JP2012084089A - Conveyance vehicle system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a conveyance vehicle to travel smoothly when travelling on a curved part in a conveyance vehicle system that uses the conveyance vehicle capable of driving left and right wheels independently.SOLUTION: A conveyance vehicle system 1 is configured such that a first traveling wheel 25 and a second traveling wheel 28 are provided on right and left sides of a conveyance vehicle body 15, respectively, so as to be driven by a first motor 26 and a second motor 29. A pair of front side guide rollers 81 and a pair of rear side guide rollers 83 are provided at the front side and the rear side of the first traveling wheel 25, respectively. A speed pattern generating section 62 gives a speed command to the first motor 26 and the second motor 29 when a conveyance vehicle 3 travels in a curved part 203, the speed command being prepared based on a travel track in which the pair of front side guide rollers 81 and the pair of rear side guide rollers 83 are not brought into contact with a guide rail 6.

Description

  The present invention relates to a transport vehicle system, and more particularly, to a transport vehicle system using a transport vehicle capable of independently driving left and right wheels.

2. Description of the Related Art A transport vehicle for transporting a large glass substrate or a cassette in which a plurality of glass substrates are stored is known. The transport vehicle automatically travels in the clean room of the factory and transports articles between the processing apparatuses. The track on which the transport vehicle travels is, for example, a rail suspended from the ceiling. In this case, the space in which the rail and the transport vehicle travel is a clean room.
The conveyance vehicle has wheels on both the left and right sides. A motor is connected to one wheel to form a driving wheel, and the other wheel serves as a driven wheel. The transport vehicle further includes guide rollers for being guided by the left and right guide rails.
Two-wheel differential speed control is also performed in which separate motors are connected to the left and right wheels so that an appropriate speed difference is generated between the left and right wheels when the transport vehicle travels a curve (for example, , See Patent Document 1).

JP 2008-52323 A

  In a conventional transport vehicle, for example, when traveling on a curved portion, a front guide roller pair and a rear guide roller pair provided in front of and behind a wheel are arranged at positions close to the guide rail, and grip the guide rail. Yes. Therefore, when the two-wheel differential speed difference control is performed, the deviation of the traveling position due to the difference between the command value and the actual rail shape is corrected. However, in that case, there is a problem that the wheel slips and the guide correction force acts as a load on the servo.

  SUMMARY OF THE INVENTION An object of the present invention is to enable a transport vehicle to smoothly travel during traveling on a curved portion in a transport vehicle system using a transport vehicle capable of independently driving left and right wheels.

  Hereinafter, a plurality of modes will be described as means for solving the problems. These aspects can be arbitrarily combined as necessary.

A transport vehicle system according to an aspect of the present invention includes a travel rail, a guide rail provided along the travel rail, a transport vehicle that travels along the travel rail, and a control unit that controls travel of the transport vehicle. I have. The transport vehicle includes a vehicle body, a first traveling wheel and a second traveling wheel, a first motor and a second motor, a front guide roller pair, and a rear guide roller pair. The first traveling wheel and the second traveling wheel are provided on the left and right sides of the vehicle body. The first motor and the second motor are connected to the first traveling wheel and the second traveling wheel, respectively. The front guide roller pair and the rear guide roller pair are provided on the front side and the rear side of the first traveling wheel, respectively. The control unit provides the first motor and the second motor with a speed command created based on a travel locus in which the front guide roller pair and the rear guide roller pair do not contact the guide rail when the transport vehicle travels on the curved portion. .
In this transport vehicle system, the control unit controls the first motor and the second motor, whereby the first traveling wheel and the second traveling wheel are driven independently. As a result, the transport vehicle moves along the traveling rail.
When the transport vehicle travels on the curved portion, the front guide roller pair and the rear guide roller pair are in the guide position close to the guide rail. On the other hand, the control unit gives a speed command created based on an ideal travel locus to the first motor and the second motor when the transport vehicle travels along the curved portion. Therefore, the front guide roller pair and the rear guide roller pair are unlikely to contact the guide rail at the curved portion. Conventionally, the control is based on the assumption that the front guide roller pair and the rear guide roller pair of the transport vehicle are in contact with the guide rails at the entrance and exit of the curved portion. It was big. In contrast, in this transport vehicle system, control is actively performed so that the front guide roller pair and the rear guide roller pair of the transport vehicle are not in contact with the guide rails even at the guide positions at the entrance and exit of the curved portion. is doing. Therefore, it is difficult for the guide roller to contact the guide rail.

In order to calculate a travel locus, the control unit is configured to move the first travel wheel, the second travel wheel, and the turning shaft with respect to the movement from when the front guide roller pair enters the curved portion until the rear guide roller pair enters the curved portion. The center position may be determined at predetermined distance intervals.
In this transport vehicle system, an ideal travel locus is determined with respect to the movement from when the front guide roller pair enters the curved portion until the rear guide roller pair enters the curved portion. Therefore, it is difficult for the guide roller to contact the guide rail.

The control unit may calculate the speeds of the first traveling wheel and the second traveling wheel at each point based on the traveling locus.
In this transport vehicle system, the guide roller is unlikely to contact the guide rail.

The control unit may store a two-wheel speed difference command table created by compensating a delay time at the time of behavior change for the calculated speeds of the first traveling wheel and the second traveling wheel. Further, the control unit may give a speed command to the first motor and the second motor based on the two-wheel speed difference command table during curve traveling.
In this transport vehicle system, since the speed command is given to the first motor and the second motor based on the two-wheel speed difference command table created by compensating for the delay time at the time of behavior change, realizable. Further, since the two-wheel speed difference command table is stored in advance, it is possible to reduce the burden of the command speed conversion processing work in the control unit.

