JPS6044280A - 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 The present invention allows a first end effector to be pressed against a fixed part by a control shaft Z, and in the pressed state, a second end effector that is unrelated to the control shaft Z This relates to a compact industrial robot that controls the position of an effector.

For example, the gripping means is a first end effector, the workpiece gripped by this is pressed against a fixed part (for example, another work) in the Z direction to position the work, and then the second end effector (for example, welding 1.- In the case of welding the workpiece by controlling the position of h), if the fixed part, that is, the other workpiece, bends due to the
If the position of the fixed part in the Z direction is displaced due to a difference in plate thickness, etc., when the workpiece is pressed against the displaced fixed part by the gripping means, naturally the position of the fixed part of the gripping means is For installation in the Z direction, only the front displacement product is displaced from the previously taught position. In such a state, even if the position of the torch is controlled based on the command position taught in advance, the operating point of the torch will not match the location to be welded formed by the two workpieces, and accurate welding will not be possible. becomes impossible.

The present invention has been made in view of the above-mentioned circumstances, and even when the fixed part is displaced in the Z direction, the second end effector can press the workpiece against the fixed part by the first end effector. The present invention aims to provide an industrial robot that can accurately perform machining using an Ector, and examples thereof will be described in detail below.

Although FIG. 1 shows an articulated robot (R) that forms the background of this invention and is effective in implementing this invention, the invention is not limited to this embodiment.

1 is the base of this robot R.

Reference numeral 2 denotes a horizontal first arm pivotally attached to the base 1 so as to be pivotable about a vertical axis. The arm 2 is forced to have its turning angle β1 by a power M1 whose details are not shown.

3 is a horizontal second arm pivotally attached to the tip of arm 2 so as to be pivotable around a vertical axis. The arm 3 is forced to have its turning angle β2 by a power M2 whose details are not shown.

Reference numeral 4 denotes a vertical arm that is pivotally supported at the tip of the arm 3 so as to be rotatable around a vertical axis and can be raised and lowered. Arm 4 is powered by M, details not shown.
3 forces its rotation angle β3, and the power M7
(in this example, by a hydraulic motor and a ball screw rotated thereby) by its vertical position Z
− is forced.

5 is pivotally attached to the lower end of arm 4 by a horizontal shaft 5aK,
This is a gripping means as a first end effector, and in this embodiment, the gripping claw 5b is configured to be able to be opened and closed in the vertical direction. Furthermore, the gripping means 5 is assumed to be able to be moved around the axis 5a by a small amount of power M5, so that the angle β4 can be changed between the vertical position shown by the solid line and the horizontal position shown by the two-dot chain line.

Reference numeral 6 denotes a rotating body rotatably supported coaxially with the arm 4.

The rotating body 6 is forced to a rotating angle α1 by a power Mll whose details are not shown.

Reference numeral 7 denotes a vertical first arm which is pivotally connected to the rotary body 6 so as to be able to rise and fall freely around a horizontal axis. The arm 7 is forced to have an elevation angle α2 by a power M12 whose details are not shown.

A second vertical arm 8 is pivotally attached to the tip of the arm 7 so as to be able to rise and fall freely around a horizontal axis. The arm 8 is forced to have an elevation angle α3 by a power M13 whose details are not shown.

Reference numeral 9 denotes a third arm which is pivotally attached to the tip of arm 8 so as to be able to rise and fall freely around a horizontal axis. The arm 9 is forced to have an elevation angle α4 by a power M14, the details of which are not shown.

Reference numeral 10 denotes a torch mounting arm which is pivotally connected to the arm 9 so as to be rotatable around an axis V perpendicular to the vertical axis of the arm 9.

The arm lO is rotated at a rotation angle α by a power M15 whose details are not shown.
5 is forced. A second end effector, that is, a welding torch 11 is attached to the tip of the arm 1o. The tip operating point P of the torch 11 is configured to be on the axis V.

In this way, the robot R controls the control axis β1. β2゜β3
．． In the middle of the parent robot (β-based robot) having 5 degrees of freedom of Z and β4, α1. α2. α3. α4 and α5
It supports a child robot (α-based robot) having five degrees of freedom. It should be understood that the control axis of the β-system robot is fixed to the base 1, and the control axis of the α-system robot is fixed to the tip of the arm 3.

It is assumed that each degree of freedom of the robot R is controlled by conventionally known means (for example, a microcomputer) and by a known playbank system.

In this embodiment, the control means C for the β-based robot
Two computers are used: Oβ (a computer including a CPUβ and memory) and a control means coα (a computer including a CPUα and memory) for α-based robots.
As shown in Figure (a), the computer COβ includes a β1-axis servo system, a β2-axis servo system, a β3-axis servo system, a Z-axis servo system, a β4-axis servo system, a gripping means 5, and a teaching box T. Bβ is connected via a pass line BUβ. The computer COα also has 1 teaching box TB for the servo system for the α1 axis, the servo system for the α2 axis, the servo system for the α3 axis, the servo system for the α4 axis, and the servo system for the α5 axis.
α, and welding power source ws are connected. Furthermore, both computers COβ and CO are connected via a known interface.

