For a pet project of mine, I'm interested in finding a tubular solenoid which force is spread linearly over a longer length. The project is based on IA and uses a programmed controller (and sensors) to feed several solenoids (the question is for one solenoid) quickly in order to "grab" something falling vertically, from below, this silently (done) but also a bit more smoothly (the problem). Currently, while the programming seems to work, the test prototype with two solenoids lack control. Basically the solenoids force goes from 0 / 1 [didn't try to control current yet].
but the force is basically 0 / 1... meaning the force grows exponentially over a short distance.
Ideally, the force would be linearly spread over a length I decide. Thus my question
Preferably with only one solenoid, how to choose/select the core and wires in order to spread the force over a longer length (i.e. not exponential growth)
If 2+ solenoids are necessary please explain how you would arrange them to reach such result (1 is preferable though).
Note: if that helps, the current applied to the solenoid can be precisely controlled from a chip.