JP2001269892A - Absolute position detecting device for robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absolute position detecting device for a robot capable of keeping the detection precision of the absolute position of a drive motor high with a simple and inexpensive circuit structure and reducing power consumption. SOLUTION: This absolute position detecting device is provided with an excitation rotation position information acquiring means 15 acquiring the excitation rotation position information of a motor 6 at excitation, an de-excitation rotation position information acquiring means 16 acquiring the de-excitation rotation position information of the motor 6 when power feed is cut off by a power stoppage or severance of wire, and a switching means 17 operating the excitation rotation position information acquiring means 15 at excitation and operating the de-excitation rotation position information acquiring means 16 at de-excitation. When power feed is started after de-excitation, the absolute position of the motor 6 is detected based on the excitation rotation position information and the de-excitation rotation position information. The absolute position detecting device for a robot 1 is also provided with a de- excitation delay means 11c continuing the acquisition of the excitation rotation position information by the excitation rotation position information acquiring means 15 after the rotation of the motor 6 is stopped at de-excitation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple and inexpensive circuit configuration for controlling the number of rotations and the number of rotations of a drive motor even when a so-called power interruption occurs in which power supply is interrupted due to a power failure, disconnection, or the like during high speed rotation of the drive motor. The present invention relates to a robot absolute position detecting device capable of maintaining high accuracy of detecting an absolute position including an angular position.

[0002]

2. Description of the Related Art The speed of a robot is increasing year by year, and there are some robots in which the rotation speed of a drive motor has reached 8500 rpm to 10000 rpm. Also, even at a low rotation speed of about 5000 rpm, some robots cannot be instantaneously stopped due to a long arm length and large inertia. In the case of a robot equipped with such a high-speed rotation type drive motor or a robot having a long arm length, if the power supply is suddenly cut off, the brake circuit cannot be stopped instantaneously even if operated, but will rotate to some extent.

[0003] As a control device of this kind of robot, a resolver as a sensor for detecting the rotational position of the motor, and an R / R for detecting and storing the absolute position of the drive motor when energized based on the rotational position detection information of the resolver. A D converter circuit, a multi-rotation information backup circuit for detecting and holding the number of rotations of the drive motor at the time of power interruption, and the R / D converter circuit side during normal operation of the resolver detection information.
Some include a switching circuit for switching to the multi-rotation information backup circuit at the time of power failure.

[0004]

When a power failure occurs in a robot equipped with the above-mentioned conventional control device, first, an R / D
The converter circuit detects and stores the absolute position of the drive motor at the time of power failure, and switches to the multi-rotation information backup circuit by the switching circuit, and detects the multi-rotation information after power failure by the backup circuit. When the power is turned on, the current absolute position is determined based on the detection information from the R / D converter circuit and the detection information from the multi-rotation information backup circuit. However, there is a problem that the rotation angle during the switching time by the switching circuit is not detected, and accordingly, the detection accuracy of the absolute position is reduced accordingly.

Therefore, in order to avoid the above-mentioned problem, it is necessary to employ a high-speed and low-impedance switching element as the switching circuit in the conventional device. However, such a high-speed and low-impedance switching element is very expensive. And the cost is high. Further, the power consumption of the conventional device is large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has a simple and inexpensive circuit configuration capable of maintaining high absolute position detection accuracy of a drive motor and reducing power consumption. It is an object of the present invention to provide an absolute position detecting device.

[0007]

According to the first aspect of the present invention, there is provided an energized rotational position information acquiring means for obtaining energized rotational position information of a motor at energized time, and a power supply interrupted by a power failure or disconnection ( In the following, when the power is interrupted, the rotational position information obtaining means for obtaining the rotational position information of the motor at the time of power interruption, and the rotational position information obtaining means at the time of power supply, Switching means for activating the rotation position information acquisition means, and detecting the absolute position of the motor based on the power-on rotation position information and the power-off rotation position information when power supply is started after the power failure. In the robot absolute position detection device,
A power interruption delay means is provided for continuing the acquisition of the energized rotational position information by the energized rotational position information acquiring means until after the rotation of the motor is stopped.

