Jog feed information display apparatus for a robot

When an operator selects one of many jog modes, including a tool feed mode, robot coordinate system feed mode, user coordinate system feed mode, joint feed mode, etc., a display controller displays a jog feed direction adapted for the selected mode for superposition on a robot image on a monitor screen. If the operator depresses any of jog feed direction selector keys, the jog feed direction corresponding to the depressed key is displayed for discrimination.

BACKGROUND OF THE INVENTION 
1. Field of the Invention The present invention relates to an apparatus for 
displaying jog feed information for a robot, to be used for teaching an 
industrial robot (hereinafter referred to simply as "robot") which is 
operated by a teaching-playback method. 
2. Description of the Related Art 
In executing various operations by utilizing a system which includes a 
robot, the robot must be subjected to position teaching ("position 
teaching" includes "posture teaching" in the following) so that it may 
behave accurately in compliance with intended contents of work. The 
so-called off-line teaching is utilized in order to lighten an operator's 
work load required by this teaching operation. 
It is generally known that this off-line teaching system is very effective 
in the case where accurate data for an object of work, such as a 
workpiece, and work environment are provided in advance, and the contents 
of work are so simple that robot position does not require a very high 
accuracy. 
In many cases, however, it is hard completely to settle robot position only 
in accordance with the data provided at the time of off-line teaching. 
Accordingly, the so-called teaching-playback system is utilized 
frequently. According to this system, the operator carries out final 
position teaching while actually moving the robot by manual operation on 
the scene of work. This system also applies to the case where the off-line 
teaching is already executed. 
In order to meet this requirement in the main, most robot control devices 
have a jog feed function such that the robot position is gradually changed 
by manual operation. Normally, jog feed is carried out in a manner such 
that the robot is translated in an assigned direction (positive or 
negative direction) along an assigned coordinate axis (X-, Y-, or Z-axis 
or first, second, or third axis) of an assigned coordinate system of the 
robot or rotated in an assigned direction (positive or negative direction 
W, P or R) around an assigned coordinate axis of an assigned coordinate 
system. 
In executing a jog feed operation, the operator operates a keyboard of a 
teaching control panel of the robot control device, thereby selecting and 
assigning a reference coordinate system (world coordinate system, user 
coordinate system, etc.) which is believed to be best suited for the 
contents of work, or confirming the already assigned contents. This is 
referred to as assignment of a jog mode. If the operator selectively 
depresses one of jog keys indicated by X+, X-, Y+, Y-, Z+, Z-, .alpha.+, 
.alpha.-, .beta.+, .beta.-, .gamma.+, .gamma.-, etc. with the jog mode 
assigned in this manner, the robot starts translation or rotation 
correspondingly. The translation or rotation is adjusted by changing the 
time of duration or repetition cycles of depression of the jog key. 
Besides the system using these jog keys, there is a system which uses a 
joy stick. 
Generally, the selection of the reference coordinate system for jog feed is 
referred to as jog mode assignment. If the operator mistakes the actually 
assigned log mode for another in executing the jog feed, due to a failure 
to change the log mode, the robot moves in an unexpected direction, 
thereby lowering the operating efficiency, and in some cases, causing an 
interference or accident resulting in injury. 
Conventionally, a log mode to be executed or in execution is displayed only 
in a simple form, e.g., in characters. Therefore, the operator is liable 
to execute log feed continuously without being aware of the failure to 
change the log mode, misassignment, etc. Even in the case where the log 
mode is assigned correctly, the operator cannot easily grasp the 
expectable or real-time jog feed direction in the form of an image, and 
therefore, cannot forward the work without a feeling of uneasiness. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide a jog feed information 
display apparatus for a robot, whereby an operator can grasp the 
expectable or real-time jog feed direction in the form of an image so that 
he can execute jog feed operation without a feeling of uneasiness, and 
that the jog feed operation can be prevented from being executed or 
continued in a mistaken jog mode. 
The following is a description of an outline of the present invention. 
When the operator assigns (changes or confirms) the jog mode by operating a 
keyboard of a teaching control panel of a robot control device, the 
substance of the jog mode assignment, along with an image representing a 
robot, is graphically displayed on a screen of a jog feed information 
display apparatus. By observing the image of the robot, the operator can 
immediately recognize the relative postures of the robot and coordinate 
axes of a reference coordinate system selected through the assignment of 
the jog mode. 
Since the operator's sense of direction varies depending on the assigned 
jog mode, it is believed that the form of the robot image convenient to 
the operator also varies. 
In a tool feed mode based on a tool coordinate system, for example, the 
operator's consciousness may be supposed to center around the tool center 
point of a robot arm. Preferably, therefore, the robot image to be 
displayed should be a graphic image which briefly represents an area 
around the tool center point of the robot arm. More specifically, the 
robot arm end should be displayed with a hand thereon, and images of 
individual axes of the tool coordinate system should be superposed on the 
graphic image, in order to make the sense of direction clear. 
