All the cylinders that we have used in the past have an adjustable valve that allows you to adjust actuation speed/force manually. You should be able to design a servo- operated link to this valve knob to adjust the applied pressure. The servo has a built in encoder, and use a continuous rotation type. Some years we were only allowed to use certain servos, all of which had limited rotational capability (180 DEG. or less). check this year's rules on servos that are allowed. they are usually very specific on maximum torque and capability specs.
