JP5280076B2 - Traverse attitude control device and traverse attitude control method for automated guided vehicle - Google Patents

Description

The present invention relates to an apparatus and a method for controlling the traverse posture of an automatic guided vehicle.

2. Description of the Related Art Various types of self-propelled automated guided vehicles (AGVs) for the purpose of automating logistics have been proposed in factories and the like. For example, an automated guided vehicle having a transverse mode in which the front and rear drive units move respectively on two parallel tracks has been developed. In such an automated guided vehicle, the wheels may slip during traversal or may receive some external impact, and the traveling speeds of the two drive units may not match. In such a state, it may interfere with traveling. For example, in Patent Document 1, a sensing device such as a rotary encoder is provided on the rotation center axis of the drive unit to detect the angular relationship between the drive unit and the vehicle body. Thus, the vehicle body posture is detected and feedback control is performed so that the vehicle body posture does not collapse.
JP-A-8-272443

  However, such a sensing device is expensive, and the manufacturing cost of the automatic guided vehicle increases.

The present invention has been made paying attention to such a conventional problem, and the traverse posture control device and traverse posture of an automatic guided vehicle that can reduce the manufacturing cost without complicating the device. An object is to provide a control method.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

The present invention provides a transverse mode in which a drive unit (11-1) provided on the front side of a vehicle and a drive unit (11-2) provided on the rear side move on different tracks (20-1, 20-2). A traverse attitude control device for an automated guided vehicle having a front drive unit (11-1) and a rear drive unit (11-2) passing simultaneously when the vehicle is in a correct attitude. Checkpoints (21-1 and 21-2) provided on the tracks (20-1 and 20-2) are connected to the front drive unit (11-1) and the rear drive unit (11-2). A traverse state estimation means (S2) for estimating the traverse state of the vehicle based on a time difference in which the vehicle passes, and based on the estimated traverse state , maintaining the speed of the preceding unit and speeding up the following unit Or keep the speed of the following unit Policy setting means (S4) for setting a correction policy for speed reduction of the preceding unit, and a unit for speeding up or following the following unit while maintaining the speed of the preceding unit based on the set correction policy Correction control means (S6, S7) for reducing the preceding unit while maintaining the above speed .

According to the present invention, the traverse state is estimated based on the time difference between the two drive units passing through the check point. Therefore, the traverse of the automatic guided vehicle can be performed without using an expensive sensing device such as a rotary encoder. The posture can be estimated .

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing an example of an automatic guided vehicle to which a traveling mode switching control device according to the present invention is applied. FIG. 1 (A) is a side view, and FIG. 1 (B) is a plan view of a drive unit seen from above. It is.

  Two drive units (a first drive unit 11-1 and a second drive unit 11-2) and four casters 12 are arranged at the lower part of the vehicle body 10. The first drive unit 11-1 and the second drive unit 11-2 basically have the same structure. Therefore, the drive unit 11 will be described when it is not necessary to distinguish between them.

  The drive unit 11 includes a drive wheel 11a, a trajectory detection sensor 11b, and a marker detection sensor 11c.

  An individual drive motor is connected to each drive wheel 11a. If the left and right drive wheels 11a rotate in the same direction, the vehicle moves forward or backward. If the rotational speed is given a phase difference, it is possible to travel on a curve. If the two drive wheels 11a are differentially rotated in opposite directions, they can turn around the support shaft 11d and change direction.

  The track detection sensor 11b detects a track laid on the floor surface. The trajectory detection sensor 11b is, for example, a magnetic sensor. In the present embodiment, three track detection sensors 11 b are arranged on the front side and the rear side of the drive unit 11. The drive unit 11 travels so that the track is always detected by the track detection sensor 11b.

