JPS5850364B2 - Steering method of automatic transfer vehicle - Google Patents

Description

[Detailed description of the invention] The present invention relates to a steering system for an automatic transport vehicle,
More specifically, the present invention relates to a steering method for automatically driving a car that carries various articles, etc., or a wheelchair, bed, or the like that carries a person, along an arbitrary scheduled route set in advance.

One method that has already been proposed for making cars drive autonomously is to bury guidance cables along a planned route on the road surface, and use those cables to generate low-frequency electromagnetic fields that can be applied to the left and right sides of the car as it moves. There is a method in which the steering wheel is operated by detecting this with a provided hike-up coil, and controlling the steering motor so that the difference becomes zero by using the difference in voltage generated between the two coils.

In addition, instead of the above-mentioned induction cable, a metal tape or the like is pasted on the road surface, and this is detected by photosensors, etc. arranged in a row perpendicular to the direction of travel, and based on the position deviation of the car obtained thereby. There is also a method of controlling the steering motor.

However, these methods require the continuous installation of guidelines on the road surface using induction cables or metal tapes, which requires a large amount of money to install if the planned route is relatively long. The route is fixed and it is difficult to change it freely when winning,
In addition, since the car drives while only obtaining information about the direction of travel based on the guidelines, it is not possible to branch, merge, or cross the guidelines, and when it is necessary to do so, it is necessary to separately obtain information on decisions such as turning left, right, stopping, etc. The control mechanism becomes extremely complex and expensive.

The method of the present invention provides an automatic transfer vehicle with angle information about the attitude angle and position information about the positional deviation with respect to the planned route.
In addition, judgment information such as right or left turns is provided intermittently using marks attached to the road surface, and based on this information, steering control including correction of the vehicle's attitude and position is performed until the next information is provided. In particular, since the marks provide angle information, position information, and judgment information, the route is variable, and the route can be changed simply by changing the attachment of marks. Furthermore, the driving route can be branched, merged, and intersected, and three modes can be set for the steering method to control the steering of the car, and the necessary mode can be selected based on the above judgment information to obtain angle information and position information. Since the steering is performed with a steering amount according to the amount of steering, it is possible to perform simple and accurate steering control along the planned route.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

First, as shown in Fig. 1, directional marks M are placed on the road surface along the planned route, but the next mark in the direction of travel of each mark is in the direction of travel indicated by that mark M. (direction of the apex of the triangle).

The ITV camera attached to the car captures images of the marks on the planned route as the car drives, but it is extremely difficult to always accurately drive the car along the planned route. There will be an angular deviation and a positional deviation.

Therefore, the vehicle is run while performing steering control to correct the angular deviation and positional deviation before reaching the next mark position.

When a vehicle V travels with an angular deviation θ and a positional deviation XG relative to its planned route, there is a second
It is possible to obtain an image (2) as shown in the figure.

In order to find the angular deviation amount of the car from this image, it is sufficient to measure the attitude angle θ of the image (2).

Therefore, the attitude angle θ of the image of the mark is measured by the method described below, and this is used as the angle information of the car.

A Q value is used as the attitude angle detection parameter for the mark image (■).

This Q value is as follows.

Assume now that a planar figure P is placed on a fixed orthogonal coordinate system at an arbitrary attitude angle θ, as shown in FIG. 3A.

Here, θ is positive in the counterclockwise direction and negative in the opposite direction.

As shown in the opening of Figure 3, take the projection of the plane figure P onto the X-axis, and define the maximum width of the projected figure P' in the X-axis direction as Ax,
When Ap is the width between the X coordinate of the point with the maximum height in the Y-axis direction and the minimum value on the X-axis of the projected figure P', M and A,
The ratio is the Q value, and this is taken as the attitude angle measurement parameter.

X As is clear from the above equation (1), Pohi l+ Possible range of Q Figure 4 shows the calculation results for a triangular shape.

It can be seen that the Q value obtained in this manner uniquely corresponds to the attitude angle θ within a certain range centered on the case of θ−0, and therefore the attitude angle θ can be determined by measuring the Q value.

Note that when the attitude angle exceeds a certain range (1θ in Figure 4)
100,000), it becomes impossible to immediately determine the attitude angle θ using the Q value, but in reality, the attitude angle θ cannot be extremely large, so there is no possibility that the attitude angle θ will become extremely large. There isn't.

Next, a method for determining the positional deviation of the vehicle from the image (2) of the ITV camera will be explained.

Assuming that the ITV camera is placed at the center of the car, if the car enters the position of mark M with a positional deviation,
The camera captures an image shown in Figure 5, and since the center of gravity (centroid) of this mark is on the car's planned travel route, by measuring positional deviations can be recognized.

To measure the position of the center of gravity of a mark, if the shape of the mark is placed on a rectangular coordinate system as shown in Fig. 3A, then the coordinates (X) of the center of gravity are determined.