The control unit may compensate for the deviation between the command speed and the actually measured value in order to compensate for the delay time when the behavior changes.
In this transport vehicle system, transport vehicle travel according to the intention can be realized.

  In the transport vehicle system according to the present invention, the transport vehicle can smoothly travel during the curve section travel.

The schematic diagram of the conveyance vehicle system by which one Embodiment of this invention was employ | adopted. The partial top view of a conveyance vehicle system. The block block diagram which shows the control structure of a conveyance vehicle system. The block block diagram which shows the traveling control part of a conveyance vehicle. The top view which shows the ideal driving | running | working locus | trajectory obtained by calculation. The elements on larger scale of FIG. The figure which shows the dimensional relationship of a traveling wheel. The figure which showed typically the positional relationship of the guide rail and guide roller in a curved part. Speed ratio table when driving on a curve. The flowchart which shows operation | movement of the traveling control part at the time of curve part traveling.

(1) Carrier Vehicle System A carrier vehicle system 1 in which an embodiment of the present invention is adopted will be described with reference to FIG. FIG. 1 is a schematic diagram of a transport vehicle system in which an embodiment of the present invention is adopted.

  The transport vehicle system 1 includes a track 2 and a transport vehicle 3 that travels on the track 2. In this embodiment, the track 2 is suspended from the ceiling, and the periphery of the track 2 is a clean room.

  The track 2 has a traveling rail 4 and a guide rail 6. The traveling rail 4 is composed of left and right first traveling rails 4a and second traveling rails 4b. The first traveling rail 4a and the second traveling rail 4b have flat traveling surfaces.

  The guide rail 6 has a first guide rail 6a and a second guide rail 6b. The first guide rail 6a and the second guide rail 6b are provided at the outer ends of the first travel rail 4a and the second travel rail 4b, respectively. The first guide rail 6a and the second guide rail 6b extend upward.

  A power supply line (not shown) is provided along the first traveling rail 4a and the second traveling rail 4b.

  The layout of the transport vehicle system 1 will be described with reference to FIG. FIG. 2 is a partial plan view of the transport vehicle system. As shown in FIG. 2, the track 2 includes a first straight part 201, a branch part 206 at the tip of the first straight part 201, a curved part 203 that turns to the right from the branch part 206, and a straight line from the branch part 206. And a second linear portion 202 extending in a shape. Hereinafter, the curved portion 203 is used as an example of the curved portion in the description of the traveling of the curved portion of the transport vehicle 3.

  The first traveling rail 4 a and the second traveling rail 4 b extend from the first straight portion 201 through the branching portion 206 into both the second straight portion 202 and the curved portion 203.

  The first guide rail 6 a is not provided at the branching portion 206 in the portion of the first traveling rail 4 a from the first straight portion 201 toward the second straight portion 202. Furthermore, the second guide rail 6 b is not provided at the branching portion 206 in the portion of the second traveling rail 4 b from the first straight portion 201 toward the curved portion 203.

(2) Transport Vehicle The transport vehicle 3 includes a transport vehicle main body 15, a drive travel unit 18, and a driven travel unit 19. Since the structure of the transport vehicle body 15 is the same as the conventional one, the description thereof is omitted. The drive travel unit 18 and the driven travel unit 19 are bogies that are rotatably attached to the transport vehicle body 15. In FIG. 1, the pivot axis center 38 of the drive travel unit 18 is shown.

  The drive travel unit 18 will be described with reference to FIG. The drive travel unit 18 mainly includes a main body frame 20, a first drive wheel unit 21, a second drive wheel unit 22, a fixed guide roller mechanism (31, 32), and a branch guide roller mechanism (33, 34, 35).

  The first drive wheel unit 21 is attached to the right end portion of the main body frame 20 and has a first traveling wheel 25, a first motor 26, and a first encoder 27. The first traveling wheel 25 is placed on the traveling surface of the first traveling rail 4a. The first motor 26 is connected to the first traveling wheel 25. The first encoder 27 measures the rotation of the first motor 26 and transmits a pulse signal. Thereby, the rotation speed and the number of rotations of the first motor 26 are obtained.

  The second drive wheel unit 22 is attached to the left end portion of the main body frame 20, and includes a second traveling wheel 28, a second motor 29, and a second encoder 30. The second traveling wheel 28 is placed on the traveling surface of the second traveling rail 4b. The second motor 29 is connected to the second traveling wheel 28. The second encoder 30 measures the rotation of the second motor 29 and transmits a pulse signal. Thereby, the rotation speed and the number of rotations of the second motor 29 are obtained.

  The fixed guide roller mechanism (31, 32) has a pair of first fixed guide rollers 31 and a pair of second fixed guide rollers 32. The pair of first fixed guide rollers 31 are disposed at the right end portion of the main body frame 20 so as to be separated from each other in the traveling direction. More specifically, the first fixed guide roller 31 is disposed away from both the front and rear sides of the first traveling wheel 25 in the traveling direction, and is always close to the inside of the first guide rail 6a. The pair of second fixed guide rollers 32 are disposed at the left end portion of the main body frame 20 so as to be separated from each other in the traveling direction. More specifically, the second fixed guide roller 32 is disposed away from both the front and rear sides of the second traveling wheel 28 in the traveling direction, and is always close to the inside of the second guide rail 6b.

