</font><font color="blue" class="small">( ...I would like to think that something that is actually powered and pushes the tines vertically in and out of the ground...)</font>
As long as the tines roll, they won't follow vertical path in the soil. All tines rotating/rolling on/in the soil will tear the soil. To reduce the tear amount, the diameter of circular motion of the tine around itself should be as small as possible. This means you will use shorter aerator tines which are not wanted. I can think of another method, somethings like a tens of small post hole diggers. Such a machine can be very simple. Just use some chain-chain gear systems or belt-pulley systems to distribute the pto power to small drills mounted on a beam. They will drill the soil exactly vertical or in any angle you want.
As long as the tines roll, they won't follow vertical path in the soil. All tines rotating/rolling on/in the soil will tear the soil. To reduce the tear amount, the diameter of circular motion of the tine around itself should be as small as possible. This means you will use shorter aerator tines which are not wanted. I can think of another method, somethings like a tens of small post hole diggers. Such a machine can be very simple. Just use some chain-chain gear systems or belt-pulley systems to distribute the pto power to small drills mounted on a beam. They will drill the soil exactly vertical or in any angle you want.