The marker detection sensor 11c detects a marker laid near the track. In the present embodiment, check markers 21 provided at check points in particular (when the check markers need to be distinguished, branch numbers such as -1 and -2 are appropriately added, and there is no need to distinguish them. Are collectively referred to as a check marker 21) . The marker detection sensor 11c is a magnetic sensor, for example. Marker detection sensor 11 c provided in the first drive unit 11-1 in the forward direction is arranged on the outside of the track detection sensor 11b a rear side of the first drive unit 11-1. Marker detection sensor 11 c of the first drive unit 11-1 also detects a marker in normal forward-reverse mode and transverse mode. Marker detection sensor 11 c of the first drive unit 11-1, also a command of the marker of the marker and stop / pause command or the like for switching of the speed switching and driving mode is detectable. Marker detection sensor 11 c provided on the second drive unit 11-2 of rear side is disposed outside the track detection sensor 11b a front side of the second driving unit 11-2. The marker detection sensor 11c of the second drive unit 11-2 detects the marker in the transverse mode and does not detect the marker in the normal forward / reverse mode. Marker detection sensor 11 c of the second drive unit 11-2, command switching of detectable and is the velocity switching and driving mode the marker commands, such as stop / pause not detect.

  The caster 12 supports the weight of the vehicle and changes its direction following the moving direction of the vehicle.

  2A and 2B are diagrams showing the state of the drive unit when the automatic guided vehicle travels. FIG. 2A shows a forward / reverse mode state, and FIG. 2B shows a transverse mode state.

  In the forward / reverse mode, the drive wheels 11a of the first drive unit 11-1 and the second drive unit 11-2 are parallel to the vehicle body 10. In the forward / reverse mode, the first drive unit 11-1 and the second drive unit 11-2 travel along one track 20. The track detection sensor 11b in the forward direction detects the track 20 laid on the floor surface. In FIG. 2, the sensor in operation is painted black.

  In the transverse mode, the drive wheels 11a of the first drive unit 11-1 and the second drive unit 11-2 are orthogonal to the vehicle body 10. In the transverse mode, the first drive unit 11-1 and the second drive unit 11-2 travel along different tracks. That is, the first drive unit 11-1 travels along the track 20-1. The second drive unit 11-2 travels along the track 20-2.

  Here, the points of the invention will be described so that the present invention can be easily understood. In the conventional apparatus, when the automatic guided vehicle travels in a traverse mode in which a plurality of drive units move on different tracks, the drive wheels slip depending on the track state or receive some external impact, thereby driving two drives. Unit speed may not match. In such a case, as shown in FIG. 3, the vehicle body of the automatic guided vehicle moves in a slanting manner while being inclined. And when switching from the transverse mode to the forward / reverse mode, there is a possibility of getting out of orbit. Therefore, conventionally, a sensing device such as a rotary encoder is provided on the rotation center axis of the drive unit to detect the angular relationship between the drive unit and the vehicle body, thereby detecting the vehicle body posture and preventing each vehicle body posture from being disturbed. I was controlling the speed of the unit. However, such a sensing device is expensive, and the manufacturing cost of the automatic guided vehicle increases.

Accordingly, the present inventors provide a check point (check marker) at a position that is simultaneously detected by each drive unit if the vehicle body posture is not collapsed in the middle of the traverse track, and the preceding drive unit of the two drive units The traverse state is detected on the basis of the time difference from when the drive unit passes the checkpoint until the drive unit that follows passes the checkpoint. Then, the traverse posture is corrected by speeding up the trailing unit or speeding down the preceding unit. The present inventors have conceived of correcting the traverse posture of the automatic guided vehicle by such a simple method. Hereinafter, a specific apparatus / method for realizing such a technical idea will be described.

FIG. 4 is a main flowchart of the traverse posture control apparatus according to the present invention.

  The controller repeatedly executes the following processing every minute time (for example, 10 milliseconds) during the traversing mode.

  In step S1, the controller determines whether or not a traversing state has been detected. If not detected, the process proceeds to step S2, and if detected, the process proceeds to step S3.

  In step S2, the controller detects a traversing state. Specific contents will be described later.

  In step S3, the controller determines whether or not a correction policy has been set. If not set, the process proceeds to step S4, and if set, the process proceeds to step S5.

  In step S4, the controller sets a correction policy. Specific contents will be described later.

  In step S5, the controller determines whether or not the set correction policy is to speed up the succeeding unit. If the speed of the succeeding unit is increased, the process proceeds to step S6, and if not, the process proceeds to step S7.

  In step S6, the controller speeds up the succeeding unit and corrects the posture. Specific contents will be described later.

  In step S7, the controller reduces the speed of the preceding unit and corrects the posture. Specific contents will be described later.

