JPS59123012A - Robot driving controller - Google Patents

Abstract

PURPOSE:To always secure coincidence between the stop position of the movable part of a robot and a target position by providing a subtractor for error speed command value to a driving controller containing a switching function of position loop gains. CONSTITUTION:The error speed command value vx due to the noise voltage is delivered from a data selector 19 when a servo amplifier 12 which functions as a power supply circuit of a driving system for movable part of a robot is turned on. The value vx is latched by a latch circuit 28 which serves as a setting means for error speed command value. Then a subtractor 29 the value vx latched by the circuit 28 from the real speed command value (v) velivered from the selector 19 to obtain the compensated speed command value v'. The value v' is delivered to a D/A converter 20. Thus, it is possible to always obtain the coincidence between the stop position of the movable part of the robot and the target position.

Description

[Detailed Description of the Invention] This invention reduces the position loop gain when the deviation amount between the current value and the target value of the movable part of the robot reaches a predetermined value and enters the positioning range. This invention relates to improvements in drive control devices for robots.

First, an example of a conventional robot and its drive control device will be explained with reference to FIGS. 1 and 2.

The articulated robot shown in Fig. 1 has a base 1 and a base 1.
A shoulder part 2 is attached to the upper surface so as to be rotatable in the direction of the arrow A by an axis 1a perpendicular to the internuclear region, and an upper arm 6 is connected to the shoulder part 2 so as to be rotatable in the direction of the arrow B by the axis 2a. A middle arm 47 is connected to the distal end of the upper arm 6 so as to be pivotable in the direction of the arrow C by a shaft 6a, and a first lower arm 5 is coupled to the distal end of the middle arm 4 so as to be pivotable in the direction of the arrow C by the shaft 4a. A second lower arm 6 is rotatably connected in the direction of arrow E by a shaft 5a provided at the tip of the first lower arm 5 in a direction orthogonal to the shaft 4a, and a shaft 6a is connected to the second lower arm 6. It is connected so as to be able to rotate in the direction of arrow F, and has six axes including a mechanical knife 8 or a wrist 7 to which a welding gun or the like is attached.

Drive motors (not shown) are attached to each of the movable parts from the shoulder 2 to the wrist 7, and these drive motors are driven and controlled by the drive control device shown in FIG. As a result, each of the movable parts is driven.

Next, the outline of the drive control device for the robot shown in FIG. 1 will be explained with reference to FIG. 2.

In addition, in the figure, in each movable part from the shoulder part 2 to the wrist 7, only the block circuit related to the shoulder part 2 is specifically shown, but each circuit related to each movable part from the upper arm 6 to the wrist 7 is shown in detail. Since the configuration is exactly the same as 2, the explanation thereof will be omitted.

In the figure, a microcomputer 9 constituting a control section of the robot stores target value data P indicating the total amount of rotation of the motor 10 that drives the shoulder section 2 and positioning range data Δe (absolute value) which is a predetermined value. It also outputs target value data and positioning range data for each movable part from the upper arm 6 to the wrist 7, respectively.

Target value data P output from the microcomputer 9 is written into the target value register 11 .

In the current value register 12, current value data Px indicating the current value of the shoulder portion 2 is written from, for example, a photoelectric absolute encoder 13 attached to the output shaft 10a of the motor 10 via a speed reducer (not shown).

Note that the code disk in the absolute encoder 12 is
A speed reducer (not shown) attached to the output shaft 10a of the motor 10 allows the shoulder portion 2 to rotate once within the maximum movable range, and the current value data Px written in the current value register 12 changes according to the rotation of the motor 10. It is updated sequentially.

Further, the current value data Px of the absolute encoder 16 is also input to the microengine computer 9, and is provided as data for displaying the current value of the shoulder 2 and determining abnormality.

The subtracter 14 subtracts the target value data P of the target value register 11 and the current value data Px of the current value register 12 to obtain a deviation amount ef between the two.

1st. The second function generators 15 and 16 are for determining a part of the position loop gain/Kv of this drive control device, respectively, and as shown in FIG.
5, the subtracter 14 generates a speed command v, f that becomes θ1×e according to the deviation amount e, and the second function generator 16 generates a speed command vf that becomes θ1×e (θz×θ) according to the deviation amount e. Output each.

The position loop gain Kv is the total value of the amplification factor (gain) of the position feedback servo loop, and the position loop gain Kv is the total value of the amplification factor (gain) of the position feedback servo loop.
It is defined as the value obtained by dividing the operating speed (mm/5ec) by the deviation amount e (mm).

Therefore, this position loop gain Kv also includes the gain of the servo amplifier 21, which will be described later.

The comparator 17 receives the absolute value 1e1 (obtained by an absolute value circuit not shown) of the deviation amount e which is also output from the subtractor 14,
The positioning range data Δe of the positioning range register 18 written from the microcomputer 9 is compared with the positioning range data Δe, and only when e≦Δe, the positioning signal a is output to the data register 19 and the microcomputer 9, respectively.