The branch guide roller mechanism (33, 34, 35) is a mechanism for performing a branch operation in the branch portion 206, and includes a pair of first branch guide rollers 33, a second branch guide roller 34, and a first branch guide roller. And a drive unit 35 (FIG. 3).
The first branch guide roller 33 is arranged corresponding to the first fixed guide roller 31, and constitutes a front guide roller pair 81 and a rear guide roller pair 83 by both. The second branch guide roller 34 is arranged corresponding to the second fixed guide roller 32, and constitutes a front guide roller pair 85 and a rear guide roller pair 87 by both. The first branch guide roller driving unit 35 (FIG. 3) is a mechanism for changing the positions of the first branch guide roller 33 and the second branch guide roller 34.
With the above structure, the first branch guide roller 33 and the second branch guide roller 34 are moved between the guide position and the non-guide position by the first branch guide roller driving unit 35 (FIG. 3). At the guide position, the first branch guide roller 33 and the second branch guide roller 34 are close to the outside of the first guide rail 6a. In the non-guide position, the first branch guide roller 33 and the second branch guide roller 34 are separated upward from the first guide rail 6a.

The driven traveling unit 19 mainly includes a main body frame 23, a first driven wheel 36, a second driven wheel 37, a second fixed guide roller mechanism (40, 41), and a second branch guide roller mechanism (42, 43, 44).
The first driven wheel 36 is placed on the first traveling rail 4 a of the traveling rail 4. The second driven wheel 37 is placed on the second traveling rail 4 b of the traveling rail 4.

  The second fixed guide roller mechanism (40, 41) has a pair of third fixed guide rollers 40 and a pair of fourth fixed guide rollers 41. The third fixed guide roller 40 is disposed at the right end of the main body frame 23 so as to be separated in the traveling direction. More specifically, the third fixed guide roller 40 is disposed away from both the front and rear sides of the first driven wheel 36 in the traveling direction, and is always close to the inside of the first guide rail 6a. The fourth fixed guide roller 41 is arranged at the left end of the main body frame 23 so as to be separated in the traveling direction. More specifically, the fourth fixed guide roller 41 is disposed away from both the front and rear sides of the second driven wheel 37 in the traveling direction, and is always close to the inside of the second guide rail 6b.

The second branch guide roller mechanism (42, 43, 44) is a mechanism for performing a branch operation in the branch portion 206, and includes a pair of third branch guide rollers 42, a fourth branch guide roller 43, and a second branch. And a guide roller driving unit 44 (FIG. 3).
The third branch guide roller 42 is disposed corresponding to the third fixed guide roller 40. The fourth branch guide roller 43 is disposed corresponding to the fourth fixed guide roller 41. The second branch guide roller driving unit 44 (FIG. 3) is a mechanism for changing the positions of the third branch guide roller 42 and the fourth branch guide roller 43.
With the above structure, the third branch guide roller 42 and the fourth branch guide roller 43 are moved between the guide position and the non-guide position by the second branch guide roller driving unit 44 (FIG. 3). At the guide position, the third branch guide roller 42 and the fourth branch guide roller 43 are close to the outside of the first guide rail 6a. In the non-guide position, the third branch guide roller 42 and the fourth branch guide roller 43 are separated upward from the first guide rail 6a.

  When the transport vehicle 3 travels on the curved portion 203 in FIG. 2, the first branch guide roller 33 and the third branch guide roller 42 are disposed at the guide position. On the other hand, at that time, the second branch guide roller 34 and the fourth branch guide roller 43 are arranged at the non-guide position. In addition, when the conveyance vehicle 3 travels the first linear portion 201, each branch guide roller may be disposed at either the non-guide position or the guide position.

(3) Detected part and sensor A plurality of types of detected parts provided along the traveling rail 4 will be described with reference to FIG. The detected part includes a reflective tape 11, a barcode 13, and a magnetic mark 14. In FIG. 2, the reflective tape 11, the bar code 13, and the magnetic mark 14 are illustrated inside the traveling rail 4, but are actually provided on the traveling rail 4 or the upper surface of the guide rail 6. .
The reflective tape 11 is a member for detecting the position of the transport vehicle 3 in the curved portion 203 and is disposed in the curved portion 203. In this embodiment, the start end 11a of the reflective tape 11 is disposed before the actual start position 203a of the curved portion 203 in the traveling direction. Further, the end (not shown) of the reflective tape 11 is arranged in front of the actual end of the curved portion (not shown).
The bar code 13 functions as an origin mark and a plurality of reference marks of the traveling rail 4.
The magnetic mark 14 is a member that indicates the stop position of the transport vehicle 3. The magnetic mark 14 is made of a magnetic material such as steel or a non-magnetic material such as copper or aluminum. In this embodiment, the magnetic mark 14 is disposed on the first straight portion 201, and the stop position 80 is in the middle of the magnetic mark 14.

  As shown in FIG. 3, the driving traveling unit 18 and the driven traveling unit 19 are further provided with a photoelectric sensor 47, a linear scale 49, and a barcode reader 50. The photoelectric sensor 47 is for detecting the reflective tape 11. Note that the photoelectric sensor 47 in the figure is a sensor for detecting a position during traveling on a curved portion that is bent to the right, and a sensor (not shown) for the curved portion that is bent to the left is provided separately. The linear scale 49 is for detecting the magnetic mark 14. The linear scale 49 obtains the absolute position of the transport vehicle 3 with respect to the magnetic mark 14, in other words, the position based on the magnetic mark 14. The barcode reader 50 is for detecting the barcode 13.

