JP2944664B2 - Abnormal state detection device equipped with power detection circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power detection circuit that monitors the load state of a tool by detecting the power of a power tool, and to an apparatus that detects an abnormal state. <Prior Art> Conventionally, for example, in a robot equipped with an electric grinder, the power of a power tool is detected and the load of the tool is monitored to control the processing feed speed of a workpiece. <Problems to be Solved by the Invention> However, in the above-described apparatus, there is a problem that the machining feed rate cannot be controlled when the power detection circuit itself has some abnormality and cannot accurately detect power. . <Means for Solving the Problems> The present invention has been made to solve the above-described problems, and includes a tool state detecting means for detecting starting or stopping of a power tool, and a power signal detected by the power detecting circuit. A first comparator that compares the power signal with a second reference signal that is smaller than the first reference signal and outputs an output signal. State determination means for determining at least one of the power tool and the power detection circuit based on a state of the power tool detected by the tool state detection means and an output signal from the first and second comparators; Is provided. <Operation> Attention is paid to the fact that the electric power temporarily increases at the start of the electric power tool and then becomes the steady electric power. The power signal that changes at the start and the first and second reference signals are converted into the first and second reference signals. Each is compared by a comparator. From the output signals output from the first and second comparators and the state of the power tool detected by the tool state detection means, at least one of the power tool and the power detection circuit determines an abnormal state. <Example> Hereinafter, an example in which the present invention is applied to a robot will be described with reference to the drawings. In FIG. 1, reference numeral 10 denotes a wrist of the robot 11.
It is an electric grinder attached to 13. The electric grinder 10 processes the workpiece W placed on the table 14 by rotating the grindstone 20 and moving the arm of the robot 11, and the electric grinder 10 and the robot 11 are controlled by a robot controller 12. Is done. A power supply 16 is connected to the electric grinder 10 via a power cord 15, and a power detection circuit 17 for detecting the power of the electric grinder 10 is interposed between the power supply 16 and the electric grinder 10. . The power detection circuit 17 includes a first comparator 18 and a second comparator 18.
The comparator 19 is connected to the first and second comparators.
18 and 19 compare the reference powers P1 and P2 shown in FIG.
An ON signal is output to the robot controller 12 when it is larger than 1, P2. Here, the reference power P1 is set to the maximum power consumption when the grinder 10 is activated, and the reference power P2 is set to the minimum power consumption. The operation of the above configuration will be described with reference to the timing chart of FIG. 2 and the flowchart of the program stored in the robot controller 12 of FIG. When power is supplied to the robot, the program starts operating, and in step 100, the first and second comparators 1
Check that the output signals of 8, 19 are OFF signals, and grinder 10
The state of the power detection circuit when the power supply is stopped is monitored. If the output signal is the OFF signal, the monitoring is continued until the start signal of the grinder 10 is input in step 101. If the output signal is other than the OFF signal, a failure is displayed in step 102,
Next, as shown in FIG. 2 (b), when a start signal is input to the grinder 10 at time T0 as shown in FIG. 2 (b), the power temporarily increases as shown in FIG. To be stable. As shown in FIGS. 2 (c) and 2 (d), during the temporary increase of power,
1. The second comparators 18 and 19 are sequentially turned ON. This is detected in step 104, and the first and second comparators 18 and 19 are both turned on.
If so, proceed to step 105.If not ON, proceed to step 106.
If not, a failure is displayed in step 107 and step 1
In 08, the grinder 10 is stopped, and if ta time has not elapsed, the process returns to step 104. Here, the “ta time” means that the power signal P passes from time T0 to time T1 in FIG.
Is reduced until the steady-state no-load power is reached. When the process proceeds to step 105, the power signal P waits until a stable state after the time T2, and when the power signal P is stabilized, the process proceeds to step 109, where the first comparator 18 is turned off and the second comparator 19 is turned off.
By monitoring whether it is N or not, it is monitored whether the power signal P at the time of operation of the grinder 10 is normal or not until the stop signal of the grinder 10 is input in step 110. Here is the first
If the comparator 18 is OFF and the second comparator 19 is a signal after ON, it is determined that some abnormality has occurred in the power detection circuit 17 or the abnormal state detection device itself, and a failure is displayed in step 102, and a failure is displayed in step 102. To stop the grinder 10 abnormally. When the stop signal of the grinder 10 is input in step 110, the process proceeds to step 111 to check whether the output signals P1 and P2 of the first and second comparators 18 and 19 are OFF signals, and the output signals P1 and P2 are turned off.
If it is not a signal, a failure is displayed in step 102, and the grinder 10 is stopped abnormally in step 103, and if normal, the program ends. By doing so, the failure of the grinder 10 and the power detection circuit 17 can be detected. In the above-described embodiment, the output signals P1 and P2 of the first and second comparators 18 and 19 are detected to change in the robot controller 12, but the machining robot is controlled by a programmable controller or the like. For example, in the case of using in a processing line, the detection timing signal may be input by inputting a detection timing signal at predetermined intervals by a programmable controller. Hereinafter, the flowchart of FIG. 4 will be described with reference to FIG. In step 200, output signals of the first and second comparators 18 and 19
The state of the power detection circuit when the grinder 10 is stopped is monitored by checking whether P1 and P2 are OFF signals, and the output signals P1 and P2 are monitored.
If both are OFF signals, in step 201 the grinder 10
Monitoring is continued until the start signal of is input from the programmable controller. If the output signals P1 and P2 are other than the OFF signal, a fault is displayed in step 202, and the grinder 10 is abnormally stopped in step 203. Next, as shown in FIG. 2 (b), when the start signal is input to the grinder 10 at the time T0, the process proceeds to step 204, and after the elapse of the time T1 after the start, the signal is held until the timing signal T1 is input from the programmable controller. At this point, the process proceeds to step 205 to detect whether both the first and second comparators 18 and 19 are ON. If the first and second comparators 18 and 19 are both ON, the process proceeds to step 206, where
If not, proceed to step 202 to display the failure, and step 2
03 stops the grinder 10 abnormally. Next, in step 206, when the time T2 elapses after the start, the timing signal T2 is input, and in step 207, whether the first comparator 18 is OFF and the second comparator 19 is ON in step 207 is determined by whether the power signal P is in a steady state. In step 208, detection is performed until a grinder stop signal is input. If the first comparator 18 is OFF and the second comparator 19 is other than ON, the process proceeds to step 202 to display a failure, and in step 203, the grinder 10 is abnormally stopped. When a stop signal is input in step 209, the process proceeds to step 210,
Wait for the timing signal T3 to be input. When the time T3 elapses after the stop signal is input, the timing signal T3 is input,
Proceeding to step 210, it is detected whether the first and second comparators 18, 19 are both OFF. If not OFF, proceeding to step 202, a fault is displayed.
Is abnormally stopped, and if it is OFF, the program ends. In the second embodiment, the timing signal is given by an external device such as a programmable controller. However, the timing signal may be given by the robot controller 12 itself. <Effects of the Invention> As described above, the present invention compares the power signal detected by the power detection circuit with the first reference signal and outputs an output signal, with the tool state detection means for detecting the start or stop of the power tool. And a second comparator that compares the power signal with a second reference signal smaller than the first reference signal and outputs an output signal, wherein the power tool detected by the tool state detection unit is provided. State determination means for determining that at least one of the power tool and the power detection circuit is in an abnormal state based on the state of the power tool and the output signal from the first and second comparators.
An abnormal state of the power tool or the power detection circuit can be reliably performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention. FIG. 1 is a diagram showing the overall configuration of the device, FIG. 2 is a time chart showing signal changes of a failure detection device, and FIG. FIG. 4 is a flowchart of the robot controller according to the first embodiment, and FIG. 4 is a flowchart of the robot controller according to the second embodiment. 10 ... Grinder, 11 ... Robot, 12 ... Robot controller, 16 ... Power supply unit, 17 ... Power detection circuit, 18 ...
... first comparator, 19 ... second comparator.

