JPH0798638B2 - Balanced equipment safety circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an actuator for raising and lowering a work, a drive circuit for driving the actuator, a force detector for detecting the weight of the work, and an operator for issuing a speed command. Equipped with a speed commander to input and a calculation circuit that calculates the output to the drive circuit based on the detected work weight and speed command, and the actuator outputs the force corresponding to the weight for the work of arbitrary weight The present invention relates to a safety circuit of a balanced cargo handling apparatus that realizes a balanced state by allowing a person to directly touch a work and move up and down with a light force.

[Conventional technology]

 The present applicant has previously applied for the balanced cargo handling device shown in FIG.

That is, the rope 3 is wound around the drum 2 which is rotated by the motor 1 as an actuator, and the work 7 is hung on the rope 3 via the speed commander 4, the acceleration detector 5, and the force detector 6, and the motor 1 A speed detector 8 for detecting the rotation speed, a position detector 9 for detecting the rotational position of the motor 1, and an arithmetic circuit 10 are provided, and by inputting each detected value into the arithmetic circuit 10, a control signal commensurate with the weight of the workpiece 7 Drive circuit 11
The holding force of the motor 1 commensurate with the work weight can be given to make the balance, and when the command speed is input with the lever 4a, the motor 1 is rotationally controlled so as to match the command speed, and the person can use a light force. It is configured so that the work 7 can be raised and lowered.

[Problems to be Solved by the Invention]

In such a balanced cargo handling apparatus, the holding torque of the motor 1 is set to a value commensurate with the weight of the work 7, and the work is lifted by applying an operating force to the work while the work being lifted is stationary.
During equilibrium operation of descending, sudden changes in load due to work dropping or jumping can be very dangerous.

Therefore, it is an object of the present invention to provide a safety circuit of a balanced cargo handling apparatus in which the balanced operation is stopped at the time of a sudden load change and the work can be prevented from moving suddenly.

[Means and Actions for Solving the Problems]

Input the load differential signal obtained by differentiating the load signal from the load detector of the balanced cargo handling equipment and the speed signal from the speed detector.The absolute value of the load differential signal is larger than the threshold value and the absolute value of the speed signal is Provide a safety circuit that outputs a command to stop the equilibrium operation when it is larger than the threshold value, stops the actuator, and increases the threshold value of the load differential signal in proportion to the stored load value W _0. This makes it safe to stop the actuator by stopping the equilibrium operation when the load suddenly changes, and the threshold value of the load differential signal increases as the work weight increases, so even if the work weight becomes heavy, the load sudden change can be accurately determined. It can be done without malfunction.

〔Example〕

As shown in FIG. 1, the calculation circuit 10 includes a speed command calculation circuit 12 that calculates a speed command to the motor 1 based on a lever operation mode, a position mode, and a balanced operation mode, and a mode selection circuit that selects the mode. 13, a storage circuit 14 for storing the weight of the suspended work, and a safety circuit 15 according to the present invention are provided.

The speed commander 4 outputs a speed command signal R corresponding to the operation amount of the lever 4a, and the force detector 6 detects the load (force) acting on the work 7 and outputs the signal _FL. Is output. Further, the position detector 9 outputs a rotational position signal θ of the motor 1 and the speed detector 8 outputs a speed signal.

The drive circuit 11 is composed of an adder 16 that takes the deviation between the command value Vf and the speed signal of the motor 1, and a drive unit 17,
The motor 1 is driven according to the deviation Vf− between Vf and the speed signal.

18 is a motor acceleration feedback circuit, which is a motor 1
Has a differentiator 19 for differentiating the speed signal output from the speed detector 8 to obtain the acceleration signal of the motor 1, and an adder 20. In the adder 20, the acceleration signal and the speed from the arithmetic circuit 10 described later are included. The command value V _M is fed back and the command value V f is output.

The storage circuit 14 stores the weight W of the work 7 and outputs a weight command W ₀ .

Next, the operation of the safety circuit 15 will be omitted and the overall operation will be described.

(1) Lever operation mode The lever operation mode is the operation when the lever 4a of the speed command device 4 is operated. When the lever 4a is operated, the mode selection circuit 13 gives priority to other modes and the speed command calculation circuit 12 operates.
Is switched to the lever mode calculation, and the motor speed at which the workpiece moves at that speed is calculated based on the speed command signal R input from the speed command unit 4, and is output as the speed command value V _M.

At this time, the speed command value V _M the velocity signal from the speed detector 8 is negative feedback (negative feedback), the speed command value V _M is stabilized.

Note that the speed signal is actually multiplied by the gain.

