I am thinking about a project with one robot arm that should throw away a ping-pong balls in to two baskets.
There should be two or three baskets in different distance from the arm.
The balls should have different colors, say green and red only.
The balls should get automatically rolls into the robot arm's palm.
A sensor should detect the color of the actual ball in the robot arm palm.
The arm should throw away the ball in to the correspondig basket number 1 or 2 that depends on the color of the ball.
The essence of this project is the accelerations that get balls to fall in to a corresponding basket.
Can a servo been controlled to get different accelerations?
If option #1 is not possible, then mybe the servo should used just to pull a spring, and a relay should free the spring so the ball can be throwed away?
Is this goal can be achieved with Arduino UNO and a corresponding robot arm?
I'm not sure that acceleration is the correct word.
The distance an object "flies" after being thrown depends on the release velocity and the vertical angle it is moving at at the moment of release.
I don't know if a servo would be suitable. Their speed is determined by their internal system. It is possible to give the appearance of slowing them down by getting the Arduino to move them in short steps - see the Servo Sweep example. But each small movement will be close to the full servo speed which may not be suitable for your project.
I suppose it may be possible to adjust the range entirely by using a constant release speed and adjusting the trajectory.
Lots of opportunity for some interesting experiments.
I can't answer that as you have not provided any diagram of the mechanical arrangement of your machine and I am very conscious that servo arms move in circles, not straight lines.
It just occurred to me that you could use a servo to compress a firing spring and the amount of compression could determine the force on (and velocity of) the projectile.
DrDiettrich:
Also a solenoid may be usable for pushing the ball.
I think the OPs aim is to THROW, rather than FIRE like a gun, the ping pong ball.
So the servo arm swings and stops to send the ball on a hopefully predicted trajectory.
The coding would have to set the stop position and the velocity at that position to send the ball on its way.
The need is to see if a servo arm can attain the velocity, try different lengths of throwing arm.