JPS6228187A - Controller for industrial robot - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Utilization] This invention is applicable to, for example, arc welding in a production line,
Alternatively, the present invention relates to a control device for an industrial robot that automatically performs equal portions of laser welding.In particular, the present invention relates to a visual feedback control system for an industrial robot that performs arc welding or laser welding, that is, visual online seam tracking, or The present invention relates to a visual servo control device for online tracking of cast iron in a visual counterfeiting robot.

[Conventional technology]

Figure 4 is a block diagram showing a conventional visual servo control device for industrial robots, in which (1) indicates the object to be detected;
2) is a visual sensor, (3) is a visual information processing device, (4)
is the coordinate calculation device, (5) is the servo controller 5 equipment
t, (6) is a servo amplifier, (the force is a motor that drives each joint of the robot, (8) is a speed detector attached to the output shaft of the motor (7), and (9) is the same as that of the motor (7). The position detector (LO) attached to the output shaft is the robot body.

Since the visual servo control device in the industrial robot is configured as described above, the position rSJ of the workpiece (1a) of the workpiece (1) being conveyed by a conveyor or the like is now detected by the visual sensor (2). , considering the task of following this in real time, the edge (1a) is detected by the visual sensor (2) K, and the visual information processing device (3) detects the edge (1a).
), the displacement ΔX between the current line-of-sight direction of the visual sensor and the actual position rSJ of the edge (1a) is sent to the coordinate calculation device (4). However, this coordinate calculation device (
4) is configured such that coordinate calculation is performed every sampling time ΔTm.

Control of a multi-degree-of-freedom robot, such as a six-degree-of-freedom robot, is performed by motors (7) K placed at each joint.
Position expressed in absolute coordinate system and orientation ¥==(x,
y, z, o, A, T) to each joint angle Q ''(q + lq
21q31q4 +q5+Qa), but in this case,
The coordinate transformation from the joint angle Q to the absolute coordinate system P is A1, and the transformation from the absolute coordinate system P to the joint angle Q is rA-'J.

In addition, in the coordinate calculation device (4), a visual sensor (2
) and the output Q of the position detector (9) attached to the drive motor (7) of each joint as the coordinate A (4b). Create the position xd, coordinate convert it to the joint angle (4a) t, take the difference between the new target position of the joint angle "?Sd" and the current value, and set the movement amount per ΔTm as the servo controller device. (5), and the coordinate calculation device (4) performs the above operation at a sampling time △Tm
Repeat each time, and also use the servo controller device (5
) operates at a sampling time ΔTs which is 1/of the sampling time Δrm of the coordinate calculation device (4), and performs position servo control at high speed in response to the movement command Qd.

Note that the output of the servo controller device (5) is used to drive the drive motor (7) of each joint by the servo amplifier (6) to operate the robot.

Next, FIG. 5 is a time chart showing the flow of data at each sampling time of the arithmetic device (4) and the servo controller device (5), and shows the control cycle (main cycle, Δ'I' m), first take in the output of the visual information processing device (3) and calculate its value (ΔX
) The target position Xd in the next cycle is calculated based on the teeth. This target position Xd is converted into a movement amount Qd on the joint axis by coordinate transformation AIK, and the movement amount Q d s is output to the servo controller device (5). The servo controller device (5) is controlled with a fast sampling time of △Ts, but the moving lid Qds is captured in a servo cycle synchronized with the next main cycle, and in this servo cycle, the visual sensor A target value is given according to the detected value in (2).

[Problem that the invention seeks to solve]

As described above, conventional industrial robot control devices have the disadvantage that high-speed control is not possible because the position error signal detected by the visual sensor is fed back to the coordinate calculation device with a slow sampling period.

The present invention has been made with this point in mind, and it is an object of the present invention to provide a control device that can perform real-time visual servo control of an industrial robot at high speed.

[Means for solving problems]

A control device for an industrial robot according to the present invention includes a visual sensor, a visual information processing device that processes information from the visual sensor to detect a change in the position of a detection target, and An arithmetic device that calculates an inverse matrix, and a servo controller device that drives and controls each joint of the robot at a high-speed control cycle from this arithmetic device, and directly converts the detection signal from the visual sensor into positive movement in the open space. It is equipped with the following.

[For production]

In the present invention, the position signal of the target object from the visual sensor is transmitted to the servo controller device ='rr! corresponding to the high-speed control period. , is directly fed back, and coordinate calculations are performed within this servo controller device, making high-speed control possible.

[Embodiments of the invention]

FIG. 1 is a block diagram showing an embodiment of the present invention.
<1) is the detection target, (2) is the visual sensor, (3) is the visual information processing device, (4) is the coordinate calculation device, (5a) is the multiplication unit, (6) is the servo amplifier, and (7) is A motor that drives each joint, (8) a speed detector, (9) a position detector,
0■ is the robot body.

Next, FIG. 2 shows the notes in the control device of the present invention.
In the software construction block diagram, U]) is the main processor,
0 power is the local bus of this main processor αD,
(l:→ is the local memory of the main processor αυ connected to local bus 02, (14) is the shared memory, (
I5) is the servo processor, αυ is the local memory of this servo processor 0ω, αη is the local memory IJ of the servo processor α9 connected to this local memory (16), (IE is the general-purpose parallel input device, I is the D
//A converter, (2G is the system bus that connects the main processor αυ, the shared memory circle and the servo processor 05).

The control device for an industrial robot according to the present invention is configured as described above, and the position of the detection target object (1) as seen from the visual sensor (2) attached to the tip of the robot hand is determined by the visual sensor (2). ) coordinate system oh -xh.