(4) Control Configuration The control configuration of the transport vehicle system 1 will be described with reference to FIG. FIG. 3 is a block diagram showing a control configuration of the transport vehicle system.

  The transport vehicle system 1 includes a transport vehicle controller 52. The transport vehicle controller 52 is a controller for managing the traveling of the plurality of transport vehicles 3. The transport vehicle controller 52 and the transport vehicle 3 can communicate with each other. The transport vehicle controller 52 includes a controller main body 54 and a memory 55. The controller body 54 is a computer that includes a CPU, a RAM, a ROM, and the like and executes a program. A route map is stored in the memory 55. The route map is a map that describes the arrangement of the travel route, the position of the origin, the reference position based on the origin, and the coordinates of the transfer position. The coordinates are obtained by converting the travel distance from the origin into the number of output pulses of the encoder of the transport vehicle.

  The transport vehicle 3 has a travel control unit 59. The travel control unit 59 can transmit a drive signal to the first motor 26 and the second motor 29 based on a command from the transport vehicle controller 52. The travel control unit 59 is further connected to the branch control unit 60. The branch control unit 60 can transmit a drive signal to the first branch guide roller driving unit 35 and the second branch guide roller driving unit 44 based on a command from the transport vehicle controller 52.

(5) Travel control system of conveyance vehicle The travel control unit 59 will be described with reference to FIG. FIG. 4 is a block diagram illustrating a travel control unit of the transport vehicle.
The traveling control unit 59 is a computer that includes a CPU, a RAM, a ROM, and the like and executes a program. The travel control unit 59 includes a route map 61, a speed pattern generation unit 62, a first motor control unit 63, a second motor control unit 64, and a compensation speed ratio table 90. The route map 61 is stored in a memory in the travel control unit 59. The speed pattern generation unit 62 can communicate with the transport vehicle controller 52.
Furthermore, the first encoder 27, the second encoder 30, the photoelectric sensor 47, the linear scale 49, and the barcode reader 50 are connected to the travel control unit 59.

  When the travel control unit 59 receives a transport command from the transport vehicle controller 52, the travel control unit 59 obtains a distance from the current position to the stop position based on the route map 61 and inputs the distance to the speed pattern generation unit 62. The speed pattern generation unit 62 calculates a travel distance from the difference between the coordinates of the current position on the route map 61 and the coordinates of the target position, thereby generating a pattern of travel speed to the stop position.

  The first motor control unit 63 mainly includes a first error amplification unit 65A, a first feedback control unit 66A, and a first amplifier 67A. The first error amplifier 65A amplifies the error. The first feedback control unit 66A performs, for example, PID control or PI control based on the error obtained by the first error amplification unit 65A. PID control and PI control can be switched. The first amplifier 67A transmits a current-amplified speed command to the first motor 26. The first encoder 27 detects the rotation speed of the rotation shaft of the first motor 26, and the current position and speed of the first traveling wheel 25 obtained thereby are input to the speed pattern generation unit 62 or the first error amplification unit 65A. Is done. In addition, the structure of the 1st motor control part 63 is one Example, Comprising: This invention is not limited to this.

  The second motor control unit 64 mainly includes a second error amplification unit 65B, a second feedback control unit 66B, and a second amplifier 67B. The second error amplifying unit 65B amplifies the error. The second feedback control unit 66B performs PID control or PI control based on the error obtained by the second error amplification unit 65B. PID control and PI control can be switched. The second amplifier 67B transmits the current-amplified speed command to the second motor 29. The second encoder 30 detects the rotational speed of the rotating shaft of the second motor 29, and the current position and speed of the second traveling wheel 28 obtained thereby are input to the speed pattern generator 62 or the second error amplifier 65B. Is done. In addition, the structure of the 2nd motor control part 64 is one Example, Comprising: This invention is not limited to this.

(6) General Explanation of Travel Control Operation Generally, the transport vehicle 3 has a required travel distance obtained from the route map 61 along the track 2, a current position obtained from the first encoder 27 and the second encoder 30, and Travel control is performed according to the current speed.

  A control operation when the transport vehicle 3 travels along the curved portion 203 will be described. When traveling on the curved section 203, generally, the left and right motors cannot be perfectly synchronized, so that the travel locus does not match the actual curve rail and the traveling wheel collides with the guide rail. There is a problem that the behavior becomes unstable. The present invention uses the following means for solving the problem.

  The speed pattern generator 62 confirms the current position of the transport vehicle 3 by collating the detection results from the photoelectric sensor 47 and the detection results from the first encoder 27 and the second encoder 30. The speed pattern generation unit 62 uses the current position information and the compensation speed ratio table 90 (described later) to generate a target speed signal so that an appropriate left-right speed difference is generated. The first motor control unit 63 and the second motor control unit 64.

  When entering the curved portion 203, the speed pattern generator 62 decelerates the inner wheel and accelerates the outer wheel, thereby causing the center speed of the transport vehicle 3 to run in accordance with a specified speed (for example, 60 m / min). The speed pattern generation unit 62 uses the compensation speed ratio table 90 calculated in advance to improve calculation efficiency and reduce the processing load.

  As described above, when the transport vehicle 3 travels the curved portion 203, the behavior is stable even though the left and right motors cannot be perfectly synchronized.

(7) Curved portion traveling locus The speed pattern generating unit 62 has an ideal curved portion traveling locus table in advance. The curved portion traveling locus is a locus on which the guide roller can accurately trace the shape of the guide rail. That is, in this locus, the guide roller does not contact the guide rail.