Furthermore, the configuration for controlling the arm 4 in the Z direction will be explained in more detail. Please refer to Figure 3 (b).

As mentioned above, the arm 4 is supported by the power M7 via the ball screw 4a, and the hydraulic power source OI) and the power M7
．． A servo valve SV is interposed between them. computer co
A register RE and a counter CT are connected to the pass line BUβ of β. Computer CO is in register RE.
This is done to take in command position information from β. The counter CT is configured to input and count the output of the incremental shaft encoder E2 which is linked to the power Mz.

And the contents of counter CT and register RE are subtracted by A.
D, and its output is further amplified by amplifier A.
It is configured to control the servo valve S■. The deflected DP is an input value detection means for the power M7 (in this embodiment, a pressure difference detection means for the hydraulic motor), and its output information is connected to the pass line BUβ.

Next, the operation of the above-mentioned structure will be described.

A steel plate W1 is positioned and placed on a table (not shown) by another device (not shown), and a short channel material W2 is held onto the steel plate W1 by the gripping means 5 and pressed as shown. Torch 1 part of WP
According to 1, temporary attachment shall be done by welding.

First, the operator teaches the robot (R) step by step how to work in auto mode using known means.

In another step of the user program, Z and R3 are controlled so that when the gripping means 5 holds the channel material W2 and lowers it, it can be positioned at a predetermined position and attitude on the upper surface of the steel plate W1, Assume that there is a command to lower this and press it against the steel plate W with a force Fd.

(A1) Combi coater CO has means DP in this state.
, that is, △Pic (processing PRY
,). That is, even if the means 5 is stopped, the dead weight of the entire structure (including the channel material W2) to be raised and lowered acts on the power M7, causing a difference in the output oil pressure of the hydraulic motor M7.

(A2) A = (Fd/niten Sign (△P
IC)・ΔPic 12 is calculated. Here, Fd is the target force when pressing the means 5, that is, the channel W2, against the steel plate W1, and k is a proportionality constant. That is, Fd
The value in / is the target pressing force converted into the output hydraulic pressure difference △Pd of hydraulic motor M2, and the value in parentheses on the right side is the value required for hydraulic motor M2 when pressing with force Fd, taking into account its own weight. This is the difference in the number of people and the oil pressure. As is well known, the output amount variation e of hydraulic operating power is a△p, where ΔP is the difference in oil pressure
=v''1li- Therefore, the value of A is a linear function of the value of e when the weight is taken into consideration when pressing with the force Fd.Also, a is a constant determined by the control system.

(A3) Then, the manpower oil pressure difference ΔPi at that time, that is, the output information of the means DP is taken in. In this case, △Pi−
ΔPie, but when the means 5 is being lowered as will be described later, ΔPi>ΔPic.

(To) Next, ΔPi2 is calculated (processing PR4).

(A5) Next, the current position information ZO1 of the means 5, that is, the contents of the counter CT is taken in (process P'R5).

(Act) Zn=Zo+Ga2(A-8ign(△P
i)・ΔPi2) is calculated (processing P Rg). In this equation, the value in parentheses on the right side is 0, which is the value of △P2 necessary to push the means 5 with the FdO force, taking into account its own weight while lowering the means 5. The value of G is the value of the deviation e in the Z direction. is a constant that is converted to the amount of displacement. Therefore, the second term on the right side of this equation is the value of Δ2, which indicates how much downward displacement from the current position is required to obtain the pressing force Fd.

(A7) Next, 1zn-2o1<Δzt is determined (processing PR7). ΔZzld h is a predetermined minute displacement amount in the Z-axis direction, and is set to be the same as the width of the dead zone of the Z-axis servo system, for example. Channel material W2 now gripped by means 5
While it does not hit the steel plate W1, Zn is updated by △Z corresponding to △P according to the second term on the right side of the process PR6, which corresponds to the difference between the presser force Fd and its own weight, but after it hits, The value of △Z becomes smaller successively, and the value of △Z becomes △22
This is to judge whether or not it is smaller than that.

(A8) If Δ2 is not smaller than ΔZt, output the ZnO value as the next target command position (processing PRs).

(A9) Then, the process returns to the process PR3 after a certain period of time has elapsed.

In this way, the target value is updated by △Z corresponding to the insufficient △P considering the own weight for pushing with force Fd, and the update of this target value is continued until contact occurs and the manpower oil pressure difference further increases by △P. This is what ultimately generates the force Fd.

