JPH0413109B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an industrial robot that can control the position of an end effector at a specified moving speed by operating a manual operation switch.

(Prior Art) When moving the end effector to a target position using a manual operation switch, it is desirable to move the end effector at a faster speed because this will shorten the working time. However, the high movement speed also makes accurate positioning by manual operation extremely difficult. Therefore, in order to solve this problem, a plurality of limiters with different output levels are provided, and the limiters are selectively connected to the control line depending on the difference between the target value and the actual value. It has been proposed to have a control device that allows movement at low speed when the time is short. Alternatively, it has been proposed that during teaching, the servo system is separated from the amplifier and each control axis is operated by a manual operation switch to set the target position, thereby facilitating positioning.

(Problem to be solved) However, as mentioned above, in the conventional system, the hardware of the control position was devised to enable accurate positioning in a short time by manual operation, so the control circuit was complicated. Of course, this will also affect the system program, and the number of improvements will increase.

The present invention has been made in view of the above-mentioned circumstances, and is an industrial device having a control device that enables accurate positioning work in a short time by manual operation using a system program without changing the hardware. The purpose is to provide robots.

(Means for Solving the Problem) This invention calculates the forward deviation Ysp in the moving direction of each control axis from the minute velocity Vc of each control axis of the specified moving speed V of the end effector, and The deviation Yn in the forward direction of movement of each control axis is determined at a certain rate of increase at every fixed time t, and output is output to move each control axis at a speed corresponding to this Yn, and if Yn>Ysp, After that, Yn＝
Constant speed as Ysp (the specified movement speed V
(corresponding to ) to move each of the control axes.

(Operation) First, when moving the end effector, its moving speed V is specified. Then, operate the manual operation switch to move the end effector to the target position. At this time, the minute velocity Vc of each control axis is determined from the movement speed V, and furthermore, the deviation Ysp of each control axis in the forward direction of movement is determined as follows: Ysp=Vc/K (K is a constant). Furthermore, n is updated every fixed time t to obtain the forward deviation Yn of each control axis in the moving direction, Yn=f(tn)=C・f(tn-1) (C is the rate of increase, C>1 ). Then, each control axis is moved at the corresponding speed by sequentially outputting Yn. Meanwhile Yn
>Ysp, then each control axis is moved at a constant speed with Yn=Ysp.

As described above, by lowering the rise speed of each control axis when operating the manual operation switch, accurate positioning can be easily performed near the target position by inching the manual operation switch, and when the target position is far away. In this case, the robot can be moved at a specified high speed by continuously operating the manual operation switch until it reaches the vicinity of that position.

(Example) FIG. 1 is an overall view including a rectangular coordinate welding robot RO, which is the background of this invention and is effective when implementing this invention, but this invention is not limited to this embodiment. do not have.

1 is a well-known rectangular coordinate (x,
y, z) is the vertical axis configured at the terminal of the robot RO.

Reference numeral 2 denotes a first arm supported at the lower end of the vertical shaft 1 so as to be able to rotate α around the shaft 1.

A second arm 3 is supported at the tip of the arm 2 by an oblique shaft 3a so as to be rotatable β. At the tip of the second arm 3 is a processing tool (in this embodiment) as an end effector.
A gripping tool 3b for gripping the MIG welding torch T) is provided.

and the central axis of shaft 1, shaft 3a and torch T
The TCs are constructed so that they can intersect at one point P.
Furthermore, the torch T is configured such that its welding operating point can coincide with the point P. Thus, by controlling the angles α and β, the attitude angle θ and the turning angle of the torch T with respect to the vertical axis 1 can be controlled.

4 is a known welding power supply device. The device 4 includes a spool 4a that winds up the consumable electrode TW of the torch T, and a welding power source 4 between the electrode TW and the workpiece WK.
b.

Reference numeral 5 denotes a known computer as a control means for the entire embodiment. Computer 5 has
Including CPU and memory.

