JP2020140424A - Transport vehicle and steering control program for transport vehicle - Google Patents

Abstract

To provide a transport vehicle that can stably travel even on a curved road, and a steering control program for the transport vehicle.SOLUTION: A distance Lip of virtual origins Cf and Cr with respect to a guide sensor 4 is set shorter when a traveling path is curved than when it is linear. As the distance Lip is longer, a steering angle θv becomes smaller even if deviation amounts df and dr are the same, so that the vehicle can travel stably on a straight traveling path. On the other hand, the shorter the distance Lip is, the larger angles θf and θr formed for calculating a turning center C with respect to the deviation amounts df and dr are, and the smaller a turning radius from the turning center C to each rotation axis 3c is. As a result, even if the deviation amounts df and dr are the same, the steering angle θv becomes large, so that a followability on a curved traveling path is improved. Therefore, stable running can be realized even on a curved running road.SELECTED DRAWING: Figure 3

Description

The present invention relates to an automated guided vehicle and a steering control program for an automated guided vehicle, and more particularly to an automated guided vehicle and an automated guided vehicle that can stably travel even on a curved traveling path.

Patent Document 1 discloses a transport vehicle 100 that lifts the lifter 140 to lift the pallet 200 after entering below the pallet 200, and unmannedly transports the work 280 placed on the pallet 200 together with the pallet 200. ing. The transport vehicle 100 protrudes downward from the lower surface of the pallet 200 and enters the lower part of the pallet 200 along the bracket 230 extending so as to penetrate the center line of the pallet 200. Specifically, the automatic guided vehicle 100 detects the bracket 230 by the laser sensor 150 provided on the upper surface of the vehicle body 110, performs steering control so that the bracket 230 is located at the center of the vehicle body 110, and lowers the pallet 200. Enter into.

Such steering control is performed as follows (see FIG. 6 of Reference 1). First, two virtual origins VP1 and VP3 are set behind the laser sensor 150 and on the vehicle width direction center line CL of the vehicle body 110. Next, the turning center AR of the vehicle body 110 is calculated based on the virtual origins VP1 and VP3 and the distance (deviation amount) LZS1 and LZS3 from the vehicle body center CL measured by the laser sensor 150 to the bracket 230. Steering control is performed by rotating each rotation axis in a direction orthogonal to a straight line connecting the rotation center AR and the rotation axis of each traveling device 120.

JP-A-2017-228158

However, if the virtual origins VP1 and VP3 are set so that the guided vehicle 100 travels along the bracket 230 formed in a straight line, stable traveling can be performed on a straight traveling road, but steering control is performed on a curved traveling road. A follow-up delay occurred, and in some cases, the transport vehicle 100 was deviated from the traveling path. This is because the follow-up delay inevitably occurs when the angle of the vehicle body 110 is changed after the steering control.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a transport vehicle capable of stable traveling even on a curved traveling road and a steering control program for the transport vehicle.

In order to achieve this object, the transport vehicle of the present invention includes a vehicle body, a plurality of rotating shafts rotatably arranged on the vehicle body, and a plurality of steering means for individually steering the plurality of rotating shafts. A guide sensor that includes wheels attached to the plurality of rotating shafts via axles, driving means for rotationally driving the wheels, and a guide sensor that can detect a guide indicating a traveling path, and the carrier vehicle. Steering control that calculates the turning center based on the amount of deviation detected by the guide sensor and calculates the steering angles of the plurality of steering means based on the turning center so as to travel along the guide. The guide sensors are provided at least two places in front of and behind the vehicle when the traveling direction of the vehicle body is set as the vehicle length, and the positions of the guides with respect to the vehicle width center of the vehicle body at each of the two front and rear locations. The steering control means provides virtual origins for calculating the turning center on the vehicle width center line of the vehicle body for each of the two front and rear guide sensors. The distance of the virtual origin with respect to the guide sensor is set shorter when the traveling path is curved than when it is linear.

Further, the steering control means is based on an integrated value obtained by further integrating the difference value between the current detection value and the previous detection value of the deviation amount of the guide position detected by the guide sensor into the integrated value up to the previous detection. The turning center is calculated.

