JP2676869B2 - Control device for unmanned carrier - Google Patents

Description

Description: [Industrial field of use] The present invention relates to a control device for an automated guided vehicle that travels along a predetermined travel route.

[Prior Art] In recent years, along with the automation of the production process, a trackless automatic guided vehicle is widely adopted in the field of factory automation.

Next, FIGS. 3 to 5 show an outline of the configuration of an unmanned guided vehicle and a control circuit for the guided vehicle which have been conventionally implemented. First, as shown in FIG. 3, the carrier truck 1 has electric motors 2a, 2
A pair of left and right moving wheels 3a, 3b individually driven by b, and a position detector 4 mounted at the center of the tip of the bogie are provided, and a guide wire 5 from a guide wire 5 laid on the floor side along a designated travel route in advance. Drive under the guidance.

Here, the position detector 4 is as shown in FIG. 4, and includes a pair of left and right pickup coils 6a and 6b, rectifiers 7a and 7b, a subtractor 8 and a filter 9 and the like, and is generated from the above-mentioned induction wire 5. The voltage signal proportional to the magnitude of the magnetic field is taken out from the pickup coils 6a and 6b, the difference between them is calculated, the displacement x (FIG. 3) between the center of the carriage 1 and the guide wire 5 is detected, and the detection signal Xo is obtained. Output.

The control circuit of the carrier vehicle is constructed as shown in FIG. Here, the output Xo of the position detector 4 described above is compared and adjusted with the position set value X in the position adjuster 10, and its output ΔN is guided to the adders 11a and 11b. In addition, 12 is an inverting amplifier. The adders 11a and 11b are the position adjusters 10
Output ΔN and speed setting value No are input, and speed target values Na, Nb for motors 2a, 2b (Na = No + ΔN, Nb = No-ΔN)
make. The target speed values Na and Nb are the speed controller (ASR) 13a,
13b, where the speed detectors 14a, 14b of the motors 2a, 2b
The current target values Ia and Ib are created by comparing with the speed detection value obtained in.
Further, the current target values Ia, Ib are guided to the current regulators 15a, 15b and compared with the current detection values obtained by the current detectors 16a, 16b of the motors 2a, 2b, and the power converters 17a, 17b are based on the deviations. Adjusts the conversion output so as to supply the electric currents corresponding to the current target values Ia, Ib to the electric motors 2a, 2b.

That is, when the carriage 1 is traveling, the displacement x
When this occurs, the target velocity value No
On the other hand, the speed of the electric motor 2a is increased and the speed of the electric motor 2b is reduced to correct the trajectory in the traveling direction.

By the way, in the above-mentioned unmanned transfer system, there is a tendency that the demand for speeding up the traveling speed of the truck and short-circuiting of the radius of curvature of the curved track from the space saving of the traveling route is increasing. It is a very important issue to improve the control stability of the device. Therefore, conventionally, the adjusting element of the position adjuster described above is changed from P (proportional) operation to PI (proportional and integral) operation (Japanese Patent Laid-Open No. 61-288705), or the position of the position detector attached to the carriage. We are trying to deal with it by approaching the wheel from the tip to the driving wheel in the center of the bogie.

[Problems to be solved by the invention]

However, as described above, only changing the position adjuster from P operation to PI operation has a limit to the improvement and stabilization of the traveling performance due to the relationship of the transfer characteristics thereof. It may not be possible to meet the demand for shortening the radius of curvature of the orbit. In addition, there is a problem that the vibration of the bogie to the left and right increases if the position detector is too close to the driving wheel. It takes a lot of time and effort.

The present invention has been made in view of the above points, and the optimum mounting position of the position detector is quantitatively determined from the traveling speed of the trolley and the delay of the control system, and the time constant in the transfer function of the position adjuster is trolleyed. An object of the present invention is to provide a control device for an unmanned traveling vehicle, which aims to improve traveling performance on a curved track of the traveling vehicle by appropriately selecting the traveling speed and the mounting position condition of the position detector. To do.

[Means for solving the problem]

In order to solve the above-mentioned problems, in the control device of the present invention, the distance l between the position detector and the line segment connecting the left and right driving wheels is set as follows: l = kN (Tp + Ts) where N: Travel speed, Tp: Equivalent time constant when the transfer function of the position detector is approximated to temporary delay, Ts: Equivalent time constant when the transfer function of the speed control system is approximated to temporary delay, k: Constant (preferably 4 Degree).

Furthermore, the adjusting element of the position adjuster is not assumed to have the characteristic of multiplying the sum of the proportional element and the derivative element by the first-order lag element, and the traveling speed of the truck is N, and the line segment connecting the position detector and the left and right driving wheels is The distance between them is 1, and the time constant of the first-order lag element is selected so that T = 1 / N.

