For more on actuators, check out our in depth Blog on how actuators work
How do actuators work
let me show you the difference between hydraulic actuators, pneumatic actuators and electromechanical actuators with respect to precision or control using Lego. for this simple actuator you turn this and the shaft will go in and out when you restrain it and that's just because it's just a simple lead screw inside here. This just goes in and out by turning this clockwise so we're just converting rotary motion into linear motion. Its very very simple and we have very fine control over it, now let's show you using a DTI exactly how much control we have using this Lego actuator. Here as you can see very finely controlled from here to here is half a millimeter I can control it within microns if we want to just, by turning this the slides in and out, we have extremely precision control which is what you would expect.
Now let's look what we get if we use a hydraulic or pneumatic actuator again using Lego so this is a simple Lego hydraulic actuator and all is it's just a air goes in one side and out the other and this slides in and out depending on where we pump it in if we pump air in here this will slide backwards if we pump in here this will slide outwards and then we can use a simple pump like this so I'll show you this working we have a valve that that distributes air either this way or this way and if this was hydraulic it would be exactly the same so when I pump it you can see this slides out to go backwards it just goes back in as you can see.
Now let's see how precise we can actually control this using this dial test indicator turn the valve to extend it let's see what happens and you can see there's a huge delay and that's because air is compressible so we cannot finely control this thing at all. If this was hydraulic fluid inside here it would be better because hydraulic fluid is not compressible but because this is air very little control come at all so for to move it is a small amount it's just such a huge delay in anything that happens back again so as you can see mechanical actuators like this will give you such fine control they're much better for applications where you need to finally control something to great accuracy