The steering control program for a carrier vehicle of the present invention includes a vehicle body, a plurality of rotating shafts rotatably arranged on the vehicle body, a plurality of steering means for individually steering the plurality of rotating shafts, and the steering means thereof. The steering control is executed on the computer for a transport vehicle provided with a computer for steering and controlling the wheels, wheels attached to the plurality of rotating shafts via axles, and driving means for rotating the wheels. The transport vehicle is provided with a guide sensor capable of detecting a guide indicating a traveling path, and the guide sensor is provided at least two places before and after when the traveling direction of the vehicle body is the vehicle length. The amount of deviation of the guide position with respect to the vehicle width center of the vehicle body is detected at two locations before and after the guide, and the steering control program is such that the carrier vehicle travels along the guide. A turning center calculation step that calculates the turning center based on the amount of deviation detected by the guide sensor, and a steering angle calculation step that calculates the steering angles of the plurality of steering means based on the turning center calculated in that step. The computer is made to execute a steering control step that executes steering control based on the steering angle calculated in that step, and the turning center calculation step is a deviation of the position of the guide detected by the guide sensor. The turning center is calculated based on the integrated value obtained by further integrating the difference value between the current detection value and the previous detection value of the quantity into the integrated value up to the previous detection.

According to the automatic guided vehicle of the present invention, virtual origins for calculating the turning center are provided on the vehicle width center line of each of the two front and rear guide sensors, and the distance of the virtual origin with respect to the guide sensors is the traveling path. Is set shorter when is curved than when is linear. Here, the longer the distance between the virtual origin and the guide sensor, the smaller the angle for calculating the turning center with respect to the amount of deviation detected by the guide sensor, and the larger the turning radius from the turning center to each rotation axis. Therefore, as the distance between the virtual origin and the guide sensor becomes longer, the steering angle becomes smaller even if the deviation amount is the same, so that the linear traveling path can be stably traveled. On the other hand, the shorter the distance between the virtual origin and the guide sensor, the larger the angle for calculating the turning center with respect to the deviation amount, and the smaller the turning radius from the turning center to each rotation axis. Therefore, the shorter the distance between the virtual origin and the guide sensor, the larger the steering angle even if the amount of deviation is the same, so that the followability on a curved traveling path is improved. Therefore, stable running can be realized even on a curved running road.

By the way, when the calculation of the turning center is performed based only on the current detection value of the deviation amount of the guide position, if the detection position of the guide varies due to the influence of noise or the like, the calculated turning center varies greatly each time. It ends up. Then, as a matter of course, the steering angle also varies, so the guided vehicle repeats small vibrations. That is, stable running is not possible. Such vibration becomes more pronounced as the distance between the virtual origin and the guide sensor becomes shorter. This is because the shorter the distance between the virtual origin and the guide sensor, the closer the turning center is to the vehicle body and the smaller the turning radius.

On the other hand, according to the transport vehicle and the steering control program of the transport vehicle of the present invention, the difference value between the current detection value and the previous detection value of the deviation amount of the guide position detected by the guide sensor is set up to the time of the previous detection. The turning center is calculated based on the integrated value further integrated with the integrated value. Therefore, even if the detection position of the guide varies, the calculated variation in the turning center can be suppressed as much as possible. That is, the steering angle can be stabilized and the guided vehicle can be stably driven along the guide. In particular, such a configuration is effective when the distance between the virtual origin and the guide sensor is short.

(A) is a side view of the automatic guided vehicle according to the embodiment of the present invention, and (b) is a top view of the automatic guided vehicle seen from the direction of arrow Ib in FIG. 1 (a). It is a block diagram which shows the electric structure of an automatic guided vehicle. It is a flowchart which shows the main process. (A) is a flowchart showing curve processing, and (b) is a diagram for explaining integration of difference values. It is a graph for comparing the current detection value and the integrated value of the deviation amount.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, the configuration of the automatic guided vehicle 1 in the present embodiment will be described with reference to FIG. FIG. 1A is a side view of the automatic guided vehicle 1 according to the embodiment of the present invention, and FIG. 1B is a top view of the automatic guided vehicle 1 as viewed from the direction of arrow Ib in FIG. 1A. Is. The direction of the arrow F in FIG. 1 is the traveling direction of the automatic guided vehicle 1. The automatic guided vehicle 1 is a vehicle on which a transported object (not shown) is placed and travels according to a magnetic guide G made of magnetic tape installed on a traveling path, and is a vehicle body 2 having a rectangular shape in a top view and a traveling device. 3 and a guide sensor 4. Since the other configurations of the automatic guided vehicle 1 are known, the description thereof will be omitted.

