JPH09269833A - Travel controller for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve resolution at the time of low speed and to improve travel stability and track controllability at the time of low speed travel and at the time of low speed transportation by providing pulse number variable means for increasing the number of the pulses of an encoder at the time of low speed compared to that at the time of high speed. SOLUTION: Driving motors 6 and 7 are fed back so that values become command values by means of a deviation between a travel speed command value and real travel speed. Variable frequency division parts 37 and 38 are the pulse number variable means increasing the number 2000 of the pulses of the encoder 18 at the time of low speed compared to that at the time of high speed, and they are used in the state of 500 pulses with a frequency division ratio at the time of low speed as 1/1 and that at the time of high speed as 1/4, for example. Since resolution improves by the relative increase of the number of pulses at the time of low speed, travel stability and track controllability at the time of low speed travel and at the time of low speed transportation can be improved, and stop precision at the time of stop can be improved. At the time of high speed, the number of pulses is relatively reduced, operation quantity can be reduced and processing time can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic guide vehicle (so-called AGV) which travels (moves) in a factory along guide means such as a magnetic tape provided on a floor or a white line tape for light reflection. The present invention relates to a vehicle travel control device.

[0002]

2. Description of the Related Art Conventionally, as a vehicle travel control device of the above-mentioned example, there is a device disclosed in Japanese Patent Laid-Open No. 6-67722. That is, a guide tape is attached to the floor surface of a vehicle such as an AGV that is a traveling path, a guide sensor for detecting the guide tape is provided on the vehicle side, and a drive motor that drives the left and right drive wheels is provided, and The vehicle travel control device is provided with an encoder that detects the number of revolutions of each of these drive motors, and is configured to perform speed feedback.

This conventional device has the advantage that the vehicle can be autonomously controlled by the encoder described above, but on the other hand, the pulse is transmitted from the encoder regardless of the traveling speed (low speed, medium speed, high speed, etc.) of the vehicle. If the number of rotations is uniform to the number of revolutions, sufficient number of pulses cannot be obtained when driving at low speeds, running stability at low speeds and trajectory controllability become insufficient, and the stopping speed of the vehicle deteriorates. However, there are problems that the number of pulses becomes excessive during high-speed traveling, the processing time becomes long, and overscale occurs.

[0004]

The invention according to claim 1 of the present invention is configured to perform feedback control of the actual traveling speed, and by increasing the number of pulses of the encoder at low speed as compared with at high speed, By increasing the number of pulses, the resolution at low speed is improved, and the traveling stability and trajectory controllability during low speed traveling and low speed conveyance are improved.
Further, it is an object of the present invention to provide a vehicle travel control device capable of improving stop accuracy and reducing the processing time at high speed because the number of pulses is smaller than at low speed.

In addition to the object of the invention described in claim 1, the invention described in claim 2 of the present invention variably adjusts the control value to the traveling motor in accordance with the increase / decrease control of the number of pulses, and It is easy to control the increase / decrease of the number of vehicles, and by changing the control value to the traveling motor in accordance with the increase / decrease of the number of pulses, it is possible to achieve appropriateness of driving of the traveling motor. For the purpose of provision.

According to a third aspect of the present invention, in addition to the object of the second aspect of the invention, a low speed command from an address means provided on a moving route of the vehicle is detected by an address sensor on the vehicle side. Then, by controlling the pulse number varying means and the variable adjusting section described above, the traveling speed of the vehicle can be switched to a low speed at an appropriate position on the moving route, and the traveling stability during low speed traveling and low speed transportation can be achieved. An object of the present invention is to provide a vehicle travel control device capable of improving trajectory controllability and stopping accuracy performance.

The invention according to claim 4 of the present invention, together with the object of the invention according to claim 3 above, is configured so that steering can be performed by the difference in driving speed between the left and right driving wheels. Thus, it is an object of the present invention to provide a vehicle travel control device capable of ensuring good steering performance by steering the left and right drive wheels.