  The method for obtaining the curve portion traveling locus will be described with reference to FIGS. FIG. 5 is a plan view showing an ideal travel locus obtained by calculation. FIG. 6 is a partially enlarged view of FIG. FIG. 7 is a diagram showing the dimensional relationship of the traveling wheels. FIG. 8 is a diagram schematically showing the positional relationship between the guide rail and the guide roller in the curved portion.

An ideal curved portion traveling locus is obtained as follows. First, a reference entrance trajectory is determined. Specifically, the rear guide rollers of the position x _a, from the curve portion start position 203a to a position spaced above the pitch L of the front roller pair 81 and the rear rollers 83, turning at a predetermined interval [Delta] x _a resolution center The coordinates of the track P ₀ , the inner ring track P ₁ , and the outer ring track P ₂ are obtained. For example, the distance of the interval for changing the _{x a} is 500mm from the curved portion start position 203a, the pitch L of the guide rollers is 480 mm, [Delta] x _a is 0.05 _mm, P 0, _{P 1} and P ₂ is obtained for 1000 places.

The specific calculation formula is as follows.
First, the turning angle alpha ₂ is calculated. Incidentally, R is the radius of the first guide rail 6a, L is the longitudinal pitch of the guide roller pairs, x _a is the x-coordinate of the rear guide rollers, x _R is X curved portion start position 203a Coordinates.
l = √ ((x _R −x _a ) ² + R ² )
R ² = l ² + L ² −2lL cos α ₁
α ₁ = cos ⁻¹ ((R ² −l ² −L ² ) / (− ² lL))
α ₀ = tan ⁻¹ R / (x _R −x _a )
α ₂ = α ₀ −α ₁

Next, the coordinates of P ₀ , P ₁ and P ₂ are calculated from the turning angle α ₂ .
θ ₀ = θ ₀₀ −α ₂
θ ₁ = θ ₁₀ -α ₂
θ ₂ = θ ₂₀ −α ₂
Thus, the coordinates of P ₀ , P ₁ and P ₂ are as follows.
P ₀ (x ₀ , y ₀ ) = (x _a + l ₀ cos θ ₀ , l ₀ sin θ ₀ )
P ₁ (x ₁ , y ₁ ) = (x _a + l ₁ cos θ ₁ , l ₁ sin θ ₁ )
P ₂ (x ₂ , y ₂ ) = (x _a + l ₂ cos θ ₂ , l ₂ sin θ ₂ )
By integrating the intervals of P ₀ , P ₁ , and P ₂ , the moving distances of the first traveling wheel 25, the second traveling wheel 28, and the turning shaft center 38 are obtained.
The positional relationship between the guide rail and the guide roller at the curved portion entrance will be described with reference to FIG. An intermediate point between the front guide roller pair 81 is a first intermediate point 95, and an intermediate point between the rear guide roller pair 83 is a second intermediate point 97. In FIG. 8, the front guide roller pair 81 and the rear guide roller pair 83 are denoted by reference numeral A in the first straight line portion 201, and indicate a state in which the front guide roller pair 81 is at a position that has reached the curved portion start position 203 a. A state where the rear guide roller pair 83 is in a position where it reaches the curved portion start position 203a is indicated by reference symbol C, and is indicated by reference symbol D in the curved portion 203. At any position, the first intermediate point 95 and the second intermediate point 97 coincide with the intermediate in the width direction of the first guide rail 6a. In this way, the guide rollers on both sides of the first guide rail 6a are arranged so as to always leave the maximum gap.
The reference exit trajectory is extracted from the calculation result of the reference entrance trajectory. Specifically, a point where the rear guide roller pair 83 enters the curved portion 203 is searched as a change end point, and rearranged in the reverse direction. Further, by integrating the intervals of P ₁ and P ₂ , the moving distances of the first traveling wheel 25, the second traveling wheel 28, and the turning shaft center 38 are obtained.
The reference entrance trajectory and the reference exit trajectory obtained as described above are stored in the speed pattern generation unit 62.

(8) Speed Ratio Table A reference speed ratio table (wheel speed conversion table) 70 at the time of curve traveling that the speed pattern generation unit 62 uses as a reference speed command will be described with reference to FIG. The reference speed ratio table 70 is a table that determines the reference speed ratio of the left and right drive wheels with respect to the curve travel time, and has a reference outer wheel speed ratio 71 and a reference inner wheel speed ratio 73.

As is apparent from the figure, when the speed ratio between the inner ring and the outer ring is 100% when entering the curve, the reference inner ring speed ratio 73 decreases as the reference outer ring speed ratio 71 increases. When the reference outer wheel speed ratio 71 becomes 100 + α% (for example, a total of 115%) and the reference inner wheel speed ratio 73 becomes 100−α% (for example, a total of 85%), this state continues in a predetermined travel section. Finally, the reference outer ring speed ratio 71 becomes smaller, the reference inner ring speed ratio 73 becomes larger along with it, and finally both become 100%.
The value of α is set to be different according to the distance between the left and right drive wheels and the curve curvature.

  In summary, in the reference speed ratio table 70, a curve travel start section in which the speed ratio is separated, a curve travel continuation section in which the speed ratio is constant, and a curve travel end section in which the speed ratio approaches are set. Has been.