The traveling device 3 is a device for traveling the automatic guided vehicle 1, and is arranged below the vehicle body 2 at four corners in the top view of the automatic guided vehicle 1. Each traveling device 3 has an axle 3a, a pair of wheels 3b arranged at both ends of the axle 3a, and a rotating shaft for steerably connecting the axle 3a and the vehicle body 2 around the upper surface of the vehicle body 2. 3c and 3c are arranged. The traveling device 3 is further provided with a rotary drive device 3d (see FIG. 2) for rotationally driving the wheels 3b and a steering drive device 3e (see FIG. 2) for steering the rotary shaft 3c. For each traveling device 3, the steering angle θv for the automatic guided vehicle 1 to travel along the magnetic guide G is calculated, and the steering drive device 3e steers the rotation shaft 3c so that the wheels 3b face the steering angle θv. To do.

The guide sensor 4 is a wide sensor that detects the position of the magnetic guide G by detecting the magnetic force generated from the magnetic guide G, and is the lower part of the vehicle body 2 in the length direction in the top view of the automatic guided vehicle 1. It is arranged at the center of both ends on the side and the width direction, respectively. In the automatic guided vehicle 1 of the present embodiment, either the length direction side or the width direction side of the vehicle body 2 is set as the traveling direction, and the magnetic guide G is detected by the guide sensors 4 at two locations in the front-rear direction in the traveling direction. To. Hereinafter, the side in the traveling direction of the automatic guided vehicle 1 will be referred to as "front side", and the side facing the traveling direction will be referred to as "rear side".

The steering angle θv of each traveling device 3 is calculated based on the deviation amounts df and dr, which are deviations between the center position of the guide sensor 4 and the magnetic guide G on the vehicle width direction side detected by the front and rear guide sensors 4. Rudder. Specifically, as shown in FIG. 1 (b), first, the front and rear guide sensors 4 are on the center line Lc in the vehicle width direction, and the distance from the center position in the top view of the front guide sensor 4 to the rear. The virtual origin Cf is set at the position where the Lip is moved, and the virtual origin Cr is set at the position where the guide sensor 4 on the rear side is moved by a distance Lip from the center position in the upper view.

Then, it is orthogonal to the detection position Gf of the magnetic guide G on the front guide sensor 4, that is, the line segment connecting the virtual origin Cf and the position corresponding to the deviation amount df from the center line Lc, and heads toward the rear side of the vehicle body 2. A straight line is drawn, and it is orthogonal to the detection position Gr of the magnetic guide G on the rear guide sensor 4, that is, the position corresponding to the deviation amount dr from the center line Lc and the line segment connecting the virtual origin Cr, and is in front of the vehicle body 2. Draw a straight line toward the side. The intersection of these straight lines is defined as the turning center C.

An arcuate turning path R is generated centering on the turning center C and passing through the center of the rotating shaft 3c of the traveling device 3. Of the tangential directions of the turning path R at the center of the rotating shaft 3c, the angle θv formed by the direction V on the traveling direction side of the automatic guided vehicle 1 is defined as the steering angle θv. Note that, in FIG. 1B, only the steering angle θv of the traveling device 3 in the upper right of the top view of the automatic guided vehicle 1 is shown, but the calculation method of the steering angle θv of the other traveling device 3 is also the same. The illustration is omitted.

By the way, since the guide sensor 4 is arranged at a position away from the traveling device 3, the steering angle θv is calculated from the deviation amounts df, dr and the virtual origins Cf, Cr, and the rotation shaft 3c is set by the steering drive device 3e. Even if the vehicle is steered, the deviation amounts df and dr actually decrease only after the automatic guided vehicle 1 has traveled for a while. Due to such a time lag, a follow-up delay may occur. In particular, when traveling on a curved traveling path, such a follow-up delay occurs remarkably, and further, depending on the curvature of the traveling path or the like, the magnetic guide G deviates from the guide sensor 4 having a finite width, so that the traveling path is deviated. It may not be able to follow, and as a result, it may deviate from the driving path.

Here, the angle formed by the line segment connecting the virtual origin Cf and the turning center C and the line segment connecting the virtual origin Cr and the turning center C is the angle θf formed by the center line Lc and the line segment GfCf and the center. It is equal to the sum of the angle θr formed by the line Lc and the line segment GrCr. Therefore, the position of the turning center C is set to a position corresponding to the size of the angles θf and θr formed, that is, a position corresponding to the size of the deviation amounts df and dr and the positions of the virtual origins Cf and Cr.

Therefore, even if the magnitudes of the deviation amounts df and dr are the same, the closer the virtual origins Cf and Cr are to the guide sensor 4 (that is, the smaller the distance Lip), the larger the angles θf and θr formed, and the turning center C is unmanned. Approaching the carrier 1. In this case, the distance between the turning center C and the center of the rotating shaft 3c, that is, the turning radius of the turning path R becomes small, and thus the steering angle θv becomes large. Therefore, the closer the virtual origins Cf and Cr are to the guide sensor 4, the sharper the automatic guided vehicle 1 can turn.

