JPH04101697A - Digital servo drive system - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital servo drive system, and particularly to a digital servo drive system used in a robot.

[Conventional technology]

In conventional servo drive systems, the entire servo drive is mounted inside a controller and the power lines for each axis are supplied to a machine or robot (hereinafter collectively referred to as a robot) using a cut-and-separate method. Therefore, in addition to the signal line, four power cables for U, V, W phase, and ground were required for each axis as cables for connecting the controller and the robot. I want to, 6
In the case of an axis robot, a 24-wood power cable was required, and the connection between the controller and the robot was extremely thick.

FIG. 3 is an example of a servo drive system of the cut-and-separate type.

6 servo drives 42□, 42□, 423.42
4425 and 426 are mounted inside the controller 41, and the controller 41 and the robot 40 are connected by a thick power line 43.

If an attempt is made to separate the control section (calculating section) and the power section in order to shorten the power cable, it is necessary to attach a CPU to the power section and read the contents of the EEPROM as described below.

Figure 4 shows the control section and power section separated (hereinafter referred to as
FIG. 2 is a configuration diagram of an example of a servo drive (referred to as a separate type).

The control section IA and the power section 2A are configured separately,
Both are detachably connected. The power unit 2A outputs the calculation results of the control unit IA to U and V.

As the W-phase PWM command, the line driver 44. It is received via the line receiver 45. The on-tilt circuit 46 generates a hash drive signal corresponding to each phase PWM command. Inverter 47 drives servo motor 48 in response to each phase base drive signal. The output current value of the inverter 47 is detected by a current detector 49, PWM modulated, and then fed back to the control unit IA as a current feedback signal.

EEFROM 51 contains the control section I, such as the current capacity of the servo motor, the gain of the current detector, and the offset take.
A constant that is necessary for calculating the PWM command and that needs to be changed in accordance with the current capacity of the servo motor is written.

When starting the servo drive system, control section I
A sends a take request signal to the PU 52 via the TxD bin (: When A sends a take request signal to the PU 52, the CPLI 52
data is read out and sent to the RxD pin of the control unit IA. The control unit IA generates the PWM command using the read contents as internal constants.

In this way, the power part is equipped with parts that must be changed according to the current capacity of the servo motor 48, so if there is a change in the current capacity of the servo motor, only the power part can be replaced. It is possible to use the control section in common. In this way, by converting the servo system into a digital system and reading constants necessary for calculating the PWM command from the memory and calculating them at the initial stage of operation, the control section itself can be configured regardless of the current capacity of the servo motor.

[Invention or problem to be solved]

In the above-mentioned cut-and-separate servo drive system, not only does the cable connecting the controller and robot body become thicker, but since the servo drive is housed inside the controller, a large heat sink is required for heat dissipation. Therefore, there is a problem that the controller itself cannot be made smaller.

In addition, in the separate servo drive system, in accordance with the technical idea that all parts that need to be changed according to the current capacity of the servo motor are mounted in the power section, the EEPRO
If M is also installed in the power section, there is a problem that the CPU must also be installed in the power section, and furthermore, a signal line is required only for transmitting takes read from the memory.

An object of the present invention is to provide a separate servo drive system in which the control section is small, the power cable is thin, and there is no need to install CPt1 in the power section.

[Means to solve the problem]

A first technical support tribe stem of the present invention includes a control unit that calculates U, V, and W phase current commands that control a servo motor, and a current detection unit that drives the servo motor in response to the current command. The control section and the power section are placed separately, and between them are a transmission line for U, V, and W phase current commands and a current feedback signal. A signal transmission line is connected to the power section, and a servo amplifier, a current detection means, and a control section are necessary for calculating the current command, and
The Tesstal Serpo Tribe system is equipped with a memory in which constants or constants that need to be changed in accordance with the current capacity of the servo motor are written, and the control section includes U, ■ phase current commands and data readout. When the command is human-powered, the UvMJ current command is selected when the switching signal is at the first logic level, and the data read command is selected when the switching signal is at the second logic level, and the second signal is transmitted onto the transmission line for U and V phase current commands. 1 selector and a W-phase connection that connects the W-phase current command to the W-phase current command transmission line when the switching signal is at the first logic level, and disconnects the transmission line when the switching signal is at the second logic level. The power section further includes: disconnection detection means for detecting a disconnection, deactivating the servo amplifier, and enabling readout of the memory when the W-phase current command transmission line is disconnected; The current feedback signal and the output of the memory are input, and when the disconnection is not detected, the current feedback signal is selected, and when the disconnection is detected, the output of the memory is selected and the output is used for the current feedback signal. It has a second selector that communicates on the transmission line.