According to a second aspect of the present invention, in the first aspect, the power interruption delay means executes the switching by the switching means after the rotation of the motor is stopped.

According to a third aspect of the present invention, in the first or second aspect, the power interruption delay means stops supply of control power to the energized rotational position information acquisition means at least after rotation of the motor after the power interruption. It is characterized in that it continues until it does.

[0010]

According to the first aspect of the present invention, the power interruption delay means is provided for continuing the acquisition of the energized rotational position information by the energized rotational position information acquisition means until the motor stops when the electric power is interrupted. In addition, the absolute position of the motor when the motor is stopped can be detected, so that the rotation of the motor after the power interruption does not affect the detection accuracy of the motor rotation position. As a result, the rotation position detection accuracy of the motor can be improved.

According to the second aspect of the invention, after the motor is stopped, switching to the rotational position information obtaining means at the time of power failure is performed, so that it is not necessary to use a high-speed and low-impedance switching circuit. It is possible to adopt a relay type, which can avoid high costs.

According to the third aspect of the present invention, the supply of the control power to the energized rotational position information acquiring means is continued until at least the rotation of the motor is stopped after the power interruption. The functions and effects of the first and second aspects can be realized by a simple and inexpensive circuit configuration including C) and the resistor (R).

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 to 5 are views for explaining a robot absolute position detecting apparatus according to an embodiment of the present invention. FIGS. 1 and 2 are side views, plan views, and FIGS.
FIG. 4 is a block diagram of the control device, FIG. 4 is a flowchart for explaining the operation, and FIG. 5 is a schematic diagram for explaining the operation.

In FIG. 1, reference numeral 1 denotes a scalar robot for positioning and mounting an electronic component such as an IC chip at a predetermined position. The robot 1 supports a first arm 3 rotatably around an X-axis by a base 2 arranged and fixed on a support surface of a component mounting apparatus or the like, and supports a second arm 4 by a tip end of the first arm 3 in a Y-direction. A work shaft 5 for supporting a work such as an electronic component by a tip of the second arm 4 so as to be rotatable about an axis and supported so as to be rotatable about an R axis and vertically movable in the Z axis direction. Of structure. In addition, 4
a is a cover that covers the drive mechanism mounted on the second arm 4.

A drive motor 6 for driving the first arm 3 around the X axis is accommodated in the base 2. The drive motor 6 is provided with a resolver 6a functioning as a motor rotational position detecting means. The resolver 6a is a one-phase excitation two-phase output type having a one-phase excitation coil and two-phase output coils shifted by 90 degrees, and supplies an excitation pulse of a predetermined frequency to the excitation coil. As a result, a waveform corresponding to the rotation angle position of the motor 6 is output.

A second arm drive motor 7 for driving the second arm 4 about the Y axis is accommodated on the second arm 4 and the work shaft 5 is rotated about the R axis. A swing motor 8 to be driven and an elevating motor 9 to be driven up and down in the Z-axis direction are accommodated and arranged. Although not shown, each of the motors 7 to 9 also has a rotation detection sensor of the same type as the drive motor 6.

In FIG. 3 showing the block configuration of the control device 10 of the robot 1, reference numeral 11 denotes a power supply unit, and 12 denotes the calculation of the rotational positions of the motors 6 to 9;
And a motor control device 13 for performing motor braking control and the like, and a motor driving circuit 13 for driving and braking the motors 6 to 9.

[0018] The motor control device 12 determines the two-phase output (rotational position detection information) from the resolver 6a.
R / D converter circuit (power-on rotation position information acquisition means) 15 for obtaining absolute rotation positions (power-on rotation position information) 15 of motors 6 to 9 during normal operation (power-on); A multi-rotation information backup circuit (rotational position information acquisition means at power interruption) 16 for detecting the number of rotations (rotational position information at power interruption) 9; a two-phase output from the resolver 6a; Circuit 15
And a switching circuit 17 for switching to the multi-rotation information backup circuit 16 in the event of a power failure.

The output from the R / D converter circuit 15 and the multi-rotation information backup circuit 16
The CPU 18 stores the absolute position detection information from the R / D converter circuit 15 in a memory 19, and the rotation position information in the memory 19 and the rotation from the multi-rotation information backup circuit 16 when the power is turned on. The current absolute position is calculated based on the position information, and a control signal is output to the motor driving circuit 13.