  FIG. 5 is a flowchart showing a traverse state detection routine according to the present invention.

  In step S21, the controller determines whether or not the preceding unit has detected a check point (check marker). Until it is detected, the process is temporarily exited. When it is detected, the process proceeds to step S22.

  In step S22, the controller counts up the elapsed time since the preceding unit detected the check point (check marker). As described above, since the flowchart flows at regular intervals, the elapsed time can be determined by incrementing the counter.

  In step S23, the controller determines whether the succeeding unit has detected a check point (check marker). Until it is detected, the process is temporarily exited. When it is detected, the process proceeds to step S24.

  In step S24, the controller obtains a time difference Δt from when the preceding unit detects the check point (check marker) until the succeeding unit detects the check point (check marker).

  In step S25, the controller obtains a distance difference D between the preceding unit and the succeeding unit from the following equation (1) based on the time difference Δt. Va is a set speed of the drive unit.

  FIG. 6 is a flowchart showing a correction policy setting routine according to the present invention.

  In step S41, the controller determines whether or not it is possible to speed up and correct the succeeding unit. If the following unit can be speeded up and corrected while maintaining the preceding unit at a constant speed, the cart will not be delayed even if correction control is performed, and the tact time will not be extended. Therefore, it is desirable to correct the subsequent unit by speeding up. However, if the distance difference D is large, when the subsequent unit is speeded up, the preceding unit has already advanced further by the distance D than the succeeding unit, and the correction area (orbit length for correction) is shortened accordingly. End up. Therefore, if there is a sufficient correction area (trajectory length for correction) for the succeeding unit to catch up with the preceding unit, the process proceeds to step S42 and the speed up of the succeeding unit is set as a correction policy. If there is not a sufficient correction area (orbit length for correction), the process proceeds to step S43 and the speed reduction of the preceding unit is set as the correction policy.

  Whether or not the length is sufficient is important whether or not the original correction area (orbit length for correction) can be secured long, but the degree to which the subsequent unit can be speeded up (i.e. realized) It depends on the possible acceleration). If the succeeding unit can be accelerated / decelerated rapidly, the original correction area (orbit length for correction) may be short. Whether or not the succeeding unit can be accelerated / decelerated suddenly depends on the load weight with respect to the output (motor output) of the drive unit. Therefore, if the loaded weight is light, the succeeding unit can be accelerated / decelerated rapidly. Whether or not the succeeding unit can be accelerated / decelerated rapidly also depends on the load balance. Therefore, if the trolley (the roof) is low, the load is low, and the center of gravity is low, the subsequent unit can be easily accelerated / decelerated rapidly. The above characteristics may be set in advance through experiments and stored in the controller ROM.

  FIG. 7 is a flowchart showing a subsequent unit speed-up correction control routine according to the present invention.

  In step S61, the controller speeds up the succeeding unit.

  In step S62, the controller determines whether or not the succeeding unit has reached the target speed Vb. The speed Vb is higher than the speed Va of the preceding unit (that is, the setting speed Va of the drive unit), and is set in advance based on the degree of speed up of the succeeding unit (that is, realizable acceleration). The process once exits until it reaches, and when it reaches, the process proceeds to step S63.

  In step S63, the controller maintains the trailing unit at the speed Vb.

  In step S64, the controller determines whether or not a predetermined time has elapsed since the succeeding unit maintained the speed Vb. Until the time elapses, the process once exits. When the time elapses, the process proceeds to step S65.

  In step S65, the controller speeds down the succeeding unit.

  In step S66, the controller determines whether the succeeding unit has reached the target speed Va (that is, the same speed as the preceding unit). The process once exits until it reaches, and when it reaches, the process proceeds to step S67.

  In step S67, the controller completes the correction control.

  FIG. 8 is a flowchart showing a preceding unit speed-down correction control routine according to the present invention.

  In step S71, the controller speeds down the preceding unit.

  In step S72, the controller determines whether or not the preceding unit has reached the target speed Vc. The speed Vc is lower than the speed Va of the succeeding unit (that is, the set speed Va of the driving unit), and is set in advance based on the degree of speed reduction possible (that is, realizable deceleration) of the preceding unit. . For example, if the speed Vc is set to zero, the preceding unit stops, so that the correction area (orbit length for correction) can be made very short. The process once exits until the speed Vc is reached, and when it reaches, the process proceeds to step S73.