Next, a method for creating the reference speed ratio table 70 will be described. The traveling pattern generation unit 62 sets the P ₁ and P ₂ positions on the time axis so that the moving speed at the turning axis center P ₀ becomes a set constant value (for example, 60 m / min) from the output of the reference trajectory. Extract by criteria. Specifically, separated by P ₀ position, generates a speed pattern to the outlet from the curve section inlet. Δt is the resolution of the time axis is required to be sufficiently larger than [Delta] x _a, for example, 1 millisecond. The boundary condition division and velocity pattern creation method by the P ₀ position is as follows.
- straight portions constant speed movement ... P ₀ and translation-inlet (two-wheel differential velocity difference starting position 1-2 wheel differential velocity difference ending position 1) extracted from ... reference inlet locus curves Chujo uniform motion .. Curve Speed reference (simple calculation from curve radius)
And outlet (two-wheel differential velocity difference starting position 2-2 wheel differential velocity difference end position 2) parallel ... From the reference outlet path and the extraction-linear portion constant speed movement ... P ₀ moves

  When the transport vehicle 3 travels on the curved portion 203 in FIG. 2, the first feedback control unit 66 </ b> A of the first motor control unit 63 controls the first motor 26 on the inner ring side, that is, the side holding the guide rail. PID control is continuously performed. On the other hand, on the outer ring side, that is, the side not holding the guide rail, the second feedback control unit 66B of the second motor control unit 64 switches from PID control to PI control. In other words, during traveling on the curved portion, the first motor 26 is PID-controlled and the second motor 29 is PI-controlled. The reason why the inner wheel PID-outer wheel PI control is left in this way despite the formation of the speed command so as to travel on the ideal locus is that the guide roller may come into contact with the guide rail due to the rail shape error and the installation error. This is to reduce the load at the time of contact.

  Next, servo following compensation for the reference speed command will be described. Servo tracking compensation is performed to compensate for the difference between the left and right wheels caused by inner wheel PID-outer wheel PI control by adding feedforward control to the reference speed command. The parameters for servo tracking compensation employed in this embodiment are response and deviation. The response is a delay time at the start of behavior change and a delay time at the end of behavior change. The deviation is a percentage with respect to the desired speed at the time when the curve portion constant speed is reached.

With reference to FIG. 9, a compensation speed ratio table 90 at the time of curve travel that is used as a speed degree command for which the speed pattern generation unit 62 has performed servo tracking compensation will be described. The compensation speed ratio table 90 has a compensation outer ring speed ratio 91 and a compensation inner ring speed ratio 93. The compensated outer ring speed ratio 91 is earlier than the reference outer ring speed ratio 71 at the start of behavior change and at the end of behavior change. The compensated inner ring speed ratio 93 is also earlier than the reference inner ring speed ratio 93 when the behavior change starts and when the behavior change ends. Compared to the compensated inner ring speed ratio 93, the compensated outer ring speed ratio 91 is earlier when the behavior change starts and when the behavior change ends.
Further, the compensated outer ring speed ratio 91 has a constant speed larger than the reference outer ring speed ratio 71.

The compensation speed ratio table 90 is created as follows. First, the time delay and the speed deviation are obtained by a separate experiment. The speed pattern generator 62 creates a reference entrance locus and a reference exit locus in the time domain, and further extracts a boundary time from the reference speed command. Furthermore, the speed pattern generation unit 62 creates a compensation table by simply performing linear interpolation in the time domain, for example.
The speed pattern generation unit 62 generates a speed pattern from the entrance to the exit of the curve section by dividing it by the boundary time from the compensation table.
The boundary condition division by time and the speed pattern creation method are as follows.
- straight portions constant speed movement ... P ₀ and translation-inlet (two-wheel differential velocity difference starting time 1-2 wheel differential velocity difference end time 1) ... compensation inlet trajectory extraction curves Chujo uniform motion .. curve from Speed reference (simple calculation from curve radius)
And outlet parallel to the (two-wheel differential velocity difference starting time 2-2 wheel differential velocity difference end time 2) ... extracted from the compensation outlet path traveled straight portion constant speed movement ... P ₀ moves

(9) Detailed explanation of curve section traveling control

Hereinafter, the control operation of the speed pattern generator 62 will be described with reference to FIG. FIG. 10 is a flowchart illustrating the operation of the traveling control unit during traveling on the curved portion. Note that the speed pattern generator 62 gives a speed command to the first motor 26 and the second motor 29 even before entering the curve section 203.
When the transport vehicle 3 travels on the curved portion, the following steps S1 to S7 are continuously executed.

  In step S <b> 1, the speed pattern generation unit 62 waits for reaching the start position 203 a of the curve unit 203. The fact that the start position 203 a of the curved portion 203 has been reached is grasped by the photoelectric sensor 47 detecting the start end 11 a of the reflective tape 11.

  In step S <b> 2, the speed pattern generation unit 62 determines whether or not the position of the transport vehicle 3 obtained from the detection results from the first encoder 27 and the second encoder 30 in the curve unit 203 is accurate. Judgment based on. If so, the process skips step S3 and moves to step S4. If not, the process moves to step S3.

  In step S3, the speed pattern generator 62 updates the output values from the first encoder 27 and the second encoder 30 to correct values.

  In step S4, the speed pattern generator 62 generates a speed command based on the turning center speed.

  In step S <b> 5, the speed pattern generation unit 62 converts the speed command into a left / right speed difference command using the compensation speed ratio table 90. Specifically, the inner wheel speed and the outer wheel speed at the corresponding position are obtained by obtaining the multiplication factor of the corresponding position from the position of the carriage 3 in the curved portion 203 and the compensation speed ratio table 90 and multiplying the current speed by the multiplication factor. Is calculated. That is, an outer ring speed command is created by integrating the value of the compensated outer ring speed ratio 91 with respect to the turning center speed, and an inner ring speed command is created by adding up the value of the inner ring speed ratio 93 with respect to the turning center speed. To do.