In the second digital thermodrive system of the present invention, the servo motor of the first digital thermodrive system of the present invention serves as an actuator for operating the robot body, and the power section is installed in the robot body.

[Operation] When the switching signal is at the first logic level, the first selector sends the U and V phase current commands onto the U and V phase current command transmission line (hereinafter referred to as the U and V phase transmission line). The W-phase connection means connects the W-phase current command to a W-phase current command transmission line (hereinafter referred to as a W-phase transmission line). The servo amplifier is
U, V, W transmitted via U, V, W phase transmission line
Drives the servo motor in response to phase current commands. The current feedback signal is fed back to the control section via a current feedback signal transmission line (hereinafter referred to as a current feedback transmission line). Hereinafter, the above operating mote will be referred to as a drive mote.

When the switching signal is at the second logic level, the first selector transmits a data read command onto the U and V phase transmission lines, and the W
The phase transmission line is cut. As a result, the disconnection detection means detects the disconnection, whereby the servo amplifier is deactivated and the memory is read-enabled to be taken or read. A second selector outputs the take onto a current feedback transmission line. The constants written in the memory in this way are directly read out by the control section without using the CPll, and are used as parameters in the calculation of the U, V, and W phase current commands. Further, there is no need to use a new signal line for reading this data. Hereinafter, this operating mote will be referred to as a disconnection mote.

In the servo drive system of the present invention, since the servo amplifier is mounted on the power section, the power section is installed on the robot body and the servo amplifier is attached to the robot body, thereby making the control section smaller and connecting the power cable to the servo amplifier. This means that you only need one power cable. Furthermore, since the main body of the main body can be used as a heat sink for the power transistor, there is no need to use a dedicated heat sink.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of the digital surf drive system of the present invention.

The technical support system of this embodiment is composed of a control section 1 and a power section 2, both of which are U and V.
Phase transmission line 20. It is connected by a W-phase transmission line 21 and a current feedback transmission line 22.

The control section 1 has a selector 3. U, V mutually interrivers 4. W Mutual Intriver 5. Inverter 17. U
, a line receiver 6 for the V-phase current feedback transmission line, and a disconnection detection circuit 7 for the U- and V-phase current feedback transmission lines.

The selector 3 corresponds to the first selector of claim (1), and includes a U-phase selector and a V-phase selector 32.

Each selector 3□, 32 is a known two-man power one-output selector, and the U-phase selector 3. , V-phase selector 32 receives U-phase PWM command and V-phase PW command calculated by a calculation unit (not shown), respectively.
The M command is the first input, and a serial clock signal SK data read command Di to be applied to the EEFROM, which will be described later, is the second input. U phase selector 31. V phase selector 3
゜ outputs the U-phase PWM command and the ■-phase Pt1M command when the switching signal S is at a low level, and outputs the serial clock signal S when the switching signal S is at a high level.
K and a data read command Di, and is connected to the U and V phase transmission lines 20 via the line driver 4. The line driver 5 corresponds to the W-phase connection means of claim (1),
When the switching signal S is at a low level, a W-phase PWM command is transmitted to the W-phase transmission line 21, and when it is at a high level, the transmission line 21 is made floating. line receiver 6
differentially amplifies the balanced signal transmitted via the U and ■ phase current feedback transmission lines 22 and transmits it to the arithmetic unit. The disconnection detection circuit 7 for U and V phase current feedback transmission lines is a photocoupler type disconnection detection circuit disclosed in Utility Application No. 15599/1983, and its input terminal is connected in series to each transmission line. When the wire is disconnected, its output turns off and the disconnection detection signal is inverted.

The power section 2 includes an on-delay circuit (not shown).

3-phase inverter (not shown), disconnection detection circuit 8°EEP
ROM 9. Inverter 10.16. Selector 11. Current detector (not shown), line receiver +2.13. It is equipped with line driver 14.15.