In a robot coordinate system feed mode based on a base coordinate system of 
the robot, on the other hand, the operator may be supposed to be conscious 
of the whole robot centering around the robot base. Preferably, therefore, 
the robot image to be displayed should be a graphic image which briefly 
represents the whole robot, and images of individual axes of the base 
coordinate system should be superposed on the base of the robot (near the 
origin of the base coordinate system). 
Likewise, in a user coordinate system feed mode, the graphic image which 
briefly represents the whole robot and images of individual axes in 
alignment with set positions in the user coordinate system should 
preferably be superposed as they are displayed. 
In a joint feed mode, moreover, an image which indicates the position of 
each axis and the direction of movement (translation or rotation) should 
preferably be superposed on the entire robot image. 
The operator can enjoy better convenience if he can make an additional 
display by selectively depressing one of jog keys indicated by X+, X-, Y+, 
Y-, Z+, Z-, .alpha.+, .alpha.-, .beta.+, .beta.-, .gamma.+, .gamma.-, etc. 
with the jog mode assigned. For example, the apparatus may be arranged so 
that X-axis display elements are flickered or discriminated by color when 
the key X+ is depressed, and that display elements around the Y-axis are 
flickered or discriminated by color when the key .beta.- is depressed. 
According to this arrangement, the jog feed state can be visually observed 
and grasped by the level of the actually selected jog feed direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 is a block diagram showing the principal part of a robot control 
system which incorporates a jog feed information display apparatus 
according to the present invention. 
FIG. 2 is a flowchart showing an outline of a process for displaying a 
graphic image on a CRT monitor screen. FIGS. 3 to 6 are diagrams 
schematically showing several examples of graphic images displayed on the 
CRT monitor screen during teaching operation. Referring now to FIGS. 1 to 
6, an embodiment of the present invention will be described in detail. 
Referring first to FIG. 1, the system generally comprises a display 
controller 10, a robot controller 20, a body 30 of a robot controlled by 
means of the robot controller 20, and a CRT monitor 40 for use as a 
display device for displaying jog feed information (display device type is 
optional, in general). 
The display controller 10 includes a central processing unit (hereinafter 
referred to as CPU) 11, which is connected, by means of a bus 17, with a 
memory 12 formed of a ROM, a memory 13 formed of a RAM, a keyboard 14, a 
monitor interface 15 connected to the CRT 40 for displaying graphic 
images, and a communication interface 16 used to transmit and receive 
signals associated with jog feed operation to and from the robot 
controller 20. 
The ROM 12 and the RAM 13 are previously loaded with programs, associated 
image data, set data, etc. for executing a jog feed information display 
process (see FIG. 6) in accordance with the jog feed signals delivered 
from the robot controller 20, along with programs for controlling the 
whole system. 
The robot controller 20 may be of a conventional type in which memories 
formed of a ROM and a RAM, a teaching control panel, an axis controller 
connected to the robot body 30 through a servo circuit, and a 
communication interface are connected by means of a bus. The control panel 
is provided with a jog feed start command key, jog mode selector keys, jog 
feed direction selector keys (selector keys X+, X-, Y+, Y-, Z+, Z-, 
.alpha.+, .alpha.-, .beta.+, .beta.-, .gamma.+, .gamma.-; .theta.1+, 
.theta.1-, . . . .theta.6+, .theta.6-, etc.). Here .theta.1+, .theta.1-, . 
. . represent modes in which various axes of the robot are rotated or 
translated. An amount of jog feed (amount of translation or rotation) can 
be adjusted depending upon the time of duration or repetition frequency of 
depression of each jog key. The robot controller using these jog keys may 
be replaced with one having its joy stick based on the jog feed system. 
FIG. 2 shows an example of the outline of the process for jog display 
executed by the CPU 11. This process will be described on the assumption 
that preliminary operations for the input of necessary programs, 
settlement of various coordinate systems, image data input, etc. are all 
completed. It is assumed in this process that jog modes that may be 
assigned are; 
(1) a tool feed mode based on a tool coordinate system; 
(2) a base coordinate system feed mode based on a base coordinate system of 
the robot; 
(3) a user coordinate system feed mode based on a user coordinate system 
set on a workpiece as an object of operation; and 
(4) a joint feed mode in which various axes of the robot are allowed to be 
jogged for rotation or translation. 
If an operator operates the teaching control panel of the robot controller 
20 and depresses the jog feed start command key, the CPU 11 of the display 
controller 10 triggers a program for displaying process of jog feed 
information, thereby starting the process, and immediately enters a 
standby state for jog mode signal reception (Step S1). 
If the operator further selects a jog mode adapted for the contents of 
work, from among other jog modes, and depresses a corresponding jog mode 
selector key (or confirmation key), the robot controller 20 gets ready for 
jog feed operation and transmits a signal indicative of the selected jog 
mode to the display controller 10. 
The CPU 11 of the display controller 10 receives the jog mode signal (YES 
in Step S1), immediately reads graphic image data adapted for the 
assignment of the jog mode from the memory, and causes the CRT 40 to 
display a graphic image on its screen through the monitor interface 15 
(Step SZ). 
