How The PS5’s Genuinely Clever Adaptive Triggers Work

Trigger assembly for PS5 controller in palm of hand

Sony’s Playstation 5 console and its DualSense controllers aren’t exactly new, but the triggers of the controllers have a genuinely interesting design that is worth examining. The analog triggers on the PS5 controllers are generally described as having “variable resistance”, but it turns out that’s not the whole story. Not only is the trigger capable of variable resistance when being pressed, but it can also push back in variable ways and with varying amounts of force. How it works is pretty clever.

Trigger assembly being moved in palm of handThe feedback for the trigger assembly is handled by a lever, a geared wheel, and a worm gear on an electric motor. Under normal circumstances, nothing interferes with the trigger at all and it works like a normal analog trigger. But when the motor moves the lever into place, trigger movement now has to overcome the added interference with a mechanical disadvantage. The amount of resistance felt can be increased a surprising amount by having the motor actively apply additional force to counter the trigger’s movement.

That’s not all, either. The motor can also actively move the lever into (or out of) position, which means that pulling the trigger not only has the ability to feel smooth, mushy, or stiff in different places, but it can also actively push back. This feedback can be introduced (or removed) at any arbitrary point along the trigger’s range of motion. A trigger pull can therefore feel like it has a sharp breakpoint, a rough travel, a hard stop, an active recoil, or any combination of those at any time.

It’s a little hard to describe, but you can get a better idea of it all works in practice by watching part of this teardown by [TronicsFix] (video cued to about 9:17 where the trigger teardown begins.) It’s also embedded below, so give it a peek.

A small amount of force applied in the right place can produce outsized results, but a force feedback project doesn’t have to be subtle. One can always shake things up by mounting a whole bunch of solenoids onto a mouse.

27 thoughts on “How The PS5’s Genuinely Clever Adaptive Triggers Work

    1. To me, resistance is a constant factor which is applied regardless of user input. “Push back” implies an active action on the receiver’s end, attempting to maintain resistance despite (or up to) the user’s applied force.

    2. As a non-native speaker, I understand that “resistance” is “you have to do extra force to push it”, while “push back” is that, after you have pressed it, the force that it makes increases suddenly (like “recoil”).

      BTW: Finally HaD added a popup to confirm a “Report comment”! :-D

    3. One is (or can be) passive and resists and outside force, the other actively applies a force.

      In other words, as intended in this article (if I understand correctly) resistance means simply that the trigger resists motion from an outside force applied to it. The higher the resistance the more force has to be applied to move the trigger, however, if the outside force is removed the trigger doesn’t move on it’s own (or only some light spring pressure). When “push back” is enabled, not only is there this resistance to motion but the trigger is actively being moved against the force in the other direction. In other words, if you push with less force on the trigger, it will move outwards.

      1. Proper answer: All of the above. This mechanism can simulate both resistance, push back, sudden loss of resistance and even simulate a trigger connected to something which oscillates back and forth like a gear lever in old tractor.

  1. it’s clearly a motor that acts as a generator also. Therfore it can be pushed with varying degrees of stiffness to the push. it can also be driven so the button can move in and out by itself. You can push a car with the engine turned off (and out of gear) ….A car can push you with its engine on..

    1. lol. One of our projects was engineered with this thinking… turns out if you load up 20k lbs the worm gear will back drive until it over heats, it locks up until it cools and the cycle repeats. A broken shaft to the brake system proved this…. There are calculations for backdrive force of worm drives and the teeth per inch of the worm gear makes a huge difference, low number like the device shown, is more like a helical cut gear on a differential.

      Very cool device to get feedback in such a compact package.

    1. Now that is an interesting thought, I suspect it would be better than your normal trigger – as its go so much variability in force required you will be engaging more and probably different muscles as it fights you, subtle effect but I expect it will make you want to shift your grip and flex motions often, even if its only by small amounts…

      But maybe it could be much worse though..

  2. Bah! Newfangled nonsense! When I was a kid the TAC-2 joystick was all we had and we had no problem blasting away all of the aliens that Gorf or Galaxian could throw at us! You could trip up over a connecting cable and face-plant a glass CRT back in them days too! Who the hell needs more than one functional button anyway? Hack that thing properly by ripping all those superfluous doohickeys out of there and if you’re going to leave more than one button in there then just wire them all in parallel for crying out loud. And how the hell do you even plug this thing into an Atari port anyway?

      1. The Optimus Maximus keyboard was thought to be impossible once too. It’d probably be thick, and yes potentially power hungry (relatively for a keeb) but these are not insurmountable issues.

    1. a real world gun trigger has a sharp breakover point. a car’s gas pedal has a smooth linear spring tension. This is an analog trigger as have been most game controller lower-shoulder since the Gamecube (First, also had a button at the bottom-of-travel) and the PS3 (Semantic: Lower analog is Trigger, upper button is Bumper)

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