[0008]

According to a first aspect of the present invention, there is provided a traveling control device for a vehicle, wherein a traveling motor is driven in accordance with a traveling speed command value to feedback-control an actual traveling speed. The vehicle drive control device is characterized by being provided with an encoder for speed feedback and a pulse number varying means for increasing the pulse number of the encoder at low speed as compared with high speed.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, a pulse number varying means for increasing / decreasing the detection pulse of the encoder, and a pulse number of the pulse number varying means. A travel control device for a vehicle, comprising: a variable adjustment unit that changes a control value for the travel motor according to an increase or decrease.

According to a third aspect of the present invention, in addition to the configuration of the second aspect of the invention, an address sensor for detecting a low speed command of an address means provided on a moving route of the vehicle is provided on the vehicle side. When the address sensor detects a low speed command, the number of pulses is increased by the pulse number changing means, and the variable adjusting section appropriately changes the control value to the running motor. Characterize.

According to a fourth aspect of the present invention, in addition to the configuration of the third aspect of the invention, the vehicle is a traveling control device for a vehicle that is steered by a difference in driving speed between left and right driving wheels. Is characterized by.

[0012]

According to the invention described in claim 1 of the present invention, the traveling motor is feedback-controlled so as to become the command value by the deviation between the traveling speed command value and the actual traveling speed. The number-of-pulses changing means increases the number of pulses of the encoder at low speed as compared with high speed. Since the resolution is improved by the increase in the number of pulses at the low speed, it is possible to improve the traveling stability and the trajectory controllability during the low speed traveling and the low speed conveyance, and it is possible to improve the stopping accuracy when the vehicle is stopped. effective. Also, since the number of pulses is relatively smaller at high speed than at low speed,
There is an effect that the amount of calculation can be reduced and the processing time can be shortened.

According to the invention described in claim 2 of the present invention,
In addition to the effect of the invention as set forth in claim 1, the pulse number varying means controls increase / decrease of the detection pulse of the encoder, and the variable adjusting section changes the pulse number of the pulse number varying means to the traveling motor. Change the control value of. Since the control value to the traveling motor is changed in accordance with the increase / decrease in the number of pulses in this way, there is an effect that the traveling motor drive can be optimized.

According to the third aspect of the present invention,
In addition to the effect of the invention as set forth in claim 2, the low speed command from the address means provided on the moving route of the vehicle is detected by the address sensor on the vehicle side, and the pulse number varying means and the variable adjusting section are provided. Since it is controlled, the traveling speed of the vehicle can be switched to a low speed at an appropriate position on the moving route, and the increase in the number of pulses at a low speed allows the traveling stability during low-speed traveling and low-speed transportation, trajectory controllability, and stopping There is an effect that the stop accuracy performance can be improved.

According to the invention described in claim 4 of the present invention,
In addition to the effect of the invention described in claim 3, since the steering is configured to be performed by the driving speed difference between the left and right driving wheels, the left and right driving wheels are steered by the high resolution at a low speed in which the number of pulses is increased. This has the effect of ensuring good steering performance.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. The drawings show a travel control device for a vehicle, and FIGS.
In FIG. 1, a guide tape 2 as an example of guide means is laid on the floor portion 1 along a moving route (running course), and an unmanned moving vehicle (a self-propelled vehicle, so-called AGV, but hereinafter simply referred to as vehicle). On the 3 side, a base 5 that is horizontally rotatable around a steering center 4 is provided, and left and right drive wheels that are independently driven by left and right drive motors 6 and 7 installed on the base 5. It has 8 and 9.

Further, the vehicle 3 described above is provided with left and right driven wheels 10 and 11 each having a free wheel structure or a non-free wheel structure, and a guide sensor 12 arranged in a direction intersecting the guide tape 2 at right angles. Is equipped with. Further, the vehicle 3 described above is provided with an address sensor 14 for detecting an address plate 13 as an address means arranged at a predetermined position on the floor 1.

Here, the guide sensor 12 has a plurality of, for example, 16 point sensors C1 to C16 arranged in a direction intersecting with the guide tape 2 as shown in FIG. 3, and each of these point sensors C1. C16 is used to detect the lateral displacement (lateral displacement) of the guide tape 2 and the vehicle 3. Further, while the above-mentioned guide tape 2 is set to a magnetic tape (magnetic recording medium), each of the above-mentioned point sensors C1 to C16 is set to a magnetic Hall element as an example of a magnetic sensor to prevent contamination of the floor portion 1 and the road surface. It is not easily affected and is configured to always ensure good magnetic detection accuracy.