On the other hand, when the virtual origins Cf and Cr are brought closer to the guide sensor 4 on a straight running path, the angles θf, θr and the steering angle θv formed by even a slight change in the deviation amounts df and dr change significantly. That is, since it takes time to steer, the followability is lowered, and there is a possibility that the vehicle will meander on a straight running path.

Therefore, in the present embodiment, when the automatic guided vehicle 1 is traveling on a curved traveling path, the distance Lip is made smaller than that when traveling on a straight traveling path, and the virtual origins Cf and Cr are guided. By bringing it closer to the sensor 4, the steering followability is improved.

Next, the electrical configuration of the automatic guided vehicle 1 will be described with reference to FIG. FIG. 2 is a block diagram showing an electrical configuration of the automatic guided vehicle 1. The automatic guided vehicle 1 includes a CPU 10, a flash ROM 11, and a RAM 12, each of which is connected to an input / output port 14 via a bus line 13. The guide sensor 4, the rotation drive device 3d, and the steering drive device 3e described above are connected to the input / output port 14, respectively. The guide sensor 4, the rotation drive device 3d, and the steering drive device 3e are arranged four by each with respect to the automatic guided vehicle 1, but in FIG. 2, one guide sensor 4, the rotation drive, and each of them are collectively driven. It is represented as a device 3d and a steering drive device 3e.

The CPU 10 is an arithmetic unit that controls each unit connected to the bus line 13 and the input / output port 14. The flash ROM 11 is a rewritable non-volatile memory, and stores the control program 11a and the map data 11b. The control program 11a is a program that causes the CPU 10 to execute the main process of FIG. 3 and the curve process of FIG. The map data 11b is a data area in which information about the travel path of the automatic guided vehicle 1 is stored, and the shape (straight line or curve) of the travel path for each point is stored together with the map information of the travel path.

The RAM 12 is a memory for the CPU 10 to rewritably store various work data, flags, and the like when the control program 11a or the like is executed. The rotation center memory 12a in which the rotation center C is stored and the distance Lip are stored. The virtual origin distance memory 12b and the deviation amount df, dr (hereinafter, also referred to as "the current detection value of the deviation amount") detected by the guide sensor 4 are stored. The deviation amount memory 12c and the previous deviation amount df, dr. The amount of deviation in which the value (hereinafter also referred to as the "previously detected value of the amount of deviation") is stored. The amount of deviation between the previous value memory 12d and the amount of deviation of the current value memory 12c. The deviation amount difference value memory 12e in which the difference value from the previously detected value is stored, the difference integrated value memory 12f in which the integrated value obtained by integrating the difference values of the deviation amount difference value memory 12e is stored, and the output value memory 12g Provided.

The output value memory 12g is a memory in which values corresponding to the deviation amounts df and dr used for calculating the turning center C and the steering angle θv are separately stored. The details will be described later, but when traveling on a straight traveling path, a value corresponding to the current detection value of the deviation amount detected by the guide sensor 4 is stored in the output value memory 12g, and the curved traveling path is displayed. When traveling, a value corresponding to the above-mentioned integrated value is stored.

The deviation amount current value memory 12c, the deviation amount previous value memory 12d, the deviation amount difference value memory 12e, the difference integrated value memory 12f, and the output value memory 12g are the values corresponding to the guide sensor 4 on the front side and the values on the rear side. The values corresponding to the guide sensor 4 are stored in a distinguishable manner.

Next, the main process executed by the CPU 10 of the automatic guided vehicle 1 will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing a flowchart of the main process. The main process is repeatedly executed immediately after the power of the automatic guided vehicle 1 is turned on.

First, in the main process, the deviation amounts df and dr are acquired from the detection positions Gf and Gr detected from the front and rear guide sensors 4, respectively, and the deviation amount is stored in the current value memory 12c (S1). In the main processing of FIG. 3 and the curve processing of FIG. 4 below, the processing related to the amount of deviation acquired from the guide sensor 4 is performed for each of the front and rear guide sensors 4, but the processing contents are front and back. Since the same applies to the guide sensors 4 of the above, the same applies to the front and rear guide sensors 4 unless otherwise specified.

After the processing of S1, the current travel point detected by the known position detection device (not shown) mounted on the automatic guided vehicle 1 is referred to by the map data 11b, and the shape of the corresponding travel path is acquired (). S2). After the processing of S2, it is confirmed whether the shape of the acquired traveling path is curved (S3). In the process of S3, when the shape of the acquired travel path is curved (S3: Yes), "500 mm" is set in the virtual origin distance memory 12b (that is, the distance Lip in FIG. 1) (S4), and FIG. The curve processing described later is performed (S5).