A power supply 4b is connected to the bus line B of the computer 5.

The bus line B is further connected to the x-axis servo system Sx of the robot R. The servo system Sx has the x-axis power Mx and an encoder that outputs its position information.
Includes Ex. Similarly, bus line B has a y-axis servo system Sy, a z-axis servo system Sz, an α-axis servo system Sα, and a β-axis servo system configured in the same way.
Sβ is connected.

The RE is a remote control panel and is equipped with a group of manually operated snap switches. And x, y,
Manual operation for z, θ and each control axis If the snap switch stay is tilted toward the "U" side, the end effector will move in the direction in which the position information for that control axis increases, and if tilted toward the "D" side, the end effector will move in the opposite direction. configured to do so. In this case, a transformation is performed between the mechanical systems of α and β and the control systems of θ and. However, the details of this conversion are not the gist of this invention and are well known, so they will not be described in detail.

The operation panel RE is also provided with a speed command rotary switch SV. Furthermore, a mode changeover switch SM is provided so that the mode can be switched to manual mode M, test mode TE, and auto mode A. SE is a designation switch, and by switching up in the figure and operating the up-down switch SU, you can select the repeat pattern number (RNo.).
is displayed and selected. Furthermore, by setting the switch SE to the left as shown in the figure and operating the switch SU, linear interpolation "L", circular interpolation "C", and repetition "R" are selected and displayed in this order. There is. Furthermore, switch the switch SE to the right in the diagram, and
When SU is operated, the welding condition number (WNo.) is displayed and is to be selected. Furthermore, the operation panel RE is equipped with a start switch ST. The functions of the switch ST will be explained in detail in the explanation of the operation described later. These switches are then connected to bus line B.

In addition, when Switch SV is in manual mode,
By pressing the head, the moving speed of the torch T in manual mode is stored as a constant value.

In addition, in order to realize the moving speed Vmm/sec specified by the switch SV, if the component of the speed V for each axis is V _c , then, for example, the constant K=
10, this is done by so-called follow-up control, which can be executed by outputting the Yn value of Ynmm = Vc / 10 as the forward deviation in the moving direction of each axis every 100 mmsec. .

The effects of the above-mentioned embodiments will be described below. Please also refer to Figure 2 et seq.

The current workpiece WK is a horizontal fillet weld line as shown.
Suppose you have WL ₁ and WL ₂ , and you want to horizontal fillet weld these weld lines WL ₁ and WL ₂ .

The operator first performs teaching as follows.

(1) Operate the switch SM to set the manual mode as shown in the figure, and set the switch SV to manual operation.Set the speed Vmm/
Select to sec. At this time, it is assumed that the position of the torch T (the position of point P) is at the position R ₀ in the figure.

(2) Next, operate the switch SW status,
Illustrated torch T L _W1 (welding starting point on welding line WL ₁ )
At the same time, the Euler angle (θ
and) are controlled to an appropriate posture for welding (double-dashed line in the figure).

In this case, the computer 5 determines that one of the stakes of the switch SW is operating (processing PR ₁ ), and first gives Y ₀ as the initial value f(t ₀ ) (processing
_PR2 ). It is assumed that the value of Y ₀ is stored in advance in the computer 5 for each control axis from x to β.

Then, the value of Y _o (Y ₀ in this case) and
The value of Ysp (the value of Y _o corresponding to the minute speed V _c of the moving speed V specified by the switch SV) is compared (processing PR ₃ ).

And in this case, Y _o = Y ₀ (processing PR ₄ ),
Output the value of Y ₀ as Y _o (processing PR ₅ ).

Then, it is determined whether this output has been completed (processing PR ₆ ). As mentioned above, this judgment is based on Yn
The value of is set sequentially at fixed time intervals (for example, 100 in the current case)
This is to output in mmsec). In this way, the robot RO will move at a low speed corresponding to _Y0 , giving priority to the commanded speed at that time, in accordance with the operated status of the switch SW.