The R / D converter circuit 15 outputs, to the excitation coil of the resolver 6a, a sine wave having a frequency capable of following the motor rotation speed of 10,000 rpm, for example, and a sine wave output from the resolver 6a. And a R / D converter 15c for determining the number of motor rotations and the angular position during one rotation based on the filtered sine wave.

The multi-turn information backup circuit 16
For example, an excitation circuit 16a that outputs an excitation pulse having a frequency capable of following the motor rotation speed 4000 rpm to an excitation coil of the resolver 6a, a filter 16b that filters an output pulse from the resolver 6a into a predetermined waveform, and a filter 16b Amplifier 16c that amplifies and compares the currents of the two and generates an incremental signal, and comparator 1
6d, an incremental signal generation circuit 16e, and a counter 16 for counting an incremental signal.
f. Reference numeral 16g denotes a disconnection detection circuit that detects a disconnection of the multi-rotation information backup circuit 16.

The power supply unit 11 includes a drive power supply 11a for supplying power to the motor drive circuit 13, and an AC power supply 1 for power failure, disconnection, or power supply switch off.
Power-off detection circuit 11b for detecting that the supply of power supply 4 has been interrupted (power-off); power-off delay circuit 11c for delaying the supply of control DC power supply when power-off is detected; A DC power supply 11d for supplying control power to the motor control device 12 for a predetermined time by the action of 11c. The DC power supply 11d is composed of a capacitor (C) and a resistor (R), and varies with the voltage of the AC power supply 14, but can supply control power for, for example, 0.9 to 1.2 seconds.

The motor driving circuit 13 includes a CPU 18
Motor 6 based on a drive control signal (PWM signal) from
And a brake circuit 13b for braking the motor 6 based on a braking control signal from the CPU 18.

Next, the control operation of the motor 6 will be described with reference to the flowchart of FIG.

When the power switch is turned on at the start of the operation, the switching circuit 17 has been switched to the multi-rotation information backup circuit 16 at this time. Of the number of rotations of the motor 6 (count value of the counter 16f, hereinafter referred to as multi-rotation information this time)
8 is read. Then, the CPU 18 adds the motor rotation frequency information (hereinafter, referred to as the previous multi-rotation information) in the absolute position information stored at the time of the motor stop at the previous power interruption to the current multi-rotation information to obtain the current multi-rotation information. The rotation information is used, and it is determined whether or not the current multi-rotation information has an abnormality (steps S1 to S4).
In the case of, for example, an overflow of the counter or the number of rotations that is impossible from the viewpoint of the structure of the robot, it is regarded as abnormal.

If there is no abnormality in the multi-rotation information at the present time, the switching circuit 17 is switched to the R / D converter circuit side to respond to the excitation pulse from the excitation circuit 15a of the R / D converter circuit 15. Based on the two-phase output from the resolver 6a generated as described above, angular position information during one rotation of the motor (hereinafter, referred to as one rotation information) is obtained. The rotation information is added to obtain the current absolute position information, and it is determined whether or not the absolute position information is abnormal (steps S4 to S8). If it is determined in steps S4 and S8 that an abnormality has occurred, an abnormality process is performed (step S8).
17), the processing ends.

If there is no abnormality in the absolute position in step S8, the process returns to step S1, and if the power-on process has not been performed, the process proceeds from step S1 to S9, where the absolute position is determined. The detection information is read, and the presence or absence of a power interruption is detected (step S1).
0). In the power interruption detection circuit 11b according to the present embodiment, A
When the AC voltage waveform from the C power supply 14 falls for, for example, a half cycle, it is determined that the power interruption has occurred.

When the power interruption is detected, a motor stop signal is output to the above-mentioned brake circuit 13b,
3b acts as a dynamic brake to forcibly stop the rotation of the motor at, for example, 200 to 500 msec. Then, it is detected whether or not the motor has stopped (steps S10 to S12).
The absolute position information when the motor is stopped is read from the R / D converter circuit 15, and the absolute position information value is stored in the memory 1.
9 (steps S12 to S14).