The line receiver 12 inputs the balanced signals on the U- and V-phase transmission lines 20 and differentially amplifies them, and when in drive mode, the U- and V-phase P
WM command, serial clock signal S when the wire is disconnected.
K and a data read command Di are output. The line receiver 13 outputs a W-phase PWM command in the drive mode,
In disconnection mode, the input becomes high impedance and no output occurs. The on-delay circuit is connected to the disconnection detection circuit 8 described later.
The pace block signal 23 generated by the motor is manually inputted as an enable signal, and when the drive motor is in operation, it generates a hash drive signal that responds to the U, V, and W phase PWM commands to drive the subsequent 3-phase inverter, and when the motor is disconnected, the inverter is activated. (See Figure 3). A three-phase inverter drives the surf motor in response to the drive signal.

The disconnection detection circuit 8 detects disconnections in the U-phase, ■-phase, and W-phase transmission lines, respectively.
．． ．． 82.83, and their outputs (outputs of the light receiving elements) are connected in series. In this embodiment, the anode of the light-receiving element of the U-phase photocoupler 83 is connected to the positive power supply via the resistor R2, and the anode and cathode of the light-receiving element of the W-phase photocoupler 83 are connected to the positive power supply via the resistor R2. , and connected to the ground terminal. The voltage between the anode of the light receiving element of the U-phase photocoupler 81 and the ground is used to pace-block the three-phase inverter, as will be described later.
Hereinafter, it will be referred to as a pace block signal 23. U.

(2) When any of the W-phase transmission lines is disconnected, the base block signal 23 is inverted from low level to high level. In addition, when the operation of the servo drive system is switched from the drive mode to the disconnection mode, the W-phase transmission line becomes floating, so the voltage of the anode A3 of the light receiving element of the W-phase photocoupler 83 with respect to the ground is reversed from low level to high level. do. Hereinafter, this voltage will be referred to as a disconnection detection signal 24.

The EEPROM 9 is a serial type memory, which corresponds to the memory disclosed in claim (1), and is used to calculate the current capacity of the servo motor, the gain of the current detector, the offset motor, and other current commands from the calculation unit of the control unit 1. A constant is written therein, which is necessary for the servo motor and is changed according to the current capacity of the servo motor.

The EEFROM 9 uses the disconnection detection signal 24 as a chip select signal, and when in drive mode, reading is disabled, and when in disconnection mode, it is written to the address specified by the data read command Di in synchronization with the serial clock signal SH transferred from the line receiver 12. Outputs the motor contained in the motor. The selector 11 corresponds to the second selector of claim (1). The selector 11 outputs the U-phase current feedback signal Ilj from the U-phase current detector and the EEPROM.
When the disconnection detection signal 24 is at a low level, the U-phase current feedback signal 1u is selected, and when it is at a high level, the output of the EEPROM 9 is selected and output. Line driver 14 outputs the output of selector 11 onto U-phase current feedback transmission line 22 . When the base block signal 23 is at a low level, the line driver 15 outputs a balanced signal of the V-phase current feedback signal onto the (2) phase current feedback transmission line, and when the base block signal 23 is at a high level, the output is disabled.

Next, the operation of this embodiment will be explained.

First, when operating the drive mote, the switching signal S is set to low level.

At this time, the selector 3 selects [1, V-phase PWM command, and the line driver 5 is enabled for output. As a result, the U-, V-, and W-phase PWM commands are transmitted to each line driver 4, 5 . Transmission line 20.2+.

It is transmitted to the on-delay circuit via the line receiver 12.13. At this time, U, V, W phase transmission lines 20.
2] are both in the connected state, the disconnection detection circuit 8 outputs the low level base block signal 23, and as a result, the on-tilt circuit operates, the three-phase inverter operates, and the servo motor is driven. At this time, the line driver 15 is also
is output enabled, and the V-phase current feedback signal is transmitted to the control section via the line driver 15. In addition, in this operating mode, disconnection detection signal 2
4 becomes low level, the selector 11 selects and outputs the U-phase current feedback signal, and this signal is transmitted to the control unit via the line driver 14.

In this way, normal servo drive system operation is performed.

Next, when operating the servo drive system in disconnection mode, the switching signal S is set to a high level.

Thereby, the selector 3 outputs the serial clock signal SK.
and data read command Di are selected and output.