Continuation of front page    (72) Inventor Masao Kawase               1 Toyota Town, Toyota City, Aichi Prefecture               Dosha Co., Ltd. (72) Inventor Makoto Asada               1 Toyota Town, Toyota City, Aichi Prefecture               Dosha Co., Ltd. (72) Inventor Kazuo Ito               1 Toyota Town, Toyota City, Aichi Prefecture               Dosha Co., Ltd.                    Examiner Satoru Takeda                (56) References JP-A-51-77801 (JP, A)                 Shokai Sho 56-152889 (JP, U)

Claims (1)

(57) [Claims] In an abnormal state detection device including a power detection circuit that monitors a load state of the power tool by detecting power of a power tool such as a grinder, a tool state detection unit that detects start or stop of the power tool; A first comparator for comparing the power signal detected by the circuit with the first reference signal to output an output signal, and comparing a second reference signal smaller than the first reference signal with the power signal to output an output signal A second comparator that detects whether the power tool and the power detection circuit are in an abnormal state based on a state of the power tool detected by the tool state detection means and an output signal from the first and second comparators. An abnormal state detection device including a power detection circuit, further comprising a state determination unit for determining that there is a power supply. 2. The state determination unit determines whether the comparator outputs an output signal in a predetermined order after the detection signal is input from the tool state detection unit, so that at least one of the power tool and the power detection circuit is output. Claims 1 to determine that the state is abnormal
An abnormal state detection device comprising the power detection circuit according to any one of the preceding claims. 3. The state discriminating means, after a detection signal from the tool state detecting means is inputted, after a lapse of a predetermined time, the first and second
2. An abnormal state detection device comprising the power detection circuit according to claim 1, wherein at least one of the power tool and the power detection circuit is determined to be in an abnormal state by detecting an output signal of the comparator.