On the other hand, when the acquired shape of the travel path is not curved, that is, when the shape of the travel path is linear (S3: No), first, 0 is set in the difference integrated value memory 12f (S6). Although the details will be described later, when traveling on a curved traveling path, the steering angle θv is calculated according to the integrated value of the differential integrated value memory 12f. This integrated value is accumulated only when traveling on a curved traveling path, so when traveling on a straight traveling path, when traveling on the previous curved traveling path, the integrated value is accumulated. It remains the integrated value of. Therefore, when the traveling path is straight, by initializing the integrated value of the difference integrated value memory 12f to 0, the integrated value in the previous curved traveling path becomes the integrated value in the next curved traveling path. The steering angle θv is not affected.

After the processing of S6, "1000 mm" is set in the virtual origin distance memory 12b (that is, the distance Lip in FIG. 1) (S7), and the value of the deviation amount current value memory 12c is multiplied by a predetermined gain value Gp. It is saved in the output value memory 12 g (S8). In the present embodiment, the gain value Gp is exemplified by "3.0", but it may be 3.0 or more or 3.0 or less.

That is, the virtual origins Cr and Cf when traveling on a straight traveling path are farther from the guide sensor 4 than when traveling on a curved traveling path. As a result, even if the deviation amounts df and dr are the same, the turning radius calculated in the process of S10 described later becomes large, and the steering angle θv calculated in the process of S11 becomes small. Therefore, since the amount of change in the steering angle θv can be reduced, steering is stable and a straight traveling path can be stably driven.

On the other hand, the positions of the virtual origins Cr and Cf when traveling on a curved traveling path are closer to the guide sensor 4 than when traveling on a straight traveling path. As a result, the steering angle θv can be increased even if the deviation amounts df and dr are the same. Due to such a large steering angle θv, it is possible to accelerate the reduction of the deviation amounts df and dr, so that the followability on a curved traveling path can be improved. As a result, it is possible to run stably even on a curved running road.

By the way, the current detection value of the deviation amount may suddenly vary due to noise caused by local distortion of the magnetic guide G, magnetic failure, or the like. When traveling on a curved traveling path, the positions of the virtual origins Cr and Cf are close to the guide sensor 4, so the steering angle θv vibrates greatly due to the variation in the detected value of the deviation amount this time, and the behavior of the automatic guided vehicle 1 Becomes unstable.

Therefore, when traveling on a curved traveling path by the curve processing of S5, the integrated value obtained by integrating the difference value between the current detection value of the deviation amount and the previous detection value of the deviation amount is the turning center C and the steering angle θv. By setting the deviation amounts df and dr used in the calculation of the above, the variation of the deviation amounts df and dr is suppressed as much as possible, and the curved traveling path is made to travel more stably. Such curve processing will be described with reference to FIG.

FIG. 4A is a diagram showing a flowchart of curve processing, and FIG. 4B is a diagram for explaining integration of difference values. In the curve processing, first, the difference value between the value of the deviation amount current value memory 12c and the value of the deviation amount previous value memory 12d is calculated and stored in the deviation amount difference value memory 12e (S20). After the processing of S20, the difference value is integrated into the difference integrated value memory 12f by the processing of S21 to S24 described later, and the integrated value of the difference integrated value memory 12f is multiplied by a predetermined gain value Gp. It is saved in the output value memory 12 g (S25). The gain value Gp in the processing of S25 may be the same as or different from the gain value Gp in the processing of S8 of FIG.

Next, the processes of S21 to S24 will be described with reference to FIGS. 4 (b) and 5. In FIG. 4B, the position of the center line Lc is set to 0 as the positional relationship of the guide sensor 4 on the vehicle width direction side, and the right side in the top view of the guide sensor 4 is positive and the left side is negative. FIG. 4B shows an example (patterns 1 to 4) of the transition between the current value of the four deviation amounts and the previous value of the deviation amount, and the previous value of the deviation amount is represented by a single circle and the deviation amount is shown. This time value is represented by a double circle. In the processing of S21 to S24, the difference value calculated in the processing of S20 is integrated into the difference integrated value memory 12f, and the conditions for the integration are the positive / negative of the current detection value of the deviation amount of the deviation amount memory 12c. It is based on the positive / negative of the difference between the current detection value of the deviation amount and the previous detection value of the deviation amount.

