About Base Conversion - Mitsubishi Electric CR750-Q Instruction Manual

4MELFA-BASIC V

4.5.2 About base conversion

The base conversion permits the world coordinate system to be moved, when required, to the reference
position of the work table or the work.
Under the control of this function, the robot's current position is treated as the one relative to the work table
or the work. Therefore, where there are a plurality of work groups involved on which the robot shares an
identical motional/positional relation, the robot can perform the same operations (sequence of motions) just
with a change being made to the world coordinate system, i.e., without the need to be taught the operations
(sequence of motions) for each work group. Change to the world coordinate system stated here are called
base conversion, which is accomplished by specifying parameter MEXBS with base conversion data (coor-
dinate values) or by executing a Base command.
Base conversion data to be specified should be data on the position of the origin point of the base
coordinate system as viewed from a world coordinate system which is newly established. Thus, when you
specify the data by using the robot's current position (using a Fram function, etc.), do so by inversely
converting the position data [for example, Base Inv(P1)].
When you specify work coordinate system parameters WK1CRD - WK3CRD by executing a Base
command, however, you do not have to make the inverse conversion yourself as it is done in internal
processing. (Example: Base1 to Base 8)
Fig.4-4:Base conversion
CAUTION
4-148 Coordinate system description of the robot
Zb
Base coordinate
system
Performing a base conversion changes the robot's current position to values that refer
to the newly established world coordinate system. The target position specified by the
movement command will also be treated as a position in the newly established world
coordinate system.
As a result, data taught till then may become unusable as it is. The coordinate system
when taught needs to be the same as the newly established coordinate system.
If they do not match, the robot can stray to unexpected positions, possibly resulting in
property damage or personal injury.
When using the base conversion function, be sure to maintain positive control over
relation between the base coordinate system subject to conversion and the position
which the robot is taught to take so that a proper robot operation and an effective use
of the base conversion function are insured.
Yb
base conversion data
Inv(P1)
P1
Xb
Zw
Yw
New world
coordinates system
* P1 is teaching position data.
Xw