  In step S73, the controller maintains the preceding unit at the speed Vc.

  In step S74, the controller determines whether or not a predetermined time has elapsed since the preceding unit maintained the speed Vc. Until the time elapses, the process is temporarily exited. When the time elapses, the process proceeds to step S75.

  In step S75, the controller speeds up the preceding unit.

  In step S76, the controller determines whether or not the preceding unit has reached the target speed Va (that is, the same speed as the succeeding unit). The process once exits until it reaches, and when it reaches, the process proceeds to step S77.

  In step S77, the controller completes the correction control.

FIG. 9 is a diagram for explaining the traveling state of the automatic guided vehicle (drive unit) when the transverse posture control apparatus according to the present invention is executed. In the following, in order to make it easy to understand the correspondence with the above-described flowchart, S is appended to the step number of the flowchart.

  As shown in FIG. 9A, the second drive unit 11-2 slips during the traversing mode, and may be delayed from the first drive unit 11-1. In this state, since the traversing state has not been detected, the processing in steps S1 → S2 → S21 is repeated in the flowchart.

  As shown in FIG. 9B, when the preceding first drive unit 11-1 detects a check point (check marker 21-1), the process flows in the flowchart from step S21 to step S22 to step S23. Until the second drive unit 11-2 detects the check point (check marker 21-2), the process of steps S1, S2, S21, S22, and S23 is repeated.

  As shown in FIG. 9C, when the subsequent second drive unit 11-2 detects a check point (check marker 21-2), the process proceeds from step S23 to S24 in the flowchart, and the time difference Δt is obtained. In step S24, the distance difference D between the preceding unit and the succeeding unit is obtained (step S25).

  In the next cycle, the process proceeds from step S1 to S3 to S4, and it is determined whether or not the succeeding unit (second drive unit 11-2) can be speeded up and corrected (step S41). Here, the speed-up of the succeeding unit (second drive unit 11-2) is set as the correction policy (step S42).

  In the next cycle, steps S1 → S3 → S5 → S6 → S61 → S62 flow, and steps S1 → S3 → S5 → S6 → S61 until the succeeding unit (second drive unit 11-2) reaches the speed Vb. → S62 and the process are repeated to speed up the succeeding unit (second drive unit 11-2).

  When the succeeding unit (second drive unit 11-2) reaches the speed Vb, in the flowchart, the process proceeds from step S62 to S63, and the speed Vb of the succeeding unit (second drive unit 11-2) is maintained. . The state at this time is shown in FIG.

  Until a predetermined time elapses in this state, the process proceeds from step S1 → S3 → S5 → S6 → S61 → S62 → S63 → S64, and when the time elapses, the process proceeds from step S64 to S65. The state at this time is shown in FIG.

  Then, until the succeeding unit (second drive unit 11-2) reaches the speed Va, the process of steps S1, S3, S5, S6, S61, S62, S63, S64, S65, and S66 is repeated until the succeeding unit ( The second drive unit 11-2) is slowed down. When the succeeding unit (second drive unit 11-2) reaches the speed Va, the process proceeds from step S66 to S67 in the flowchart, and the correction process is completed (step S67). The state at this time is shown in FIG.

  As described above, according to the present embodiment, the traversing state is detected based on the time difference from the time when the preceding driving unit of the two driving units passes the check point to the time when the following driving unit passes the check point. Then, based on this, the succeeding unit is speeded up or the preceding unit is speeded down, so that the transverse posture of the automatic guided vehicle can be corrected without using an expensive sensing device such as a rotary encoder.

