JPS5822764B2 - Control method for stopping a moving object in a fixed position - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a moving device such as a crane that uses an AC motor as a drive device, in which a moving object, such as a gutter or trolley in the case of a crane, is controlled by a driver using a conventional operating device such as a cam controller. Move automatically without any operation,
This invention relates to a fixed position stop control method in which the vehicle is stopped at a fixed position determined by a limit switch or the like.

This invention provides that the relationship between the position and speed during coasting and braking, which is determined by the inertia, weight, movement resistance of the moving object, and the braking torque of the brake, is such that the speed approximates the position, that is, the prespecified stopping position. It focuses on the fact that the ambiance is a function of the square root of the distance to the moving object.

This invention assumes a case where a position signal with the stop position as a reference (atmosphere) is taken out by a position detector near the stop position and inputted to a square root calculator, and the brake is applied at that position to cause the stop position to be stopped. The speed at which the vehicle is moved or the speed assumed when the vehicle is stopped at a stop position due to coasting can be taken out as the output of the square root calculator.

At this time, select the assumed speed when braking as the speed when the weight of the moving object considered in actual driving is the maximum and the minimum braking torque is applied, and the assumed speed during coasting when the weight of the moving object is the minimum. If you select the speed when the maximum deceleration torque is applied, the actual speed signal of the moving object detected by the speed detector is compared alternately with the expected speed when braking and the expected speed when coasting. Braking,
A command signal for coasting, forward rotation, or reverse acceleration can be output to the control circuit of the electric motor, and the regulating object can be stopped at a stop position.

The fixed position stop control method according to the present invention can be applied to any moving device using an AC motor, but as an example, a fixed position stop control method in the traveling direction of a moving object such as a crane gutter will be taken up and explained. .

FIG. 1 is an explanatory diagram of the control principle in the embodiment, in which the horizontal axis represents the position of the moving object in the traveling direction, and the vertical axis represents the speed.

Ls represents a permissible stopping range centered on a pre-specified stopping position S, and LSF' and LSR' are provided before and after the stopping position S, respectively, to determine whether to run to the right or to the left. Indicates the operating range of limit switches LSF and LSR for rotational direction commands.
', LSB' indicates the operating range of the stop control limit switches LSA and LSB, which indicate the range in which stop control is performed;
SS' indicates the operating range of the limit switch LSS indicating the stop range Ls.

The dotted line vb indicates that the moving object suspends the maximum load that can be considered during normal operation, brakes with the minimum braking torque, and reaches the stop position S.
The relationship between velocity and position, assuming a stop at , is approximately replaced by a parabola.

The dotted line Vf is an approximate parabolic representation of the relationship between velocity and position, assuming that the moving object is coasting with the minimum load imaginable during normal operation and the maximum deceleration torque is applied. It is.

The operating point A at the left end of the limit switch LSA is selected as the position coordinate at the point C where the speed with a slight margin above the rated speed intersects the curve vb.

The speed signal is DC5V at the speed at point C, and the position signal is DC20mA at the mermaid.

It is assumed that the current is OmA at the stop position S.

The solid lines ■ to ■ and 0 to 0 indicate examples in which the moving object is converged to the stop position S from the positions of ■ and 0, respectively, by the control method according to this embodiment.

In this example, when traveling to the right, the electric motor is assumed to rotate in the normal direction.

Figure 2 is a block diagram showing the control principle of this embodiment, where LSS is a limit switch that indicates that the crane is in the stop range, and LSF and LSR are commands that command whether the motor should rotate forward or reverse. The rotation direction command limit switches LSA and LSB are stop control limit switches that command the range in which position signals are detected and the direction of integration of the counter 10 that holds the position signals. This is a pulse transmitter that emits pulses at 1 and 2, and it emits two pulses with a phase of "lead" or "lag" depending on the direction of travel, forward or reverse.

1 is a phase discriminator that receives pulses from the pulse generator PG and outputs forward rotation pulses during forward rotation and reverse rotation pulses during reverse rotation; 3
゜4.5, 6 and 7, 8 determine whether to send an addition pulse or a subtraction pulse to the counter 10 from the forward and reverse pulses and the signals of the limit switches LSA and LSB, and use an AND gate and send each pulse. OR gate, T
G is a tacho generator that detects the speed of the traveling electric motor, 2
9 is a signal converter that converts the output signal of the tachogenerator TG into a signal of DCO~5■, and 9 is a signal converter that converts the output signal of the tachogenerator TG into a signal of DCO~5■.
This is a reset button to clear the contents of 0 and return to the atmosphere.