That is, the deviation amount e which is the output of the subtractor 14 is
Since the drive amount (rotation amount) decreases as it approaches the target value P, it is determined whether the absolute value let of the deviation amount e has reached the positioning range data Δe, which is a predetermined value. It is possible to know whether the shoulder portion 2 has entered the positioning range (region).

Note that the reason why such a determination is made is to perform the following control.

That is, in order to specify the tip trajectory and robot posture while the tip of the robot (mechanical hand 8 in the case of FIG. 1) moves from the origin to the final target position, each target value register from the shoulder 2 to the wrist 7 is used. Since a plurality of passing relay points are set between each origin and the final target position, the target value data to be written to the You must create a timing to write to the target value register.

Therefore, if we take the illustrated drive control device for the shoulder section 2 as an example, the target value data indicating each passing relay point is P1 to Pn-1,
Assuming that the target value data indicating the final target position is Pn, the comparator 17 determines whether or not the shoulder 2 has entered the positioning range P1 to Pn-i, and the microcomputer 9 writes P2 to Pn into the target value register 11 in order.

Note that if this is done, the shoulder portion 2 will not accurately reach each passing relay point of P1 to Pn-1, but Δef, for example, 4 to 5
Since it is set to mm, there is no problem.

Another thing is to make the position loop gain Kv as thick as possible (1/TM in KVmaX) in the servo system as shown in the figure.
: TM is the response time constant of the motor 1o) The tracking accuracy is better (9), but if this is done, hunting is likely to occur during positioning and determination.

Therefore, it is determined whether or not each movable part from the shoulder part 2 to the wrist 7 has entered the positioning range at each final target position, and when it enters the positioning range, the position loop gain Kv that has been increased until then is determined. Make smaller.

That is, taking the shoulder 2 as an example, the data selector 19 generates the first function before receiving the positioning signal a from the comparator 17 indicating that the shoulder 2 has entered the positioning range of the final target position. When the positioning signal a is inputted, the speed command υ of θ2e outputted from the second function generator 16 is selected.

Note that this data selector 19 is configured to ignore the positioning signal a indicating that the positioning signal a has entered the positioning range of each passing relay point, based on a command from the microcomputer 9; Alternatively, switching between θ1e and θ2e may be performed for each passing relay point.

If this is done, the deviation amount e will be 1e as shown in FIG.
When 1>Δe, the speed command υ changes as shown by the straight line ■, and when le+≦Δe, it changes as shown by the straight line ■, so the position loop gain Kv in the positioning area shown with diagonal lines is Position loop gain KV, l in other areas:
The size is small and hunting does not occur during positioning.

Returning to FIG. 2, the D/A converter 20 converts the speed command vf from the data selector 19 into a speed voltage signal SVI which is an analog value.

The servo amplifier 21 generates a voltage signal SV that amplifies the deviation between the speed voltage signal SVI from the D/A converter 20 and the speed feedback voltage signal SV2 output from the tacho generator 22 directly attached to the output shaft 10a of the motor 10.
3 to the motor 10 to rotate the motor 10, thereby moving the shoulder 2 from the origin to the final target position.

However, the robot drive control device having the position loop gain Kv switching function as described above has the following drawbacks.

That is, when the power supply circuit (motor power supply) in the servo amplifier 21 is turned on, a noise voltage is applied to the wiring cord connecting the D/A converter 20 and the servo amplifier 21, so that the deviation amount e of the subtractor 14 increases. Even if the speed command value τ input to the D/A converter 20 is zero, the motor 10 is driven by the noise voltage and the shoulder portion 2 moves.

Specifically, when the deviation amount e is zero, the second function generator 1
6 is selected, so if the noise voltage is, for example, +υ in terms of the speed command value, the motor 10 will operate at the shoulder 2 until the deviation amount e becomes -Δe and the speed command value becomes 11. It moves the .

The present invention has been made in view of the above points, and in the robot drive control device as described above, the power supply circuit (corresponding to the servo amplifier in Fig. 1) of the drive system of the movable part of the robot is turned on. The error speed command value corresponding to the noise voltage generated when the robot is moving is subtracted from the true speed command value so that the stop position of the movable part of the robot always coincides with the target position.

Embodiments of the present invention will be described below with reference to FIG. 5 and subsequent drawings.

FIG. 5 is a block circuit diagram showing one embodiment of the present invention.

In this figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and explanations of those parts will be omitted.

In the figure, 26 is a switch that is turned on in conjunction with the robot's power supply switch. When this switch 26 is turned on, the Q-point color level 'L' is pulled up by the resistor r.
One-shot multivibrator (O8)
24 and 25 are triggered respectively.

