[patrickrd]

Originally Posted by Coffeeism

To handle the big ball your motors going to have to constantly run to hold the ball along its circumfrence.

Using pneumatics to hold the ball, the piston would apply a constant force to hold up the ball so you wouldn't have to run your motor constantly.

I would use pneumatics.

I wouldn't be so quick to make this decision. Whether to use a motor or pneumatics requires a number of considerations...
- Are you planning to use pneumatics elsewhere on the robot? (the cost of using pneumatics is at least 10 lbs). This, in my opinion, is the main reason you may choose not to use pneumatics.
- How easy will it be to run pneumatic tubing vs. wires to the place of application? Tubing is generally more difficult since it can not make sharp turns like wire can.
- Do you want precise control over the posisition of the ball handler? Perhaps to use your component for some other function as well? If so, then a motor would be advantagous because you can stop at intermediate positions.
- A motor would not necessarily have to apply a constant load. If you use a worm gear or screwdrive-based design, the device will stop when you turn off power, and not move. The ball will remain deflected by a constant amount while it is in your possession, and the force will be transferred to the screwdrive, not the motor.

Pneumatics is almost definately easier, but the easy solution is not always the best solution.

- Patrick