  In step S <b> 6, the speed pattern generation unit 62 outputs a left / right speed difference command to the first motor control unit 63 and the second motor control unit 64, respectively.

  In step S <b> 7, the speed pattern generation unit 62 determines whether the transport vehicle 3 has left the curved portion 203. If not, the process returns to step S2. If so, the process ends. Whether or not the curved portion 203 has been removed is determined based on the detection result from the photoelectric sensor 47, for example.

(10) Features The above embodiment can be expressed as follows. (A) The transport vehicle system 1 includes a travel rail 4, a guide rail 6 provided along the travel rail 4, and a travel rail 4. And a traveling pattern generation unit 62 (control unit) that controls the traveling of the transportation vehicle 3. The transport vehicle 3 includes a transport vehicle main body 15, a first travel wheel 25 and a second travel wheel 28, a first motor 26 and a second motor 29, a front guide roller pair 81 (31, 33), and a rear guide roller. A pair 83 (31, 33). The first traveling wheel 25 and the second traveling wheel 28 are provided on the left and right of the carrier body 15. The first motor 26 and the second motor 29 are connected to the first traveling wheel 25 and the second traveling wheel 28, respectively. The front guide roller pair 81 and the rear guide roller pair 83 are provided on the front side and the rear side of the first traveling wheel 25, respectively. The speed pattern generation unit 62 is a speed created based on a travel locus in which the front guide roller pair 81 pair and the rear guide roller pair 83 do not contact the first guide rail 6a when the transport vehicle 3 travels the curved portion 203. Commands are given to the first motor 26 and the second motor 29.
In this transport vehicle system 1, the speed pattern generator 62 controls the first motor 26 and the second motor 29, whereby the first traveling wheel 25 and the second traveling wheel 28 are driven independently. As a result, the transport vehicle 3 moves along the traveling rail 4.
When the transport vehicle 3 travels along the curved portion 203, the front guide roller pair 81 and the rear guide roller pair 83 are in a guide position close to the first guide rail 6a. On the other hand, the speed pattern generator 62 gives the first motor 26 and the second motor 29 a speed command created based on an ideal travel locus when the transport vehicle 3 travels the curved portion 203. Therefore, the front guide roller pair 81 and the rear guide roller pair 83 are unlikely to contact the first guide rail 6a at the curved portion 203. Conventionally, the control is based on the assumption that the front guide roller pair and the rear guide roller pair of the transport vehicle are in contact with the guide rails at the entrance and exit of the curved portion. It was big. On the other hand, in the transport vehicle system 1, the front guide roller pair 81 and the rear guide roller pair 83 of the transport vehicle 3 are in contact with the first guide rail 6a at the entrance and exit of the curved portion 203 even when they are in the guide position. Do not actively control. Therefore, the guide rollers 31 and 33 are unlikely to contact the guide rail 6.

(B) In order to calculate the travel locus, the speed pattern generation unit 62 is the first regarding the movement from when the front guide roller pair 81 enters the curved portion 203 to when the rear guide roller pair 83 enters the curved portion 203. The positions of the traveling wheel 25, the second traveling wheel 28, and the turning shaft center 38 are determined at predetermined distance intervals.
In this transport vehicle system 1, an ideal travel locus is determined with respect to the movement from when the front guide roller pair 81 enters the curved portion 203 to when the rear guide roller pair 83 enters the curved portion 203. Accordingly, the front guide roller pair 81 and the rear guide roller pair 83 are unlikely to contact the first guide rail 6a.

(C) The speed pattern generation unit 62 calculates the speeds of the first traveling wheel 25 and the second traveling wheel 28 at each point based on the traveling locus.
In the transport vehicle system 1, the front guide roller pair 81 and the rear guide roller pair 83 are unlikely to contact the first guide rail 6a.

(D) The speed pattern generation unit 62 compensates the delay time at the time of behavior change with respect to the calculated speeds of the first traveling wheel 25 and the second traveling wheel 28 (two-wheel speed difference command). Table). The speed pattern generation unit 62 gives a speed command to the first motor 26 and the second motor 29 based on the compensation speed ratio table 90 during curve traveling.
In this transport vehicle system 1, speed commands are given to the first motor 26 and the second motor 29 based on the compensated speed ratio table 90 created by compensating for the delay time at the time of behavior change. Car driving can be realized. Further, since the compensation speed ratio table 90 is stored in advance, the burden of the command speed conversion processing work in the speed pattern generation unit 62 can be reduced.

(E) The speed pattern generator 62 compensates for the deviation between the command speed and the actually measured value in order to compensate for the delay time when the behavior changes.
In this transport vehicle system 1, transport vehicle travel in accordance with the intention can be realized.

  (F) Since the guide roller is less likely to come into contact with the guide rail in the curved portion traveling as described above, smooth traveling without slip or overload is realized. Further, the guide gap can be made smaller than before, and as a result, traveling accuracy when the transport vehicle travels on the straight portion is improved. From the above, the total traveling performance in the transport vehicle system 1 is improved.

(11) Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. In particular, a plurality of embodiments and modifications described in this specification can be arbitrarily combined as necessary.