Specifically, when the current detection value of the deviation amount memory 12c is positive and the difference value of the deviation amount difference value memory 12e is also positive (S21: Yes and S22: Yes), that is, FIG. 4 ( In the case of pattern 1 in b), it is determined that the amount of deviation has increased, and in such a case, the difference value is integrated into the difference integrated value memory 12f by the processing of S23.

Further, when the current detection value of the deviation amount is negative and the difference value is negative (S21: No and S24: Yes), that is, in the case of pattern 3 in FIG. 4B, the deviation amount is the same as in pattern 1. Is determined to be expanding, so the difference value is integrated into the difference integrated value memory 12f by the processing of S23.

On the other hand, when the current detection value of the deviation amount is positive and the difference value is negative (S21: Yes and S22: No), that is, in the case of pattern 2 in FIG. 4B, the current detection value of the deviation amount is Although it is located on the positive side, it is determined that the amount of deviation is reduced. In such a case, the process of S23 is skipped and the value of the difference integrated value memory 12f is kept. Similarly, when the current detection value of the deviation amount is negative and the difference value is positive (S21: No and S24: No), that is, in the case of pattern 4 in FIG. 4B, the deviation amount is set to the center line Lc. Since it is determined that the image is shrinking in the approaching direction, the process of S23 is skipped and the value of the difference integrated value memory 12f is kept. Here, with reference to FIG. 5, the current detection value of the deviation amount and the integrated value of the difference integrated value memory 12f are compared.

FIG. 5 is a graph for comparing the current detection value and the integrated value of the deviation amount. In FIG. 5, the integrated value is represented by a solid line, the current value of the deviation amount is represented by a broken line, the horizontal axis represents the time axis, and the vertical axis represents the magnitude of the current detection value and the integrated value of the deviation amount. ..

First, from time 0 to time t1, the current detection value of the amount of deviation increases. In such a case, since the current detection value of the deviation amount is positive and the difference value also shifts to the positive side, it corresponds to pattern 1 in FIG. 4B, and the integrated value is integrated.

After that, at time t1, the current detection value of the deviation amount is suddenly reduced. In such a case, while the current detection value of the deviation amount is positive, the difference value shifts to the negative side, so that it corresponds to pattern 2 in FIG. 4B, and the integrated value is kept.

From time t1 to time t2, the current detection value of the deviation amount increases again, which corresponds to pattern 1. Therefore, the integrated value is integrated, and from time t2 to time t3, the current detection value of the deviation amount is positive. On the other hand, when the difference value decreases, it corresponds to the pattern 2, so that the integrated value is kept.

At time t3, the current detection value of the deviation amount suddenly increases. In such a case, since the current detection value of the deviation amount is positive and the difference value shifts to the positive side, it corresponds to pattern 1 in FIG. 4B, and the integrated value is integrated.

Since the current detection value of the deviation amount decreases from time t4 to t5, it corresponds to pattern 3 in FIG. 4B, so the integrated value is integrated, and the deviation amount is detected this time from time t5 to t6. Since the difference value increases while the value is negative, it corresponds to pattern 4 in FIG. 4B, and the integrated value is kept.

That is, when the deviation amount is expanded to the positive side or the negative side, the difference value is integrated in the difference integrated value memory 12f, so that the value of the output value memory 12g calculated from the value of the difference integrated value memory 12f is also integrated. The steering angle θv calculated by the value of the output value memory 12g is also integrated. As a result, the automatic guided vehicle 1 is steered in a direction that reduces the amount of deviation, so that it can follow a curved traveling path.

On the other hand, in the state where the deviation amount is reduced, the value of the difference integrated value memory 12f is kept. Therefore, even if the current detection value of the deviation amount vibrates left and right due to noise and the deviation amount is repeatedly expanded and contracted, the integration of the difference value of the difference integrated value memory 12f in the direction of reducing the deviation amount is suppressed. .. As a result, the vibration of the integrated value of the differential integrated value memory 12f is suppressed, so that the vibration of the steering angle θv is suppressed as much as possible, and the automatic guided vehicle 1 can be stably driven.

Return to FIG. 4 (a). After the processing of S25, the process returns to the main processing of FIG.

Return to FIG. After the processing of S5 and S8, the value of the deviation amount current value memory 12c is stored in the deviation amount previous value memory 12d (S9). After the processing of S9, the virtual origins Cf and Cr corresponding to the distance Lip of the virtual origin distance memory 12b and the values obtained by converting the values of the output value memory 12g into the deviation amounts df and dr have been described with reference to FIG. The turning center C is calculated by the method and stored in the turning center memory 12a (S10).