Then, the multi-turn information backup circuit 1
6, the multi-rotation information count value of the counter 16f is cleared, and the switching circuit 17 is switched to the multi-rotation backup circuit 16 (steps S15 and S16).
The process ends.

The multi-turn information backup circuit 1
After the switching to 6, the above-described excitation pulse is supplied from the excitation circuit 16a to the resolver 6a, and the count value of the counter 16f is counted based on the two-phase output generated from the resolver 6a in accordance with the motor rotation angle position. Increase or decrease. Therefore, for example, when the worker
Is moved from outside, the counter 16f has a count value corresponding to the movement.

In this embodiment, as shown in FIG. 5, the motor is, for example, 8500 to 10000 rpm as described above.
When the power interruption occurs while the motor is rotating, the motor rotation is reduced to 200 to 500 by the operation of the brake circuit 13b.
msec, the power interruption delay circuit 11c,
By the operation of the DC power supply 11d, the supply of the control DC power supply to the control device 12 is, for example, 0.9 to 1..
Continued for 2 seconds. Therefore, the stop of the motor can be detected, and the absolute position information of the motor after the stop of the motor can be detected.

As described above, in the present embodiment, when a power failure occurs, the supply of DC power is continued, the absolute position of the motor is detected after the detection of the motor stop, and then the switching circuit 17 is switched to the multi-rotation information backup circuit 16 side. Since the switching is performed, the switching speed by the switching circuit 17 does not affect the detection accuracy of the absolute position at the time of power failure, and therefore, the absolute position detection accuracy can be increased while using an inexpensive low-speed switching element. it can. In this case, even when a motor having a higher rotation speed is employed, a low-speed switching element can be used.

The multi-turn information backup circuit 16
It is only necessary to detect the rotational position of the motor due to an external input to the robot after the motor stops, so that the excitation circuit 16a does not need to correspond to the high-speed rotation of the motor. For example, 4
An excitation frequency that can support a motor rotation speed of about 000 rpm is sufficient, and the consumption of the backup battery can be reduced accordingly.

[Brief description of the drawings]

FIG. 1 is a side view of a robot provided with an absolute position detecting device according to an embodiment of the present invention.

FIG. 2 is a plan view of the robot.

FIG. 3 is a block diagram of a control device of the robot.

FIG. 4 is a flowchart illustrating an operation of the control device.

FIG. 5 is a schematic diagram for explaining the operation of the control device.

[Description of Signs] 1 Robot 6 Motor 11c Power interruption delay circuit (power interruption delay means) 15 R / D converter circuit (power-on rotation position information acquisition means) 16 Multi-rotation information backup circuit (power-off rotation position information acquisition means) 17) Switching circuit (switching means)

Continued on the front page F term (reference) 2F063 AA35 BA22 CA14 DA05 EA03 GA22 LA08 LA09 LA30 2F077 AA24 FF34 NN16 PP26 TT87 3F059 AA01 BA04 BC06 DA09 DD01 DD08 DE02 DE03 FA03 FB15 FB26 FC07 FC14

Claims (3)

[Claims] 1. An energized rotational position information obtaining means for obtaining energized rotational position information of a motor at energized state, and a power supply interrupted by a power failure or disconnection (hereinafter referred to as "power interruption"). A power-off time rotational position information obtaining means for obtaining a power-off time rotational position information of the motor; a power-on time rotational position information obtaining means for energizing; a switching means for operating the power-on rotational position information obtaining means for power off; When the power supply is started after the power interruption, the robot absolute position detection device that detects the absolute position of the motor based on the energized rotation position information and the power interruption rotation position information, A power interruption delay means for continuing the acquisition of the energized rotational position information by the energized rotational position information acquiring means until after the rotation of the motor is stopped during a power interruption. Absolute position detection device. 2. The power interruption delay means according to claim 1,
An absolute position detecting device for a robot, wherein the switching by the switching means is performed after the rotation of the motor is stopped. 3. The power interruption delay means according to claim 1, wherein the power interruption delay means continues to supply control power to the energized rotational position information acquisition means at least until the rotation of the motor stops after the power interruption. A robot absolute position detecting device characterized by the following.