Then, it is further determined whether the switch SW stay is still operating (processing PR ₇ ).

If it is not continuing, it moves to the next process, but if it is continuing, it returns to process PR ₃ .

Furthermore, if Y _N ≦ Y _SP , then Y _o in processing PR ₄
Determine =Y ₀ . In this case, this is not the case, so
For example, if the increase rate C=2, f(tn)=2・f
(tn-1) is calculated (processing PR ₈ ). Then, similar processing is performed thereafter. That is, the value of Yn is outputted every 100 mmsec while making it twice the previous value.

Finally, Yn>Ysp, and after that, f(tn)=Ysp is kept constant (processing PR ₉ ). These are as represented by the curves in FIG. In the same way, the value of Ysp is output (processing PR ₁₀ ), and when it is determined that the output is completed (processing PR ₁₁ ), the operation of the switch SW stay is determined (processing PR ₁₂ ), and the status is Outputs Ysp during operation.

In any case, if the switch SW stay is not activated, the process moves to the next step.

In this way, the torch T can be manually controlled and lit.
If the required stay of the switch SW is activated to move to LW ₁ , the corresponding servo system will have a slow rise in movement speed, regardless of its servo characteristics. Furthermore, if the operator performs an inching operation on the stick of the switch SW, the moving speed can be further reduced to achieve accurate positioning.

(3) Once the torch T is thus positioned at point LW ₁ , the operator operates the switch ST.
Then, the computer 5 stores each position information of the robot RO at this time as part of the user program.
Import as step information.

(4) Similarly, the points LW ₂ , LW ₁₁ and LW ₁₂
In addition to controlling the position of the torch T, other information including the linear interpolation command L, command welding speed V, command welding condition number W No., etc., are taught by operating the switch ST.

After teaching a series of user programs in this way, the operator checks them in the test mode and makes corrections if necessary.

Then, when the operator operates the switch ST in the auto mode, the user program is executed by the computer 5. The moving speed during this execution is different from that during the teaching described above, and is controlled by the servo characteristics of the servo system for each control axis in accordance with the command speed V.

The above description is an example, and for example, robot RO
The mechanical configuration may be a cylindrical coordinate system, a polar coordinate system, or an articulated coordinate system, in which case the manual operation switch is a rectangular coordinate system and coordinate transformation is performed between it and the mechanical system. However, it is possible. Further, although the increase rate C is set to 2 in this embodiment, it is sufficient if C>1. It goes without saying that the technical scope of the present invention also includes the replacement of each component with equivalents.

(Effects) As described above, this invention allows for continuous operation of the manual operation switch SW to reach the vicinity of the target position at high speed when the target position is far away, without changing the complicated hardware of the control device. Further, in the vicinity of the target position, the end effectors can be moved at low speed by inching the manual operation switch SW, allowing accurate positioning in a short time by manual operation.

[Brief explanation of drawings]

The drawings all show one embodiment of this invention, and the first embodiment is shown in the drawings.
The figure is a partially perspective overall view, Figure 2 is a flow chart,
FIG. 3 is an action curve diagram. SW...Manual operation switch, RO...Industrial robot, 5...Computer.

Claims (1)

[Scope of Claims] 1. In an industrial robot capable of controlling the position of an end effector at a specified movement speed by operating a manual operation switch, the minute speed Vc of each control axis at the specified movement speed V From this, the deviation Ysp in the forward movement direction of each control axis is determined as Ysp=Vc/K (K is a constant), and n is updated every fixed time t to find the deviation Ysp in the forward movement direction of each control axis. Find Yn as Yn=f(tn)=C・f(tn-1) (C is the increase rate, C>1), output the Yn sequentially, and control each control axis at the speed corresponding to the Yn. In addition, if Yn>Ysp, the industrial robot is configured to move each of the control axes at a constant speed with Yn=Ysp thereafter.