YG) is given by the following equation.

However, ds is a minute area of the figure.

Here, the center of the camera image is taken as the origin, and the current traveling direction is taken as the Y-axis, and the shame required for the time being is calculated according to equation (3). Positive and the opposite is negative.

When experiments were actually conducted using several types of marks, it was confirmed that the error in measuring the center of gravity position was about 4 mm, making it possible to measure the center of gravity relatively accurately.

Through the above-mentioned measurements, the car can obtain information about the driving attitude angle and positional deviation from the mark, so by steering the car to correct the route based on this information, the car can drive along the planned route. However, in order to further expand the functionality of the car, it is configured so that decisions such as turning right, turning left, and stopping can also be obtained from the above marks.

To do this, a functional meaning is given to the shape and size of the mark in advance, and judgment information is obtained by recognizing the shape and size.

For mark recognition, shape eigenvalues S and area measurement values shown below are used.

As shown in Figure 3A, when a plane figure P is placed on a rectangular coordinate system at an arbitrary attitude angle, the area Aa of the plane figure P, the maximum width AX and the maximum height of its projected figure P' are SaA,
The ratio to the product of is defined as the shape eigenvalue S.

Generally, the shape eigenvalue S varies depending on the attitude angle θ and becomes a function of θ.

Moreover, the possible range of the shape eigenvalue S is It is.

Triangle, circle, and radius ratio r2/r1 is 0.2, 0.4
.

Figure 6 shows the shape eigenvalues of the perforated circles of 0.6 and 0.8.

Note that in these cases, the shape eigenvalues do not vary depending on the attitude angle.

If the shape and size of a mark are recognized by measuring such shape eigenvalues, the functional meaning given to the mark can be obtained as decision information, and based on that decision information, the car can be instructed to turn right or left. , stop, etc.

Through the attitude angle measurement, position measurement, and shape recognition of the marks described above, the car can obtain the angle, position, and judgment information necessary for traveling on the planned route. An example of marks will be given.

Generally, many driving functions are required for a car to arrive at a desired destination after it has started, but here we will select 10 such marks as shown in FIG. 7 and explain these marks below.

/161・・・Go straight 1 This is a mark for driving the car on a straight road or a smooth fenced road.The attitude angle and position of the car are corrected in order to drive the car along the planned route smoothly. .

Therefore, it is desirable that the shape of this mark is particularly accurate in attitude angle measurement.

A2...Going straight 2 When a car is running on a very smooth straight road, its running attitude does not change much.

Therefore, with this mark, only the position of travel is corrected,
Make the car drive straight.

Wrong 3: This mark is used when a car turns left at a left-turn road intersection; it does not correct the attitude angle or position of the car.

Consideration 4: Turn right/Similar to the i63 mark, this is a mark that directs cars to turn right at intersections.

/165...Go straight 3 This is a mark that directs the car to go straight at the intersection, but does not correct the attitude angle or position of the car.

A6...This is a mark used to recognize the form of a dummy intersection, ie, a crossroads, a T-junction, etc.

The vehicle's attitude angle and position will not be corrected.

47... Temporary stop 1 This is a mark installed just before an intersection to make the vehicle stop temporarily and maintain a posture to detect the signal indicating whether or not it is possible to enter the intersection.

Here, we only need to correct the position of the car.

/i68... Temporary stop 2 This mark is used to stop a vehicle on the road other than an intersection, and only corrects the position.

, %9... Destination and departure point A mark placed at the desired destination by the user. When the car recognizes this mark, it detects that it is the destination and stops.

Also, when going from here to another point, it functions as a mark representing the departure point, and in this case, only the position of the car is corrected.

/1610...This mark is used when reversing a vehicle, and only corrects the attitude angle.

When deciding on the shape of such a mark, the selection criteria is that the shape be simple, clear, easy to recognize, be able to capture the necessary information, and that it be common to the public in order to coexist with the human environment. It is necessary to have a shape that allows people to easily understand the meaning when looking at it.

In this way, by using marks etc. attached to the road surface of the planned route, the vehicle is intermittently provided with angular information about the attitude angle and positional information about the positional deviation with respect to the planned route, as well as decision information such as whether to turn right or left. The vehicle is caused to travel along the planned route by modifying the route for each piece of intermittent information. When controlling the steering system based on the above three pieces of information, in the present invention, in order to perform steering control extremely easily, first, the steering system is Regarding the method, the following three modes are set, and steering control is performed in a one-to-one correspondence with each of the above information.

Modified: Modification of attitude angle and position A steering method that corrects the attitude angle and position in accordance with the mark on steering wheel scrap 1, in which either left or right/time is constant to correct the attitude angle. At the same time, in order to correct the positional deviation, the left and right sides are alternately steered at the same required steering angle at a constant time.