As a result, these signals are transmitted onto the output line of the line receiver 12 via the line driver 4°U and the v-phase transmission line 20. On the other hand, since the line driver 5 makes the W-phase transmission line 21 floating, the disconnection detection circuit 8 makes the base block signal 23 high level, and as a result, the on-time delay circuit is made inactive and the three-phase inverter is placed in the base block state. be done. At this time, the disconnection detection signal 24 is also set to high level, so that the EEPROM
9 is read enabled and serial clock signal S
In synchronization with , the motor at the address specified by the data read command D1 is read out. Furthermore, at this time, the selector 11 selects and outputs the output of the EEPROM 9, and the motor read from the EEPROM 9 is transmitted to the control unit 1 via the line driver 14. Moreover, the line driver 15 is output disabled by the inverted signal of the base block signal.
No V-phase current feedback signal is transmitted.

In this way, in the disconnection mode, the serial clock signal SK is transmitted through the U and V phase transmission lines 20.

Transmit take read command Di, El', FROM 9
The take read from can be transmitted using the U-phase current feedback transmission line 22.

Next, a second embodiment of the servo drive system of the present invention will be described.

FIG. 2 is a diagram showing an example of the arrangement of the three-phase inverter unit of the digital servo drive system of the present invention.

In the servo drive system of this embodiment, the servo motor is a low-hot actuator, and the power section shown in FIG. 1 is installed in the robot body. Therefore, a power cable connecting the three-phase inverter and the robot body is no longer necessary. Therefore, the only power cable is the power cable 33 for the inverter. Furthermore, since each power transistor of the inverter unit is attached to the robot body, the robot body serves as a heat sink. As a result, the power transistor heat sink is omitted.

The functions and operations of the servo drive system of this embodiment are completely the same as those of the first embodiment.

〔Effect of the invention〕

As explained above, the present invention treats the disconnection state of the U, V, and W phase transmission lines as one status, and reads out the memory using the disconnection detection signal and the base block signal, which are status signals indicating the status. By controlling the output of the take signal onto the current feedback transmission line, the following effects can be obtained.

(1) The memory can be read directly from the control section without providing a CPLI in the power section or a new signal line.

(2) When the power transistor of the surf amplifier is installed on the robot body, only the power cable for the power transistor is required as a power cable, so it is possible to make the power cable thinner and connect the robot to the heat sink. You can do it. Even if the power section is arranged in the manner shown, there is no CPU in the power section.
It is possible to directly read the memory from the control section without providing a controller.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a first embodiment of the digital servo drive system of the present invention, FIG. 2 is a diagram showing an example of the arrangement of the three-phase inverter unit of the digital servo drive system of the present invention, and FIG. 3 is a diagram of the device. FIG. 4 is a diagram showing an example of a separate type servo drive system. FIG. 4 is a configuration diagram of an example of a separate type servo drive system. 1--Control section, 2--Power section, 3, 11--Selector, 4, 5.14.15--Line driver, 6, 12.
13--Line receiver, 7.8--Disconnection detection circuit, 81.8□, 83--Photocoupler,...EEP
ROM, 16, 17 ... Inverter, ... Base block signal, ... Disconnection detection signal, ... Power supply, 32 ... Inverter unit, ... Power cable.

Claims (2)

[Claims] (1) A control unit that calculates U, V, and W phase current commands that control a servo motor, and a control unit that drives the servo motor in response to the current command and receives a current feedback signal generated by the current detection means. The control section and the power section are placed separately, and a transmission line for U, V, and W phase current commands and a transmission line for current feedback signal are connected between them. A servo amplifier, current detection means, and control section are required to calculate the current command.
In addition, in a digital servo drive system in which a memory is arranged in which constants that need to be changed in accordance with the current capacity of the servo motor are written, the control section is configured to issue U and V phase current commands and data read commands. is input, and when the switching signal is at the first logic level, the U and V phase current commands are selected, and when it is at the second logic level, the data read command is selected and transmitted onto the transmission line for the U and V phase current commands. a first selector that connects the W-phase current command to the W-phase current command transmission line when the switching signal is at a first logic level, and disconnects the transmission line when the switching signal is at a second logic level; The power unit includes: a disconnection detection unit that detects a disconnection, deactivates the servo amplifier, and reads out and enables the memory when the W-phase current command transmission line is disconnected; , inputting the current feedback signal and the output of the memory, selecting the current feedback signal when the disconnection is not detected, and selecting the output of the memory and outputting the current feedback signal when the disconnection is detected. A digital servo drive system characterized by having a second selector that transmits data on a transmission line. (2) The digital servo drive system according to claim 1, wherein the servo motor is an actuator that operates a robot body, and the power section is installed in the robot body.