After the processing of S10, the steering angle θv is calculated from the turning center C of the turning center memory 12a and the center of the rotating shaft 3c of each traveling device 3, and each steering driving device 3e is steered based on the steering angle θv. However, the rotary drive device 3d is operated to drive the automatic guided vehicle 1 (S11). After the process of S11, the process of S1 is repeated.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and it is easy that various improvements and changes can be made without departing from the spirit of the present invention. It can be inferred from.

In the above embodiment, the automatic guided vehicle 1 has been described as an example of the automatic guided vehicle, but the present invention is not necessarily limited to this, and for example, the present invention may be applied to a unit carrier or the like.

In the above embodiment, the control program 11a is stored in the flash ROM 11. However, the present invention is not necessarily limited to this, and the control program 11a may be stored and executed in a semiconductor memory other than the flash ROM 11 such as a RAM card, an optical disk such as a DVD, or a magnetic medium such as a hard disk drive. , The control program 11a may be stored in a server on the network (Internet, intranet, etc.), and the control program 11a may be downloaded from the server and executed.

In the above embodiment, a magnetic guide G made of magnetic tape is installed on the traveling path as a guide. However, the present invention is not necessarily limited to this, and for example, a bracket suspended along the travel path may be used as a guide on the ceiling above the travel path, or the travel path may be placed on the ceiling of the pallet into which the automatic guided vehicle 1 is embedded. A bracket suspended along the guide may be used as a guide. In such a case, instead of the guide sensor 4, an optical sensor (for example, a camera, an infrared sensor, a laser sensor, etc.) may be provided on the upper part of the vehicle body 2 and the position of the bracket may be detected by the optical sensor.

Further, the guide installed on the traveling path is not limited to the magnetic guide G made of magnetic tape, and the guide may be a white line painted on the traveling path. In such a case, the position of the white line may be detected by the above-mentioned optical sensor provided in the lower part of the vehicle body 2 instead of the guide sensor 4.

In the above embodiment, the difference integrated value memory 12f is initialized to 0 when traveling on a linear traveling path by the processing of S5 and S6 of FIG. However, the initial value of the integrated value is not limited to 0, and may be 0 or more or 0 or less. In particular, as the initial value of the difference integrated value memory 12f, the previous detection value of the deviation amount of the deviation amount previous value memory 12d may be set. As a result, the difference value is added to the previously detected value of the deviation amount, that is, the deviation amount immediately before switching to the curved traveling path, so that even if the traveling path is switched to the curved path with a large deviation amount, The automatic guided vehicle 1 can be steered smoothly.

Further, the timing for initializing the difference integrated value memory 12f is not limited to the case of traveling on a straight traveling path, and may be performed immediately after the traveling path is switched from a straight line to a curved line. , Regardless of whether it is straight or curved, it may be performed immediately after the shape of the traveling path is changed.

In the above embodiment, the distance Lip is set to 500 mm on the curved running path and 1000 mm on the straight running path by the processing of S3, S4, and S7 of FIG. However, the distance is not necessarily limited to this, and the distance Lip on the curved traveling path may be set to 500 mm or more, or 500 mm or less. Further, the distance Lip on the straight running path may be set to 1000 mm or more, or 1000 mm or less. Further, the distance Lip on the curved running path and the distance Lip on the straight running path may be the same length, and the distance Lip on the curved running path may be the same length as the distance Lip on the straight running path. It may be longer than the distance Lip.

In the above embodiment, in the straight traveling path, the turning center C and the steering angle θv are calculated based on the current detection value of the deviation amount by the processing of S8, and in the curved traveling path, the integrated value is calculated by the processing of S5. Based on this, the turning center C and the steering angle θv were calculated. However, the present invention is not necessarily limited to this, and even on a straight running road, the curve processing of S5 is executed instead of the processing of S8, and the turning center C and the steering angle θv are calculated based on the integrated values. Alternatively, even on a curved traveling path, the processing of S8 may be performed instead of the curve processing of S5, and the turning center C and the steering angle θv may be calculated based on the current detection value of the deviation amount.

In the above embodiment, in the curve processing of FIG. 4, when the deviation amount is expanding, the difference value is integrated into the difference integrated value memory 12f, and when the deviation amount is reduced, the difference integrated value memory 12f I kept the value. However, the present invention is not necessarily limited to this, and the processing of S21, S22, and S24 may be omitted, and the difference value may be integrated into the value of the difference integration value memory 12f even when the deviation amount is reduced.