Mode 2...Position correction steering/% Corresponding to the marks 2, 7, 8, and 9, this is a steering method that only corrects the position, and the required steering is the same on both sides with a constant time alternating left and right. Perform corner steering.

Mode 3: A steering method that performs direction change steering corresponding to the left/right turn steering scrap 3 and /164 marks, and is a steering method that performs direction change steering at the maximum steering angle to either the left or right for a certain period of time required to change direction. I do.

FIGS. 8A to 8C show examples of travel trajectories in modes 1 to 3.

However, in the figure, a car with a length of 0.65 m is 1.25 cm/
The figure shows the case where the vehicle travels at a speed of sec.

Generally, when driving a car by setting a planned route using the above-mentioned marks, when steering is performed to correct the direction, the 9th
As shown in the figure, JD is applied to the planned route at the same time as direction correction.
An offset ψ occurs, and unless this offset is corrected, the vehicle cannot run along the planned route.

Mode 1 is a steering method mainly for such direction correction, and specifically, as shown in Figure 8A, the first
As a step, steering is performed to correct the attitude angle θ, and the second
As a step, steering is performed to correct both the offset JDψ and the positional deviation Xo.

For example, as shown in the figure, the attitude angle θ with respect to the planned route of the car
In order to correct the deviation of 15° to the left and also correct the positional deviation XG of 10 CrrL to the left with respect to the planned route, steer to the left by 19.0° for a certain period of time, then steer left and right by 12.1° each. All you have to do is to alternately steer each wheel for a certain period of time.
This allows the vehicle to travel along a predetermined route.

It has been experimentally confirmed that by performing such steering, bunching of the steered wheels can be prevented without special preventive measures, and stable travel guidance can be achieved.

Mode 2 is a case where only the positional deviation is corrected as shown in Figure 8. Similar to the second stage of steering in the case of mode 1, the steering angle corresponding to the positional deviation is sequentially adjusted to the left and right. The vehicle is steered for a certain period of time, but in this case, if there is an initial deviation in attitude angle, it will remain as is after the steering.

Mode 3 is a steering method used when the car turns left or right, and holds the maximum steering angle for a certain period of time, but the time in this case is not necessarily the same as the steering time in modes 1 and 2 above, and when the car turns left or right. Or set to the time required to turn right.

It is possible to drive the car along a planned route by combining the modes explained above, but each of these modes is different from a control system that switches forward and reverse steering for a fixed period of time, such as mode 2. , and a variable steering time control system that performs steering in one direction such as mode 3, and can be obtained by appropriately combining these.

Next, a device that performs steering control according to the above will be described.

The above-mentioned Q value for detecting the posture angle, shape eigenvalue S and area measurement value for recognizing the shape and size of the mark are the area Aa of the figure used as the mark, the maximum width AX of the projected figure, and its maximum Height A7, and width A between the X coordinate of the point with the maximum height of m and the minimum value on the X axis of the projected figure
, all can be measured by detecting .

Thus, the device for performing these detections can be intercepted as shown in FIG.

In the equipment shown in the figure, the IT installed on the vehicle is
The V camera images the mark M placed on the road, and the video signal is sent to the scanning line (Y-axis direction) in the comparator circuit ■.
The output for each sample point above is compared with the slice level voltage and converted into a binary signal depending on the brightness or darkness of the sample point.

In the AND circuit, 2 sent from the comparison circuit ■
When the value signal is "1", that is, when there is a signal indicating the presence of a figure at a sample point on the scanning line, a clock pulse is sent to the counter ■, and the counter ■ generates a clock pulse for each scanning line. The numbers are sequentially counted and sent to the adder, comparison circuit H, and NOR circuit via the storage device (2).

The adder sequentially adds the clock pulses of the scanning lines of the (1) frame, stores it in the storage device H, and calculates the total number of pulses, thereby obtaining a signal corresponding to the area Aa of the figure.

The comparison circuit (■) compares the number of pulses of a certain scanning line sent from the storage device (■) with the number of pulses of the previous scanning line already stored in the storage device (■), and determines whether the number of pulses sent is larger. In this case, the contents of the memory device ■ are rewritten to the number of pulses sent, and in this way, the number of pulses of the scanning line of one frame is compared to find the maximum number of pulses, and the number of pulses can be used to form the projected figure. The maximum height is A.

In addition, in the NOR circuit, a signal is sent to the counter H only when the signal of each scanning line sent from the storage device ■ contains a pulse, and By calculating the total number of scanning lines, the total number of scanning lines becomes the maximum width Ax of the projected figure.

Furthermore, when comparing the number of pulses stored in memory device ■ and memory device ■ in comparator circuit ■, if the number of pulses in memory device By sending the contents to the storage device (2), the width A is stored in the storage device (2).