  In addition, as long as possible, the preceding unit is maintained at a constant speed, and the succeeding unit is speeded up for correction. Therefore, even if correction control is performed, the carriage is not delayed, and the tact time can be prevented from being delayed. Whether or not such correction is possible depends on the speed-up possibility of the succeeding unit (that is, the realizable acceleration). If the succeeding unit can be accelerated / decelerated rapidly, such correction is likely to be possible. Whether or not the succeeding unit can be accelerated / decelerated suddenly depends on the load weight with respect to the output (motor output) of the drive unit. Therefore, if the loaded weight is light, the succeeding unit can be accelerated / decelerated rapidly. Whether or not the succeeding unit can be accelerated / decelerated rapidly also depends on the load balance. Therefore, if the trolley (the roof) is low, the load is low, and the center of gravity is low, the subsequent unit can be easily accelerated / decelerated rapidly. As described above, since it is determined whether or not correction by speeding up the succeeding unit is possible based on the load weight and the load balance, it is possible to determine more accurately.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

It is a figure which shows an example of the automatic guided vehicle to which the driving mode switching control apparatus by this invention is applied. It is a figure which shows the state of a drive unit when an automatic guided vehicle drive | works. It is a figure explaining the problem in automatic guided vehicle transverse mode. It is a main flowchart of the transverse posture control apparatus by this invention. It is a flowchart which shows the transverse state detection routine by this invention. It is a flowchart which shows the correction policy setting routine by this invention. It is a flowchart which shows the following unit speed-up correction control routine by this invention. It is a flowchart which shows the preceding unit speed-down correction control routine by this invention. It is a figure explaining the driving | running | working state of the automatic guided vehicle (drive unit) when the transverse attitude control apparatus by this invention is performed.

Explanation of symbols

1 Automated guided vehicle (AGV)
10 Car body 11 Drive unit Step S2 Traverse state estimation means / transverse state estimation process Step S4 Policy setting means / policy setting process Steps S6, S7 Correction control means / Correction control process

Claims (7)

A traverse attitude control device for an automatic guided vehicle having a traverse mode in which a drive unit provided on the front side of a vehicle and a drive unit provided on a rear side move in different tracks,
When the vehicle is in the correct posture, the front drive unit and the rear drive unit pass through a check point provided on a track so that the front drive unit and the rear drive unit pass simultaneously. A transverse state estimating means for estimating a transverse state of the vehicle based on a time difference to
A policy for setting a correction policy for speeding up the following unit by maintaining the speed of the preceding unit or maintaining the speed of the following unit and maintaining the speed of the preceding unit based on the estimated traversing state Setting means;
Based on the set correction policy, correction control means for maintaining the speed of the preceding unit to speed up the following unit or maintaining the speed of the following unit and speeding down the preceding unit;
A traverse attitude control device for an automatic guided vehicle characterized by comprising: The policy setting means preferentially sets the speed up of the succeeding unit over the speed down of the preceding unit.
The transverse posture control apparatus for an automatic guided vehicle according to claim 1. The policy setting means sets either the speed-up of the succeeding unit or the speed-down of the preceding unit according to the length of the correction area.
The traverse posture control device for an automatic guided vehicle according to claim 1 or 2, wherein: The policy setting means sets either the speed-up of the succeeding unit or the speed-down of the preceding unit according to the loaded weight.
The transverse posture control device for an automatic guided vehicle according to any one of claims 1 to 3, wherein The policy setting means sets either the speed-up of the succeeding unit or the speed-down of the preceding unit according to the position of the center of gravity of the automatic guided vehicle.
The transverse posture control device for an automatic guided vehicle according to any one of claims 1 to 4, wherein The correction control means, when the policy setting means sets the speed reduction of the preceding unit as the correction policy, speeds down until the preceding unit stops,
The traverse posture control device for an automatic guided vehicle according to any one of claims 1 to 5, wherein: A traverse attitude control method for an automatic guided vehicle having a traverse mode in which a drive unit provided on the front side of a vehicle and a drive unit provided on a rear side move on different tracks,
When the vehicle is in the correct posture, the front drive unit and the rear drive unit pass through a check point provided on a track so that the front drive unit and the rear drive unit pass simultaneously. A traverse state estimation step of estimating a traverse state of the vehicle based on a time difference to
A policy for setting a correction policy for speeding up the following unit by maintaining the speed of the preceding unit or maintaining the speed of the following unit and maintaining the speed of the preceding unit based on the estimated traversing state A setting process;
Based on the set correction policy, a correction control step of maintaining the speed of the preceding unit to speed up the following unit or maintaining the speed of the following unit and reducing the preceding unit;
A traverse posture control method for an automatic guided vehicle, comprising:

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