Help with a Test Rig Project

I need to make a test rig for a device to push and pull a lever at a given force of around 10-50 Newtons, through a distance of about 30mm. It will need to push the lever for a given time and force, then pull for a given time and force.

As this is a test rig I require it to be push and pull with a constant force that is controllable and repeatable.

I was thinking of a solenoid but am not sure if the force can be controlled accurately.

Does anyone have any suggestions how best to go about this.

A camshaft & spring roller comes to mind.

M1 and M2 are weights. A gear-motor driven capstan (winch) picks up either one weight or the other. The "other" weight acts on the lever. Forces are directly proportional to the weights, which can be changed at will and/or asymmetric (until gravity changes ).