1 Automatic guided vehicle (automated guided vehicle)
2 Body 3c Rotating shaft 3e Steering drive device (steering means)
3b Wheel 3a Axle 3d Rotation drive device (drive means)
10 CPU (computer)
11a Control program (steering control program)
12e deviation amount difference value memory (difference value)
12f Difference integrated value memory (integrated value)
C turning center Cf, Cr virtual origin G magnetic guide (guide)
S11 Steering control means, steering control step, steering angle calculation step S10 Turning center calculation step

Claims (6)

The vehicle body, a plurality of rotating shafts rotatably arranged on the vehicle body, a plurality of steering means for individually steering the plurality of rotating shafts, and the plurality of rotating shafts attached to the plurality of rotating shafts via axles. In a transport vehicle provided with a wheel and a driving means for rotating the wheel.
A guide sensor that can detect a guide indicating the driving path and
The turning center is calculated based on the amount of deviation detected by the guide sensor so that the guided vehicle travels along the guide, and the steering angles of the plurality of steering means are calculated based on the turning center. Equipped with a steering control means for steering control,
The guide sensors are provided at least two places in the front-rear direction when the traveling direction of the car body is the vehicle length, and detect the amount of deviation of the guide position with respect to the vehicle width center of the car body at the two places in the front-rear direction. To do
The steering control means provides virtual origins for calculating the turning center on the vehicle width center line of the vehicle body for each of the two front and rear guide sensors, and the distance of the virtual origin with respect to the guide sensors. Is a transport vehicle characterized in that the case where the traveling path is curved is set shorter than the case where the traveling path is straight. The steering control means said that the difference value between the current detection value and the previous detection value of the deviation amount of the guide position detected by the guide sensor is further integrated with the integrated value up to the previous detection, based on the integrated value. The transport vehicle according to claim 1, wherein the turning center is calculated. The vehicle body, a plurality of rotating shafts rotatably arranged on the vehicle body, a plurality of steering means for individually steering the plurality of rotating shafts, and the plurality of rotating shafts attached to the plurality of rotating shafts via axles. In a transport vehicle provided with a wheel and a driving means for rotating the wheel.
A guide sensor that can detect a guide indicating the driving path and
The turning center is calculated based on the amount of deviation detected by the guide sensor so that the guided vehicle travels along the guide, and the steering angles of the plurality of steering means are calculated based on the turning center. Equipped with a steering control means for steering control,
The guide sensors are provided at least two places in the front-rear direction when the traveling direction of the car body is the vehicle length, and detect the amount of deviation of the guide position with respect to the vehicle width center of the car body at the two places in the front-rear direction. To do
The steering control means said that the difference value between the current detection value and the previous detection value of the deviation amount of the guide position detected by the guide sensor is further integrated with the integrated value up to the previous detection, based on the integrated value. A transport vehicle characterized in that it calculates the turning center. When the deviation amount of the guide position is in the positive direction with respect to the vehicle width center, the steering control means is the difference if the difference value between the current detection value and the previous detection value of the deviation amount is positive. The turning center is calculated based on the integrated value obtained by further integrating the value to the integrated value up to the previous detection, while the difference value between the current detection value and the previous detection value of the deviation amount is negative. The transport vehicle according to claim 2 or 3, wherein the turning center is calculated based on the integrated value up to the time of the previous detection. When the shape of the traveling path is switched from a straight line to a curved line, the steering control means sets the previously detected value of the deviation amount of the guide position as the integrated value up to the previous detection. The transport vehicle according to any one of claims 2 to 4. A vehicle body, a plurality of rotating shafts rotatably arranged on the vehicle body, a plurality of steering means for individually steering the plurality of rotating shafts, a computer for steering and controlling the steering means, and the plurality of rotations. In a steering control program for a transport vehicle, which causes the computer to execute the steering control for a transport vehicle provided with wheels attached to the shafts via axles and drive means for rotating the wheels.
The guided vehicle is provided with a guide sensor capable of detecting a guide indicating a traveling path, and the guide sensor is provided at least two places before and after when the traveling direction of the vehicle body is taken as the vehicle length, and two places before and after the guide sensor. In each of the above, the amount of deviation of the position of the guide with respect to the vehicle width center of the vehicle body is detected.
The steering control program is such that the guided vehicle travels along the guide.
A turning center calculation step for calculating the turning center based on the amount of deviation detected by the guide sensor, and a turning center calculation step.
A steering angle calculation step for calculating the steering angles of the plurality of steering means based on the turning center calculated in that step, and a steering angle calculation step.
The computer is made to execute a steering control step that executes steering control based on the steering angle calculated in that step.
The turning center calculation step is based on an integrated value obtained by further integrating the difference value between the current detection value and the previous detection value of the deviation amount of the guide position detected by the guide sensor into the integrated value up to the previous detection. A steering control program for a transport vehicle, which calculates the turning center.

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