At the time of initial adjustment, the moving object is manually stopped at the stop position S, the reset button 9 is pressed, and the contents of the counter 10 are set to 0'' count.

When the moving object is subsequently moved by manual operation, the contents of the counter 10 will always maintain a value (number of counts) proportional to the distance from the eight points within the range AA' in FIG.

Also, assuming that the content of the counter 10 becomes 200 counts at point A, outside the range AA' in Figure 1, the count is always 200 counts.
A zero count is maintained, and when the moving object enters the range AA' again, the contents of the counter 10 maintain a value proportional to the distance from the 8 points.

11 is a digital/analog converter that converts the contents (O~200 counts) of the counter 10 into DCO~20 mA, and 12 is an input linear signal (DCO~20 mA).
) is a square root calculator that outputs a DCO ~20 mA signal with square root characteristics.

The variable resistor r (250Ω) converts the output signal DCO~20mA of the square root calculator 12 into a voltage signal DCO~5V, and is divided into rl and r2 by a slider, and the position of the slider is determined by the voltage. is determined so that it shows the speed at point B in FIG. 1 when the output of the square root calculator 12 is 20 mA DC.

13 is a contact point of the relay 25, which is one input 1 of the comparator 14.
This is for selecting the input signal to 1.

The capacitor C is for switching the input signal to the human power 11 bumplessly.

Then, the comparator 14 receives input signals of il and i2 (each DCO
~5V) and θ1. θ2 output signal (ON-OF
F), and each input/output signal operates as follows.

i 1 (when i 2, θ1=5ON", θ2='OFF
"When i 1 > i 2, θ1='OFF", θ2-
'ON' 15 is a switch to start automatic fixed position stop control, 16 is an AND gate to prevent restarting during stop control, 17 is a flip-flop that commands forward or reverse acceleration, and set (S side is turned ON), acceleration is commanded.

Reference numeral 18 denotes a flip-flop that maintains that stop control is in progress, and when it is set (S side is ON), stop control is in progress.

Reference numeral 19 denotes an OR gate for resetting the acceleration flip-flop 17, which sends a reset signal when the output θ1 of the comparator 14 becomes ON or when the crane enters the stop range Ls during acceleration.

20.21 is a flip flora indicating that the stop control is in progress.

The output θ of the comparator 14 is only when the output θ is set.
1. 22 is an AND gate for outputting θ2 as a control command and a coasting command; 22 is an OR gate for the braking command from the output of the comparator 14 and the braking command from entering the stop range Ls; 23.24 is an addition gate;

Limit switch LSF when speed command is issued.

An AND gate 25 which determines whether forward rotation or reverse rotation should be performed according to the state of the LSR is a relay that is energized when a braking command is issued by the output θ1 of the comparator 14.

Next, the operation of the circuit shown in FIG. 2 will be explained for the operation examples ① to [phase] shown in FIG. 1, and the initial conditions of the circuit are as follows.

([) It is assumed that the counter 10 has completed initial adjustment.

(11) It is assumed that flip-flops 17 and 18 have been reset.

Since the crane is currently stopped at a position before the stop position S, that is, at the position (■), the content of the counter 10 is 200 counts, and the content of the counter 10 is 200 counts.
1. The output of the square root calculator 12 is 20 mA, and the flip-flop 18 is in the reset state, so the relay 25
is non-excited, and its contact 13 is connected to the b side.

Therefore, since the input 11 of the comparator 14 is 5V and the input 12 is O■, the output θ2 is 'ON'.

When the start switch 15 is pressed in this state, the flip-flop 17 is set and the limit switch L S F
Since fJ5' is ON, a forward rotation command is issued to the electric motor, and the crane starts traveling toward the stop position S.

When the crane starts traveling, the speed signal, i.e. input 12 of comparator 14, increases and the crane eventually reaches the rated speed and the speed signal remains constant, but input 1 of comparator 14 increases.
1 is greater than input 12.

