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Adept Cobra PLC Robots – Application Tips

November 10, 2003

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Optimization Techniques

Things to consider that impact performance

• Mounting• Cell Layout • Part Handling• Programming Considerations

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Mounting

Mounting Surface• Mount on smooth, flat surface • Mounting structure must be rigid• Vibration and Flexing will affect

performance• Recommend minimum 25mm (1 inch)

steel plate with rigid tube frame

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When positioning a robot in the workcell, take advantage of moving multiple joints for faster motions

The “Z” and “theta” axes are the slowest, so set up conveyor heights and pick/place positions to minimize Z axis motion

Cell Layout

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• Moving multiple joints combines the joint speeds for faster motions

Cell Layout

In this example, same point-to-point distance will result in

different cycle time

• Single joint motion limits robot speed to individual joint speed

Note: animations above illustrate robot motions, but do not demonstrate robot

speed.

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o The “Z” and “theta” axes are the slowest, so set up conveyor heights and pick/place positions to minimize Z axis motion.

o In general, the shorter the move, the faster the cycle.

Cell Layout

Minimizing Z height changes in a cycle will minimize cycle time

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Part Handling

Part Handling• In order to minimize settling delays, try

to center the payload mass on Z-axis center line.

• Minimize mass of gripper and gripper tooling as much as possible. • Consider aluminum versus steel if

appropriate• Remove material that is not needed

on tooling • Minimize payload

• Stay within rated payload – the lighter the payload, the better the performance

• Robot will run with max payload, but not at peak performance

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Programming Considerations

Joint/Straight• May have little effect on speed

depending on motion• Typically Joint motion is more

efficient and therefore faster• In tight spaces, Joint motion takes

more work envelop to execute. Straight line motion may be required due to obstructions

Example: moving from A to B in straight line versus joint mode

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Programming Considerations

Finish/No Finish• Depending on the motion (and

assuming no nulling tolerance required), “No Finish” will cause motion to one point to blend with motion to the following point

Multiple/Single• “Single” limits rotation of the robot

wrist (Joint 4) to ±180°• “Multiple” allows full rotations of

the wrist• Minimizing Joint 4 rotation will

shorten motion time

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Programming Considerations

Coarse/Fine• Defines how accurately robot

achieves commanded position • “Coarse” is a looser tolerance (less

accuracy) and results in faster cycles• “Fine” is a tighter tolerance

(increased accuracy) and takes more time to achieve

Commanded position

Fine nulling tolerance

Coarse nulling tolerance

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Programming Considerations

Lefty/Righty • Change in arm configuration from

Lefty to Righty or Righty to Lefty requires more time than maintaining the current configuration during a move.

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Adept Cobra PLC Robots – Application Tips

November 10, 2003