After determining the area Aa, maximum width AX, maximum height A9, and width A of the figure in this way, the memory devices n, m, rv and the counter ■ are reset by the frame pulse, and the same measurements are carried out thereafter. Repeat.

Measuring the position of the center of gravity of the mark using equation (3) above for determining the positional deviation of the vehicle can be easily performed using existing equipment, so it will not be described in detail here.

Aas AX obtained by the apparatus shown in FIG.

Based on A and A, the Q value and shape eigenvalue S can be easily calculated using equations (1) and (5), and the position of the center of gravity of the mark using equation (3) can also be calculated using existing equipment. Since it can be measured, the vehicle can be driven along the planned route by performing angle and position correction steering according to the angular deviation and positional deviation obtained from them, and the shape eigenvalue S and the area measurement value can be obtained. By steering the vehicle to turn left or right based on the judgment information, it is possible to cause the vehicle to travel in the desired direction.

FIG. 11 shows the configuration of a control device that controls the drive of a servo motor for steering based on the angular deviation, positional deviation, and mark type as judgment information obtained by the device shown in FIG. 10 described above. It is something.

In this device, the mode determination circuit is provided with a mark type based on the shape eigenvalue, area measurement value, etc., and determines which of the modes 1 to 3 is the mode corresponding to the mark type, For example, if the mark type is a /161 triangular mark in Figure 1,
The mode determination circuit determines that the mode 1 steering method will be used, and instructs the steering pattern generator to make a determination.

On the other hand, the sign determination circuit (2) and the river, to which the angular deviation and positional deviation are respectively given, detect the sign difference of the angular deviation and positional deviation in order to determine whether to steer left or right, Each deviation is sent to the steering pattern generator along with the detection results.

The steering pattern generation device includes a steering pattern generation circuit for each of the modes 1 to 3, selects the generation circuit of the specified mode from the mode determination circuit, and selects the generation circuit of the specified mode from the mode determination circuit.
, II, and at the same time determines the steering angle based on the angular deviation and positional deviation, and outputs this to the servo motor through the controller to perform the required steering control.

Note that the mode specified by the mode determination circuit is mode 3.
In this case, steering control is performed for a certain period of time at the maximum steering angle, regardless of the presence or absence of angular deviation and positional deviation.

FIG. 12 shows a schematic configuration of the entire apparatus implementing the present invention, and the recognition section has the configuration shown in FIG. 10, and this recognition section detects marks by the ITV camera. and sends the angular deviation based on the Q value, the positional deviation based on the center of gravity position, and the judgment information based on the shape eigenvalue and the area measurement value to the control unit, and the control unit and the steering unit have a configuration as shown in FIG. Based on the information from the recognition unit, the control unit sends a signal for necessary bundle operation to the servo motor of the steering unit, and further sends signals for accelerator and brake operation to the drive/brake unit of the vehicle. to operate the drive/brake system.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the arrangement of marks suitable for setting a scheduled route in the present invention and the angular deviation of the vehicle, Fig. 2 is a front view of the ITV camera field of view of the car in Fig. 1, and Fig. 3 is an explanatory diagram regarding measurement of Q value and shape eigenvalue, etc., Figure 4 is a diagram showing an example of calculation of Q value, Figure 5 is a front view of ITV camera field of view to explain positional deviation, and Figure 6 is shape. Diagrams for eigenvalues, Figure 7 is an explanatory diagram for an example of a mark, Figure 8 A to C are explanatory diagrams for travel routes when steering control is performed in modes 1 to 3, and Figure 9 is an attitude angle diagram. An explanatory diagram of the offset that occurs in the case of correction,
FIG. 10 is a block configuration diagram of a device that performs mark recognition, FIG. 11 is a block configuration diagram of a device that performs steering control based on the present invention, and FIG. 12 is a schematic block configuration diagram of the entire device. .

Claims (1)

[Claims] 1 The vehicle is intermittently provided with angular information regarding its attitude angle relative to the planned route, positional information regarding positional deviation, and information on whether to turn right or left, etc., using marks attached along the above-mentioned planned route, and each piece of intermittent information is When running along the planned route by correcting the route, the steering method is to use either the left or right to correct the attitude angle, and the necessary steering angle at a constant time, as well as to correct the positional deviation. Mode 1, in which steering is performed alternately on the left and right sides for a constant time and the same required steering angle on the left and right sides, and Mode 2, in which steering is performed alternately on the left and right sides for a constant time and the same required steering angle on the left and right sides to correct only the positional deviation. , either left or right for direction change, and mode 3, which performs steering for a certain period of time required for direction change at the maximum steering angle, and selects the required mode based on the above judgment information. 1. A steering method for an automatic transportation vehicle, characterized in that the vehicle is steered with a steering amount according to angle information and position information.