Then the crane reaches point A and the limit switch LSA
operates, and the contents of the counter 10 begin to be decremented.

At the same time, the input 11 of the comparator 14 is at point C (5V) in FIG.
It starts to fall from 1 to 2 along the dotted line vb, and eventually matches the input i2 (rated speed) of the comparator 14.

At this point, the output θ1 of the comparator 14 becomes 1ON", and θ
2 is turned OFF, so the flip-flop 17 is reset and the normal rotation command is turned OFF.

Further, the flip-flop 18 is set, a braking command is issued, and the relay 25 is energized.

As a result, the contact 13 is connected to the a side, so that the input 11 of the comparator 14 becomes a voltage corresponding to the current position of the crane indicated by the dotted line Vf in FIG. 1, but the input 12 is higher.

At the same time, the speed of the moving object decreases, but as can be seen from the selection of dotted line vb in FIG. 1, the relationship between speed and position of the crane continues to decelerate between dotted lines vb and Vf.

During this time, the input i1 of the comparator 14. Both i2 continue to decrease, but the way they decrease can be seen from the way the dotted line Vf is selected.
12 is larger, so eventually the input i1. i2 matches and input 12 is smaller.

At this point, the output θ2 of the comparator 14 becomes 5'ON,
Switches from braking command to coasting command.

Further, since the relay 25 is de-energized, the contact 13 is connected to the b side, but the input 12 of the comparator 14 remains larger than the input 11.

When a coasting command is issued, the relationship between the speed and position of the crane is determined by the dotted line Vf, as can be seen from the selection of the dotted line Vf in Figure 1.
Continue decelerating between f and vb.

Then, a time comes when the input 11 of the comparator 14 becomes larger than the input 12 again, but the operation of the circuit is the same as before.

While repeating these operations, the position of the moving object reaches the left end of the stop range Ls, and the limit switch L
Final braking is performed by SS.

At the same time, the flip-flop 18 is reset.

In this way, the moving object stops within the stopping range Ls.

The operation side 0 to [phase] in FIG. 1 is an example in which the operation is started from the 0 position, but the moving object can be stopped in the stop range by a similar circuit operation.

Further, the same holds true whether the initial position of the moving object is behind the stop position S or within the range of AA'.

Further, in this embodiment, similar stop control can be performed by using a circuit that issues an acceleration command instead of a coasting command.

As described above, according to the fixed position stop control method for a moving object of the present invention, there is no need to operate a conventional operating device such as a cam controller, and it is possible to automatically stop a moving object at a prespecified stop position. can.

[Brief explanation of the drawing]

The drawings show an embodiment of the method for controlling a moving object to stop at a fixed position according to the present invention, and FIG. 1 is an explanatory diagram of the control principle, and FIG. 2 is a block diagram of the control principle. LSS, LSF, LSR, LSA, LSB...
Limit switch, PG...Pulse transmitter, T
G... Tacho generator, 1... Phase discriminator, 2... Signal converter, 10...
Counter, 11... Digital/analog converter, 12... Square root calculator, 14... Comparator, 15... Switch, 25... ··relay.

Claims (1)

[Claims] 1. It is confirmed that the continuous layer during braking and coasting of a moving object installed in a moving device such as a crane using an AC motor approximately follows a function of the square root of the distance to the moving object with respect to the stopping position. A rotating direction command detector is provided for detecting whether the moving object is before or after the specified stopping position, respectively, before or after the specified stopping position. Before,
A stop control detector for detecting the position of the moving object within the stop limit m range and outputting a position signal is provided in each of the rear neighborhoods, and the position signal is input to a square root calculator, and the position of the moving object is determined by braking or coasting. When the moving object is stopped at a specified stop position, an assumed speed at that position is generated as an output signal of the square root calculator, and an actual speed signal of the moving object detected by a speed detector and the output are generated. outputting a forward or reverse rotation command signal to the control circuit of the AC motor according to the detection signal of the rotation direction command detector until the moving object reaches the stop control range; After the moving object reaches the stop control range, the braking or coasting command signal is output to the control circuit based on the comparison between the speed signal and the output signal, and the actual speed is determined by A fixed position stop control method for a moving object, comprising controlling the moving object so that the stop position of the moving object converges on the specified stop position.