(2) Position mode The position mode is an operation when the work 7 is held at a predetermined position. When the lever 4a of the speed command device 4 stops and the speed command signal R disappears, the mode selection circuit 13 causes the speed command calculation circuit to operate. 12 is switched to position mode calculation.

Is switched to position mode operation, immediately calculates the weight stored value W ₀ on the basis of the workpiece weight in the memory circuit 14, the load signal F _L than the weight stored value W ₀ and the force detector 6 | F _L -W _The speed command value V _M is calculated and output so that ₀ | ≦ threshold F _0, and the holding torque of the motor 1 is set to a value commensurate with the weight of the work 7.

At this time, the deviation X−X ₀ between the motor position signal X at the moment when the position mode calculation is performed and the motor position signal X ₀ after that is obtained,
This deviation X-X ₀ is multiplied by a gain to be negatively fed back to the motor 1
Is always held at the position when it switched to position mode calculation.

(3) Equilibrium operation mode The equilibrium operation mode is an operation in which the operator applies an operating force to the work 7 to raise and lower it after a predetermined time has passed from the position mode, and the weight storage value W ₀ and the force detector 6 load signal F _L is | F _L -W ₀ |> switches the threshold F ₀ becomes an equilibrium operating mode operation.

In other words, the addition of operation force to the workpiece 7 is the load signal F _L of the force detector 6 so varied by the operating force component, it switched to the equilibrium driving mode operation and the fluctuation value is greater than the threshold value F _0.

Thus, the speed command computing circuit 12 obtains the deviation of the load signal F _L and the weight stored value W ₀ of from force detector 6 (W ₀ -F _L), calculates a speed command value V _M on the basis of the deviation The motor 1 is rotated forward and backward, and the work 7 is moved up and down.

For example, when the lifting operation force F is applied to the work 7, the force detector 6
The load signal of is (F _L −F), and the deviation (W ₀ −F _L ) between the load signal FL and the weight memory value W ₀ is reduced by F, so that the speed at which the motor 1 rotates in the rope winding direction. Calculate the command value V _M.

Since this be the case, it is dangerous because the load signal F _L is the motor 1 is rapidly driven fluctuates rapidly workpiece 7 of the force detector 6 when the load suddenly changes at equilibrium operation up and down rapidly.

Therefore, in the present invention, the safety circuit 15 is provided so that the work 7 does not move up and down rapidly when the load suddenly changes.

The safety circuit 15 will be described below.

The safety circuit 15 operates when the mode selection circuit 13 selects the balanced operation mode, does not operate in the same manner as when the safety circuit release input is input when the other mode is selected, and the safety circuit 15 the, the load differential signal _L obtained by differentiating a load signal F _L of the force detector 6 by the differentiator 21, the load signal F _L
Then, the speed signal V of the speed detector 8 and the load memory value W ₀ are input from the memory circuit 14.

As shown in FIG. 2, the safety circuit 15 uses the load differential signal.
_A first absolute value comparison circuit 22 for comparing the absolute value | _L | of _L with a predetermined threshold value ε _L and outputting a signal when the absolute value | _L | is larger than the threshold value ε _L, and the speed detector 8 Is provided with a second absolute value comparison circuit 23 which compares the absolute value || of the speed signal from the predetermined threshold value ε and outputs a signal when the absolute position || is large. The signals 22 and 23 are output to the first AND gate 24, and by the output, the first latch circuit 25 is set to change the changeover switch 26 of the mode selection circuit 13 from the balanced operation mode command 27 to the abnormal condition command 28, and the speed is changed. The command calculation circuit 12 is switched from the balanced operation mode calculation state to the abnormality command state.

As a result, the equilibrium operation is immediately stopped, and the position signal θ from the position detector 9, the speed signal from the speed detector 8 and the acceleration signal a from the acceleration detector 5 are negatively fed back to rapidly move the work 7. To prevent this.

In the above description, the magnitude of the load differential signal _L is proportional to the work weight. Therefore, if the threshold ε _L is constant, the load differential signal _L does not change abruptly when the work weight is heavy. There is a case where ε _L or more is exceeded and a wrong judgment is made.

Therefore, in the present invention, the memory load value W ₀ is input to the first absolute value comparison circuit 22, and the threshold value ε _L is changed by the memory load value W ₀ , whereby the load is irrespective of the work weight. Can accurately judge sudden changes.

For example, as shown in FIG. 3, when the load differential signal _L is in proportion to the memory load W ₀ as shown by the solid line (a) during normal equilibrium operation, the threshold value ε _L is shown by the solid line (b). Is proportional to the memory load W ₀ and the load differential signal during equilibrium operation
_It is set to about 1.5 to 5 times _L , and the signal is output when the load differential signal _L has a threshold value of _L or more.