Furthermore, in this embodiment, in the two-wheel drive type vehicle 3, a shift in the left-right direction with respect to the guide tape 2 is detected, and in other words, the difference between the rotational speeds of the left and right drive wheels 8 and 9, that is, in other words. The vehicle 3 is configured to be steered (direction correction, trajectory control) by the difference in the rotational speeds of the left and right drive motors 6, 7.

FIG. 4 shows the functional blocks of the vehicle travel control device. The CPU 20 has signals from the operation section 15 including a stop switch and a start switch, signals from the guide sensor 12 for detecting the guide tape 2, and an address plate. RO based on the signal from the address sensor 14 that detects 13
The left and right encoders that drive and control the left and right drive motors 6 and 7 through the left and right motor drive units 17 and 21 according to the program stored in the M16 and detect the speeds of the rotary shafts of these drive motors 6 and 7. Reference numerals 18 and 22 are provided for the purpose of feeding back the actual traveling speed, and signals from these encoders 18 and 22 are supplied to encoder input sections 19 and 23.
Is returned to the CPU 20 via.

The RAM 24 has a map M1 shown in FIG.
Stores necessary maps and data such as M2. One map M1 shown in FIG. 3 is a control law in which the horizontal axis represents the guide tape position and the vertical axis represents the left motor drive speed value.
Similarly, the other map M2 is a control law in which the horizontal axis represents the guide tape position and the vertical axis represents the right motor drive speed value. In FIG. 3, CL1 indicates the center position of the guide sensor 12, in other words, the vehicle center, CL2 indicates the center of the guide tape 2, and the distance between these centers CL1 and CL2 is the lateral displacement amount ΔL of the vehicle. FIG. 3 exemplifies a state in which the vehicle 3 is displaced to the right by the lateral displacement amount ΔL. In order to correct the displacement of the vehicle 3, the left drive motor 6 is rotated at the speed value a and the right side drive motor 6 is rotated. It shows that the drive motor 7 should be rotated at the speed value b (however, b> a).

FIG. 5 shows a control block equivalent to the functional block shown in FIG.
The guide position signal and the traveling speed command value are input to the motors 1, 32, and the left and right drive motor speed calculators 31, 32 calculate motor speeds for the respective motors 6, 7 based on these, and compare the outputs. Output to the units 33 and 34.

On the other hand, each encoder 18, 2 which outputs, for example, 500 pulses per one rotation of each of the left and right motors 6, 7
In the next stage of 2, the variable frequency dividers 37, 38 are provided via the multiplication rates 35, 36 for converting the above pulses into 2000 pulses of 4 times, for example.
Are connected. The multiplication rates 35 and 36 can be arbitrarily multiplied, but for convenience of explanation, the multiplication rate = 4 will be described.

The variable frequency dividers 37 and 38 described above use the number of pulses of the encoders 18 and 22 (in this embodiment, the frequency multiplier 3).
5,36) is a pulse number varying means for increasing the pulse number of the 5,36 output stages = 2000) at low speed as compared with that at high speed. In this embodiment, the frequency division ratio at low speed is 1/1, as shown in FIG. It is used in the state of 2000 pulses, and the division ratio is 1/4 at high speed, and 2000/4 = 500 as shown in FIG.
It is configured to be used in a pulsed state.

Speed converters 39 and 40 for converting pulse signals into speed signals are connected to the next stage of the variable frequency dividers 37 and 38, and feedback signals are fed back to the feedback line 4.
It is configured to feed back to the above-mentioned comparison units 33 and 34 via 1, 42. The above-mentioned comparison units 33 and 34 are calculated values (target values) from the drive motor speed calculation units 31 and 32.
And the feedback signal are compared, and the deviation signal is output to the PI control units 43 and 44 so as to reach the target value.