[Action]

In the above, in the state where the carrier is traveling on a straight track, the transfer function G (s) of the position detector that detects the displacement displacement x of the carrier with respect to the track (guide line) from the speed difference between the left and right wheels is approximate. By the way Where s is the Laplace operator, k is a constant determined by the mechanical system configuration, l is the distance between the line segment connecting the left and right driving wheels and the position detector, and N is the traveling speed of the carriage. By the way, if the transfer functions of the position detector and the speed control system are approximated to equivalent first-order lags and their equivalent time constants are Tp and Ts, the time constant T = l / N expressed by the equation (1) is given. It can be inferred from the control theory that the control system is stable by selecting T = k (Tp + Ts) (2). Note that the response of the control system becomes slower as the constant k is increased in equation (2), so the constant k is about 4, that is, l = kN (Tp + Ts) ≈4N (Tp + Ts) (3) By setting the mounting position of the position detector as described above, stable traveling performance of the carriage is guaranteed.

In addition, the stable equation (1) is Rewriting, the transfer function Go (s) of the position adjuster connected after the position detector is By correcting the time constant of the position detection system so that Therefore, if the time constant T3 is selected to be about four times the value time constant (Tp + Ts), such as the above-mentioned first-order lag, the control system can be stabilized only by adjusting the proportional gain.

〔Example〕

FIG. 1 shows the mounting positions of the position detectors on the carriage according to the embodiment of the present invention.
Distance l between the line segment connecting the center with 3b and the position detector 4
Is quantitatively selected based on the above-mentioned equation (3), l = kN (Tp + Ts) ≈4N (Tp + Ts). As a result, an appropriate mounting position of the position detector 4 can be easily determined from the traveling speed of the trolley and the condition of the primary delay of the control system without depending on experiments.

Further, in the control circuit shown in FIG. 5, the position adjuster 10 provided at the subsequent stage of the position detector 4 is provided with an operational amplifier as shown in FIG.
By configuring with OP, fixed resistors R1 and R2, capacitor C1C2 and variable resistor VR, its transfer function, Go (s), However, a: tap position of variable resistor VR and fixed resistors R1, R
A constant determined by 2. Here, the value of C2 × R2 in the above equation is selected to be a constant that matches the time constant T = 1 / N based on the more quantitatively determined distance 1 described above.

〔The invention's effect〕

Since the control device for the automatic guided vehicle according to the present invention is configured as described above, it has the following effects.

(1) According to claim 1, the proper mounting position of the position detector with respect to the carrier vehicle can be reduced in a small amount from the traveling speed of the carrier vehicle and the first-order delay condition of the control system without relying on an experiment as in the conventional case. I can decide. In addition, by determining the mounting position and moving the position detector from the tip of the truck to move closer to the driving wheel, the traveling speed of the carrier truck on a curved track can be increased, and the radius of curvature of the curved track can be reduced. Can be planned. That is, if the distance between the position detector and the line segment connecting the left and right driving wheels is set at an optimum position where the distance 1 is smaller than that of the conventional device, the traveling speed of the carrier truck on the curved track is the same as that of the conventional device. If they are the same, the radius of curvature of the curved track can be reduced in proportion to the distance l, and if the radius of curvature of the curved track is the same as that of the conventional device, the traveling speed of the carrier on the curved track is inversely proportional to the distance l. Can be raised.

(2) Further, according to claim 2, the stability of the control system can be maintained even when the position detector is brought close to the moving wheels of the carrier vehicle, and thus the running performance of the curved track can be further improved.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a state diagram of a position detector attached to a carrier, FIG. 2 is a concrete circuit diagram of a position adjuster, and FIG. 4 is a general block diagram of the position detector in FIG. 3, and FIG. 5 is a block diagram of the entire control circuit. In the figure, 1: carrier truck, 2a, 2b: drive motor, 3a, 3b: moving wheel, 4: position detector, 5: guide wire, 10: position adjuster, l: mounting position interval of the position detector to the moving wheel.

Claims (2)

(57) [Claims] 1. A control device for an unmanned transporting vehicle that travels along a predetermined travel route, which is mounted on a transporting vehicle to detect a deviation from a track, and transports based on a detection signal from this position detector. It has a position controller that adjusts the position of the carriage so that it does not deviate from the track, and a speed control system that individually controls the speed of the moving wheels attached to the left and right of the carrier, and each driving wheel is controlled based on the output of the position controller. In the one in which one is accelerated and the other is decelerated to control the traveling of the carriage, the distance 1 between the position detector and the line segment connecting the left and right driving wheels is expressed as follows: l = kN (Tp + Ts) N: Traveling speed of the carrier Tp: Equivalent time constant when the transfer function of the position detector is approximated to first-order lag Ts: Equivalent time constant when the transfer function of the speed control system is approximated to first-order lag k: Constant (preferably Is about 4) The control device. 2. The control device according to claim 1, wherein the adjusting element of the position adjuster has a characteristic obtained by multiplying the sum of the proportional element and the derivative element by a first-order lag element, and the traveling speed of the carrier vehicle. Is N, and the distance between the position detector and the line segment connecting the left and right driving wheels is l, and the time constant T of the first-order lag element is T = 1 /
An automatic guided vehicle control device characterized by being selected to be N.