Performance Considerations faster motions. On a SCARA robot, the “Z” and “theta” axes are the slowest, and motion of these joints should be minimized whenever possible. This can be accomplished by positioning the robot, and setting con- veyor heights and pick and place locations, to minimize Z-axis motion. Cell Layout Considerations Regarding cell layout and jointed arms, the same point-to-point distance can result in different cycle times. Moving multiple joints combines the joint speeds for faster motion. If the same distance is traversed using motion of a single joint, the motion of that joint will be longer, and therefore will take more time.
Part Handling Considerations For part handling, settling time while trying to achieve a position can be minimized by centering the pay- load mass in the gripper. A mass that is offset from the tool rotation point will result in excess inertia that will take longer to settle. In addition, minimizing gripper mass and tooling weight will improve settling time. This could include using aluminum versus steel, and removing material that is not needed on tooling. Programming Considerations The use of joint-interpolated versus straight-line motion has to be evaluated on a case-by-case basis. In general, joint-interpolated motion is more efficient.
Nulling tolerances should be as loose as the application will permit. This has a direct impact on cycle time. Lastly, on jointed arms, changing the arm configuration (for example, lefty versus righty for a SCARA robot) generally requires more time than maintaining the cur- rent configuration during a motion. ACE User's Guide, 3.6.x, 18316-000 Rev A Page 65