Trigger assembly for PS5 controller in palm of hand

How The PS5’s Genuinely Clever Adaptive Triggers Work

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.

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Spherical Keyboard Build Leaves Hacker Well-Rounded

Often times we as hackers don’t know what we’re doing, and we sally forth and do it anyway. Here at Hackaday, we think that’s one of the best ways to go about a new project, and the absolute fastest way to learn a whole lot as you go. Just ask [Aaron Rasmussen] regarding this spherical, standing 5×6 dactyl manuform keyboard build, which you can see in a three-part short video series embedded after the break.

[Aaron] gets right down to it in the first video. He had to get creative right away, slicing up the dactyl manuform model to fit on a tiny print bed. However, there’s plenty of room inside the sphere for all that wiring and a pair of Elite-C microcontrollers running QMK. Be sure to turn on the sound to hear the accompanying voice-overs.

The second video answers our burning question: how exactly does one angle grind a slippery sphere without sacrificing sheen or shine? We love the solution, which involves swaddling the thing in duct tape and foam.

You may be wondering how [Aaron] is gonna use any kind of mouse while standing there at the pedestal keyboard. While there is space for a mouse to balance on top, this question is answered in the third video, where [Aaron] learns the truth behind the iconic ThinkPad nubbin and applies this knowledge to build a force-feedback joystick/trackpoint mouse. Awesome answer, [Aaron]!

Not ready to go full-tilt, sci-fi prop ergo? Dip your toe in the DIY waters with a handy macropad.

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MIT’s Hair-Brushing Robot Untangles Difficult Robotics Problem

Whether you care to admit it or not, hair is important to self-image, and not being able to deal with it yourself feels like a real loss of independence. To help people with limited mobility, researchers at MIT CSAIL have created a hair-brushing robot that combines a camera with force feedback and closed-loop control to adjust to any hair type from straight to curly on the fly. They achieved this by examining hair as double helices of soft fibers and developed a mathematical model to untangle them much like a human would — by working from the bottom up.

It may look like a hairbrush strapped to a robot arm, but there’s more to it than that. Before it ever starts brushing, the robot’s camera takes a picture that gets cropped down to a rectangle of pure hair data. This image is converted to grayscale, and then the program analyzes the x/y image gradients. The straighter the hair, the more edges it has in the x-direction, whereas curly hair is more evenly distributed. Finally, the program computes the ratio of straightness to curliness, and uses this number to set the pain threshold.

The brush is equipped with sensors that measure the forces being exerted on the hair and scalp as it’s being brushed, and compares this input to a baseline established by a human who used it to brush their own hair. We think it would be awesome if the robot could grasp the section of hair first so the person can’t feel the pull against their scalp, and start by brushing out the ends before brushing from the scalp down, but we admit that would be asking a lot. Maybe they could get it to respond to exclamations like ‘ow’ and ‘ouch’. Human trials are still in the works. For now, watch it gently brush out various wigs after the break.

Even though we have wavy hair that tangles quite easily, we would probably let this robot brush our hair. But this haircut robot? We’re not that brave.

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Force Feedback Mouse Really Shakes Things Up

This is a very exciting time for those who like to spend their downtime exploring virtual worlds. The graphics in some big-budget titles are easily approaching photorealism, and immersive multi-channel sound can really make you believe you’ve been transported to another place or time. With another generation or two of GPU development and VR hardware, the line between gaming and reality is bound to get awful blurry.

That said, we’re still a far way off from the holodeck aboard the Enterprise. A high-end PC and the latest in VR can fool your eyes and ears, but that still leaves your other senses out of the fun. That’s why [Jatin Patel] has developed this clever force-feedback mouse using an array of solenoids.

The idea is pretty simple: a Python program on the computer listens for mouse click events, and tells an attached Arduino to fire off the solenoids when the player pulls the virtual trigger. It’s naturally not a perfect system, as it would seem that clicking in the game’s menus would also start your “gun” firing. But as you can see in the video after the break, when it works, it works very well. The moving solenoids don’t just vibrate the mouse around, the metallic clacking actually accentuates the gun sound effects from the game.

With this kind of tactile feedback and an omnidirectional treadmill to keep us moving, we’d be pretty close to fooling our senses into thinking we’re actually somewhere else. Which frankly, sounds quite appealing right about now.

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Feel The Virtual Road With Force Feedback

When you’re driving your virtual supercar around the Italian countryside the last thing you want is an inauthentic steering wheel feel, that’s where Open FFBoard comes in. Racing game enthusiasts will go to impossible and sometimes incredibly expensive lengths to build extravagant simulators. [Yannick] feels many of these products are just a little too pricey without much need.

Right now his board is still in a process of iteration, though it can integrate with Assetto Corsa already. You can see in the demo video after the break that it responds quite realistically to the video game state, however problems keep cropping up in search of solutions. Motor drivers burn out and power resistors are added: that energy has to go somewhere. Next up will be switching to the increasingly popular Trinamic drivers. Either way we can’t wait to see the next revision and to get another amazing simulator build sent in to us, maybe centered around the Open FFBoard.

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Feeling Force Through A Servo

Using force sensors it’s possible to chain a series of servo motors together so they not only move as one, but can detect and simulate the force that another feels. Which means if you built up a tele-presence robot with a servo-driven robotic arm, using the local control arm you could feel exactly what it feels like on the other side!

[Wolf Tronix] saw our post last week on Series Elastic Actuators, and shared what he was working on in the comments. As one tipster pointed out — it deserves its own feature!

He’s been designing his own Real Time Motion Control System and Mini Servo board, or RTMCS2 for short and shown off a short video of it in action. By adding a force feedback sensor to each servo, not only do they copy each other, but if you put a load on one, you’ll feel it on the others!

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Windows Drivers For PS3 Controllers

Recently, a Japanese coder on the DCEmu Forums released Windows drivers for DualShock 3 controllers. While the drivers only support using the controllers over USB and not bluetooth, they do include force feedback and Sixaxis support. Included with the drivers is a configuration tool, and though it appears to be in Japanese there is some explanation of how to use it included in the forum post. We have not tested these personally, but you can try out the drivers for yourself  by downloading them from the forum here.

[photo: William Hook]