Parker ACR7000 Series, Programmer'S Manual

Page: 205 / 341

MAKING MOTION
ACR Programmer’s Guide 205
Inverse Kinematics
Kinematics is a branch of mechanics that provides a mathematical means of describing motion. Inverse kinematics
looks at a position and works backwards to determine the motions necessary to obtain that position.
Robotic applications frequently use inverse kinematics. Algorithms describe the mechanical system and translate
the rotational motion of robotics into Cartesian coordinates. Consequently, an end user provides simple
Cartesian coordinates for an application and the inverse kinematics calculates necessary movements to reach that
position.
Suppose an application has a cutting tool at the end of a four-axis robotic arm and an HMI. The controller, using
algorithms developed by the application builder, transforms the motion target points from Cartesian coordinates
to rotational coordinates to position the arm joints and cutting tool. Once transformed, the controller
interpolates the target points to generate a motion path. See the illustration below:
Programming the Inverse Kinematics
Each application is different. The algorithm for your application can consist of equations, logical expressions and
commands in the AcroBASIC language. You can do the following:
•
Store algorithms in any of the programs 0 through 14 (be sure to dimension memory for the program).
•
Save the program to Flash memory.
•
Use the
PASSWORD
command to protect the program from uploading or listing.
•
Include the
INVK
commands in a program, or in the setup before a program.
Example
The following program results in a circle instead of a straight line because of the transformation described in
program 7 (PROG7).
PROG7
PROGRAM
P12361= SIN(P12360)
: REM Describe transformation in PROG7.
P12617= COS(P12360) : REM Describe transformation in PROG7.
ENDP
PROG0
ATTACH MASTER0
ATTACH SLAVE0 AXIS0 "X"