In Figure 2, 29 is a third absolute value comparison circuit for determining whether an impact during operation or sudden load change in equilibrium operation, the deviation F _L -W ₀ of the load signal F _L and stored load value W ₀ Absolute value of | F _L −W ₀ |
Is output to the second AND gate 30 when is larger than a predetermined threshold value Eemg.

The output signal of the third absolute value comparison circuit 29 is used to reset the first latch circuit 25.

In other words, in case of impact during work, the absolute value of the deviation | F _L
-W ₀ | does not become larger than the threshold Eemg momentarily for a T time, for example, 2 seconds or more continuously, and
In the case of sudden load change, the absolute value | F _L −W ₀ | does not become smaller than the threshold value Eemg continuously for T ₀ time, for example, 0.5 seconds or more, so the first and second timers 31 and 32 are used. The above-mentioned judgment is made.

The details will be described below.

The second set by the output signal of the first AND gate 24
The output of the latch circuit 33 is input to the second AND gate 30,
The output is passed through an inverter 34, a start 31a of a first timer 31, a first OR gate 35, a reset 31b, a start 32a of a second timer 32, an inverter 36, a second OR gate 37.
After being input to the reset 32b via the
The signal of the output 31c of the timer 31 is input to the third OR gate 38 and the second OR gate 37, and the signal of the output 32c of the second timer 32 is input to the first OR gate 35.

The first timer 31 is a timer for releasing the sudden load change mode, the time-up time is set to T ₀ , for example, about 0.5 seconds, and the second timer 32 is a timer for judging a sudden load change, and a signal is sent to the start 32a. After the input of T, the signal is output from the output 32c if the signal is not input to the reset 32b for 2 seconds, for example, 2 seconds.

On the other hand, the safety circuit release input signal is the third OR gate 38, the second
Reset 33a of the latch circuit 33, second and first OR gates 37,
The signal of the third OR gate 38 is input to the reset circuit 25a of the first latch circuit 25 and is reset by the reset signal 25a of the first latch circuit 25.

Then, when the load becomes large, the latch circuit 25 is set as described above and the changeover switch 26 is changed over to the abnormal condition command, and the first AND gate 24 and the third absolute value comparison circuit.
Since 29 outputs a signal, the second AND gate 30 outputs a signal and the second timer 32 starts.

At this time, if it is a shock at the time of work, the signal of the third absolute value comparison circuit 29 becomes zero by the time T has elapsed, the signal of the second AND gate 30 becomes zero, and the first timer 31 starts. After T ₀ time, the first latch circuit 25 is reset and the changeover switch 26 is changed over to the balanced operation command 27.

In addition, in the case of sudden load change, the second timer
Since the signal is not input to the reset 32b of 32, the signal is output from the output 32c to the first OR gate 35, the first timer 31 is reset, and the first latch circuit 25 is not reset.

In this way, at the time of a shock during work, an abnormal command is given for the time-up time of the first timer 31, and after that, it is possible to automatically return to the equilibrium operation.

〔The invention's effect〕

It is safe because the balanced operation is stopped and the actuator is stopped when the load suddenly changes, and the threshold value of the load differential signal increases depending on the work weight, so even if the work weight becomes heavy, it is possible to accurately judge the sudden change in load and malfunction. There is nothing to do.

[Brief description of drawings]

FIG. 1 is an overall view of a balanced cargo handling device showing an embodiment of the present invention,
FIG. 2 is an explanatory diagram of the safety circuit, FIG. 3 is a table showing the relationship between the threshold value of the load differential signal and the memory load value, and FIG. 4 is an explanatory diagram of a conventional balanced cargo handling device.

Claims (1)

[Claims] 1. An actuator for raising and lowering a work, a drive circuit for driving the actuator, a speed commander for inputting a speed command by an operator, a force detector for detecting a load, and a speed detector for detecting an actuator speed. And a position detector that detects the actuator position, and an arithmetic circuit that outputs an input signal to the actuator drive circuit based on the detection signal of each detector. In an equilibrium loading and unloading device in which the force is output by the actuator in an equilibrium state, the load differential signal obtained by differentiating the load signal from the load detector and the speed signal from the speed detector are input, and the absolute value of the load differential signal is A command to stop the equilibrium operation is output when the absolute value of the speed signal is larger than the threshold value and the absolute value of the speed signal is larger than the threshold value. A safety circuit for a balanced cargo handling apparatus, which outputs a signal for stopping the data and increases the threshold value of the load differential signal in proportion to the memory load value W ₀ .