When the switch 26 is turned on and triggered by the turning on of the power supply switch at time t□ shown in FIG. 6, pulse widths τ1.
Pulse signals 81, 8.2 of τ2 (τ1<τ2) are output.

The AND gate 26 takes the AND of the pulse signal S1 obtained by inverting the pulse signal S1 from 0824 by the inverter 27 (see FIG. 6 (b)) and the pulse signal S2 from 0825 (see FIG. 6). A latch pulse signal Sa f delayed by time τ3 from time t as shown in FIG.

The latch circuit 28, which is an error speed command value setting means, is reset in advance by a reset signal R when the microcomputer 9 is started, for example, and when the latch pulse signal s3 is input from the AND gate 26, it is output from the data selector 19. Error speed command value vz k Launch.

That is, at time t2 when the power supply switch is turned on,
Since the value of the target value register 11 is rOJ and each movable part of the robot is located at the origin, the value of the current value register 12
The value of is also "o".

Therefore, the deviation cover e which is the output of the subtractor 14 is also "0".
It is.

However, when the servo amplifier 21 is started by turning on the power supply switch, a noise voltage is generated on the output side of the D/A converter 2°, so the deviation amount e is rOJ and the speed command value υ is “0”. Even if there is a motor 10, the D/A converter 20
until a reverse voltage is output that cancels out the noise voltage.

Therefore, if the delay time τ3 (see Fig. 6) from the start-up time t of the servo amplifier 21 until the latch pulse signal S3 is generated is set to be longer than the time required until the noise voltage is canceled out, By activating the latch circuit 28 using the launch pulse signal S3, it is possible to launch the error speed command value t'zk obtained by converting the noise voltage into the speed command value.

However, the sign of the value V output from the data selector 19 has an inverse relationship to the polarity of the noise voltage, so if the noise voltage is positive and υ2 is negative, +'v, and if the noise voltage is negative, V If is positive, it is necessary to provide a sign inversion circuit so that -v can be latched.

After the above launch operation, the subtracter 29 calculates the launch circuit 2 from the true speed command value τ output from the data selector 19.
8 and subtract the error speed command value vzk,
The subtraction result is the corrected speed command value v/f D/A
Output to converter 20.

By doing this, when the shoulder 2 reaches the final target position and the deviation amount e becomes "0", the corrected speed command value τ' will be exactly -vz (the true speed command value is "0") Then, the D/A converter 20 outputs a negative reverse voltage that cancels out the positive noise voltage, so that the stopping position of the shoulder portion 2 coincides with the final target position.

Although the explanation has been omitted, the other movable parts of the robot from the upper arm 6 to the wrist 7 have the same structure as the shoulder part 2, so the mechanical node 8, which is the tip of the robot, is similar to the shoulder part 2. Positioning will also be more accurate.

In addition, in the above embodiment, the error speed command value υ is automatically detected and set every time the power supply switch is turned on, but if the error speed command value υ□ is constant, the latch circuit The value launched at 28 may be held even if the power is turned off, and the launch pulse signal S3 may not be output from the AND gate 26 from the second time onwards.

Alternatively, a nonvolatile starter or entry switch may be used in place of the latch circuit 28, and the error speed command value V obtained by back calculation from the amount actually moved by the noise voltage.
It is also possible to set the process manually.

Note that as a side effect of the above embodiment, the D/A converter 2
Even if 0 is not offset-adjusted, the offset value is also offset.

As explained above, according to the present invention, the noise voltage caused by the power supply circuit of the drive system of the movable part of the robot can be canceled out, so that the amount of deviation between the current value and the target value of the movable part of the robot is set to a predetermined value. Even in a robot drive control device that reduces the position loop gain when the position loop gain reaches a value and enters the positioning range, the stop position of the movable part always matches the target position.

[Brief explanation of the drawing]

1 is a schematic diagram showing an example of the configuration of a robot, FIG. 2 is a block diagram showing a conventional example of a drive control device for the robot shown in FIG. 1, and FIG. A diagram for explaining the second function generator, FIG. 4 is a diagram for explaining the shortcomings of FIG. 2, and FIG.
The block configuration diagram of one embodiment of the present invention, FIGS. 6(a) to 6), are timing charts for explaining the launch timing of the launch circuit of FIG. 5, respectively. 9...Microcomputer 10...
・Motor 11...Target value register 12...Current value register 16...Absolute encoder 14.29
......Subtractor 15.16...1st. Second function generator 19.
...Data selector 21... Servo amplifier (1 drive system power supply circuit)
23...Switch

Claims (1)

[Claims] 1. In a robot drive control device that reduces the position loop gain when the deviation amount between the current value and the target value of the movable part of the robot reaches a predetermined value and enters the positioning range, An error speed command value setting means for setting an error speed command value that occurs when the power supply circuit of the drive system of the section is on, and an error speed command value set in the error speed command value setting means as a true speed command. A robot drive control device comprising: a subtraction means for subtracting from a value.