The left and right PI control units 43 and 44 execute PI calculation (proportional integral calculation) based on the deviation signal, and output the calculation result to the variable amplification units 45 and 46. The variable amplification units 45 and 46 are variable adjustment units that variably adjust the control values to the drive motors 6 and 7 in accordance with the increase / decrease in the number of pulses (frequency division ratio) of the variable frequency dividing units 37 and 38. Therefore, in this embodiment, when the division ratio is set to 1/1 at low speed, the amplification factor of the variable amplification units 45 and 46 is set to 1/4, and the division ratio is set to high speed at high speed. When it is set to 1/4, the amplification factor of the variable amplification units 45 and 46 is set to 1/1 correspondingly.

The outputs of the above left and right variable amplifiers 45 and 46 are output to the left and right drive motors 6 and 7 via the corresponding motor drive units 17 and 21, and these left and right drive motors 6 and 7 are output. Drive the left and right drive wheels 8 and 9 separately, and steer the vehicle 3 due to the difference in drive speed between the left and right drive wheels 8 and 9.

In FIG. 5, reference numeral 47 denotes a mechanical traveling steering mechanism portion including the steering center 4 and the base 5. The mechanism portion 47 steers the vehicle 3 and the position of the vehicle 3 with respect to the guide tape 2 is The detection output is detected by the guide sensor 12, and the detection output is input to the left and right drive motor speed calculation units 31 and 32. Further, in FIG. 5, each element 3
1 to 34 and 43 to 46 are configured inside the CPU 20.

Here, since the frequency division ratio at low speed is 1/1 and the frequency division ratio at high speed is 1/4 by the above-mentioned variable frequency division units 37 and 38, the encoder at the time of low speed and at the time of high speed is encoder. The speed conversion output as the output of the speed conversion units 39 and 40 for the pulse frequency is as shown in FIG. That is, the division ratio =
A region B corresponding to 1/4 of the total output region A at the time of high speed corresponding to 1/4 is formed as a region D which is quadrupled at the time of low speed corresponding to the division ratio = 1/1. It is possible to improve the sensitivity by increasing the resolution per pulse.

The operation of the vehicle travel control device thus constructed will be described in detail below with reference to the flow chart shown in FIG. In the first step S1, the CPU 20 determines whether or not it is activated based on a signal from the operation unit 15 including the activation switch, and waits until it is activated when the NO determination is made, while proceeding to the next second step S2 when the YES determination is made. Transition.

In the second step S2, whether the CPU 20 detects the address plate 13 as an address means provided at a proper position along the moving route (travel course) of the vehicle 3 based on the signal from the address sensor 14. To determine. As this address plate 13, various kinds of magnetic data (address data) for high speed command, medium speed command, low speed command, etc. are magnetically recorded in advance. In this second step S2, the address plate 13 is used.
The presence or absence of is detected. Then, when NO is determined, the 10th
While skipping to step S10, if YES is determined, the process proceeds to the next third step S3.

In the third step S3, the CPU 20 determines whether or not it is a speed command based on the address data, and when the determination is NO, skips to the tenth step S10, while YE
When the determination is S, the process proceeds to the next fourth step S4. In the fourth step S4, the CPU 20 sets the traveling speed corresponding to the content of the speed command, and in the next fifth step S5, the CP
U20 determines whether or not it is a low speed command based on the above-mentioned address data.

When the low speed command is issued, the process proceeds to the next sixth step S6 for the purpose of relatively increasing the pulse number, and when the non-low speed command (for example, the high speed command) is issued, the pulse number is relatively decreased. The process moves to another eighth step S8 for the purpose. In the above-mentioned sixth step S6, the CPU 20 sets the frequency division ratio 1/1 of the variable frequency division units 37, 38 in correspondence with the low speed. That is, the number of pulses per rotation of the motors 6 and 7 is 20
00. Next, in a seventh step S7, the CPU 20 sets the amplification factors of the variable amplification units 45 and 46 to 1 / n = 1/4.
(In this embodiment, n = 4, but this n is not limited to n = 4 as long as it is a multiple of 2.)

On the other hand, in the above-mentioned eighth step S8, the CPU
20 is a variable frequency dividing unit 3 corresponding to a non-low speed, for example, a high speed
The division ratio of 7, 38 is set to 1 / n = 1/4. That is, the number of pulses per rotation of the motors 6 and 7 is 2000/4 =
It is set to 500 pulses. Next, in a ninth step S9, the CPU
20 sets the amplification factors of the variable amplification units 45 and 46 to 1/1.