(AIO) If ΔZ becomes smaller than △ZA in process PR7, it means that the robot is pushing with force Fd, and power Mz is stopped (process PRIO) 0 At this time, steel plate W1 is figure(
If the steel plate W1 is displaced from the position in the Z direction as shown in FIG. Naturally, there is a difference △Zβ between the time position Zβ and the difference △Zβ
Even if the position of the torch 11 is controlled based on the previously taught command position up to -1 with -1, the operating point P of the torch 11 does not coincide with the location WP to be welded, as shown by the solid line in FIG. 5(b). Therefore, as shown in FIG. 5(b), the Z direction command position 2 of the torch 11, which has been taught in advance, is
It is necessary to correct α by the difference ΔZβ.

(An) Therefore, after the process P&o, the difference ΔZβ between the current position zo when the Z-axis is stopped and the position Zβ when teaching is calculated (process P R11).

This difference ΔZβ corresponds to the amount of displacement of the steel plate W1 in the Z direction due to the deflection of the steel plate W1 or the difference in plate thickness.

(A12) Then, the difference ΔZβ is transferred to the computer COα of the α-based robot (processing PR+2).

(Al1) Then, by adding △Zβ to the Z-direction command position 2α of the α-system robot that has been taught in advance,
Correct the Z-direction command position of the α-based robot (processing P R
+3).

If the Z-direction command position of the α-based robot is corrected in this way, the operating point P will match the point WP to be welded by controlling the position of the torch 11 based on the corrected command position information.
Temporary attachment can be welded accurately.

In addition to the above-described embodiments, the present invention can also be modified as described below within the scope of the technical idea of the present invention.

(a) Robot R may not be an articulated robot, but may be a robot with other mechanical configurations. The control axis whose force is to be controlled in the case of pressing is not limited to a linear control axis, but may also be a rotational control axis. Furthermore, when pushing in a certain direction, the updated value ΔZ may be calculated by taking in the power input values ΔP for a plurality of related control axes. Furthermore, the robot R may be configured as two robots by completely separating the β-based robot and the α-based robot. In any case, the second end effector, that is, the torch 11 may be integrated into one.

(b) If the pushing direction is horizontal rather than vertical, it can be carried out without considering the weight of the object.

(c) The driving means may be a hydraulic linear actuator other than a hydraulic motor. Furthermore, an electric motor other than a hydraulic mechanism may be used. In this case, the human power value is for detecting the input current, etc.) It is also possible to replace it with an equivalent component of other components.

As described above, in this invention, the first end effector 5 is pressed against a fixed part (for example, a steel plate Wl) by the control shaft Z, and in the pressed state, a control shaft unrelated to the control shaft Z When machining a workpiece by controlling the position of the second end effector 11 (which is not directly or indirectly supported in Z), if the fixed part is bent or has a different plate thickness, Even if the first end effector 5 is displaced in the direction, the amount of the displacement is determined by the difference between the previously taught Z direction command position Zβ of the first end effector 5 and the Z direction position at the time of pressing. Since the Z-direction command position of the taught second end effector 11 is corrected, the operating point of the second end effector 11 always coincides with the part of the workpiece to be machined, allowing accurate machining.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings all show one embodiment of the present invention, and Fig. 1 is an overall side view, Fig. 2 is a partial view of Fig. 1, and Fig. 3 (A). , (B) is a block diagram, FIG. 4 is a flowchart, and FIG. R...Industrial robot, Z...Control axis (vertical control axis in the example), 5.First end effector (gripping means in the example), 11...Second end effector (welding device in the example) torch), CO3, COα...control means. Applicant ShinMaywa Industries Co., Ltd. Figure 3 (D) Figure 3 (A) Figure 5 (3) (B) Continuation of page 1 V?・Inventor: Shinpei Inukai, Takkino-cho, Nishinomiya City (
6 Inventor Hitoshi Kamei Nishinomiya City Takkino-cho (3-107 Taruchi ShinMaywa Industries Co., Ltd. Development Center J-107)
No. ShinMaywa Industries Co., Ltd. Development Center Procedures Amendment
(Method) 1. Indication of the case Showa Sg Year 1995 Bamboo license application No. 15 Suno C5 No. 2 Name of the case Keiza Yoguchio ゛・yto 3. Relationship with the Nagisa case to be amended Patent applicant address Nishinomiya, Hyogo Prefecture 1-5-25, Kozone-cho, Ichi 5 Number of inventions to be increased by amendment 4 to 6 Subject of amendment

Claims (1)

[Claims] The first end effector can be pressed against the fixed part by the control axis z, and the position of the second end effector, which is unrelated to the control axis Z, can be controlled in the pressed state. Industrial robot robot I/including control means
The control means includes a difference ΔZ between Z-direction position information when pressing the first end effector against the fixed part is completed and position information zB when the first end effector is tapped.
The industrial robot includes means for calculating B, and means for correcting Z-direction position information Zα taught to the second end effector in advance by the difference ΔZβ.