(A) In the said embodiment, although the conveyance vehicle detected the start and completion | finish of the curved part with the sensor, this invention is not limited to this. For example, the conveyance vehicle may make a software determination using an encoder.
(B) In the said embodiment, although the reflective tape was provided continuously along the curve part, this invention is not limited to this. The reflective tape may be provided intermittently.
(C) Although the transport vehicle travels on a track suspended from the ceiling in the above embodiment, the present invention is not limited to this. The track may be provided on the ground, or the transport vehicle may be suspended from the track.
(D) In the above embodiment, the encoder measures the rotation of the motor, but the present invention is not limited to this. The encoder may measure the rotation of the driving wheel or the driven wheel.
(E) The type and detection purpose of the combination of the detected portion and the sensor are not limited to the above embodiment.
(F) The installation position and the number of the detection target parts are not limited to the above embodiment.
(G) In the above embodiment, the left-right speed difference command is formed using the compensation speed ratio table, but the left-right speed difference command may be formed using the reference speed ratio table. Even in that case, the speed pattern generation unit gives the first motor and the second motor the speed command created based on the ideal travel locus when the transport vehicle travels along the curved portion. The front guide roller pair and the rear guide roller pair are unlikely to contact the guide rails.
(H) In the above embodiment, the parameters for servo tracking compensation are response and deviation, but may be either one.
(I) In the above-described embodiment, the description has been given of the transport vehicle system in which the driving traveling unit is provided on the front side of the vehicle body and the driven traveling unit is further provided on the rear side, but the present invention is not limited thereto. For example, the present invention can also be applied to a structure in which a front and both sides are drive travel units to form a four-wheel drive carriage. In this case, it is preferable that each drive unit independently creates a speed command for the left and right motors. In addition to the four-wheel drive cart, the present invention can be applied to a six-wheel drive cart and an eight-wheel drive cart.

  The present invention can be widely applied to a transport vehicle in which motors are separately provided on the left and right wheels and the wheels can be driven independently.

DESCRIPTION OF SYMBOLS 1 Transport vehicle system 2 Track 3 Transport vehicle 4 Travel rail 4a 1st travel rail 4b 2nd travel rail 6 Guide rail 6a 1st guide rail 6b 2nd guide rail 11 Reflective tape 11a Starting end 13 Bar code 14 Magnetic mark 15 Transport vehicle Main body 18 Drive travel unit 19 Driven travel unit 20 Main body frame 21 First drive wheel unit 22 Second drive wheel unit 23 Main body frame 25 First travel wheel 26 First motor 27 First encoder 28 Second travel wheel 29 Second motor 30 2nd encoder 31 1st fixed guide roller 32 2nd fixed guide roller 33 1st branch guide roller 34 2nd branch guide roller 35 1st branch guide roller drive part 36 1st driven wheel 37 2nd driven wheel 38 Turning axis center 40 Third fixed guide roller 41 Fourth fixed guide roller 42 Third branch guide roller 4 3 Fourth branch guide roller 44 Second branch guide roller drive unit 47 Photoelectric sensor 49 Linear scale 50 Bar code reader 52 Car carrier controller 54 Controller body 55 Memory 59 Travel controller 60 Branch controller 61 Route map 62 Speed pattern generator ( Control part)
63 1st motor control part 64 2nd motor control part 65A 1st error amplification part 65B 2nd error amplification part 66A 1st feedback control part 66B 2nd feedback control part 67A 1st amplifier 67B 2nd amplifier 70 Reference speed ratio table 71 Reference outer ring speed ratio 73 Reference inner ring speed ratio 80 Stop position 81 Front guide roller pair 83 Rear guide roller pair 85 Front guide roller pair 87 Rear guide roller pair 90 Compensation speed ratio table (two-wheel speed difference table)
91 Compensated outer ring speed ratio 93 Compensated inner ring speed ratio 95 First intermediate point 97 Second intermediate point 201 First straight line part 202 Second straight line part 203 Curved part 203a Start position 206 Branch part

Claims (5)

Traveling rails,
A guide rail provided along the traveling rail;
A transport vehicle that travels along the travel rail;
A control unit for controlling the traveling of the transport vehicle,
The transport vehicle is
The car body,
A first traveling wheel and a second traveling wheel provided on the left and right of the vehicle body;
A first motor and a second motor respectively connected to the first traveling wheel and the second traveling wheel;
A front guide roller pair and a rear guide roller pair provided respectively on the front side and the rear side of the first traveling wheel;
The control unit calculates a travel locus in which the front guide roller pair and the rear guide roller pair do not contact the guide rail when the transport vehicle travels on a curved portion, and then creates based on the calculation result. Giving a speed command to the first motor and the second motor;
Transport vehicle system.   In order to calculate the traveling locus, the control unit is configured to move the first traveling wheel with respect to movement from when the front guide roller pair enters the curved portion to when the rear guide roller pair enters the curved portion, The conveyance vehicle system of Claim 1 which determines the position of the said 2nd driving | running | working wheel and a turning axis center by predetermined distance interval.   The transport vehicle system according to claim 1 or 2, wherein the control unit calculates the speeds of the first traveling wheel and the second traveling wheel at each point based on the traveling locus.   The control unit stores a two-wheel speed difference command table created by compensating a delay time at the time of behavior change for the calculated speeds of the first traveling wheel and the second traveling wheel, and during the curved traveling The transport vehicle system according to claim 3, wherein a speed command is given to the first motor and the second motor based on the two-wheel speed difference command table.   The carrier system according to claim 4, wherein the control unit compensates for a deviation between a command speed and an actually measured value in order to compensate for a delay time when the behavior changes.

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