Next, in a tenth step S10, the CPU 20
Calculates the position of the guide tape 2, specifically, the lateral deviation amount ΔL shown in FIG. 3, based on the output of the guide sensor 12, and in the next eleventh step S11, the CPU 20 calculates the left and right motor driving speeds, and In the twelfth step S12, the CP
The U20 calculates the left and right motor rotation speed errors (see the comparison units 33 and 34) based on the target value and the feedback signal, and in the next thirteenth step S13, the CPU 20 determines PI.
A control amount (proportional integral control amount) is calculated (PI control unit 4
3, 44).

Next, in a fourteenth step S14, the CPU 20
Calculates the motor rotation speeds of the left and right motors 6 and 7, and in the next fifteenth step S15, the CPU 20 sets the left and right motor rotation speeds, and in the next sixteenth step S16, C
The PU 20 drives the left and right drive motors 6 and 7 at the set motor rotation speed.

Next, in the 17th step S17, the CPUC2
0 is the operation unit 15 including the stop switch or the address plate 13
It is determined whether or not the vehicle is stopped based on the stop command of No., and when NO is determined, the process returns to the second step S2, and when YES is determined, the process proceeds to the next 18th step S18.
In step S18, the CPU 20 causes the left and right motors 6 and 7 to operate.
The left and right drive wheels 8 and 9 are stopped to stop the vehicle 3.

In short, the above-mentioned drive motors 6 and 7 are feedback-controlled so that the command value is obtained by the deviation between the traveling speed command value and the actual traveling speed. However, the pulse number varying means (variable frequency divider 37 , 38) is encoder 1
The number of pulses of 8 and 22 is increased at low speed compared to at high speed.

Since the resolution is improved by the relative increase in the number of pulses at the low speed, it is possible to improve the traveling stability and the trajectory controllability during the low speed traveling and the low speed transportation, and the stopping accuracy is improved when the vehicle is stopped. There is an effect that can be achieved. Further, since the number of pulses is relatively smaller at high speed than at low speed, there is an effect that the amount of calculation and the processing time can be shortened.

In addition, the above-mentioned pulse number varying means (see the variable frequency dividing sections 37 and 38) controls the detection pulses of the encoders 18 and 22 to increase or decrease, and the above-mentioned variable adjusting section (variable amplifying section 4).
5 and 46), the control value (see the amplification factor) for the drive motors 6 and 7 is changed in accordance with the increase and decrease of the pulse number of the pulse number changing means. In this way, the control values for the drive motors 6 and 7 are changed according to the increase and decrease in the number of pulses.
There is an effect that it is possible to achieve appropriate drive for

Moreover, the moving route of the vehicle 3 (travel course)
The low speed command from the address means (see the address plate 13) provided in the vehicle is detected by the address sensor 14 on the vehicle 3 side, and the pulse number varying means (see the variable frequency dividing sections 37 and 38) and the variable adjusting section described above. Since the variable amplifiers 45 and 46 are controlled, the traveling speed of the vehicle 3 can be switched to a low speed at an appropriate position on the moving route, and the increase in the number of pulses at a low speed can reduce the traveling speed during low speed traveling and low speed transportation. Driving stability,
There is an effect that the trajectory controllability and the stopping accuracy performance at the time of stopping can be improved, and it is also effective, for example, when assembling articles or the like on the upper portion of the vehicle 3.

Further, since the vehicle 3 is configured to be steered by the driving speed difference between the left and right driving wheels 8 and 9, the left and right driving wheels 8 and 9 can be steered by the high resolution at a low speed in which the number of pulses is increased. Therefore, there is an effect that good steering performance can be secured.

In the above embodiment, each multiplication unit 3
2000 pulses of 5 and 36 output stages (however, the number of one rotation of motors 6 and 7) is set at a low frequency division ratio of 1/1 to increase the number of pulses relative to high speed, and at high speed The ratio is set to 1/4 and the number of pulses is relatively reduced as compared to the low speed (so-called low speed is used as a reference). However, instead of this structure, the multipliers 35 and 36 described above are used.
The number of pulses of the encoders 18 and 22 per rotation of the motors 6 and 7 = 500 is set as a reference at high speed, and the multiplication rate is 1/1 at high speed, and the multiplication rate is 4 times at low speed. The same effect is obtained.