It is expressed in yh and zh. If this detection value is set as Xv=(xv, yv, Zv), then the detection target object (
1,), the detected value Xv is the unit vector in the direction in which the robot's hand should move, Vh=(Xv.

YVlzV), when performing tracking control of the object to be detected (1), the detected value Xv is the unit vector in the direction in which the robot's hand should move.
Xv/D, yv/D, zv/D).

Note that the above rDJ is in the visual sensor coordinate system 0h-Xh.

It represents the magnitude of the detected object position vector at Yh and zh, and specifically, the following formula: D2=X2v+y2v+z2v ・・・・・・・・・
・・・・・・・・・It is given by [1].

Furthermore, in industrial robots such as articulated manipulators, the following formulas are generally known.

(dQ) - (δ, 1.δ, 2.δ, 3.δ, 4.δ, 5
．． δ,. ) t (4) Note that ( d
X ) represents the displacement amount of the robot hand coordinates (here, the coordinate system corresponds to the visual sensor coordinate system), and also the above [
(dQ) in equation 4 represents the amount of displacement of each joint angle, and J in equation [5] above is called the "Jacobian inverse matrix" (
6.6) A matrix having elements, each element of which can be calculated based on the position and orientation values of the robot. Therefore, if we use the above formula [2],
Since the target value can be converted in the hand coordinate system,
Tracking control of the target value vh can be carried out by sequentially calculating the above equation [2] and applying position servo to the target value in the joint system.

Next, the operation of the industrial robot control device according to the present invention will be explained.

In FIG. 1, the arithmetic unit (4) detects the output of the position detector (9) at the sampling time Δ'p m and calculates the output of each element of the Jacobian inverse matrix 'J''' at that position by arithmetic processing. , when each element is transferred to Δ'I'm& to the servo controller device (5), this servo controller device (5) transfers the output ΔX of the visual sensor (2) and the visual information processing device (3) to the servo controller. Device(
5) every control cycle Δ′1゛S, and the multiplier (5)
Multiplying the Jacobian inverse matrix "" according to a) also generates a one-value Qds for the eyes in the joint space. This target value output is given to the servo amplifier (6) to constitute a position servo system.

FIG. 2 shows the coordinate calculation device (4) of the control device according to the present invention.
) and a block diagram showing the detailed configuration of the servo controller device (5). , by local memory αJ? (77), and data communication with the servo controller device (5) is performed via the shared memory side. In other words, the detected value Q of the position detector (9) described above
1 or each element of the Jacobian inverse matrix J-1 is set on this shared memory 04) by the main processor 0υ or the servo processor (15), this servo processor (19 is the royal memory αη, general-purpose input port −)
(IFj) and a DA converter H, and is configured to take in the detected value of the visual sensor (2), the detected value of the position detector (9), etc. at every speed controller cycle ΔTs.

Next, FIG. 3 is a time chart showing the flow of data in the visual servo system. In the main cycle, when an external timer interrupts the main processor (11) at △Tmi, this main processor 0υ changes to the current (7) o ho7
To position i'ft (X, Y, Z, 0.A, T) wo use ite? After calculating each element of the copy inverse matrix J4 and completing the M calculation, these values are stored in the shared memory (14).

The servo cycle runs in synchronization with the main cycle, but its period is n times that of the main cycle (in FIG. 3, n = 3). That is, the servo processor 0 is interrupted every △Ts=(△Tm)/n, and in this cycle, the detection value △ of the visual sensor (2) is
X is read. Then, the servo processor (19) multiplies the detected value △X by the Jacobian inverse matrix in this cycle, and
/A Servo signal is output to the converter α9. therefore,
The same value is used for each element of the Jacobian inverse matrix every n times, but since the amount of change in this value corresponds to the change in posture, it is assumed to be constant during the main cycle (generally 20 to 3 Qms). No problem.

In the above embodiment, a visual sensor is used as the sensor, but the sensor is not limited to this, and may be a position displacement sensor such as a differential transformer or a linear tension meter. A similar effect can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the output of a visual sensor attached to the hand of an industrial robot is directly fed back to a servo controller having a high-speed control cycle, and coordinate calculations are performed within this servo controller. Therefore, a high-speed visual servo system can be constructed, and a control device for an industrial robot capable of high-speed control can be easily and inexpensively manufactured, which has an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention, FIG. 2 is a configuration block diagram showing details of a coordinate calculation device and a servo controller of a control device of this invention, and FIG. A flowchart showing the flow of data in the system, Figure 4 is a conventional control device for industrial robots.
FIG. 5 is a configuration block diagram showing the conventional arithmetic unit i''
? 3 is a time chart showing the data flow of the servo controller device. In the figure, (1) is the detection target, (1a) is the edge,
(2) is a visual sensor, (3) is a visual information processing device, (4
) is a coordinate calculation device, (5) is a servo controller device,
(Fia) is a multiplier, (6) is a servo amplifier, (7) is a motor, (8) is a speed detector, (9) is a position detector, Q
O) is the robot body. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A visual sensor attached to a predetermined position of the hand of the robot body, a visual information processing device that processes information from the visual sensor and detects the positional displacement of the object to be detected from the line of sight direction of the visual sensor, and a visual information processing device that processes the information from the visual sensor and detects the amount of positional displacement of the object to be detected from the line of sight direction of the visual sensor, and the current position of the robot. A coordinate calculation device that calculates each element of the robot's Jacobian inverse matrix from A control device for an industrial robot, characterized in that the output is directly fed back to the servo controller and multiplied by a Jacobian inverse matrix within the servo controller to enable high-speed visual servo control.