The contents of display vary in the following manner, depending on which is 
selected from among the aforementioned jog modes (1), (2), (3) and (4). 
(1) Tool feed mode: In this mode, a tool center point of the robot is moved 
on the basis of the tool coordinate system. As shown in FIG. 3, therefore, 
each axis image Ot-XYZ of the tool coordinate system is superposed on a 
graphic image which briefly represents a region RA near a tool center 
point of a robot along with a hand H. 
(2) Robot coordinate system feed mode: In this mode, the tool center point 
of the robot is moved on the basis of the base coordinate system which is 
fixed to a robot base RB. As shown in FIG. 4, therefore, each axis image 
Ob-XYZ of the base coordinate system is displayed on a graphic image which 
briefly represents an entire robot image RW including the robot base RB. 
(3) User coordinate system feed mode: In this mode, the tool center point 
of the robot is moved on the basis of the coordinate system which is set 
in a position (e.g., on the workpiece) separate from the robot. As shown 
in FIG. 5, therefore, each axis image Ou-XYZ of the user coordinate system 
is displayed on the graphic image which briefly represents the entire 
robot image RW. 
(4) Joint feed mode: In this mode, each axis of the robot is rotated or 
translated in a positive or negative direction. As shown in FIG. 6, 
therefore, an image for indicating the position and direction of movement 
(rotation or translation) of each axis is superposed on the entire robot 
image RW. 
In Step S3 which directly follows Step S2, the CPU 11 gets ready to receive 
a signal indicative of the depression of one of the jog feed direction 
selector keys (X+, X-, Y+, Y-, Z+, Z-, .alpha.+, .alpha.-, .beta.+, 
.beta.-, .gamma.+, .gamma.-; .theta.1+, .theta.1-, . . . .theta.6+, 
.theta.6-, etc.) (or assignment by means of the joy stick). 
If the operator depresses any of the jog feed direction selector keys, the 
robot controller 20 jogs the robot body 30, and at the same time, 
transmits the signal indicative of the depressed jog key (or jog feed 
direction assigned by means of the joy stick) to the display controller 
10. 
The CPU 11 of the display controller 10 receives this jog feed direction 
assigning signal (YES in Step S3), and starts an emphatic display 
indicative of the assigned jog feed direction in the graphic image already 
displayed on the screen of the CRT 40 through the monitor interface 15 
(Step S4). The emphatic display may be made by various methods, such as 
flickering the coordinate axis concerned, changing the display color of 
the coordinate axis concerned, etc. The joint feed mode or the like can be 
executed more effectively with an emphatic display of an arrow which is 
indicative of the positive or negative direction. 
This state is continued until a signal indicative of the interruption of 
jog feed in the direction concerned (e.g., interruption of the depression 
of the jog key concerned) is transmitted from the robot controller 20 
(Step S5). When the signal indicative of the interruption of jog feed in 
the direction concerned is transmitted from the robot controller 20, the 
emphatic display is interrupted (Step S6). 
Then, reception of a subsequent signal from the robot controller 20 is 
awaited (Step S7). In the case where the signal received by the display 
controller 10 is indicative of the termination of the jog feed itself (YES 
in Step S1), the jog feed information display process is finished (END). 
In the case where the received signal represents a jog mode change 
(reassignment) (YES in Step S9), the CPU 11 returns to Step S2, whereupon 
it displays a graphic image corresponding to the assigned jog mode. 
Subsequent processes are executed in the same manner as aforesaid. 
In the case where the received signal indicates the continuation of the jog 
mode, that is, if a signal for assigning the jog feed direction (e.g., 
signal for the depression of any of the jog feed direction selector keys) 
is received without any jog mode change (reassignment), the CPU 11 
advances to Step S4 after confirming the signal reception in Step S3, 
whereupon it makes an emphatic display. Subsequent processes are executed 
in the same manner as aforesaid. 
According to the present embodiment, as described herein, the image 
indicative of the substance of the jog mode assigned on the robot control 
means, along with the image which represents the robot, is displayed on 
the screen of the display means which has a function to display graphic 
images. When the operator actually starts robot movement by jog feed, the 
direction of the movement is displayed emphatically, so that the 
operator's work load during teaching operation and the like can be 
lightened considerably. 
According to the present invention, the operator can easily grasp the jog 
mode in the form of an image before or during the execution of the jog 
feed operation. Thus, the jog feed can be prevented from being started or 
continued with the jog mode mistaken for another. 
Since directions of the jog feed of a mode currently assigned or directions 
of a jog feed in operation can be grasped in the form of an image, 
moreover, the jog feed operation can be executed without a feeling of 
uneasiness, and the efficiency of the teaching operation based on the jog 
feed operation can be improved. 
Emphatically displaying the real-time jog feed direction in the graphic 
image, in particular, will enable an operator to grasp the jog feed 
direction more definitely.