That is, the pulse number varying means of the present invention may be a variable frequency dividing section (see the embodiment) or a variable multiplication section. In addition, a variable adjustment unit (variable amplification unit 45,
46) is an encoder 1 with 500 pulses per rotation
The amplification factor may be varied so that the output obtained by dividing or multiplying the 8 and 22 outputs is returned to the original state (500 pulses per rotation). Further, the number of output pulses of the encoders 18 and 22 = 500 is an example illustrated for convenience of description, and is not limited to this. In addition, when the number of pulses of the encoders 18, 22 per one rotation of the motors 6, 7 = 500 is multiplied by 8 times, 16 times, etc. by the above-mentioned multiplying parts 35, 36, the actual vehicle speed becomes, for example, 0.5 m / min. It is possible to ensure improved running stability and trajectory controllability at extremely low speeds and very low speeds.

FIG. 9 shows another embodiment of the vehicle structure. In the vehicle 3 shown in FIG. 9, the steering center 4 and the base 5 are omitted from the vehicle shown in FIG. Even with this structure, the same effects as those of the previous embodiment can be obtained. Therefore, in FIG. 9, the same parts as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the correspondence between the configuration of the present invention and the above-described embodiment, the traveling motor of the present invention corresponds to the drive motors 6 and 7 of the embodiment. Similarly, the pulse number varying means will be described below.
The variable frequency dividers 37 and 38 correspond, the variable adjusters correspond to the variable amplifiers 45 and 46, and the address means correspond to the address plate 13. However, the present invention is limited to the configuration of the above-described embodiment. It is not something that will be done.

For example, in the above embodiment, the combination of the magnetic tape and the magnetic sensor is exemplified as the combination of the guide tape and the point sensor, but this may be the combination of the light reflecting element such as the white line tape and the photoelectric sensor. Alternatively, it may be a combination of a wire body that generates a magnetic field by passing an induction current and a search coil in which a coil is wound around a cylindrical bobbin.

[Brief description of drawings]

FIG. 1 is a side view showing a vehicle travel control device of the present invention.

FIG. 2 is a plan view showing the relationship of the vehicle with respect to the guide tape.

FIG. 3 is an explanatory diagram showing a relationship between left and right motor drive speed values with respect to a guide tape position.

FIG. 4 is a functional block diagram of a vehicle travel control device.

FIG. 5 is a control circuit block diagram of a vehicle travel control device.

FIG. 6 is an explanatory diagram showing a relationship between a frequency division ratio and the number of pulses.

FIG. 7 is an explanatory diagram showing a speed conversion output corresponding to a frequency division ratio.

FIG. 8 is a flowchart showing traveling control.

FIG. 9 is a plan view showing another embodiment of the vehicle.

[Explanation of symbols]

 3 ... Vehicle 6, 7 ... Drive motor 8, 9 ... Drive wheel 13 ... Address plate 14 ... Address sensor 18, 22 ... Encoder 37, 38 ... Variable frequency divider 45, 46 ... Variable amplifier

Claims (4)

[Claims] 1. A travel control device for a vehicle, wherein a travel motor is driven in accordance with a travel speed command value to feedback-control an actual travel speed, the speed feedback encoder and the number of pulses of the encoder. And a pulse number changing means for increasing the pulse speed at a low speed as compared with a high speed at a high speed. 2. A pulse number changing means for increasing / decreasing a detection pulse of the encoder, and a variable adjusting section for changing a control value to the traveling motor in response to an increase / decrease of the pulse number of the pulse number changing means. The vehicle travel control device according to claim 1. 3. An address sensor for detecting a low speed command of an address means provided on a moving route of the vehicle is provided on the vehicle side, and when the address sensor detects the low speed command, the pulse number varying means changes the number of pulses. The vehicle travel control device according to claim 2, wherein the control value for the travel motor is increased and is appropriately changed by the variable adjustment unit. 4. The vehicle travel control device according to claim 3, wherein the vehicle is steered by a difference in driving speed between left and right driving wheels.