equations (5) to (8). The steering angle θ is equal to the shift amount S
Y is be the same, smaller than the steering angle θ _o. Therefore, when the vehicle travels straight backward at high speed, if the steering is controlled using the steering angle θ, a gentle steering operation is performed, and the reverse traveling is performed stably.

Whether the vehicle is traveling in a straight line is determined based on the value of the deviation amount SY. That When SY is smaller than the preset value, the steering control using the steering angle theta is determined that the vehicle is running straight, the steering control using the steering angle theta _o otherwise.

[0020]

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 virtual antenna length is introduced and Since the steering angle is obtained from the deviation amount smaller than the deviation amount, the set steering angle becomes smaller. For this reason, the steering becomes gentle, and even if the vehicle runs backwards at a high speed in a straight line, the vehicle can run stably without worrying about the course out.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an automatic guided vehicle.

[Explanation of symbols]

1 after the automatic guided vehicle 2 front wheel 3 wheels 4 the vehicle body 5 virtual inductive sensor 5f, 5b inductive sensor 6 control device 10 guiding line C ₁ axle line C ₂ body centerline alpha _o, alpha detection angle theta _o, theta set steering angle

Claims (1)

(57) [Claims] To 1. A vehicle body centerline C ₂ extending the center in the vehicle width direction of the vehicle body in the vehicle length direction, and two rear wheels which are arranged symmetrically along the vehicle width direction, the front wheels to the steering together with the door, by induction sensor provided along the rear portion of the vehicle body in the vehicle width direction, detects an induction line laid on the traveling path, it obtains a deviation amount SY of the vehicle body center line C ₂ on the induction line, the shift amount The set steering angle θ is calculated from SY, and the steering angle of the front wheel is set to the set steering angle θ.
In the reverse traveling control method for causing the automatic guided vehicle to travel backward along a straight guide line by performing steering control so as to obtain a set steering angle θ based on the following equations (5) to (8), A reverse traveling control method for an automatic guided vehicle, wherein steering control is performed such that a steering angle of a front wheel matches a set steering angle θ. α = arc tan {SY / ( SX + DSX)} ··· (5) r s = {(SX + DSX) / 2} / sin α ··· (6) r c = r s cos α + (SY / 2) ·· · (7) θ = arc tan (L / r c) ··· (8) where, SY is shift amount, SX is the antenna length is the distance between the inductive sensor and the axle of the rear wheel Yes, DSX
Is a virtual antenna length which is an arbitrary length set in advance , and L is a wheelbase length.