control

58 Articles

Clever Control Loop Makes This Spinning Drone Fault-Tolerant

November 9, 2022 by 18 Comments

Most multi-rotor aircraft are about as aerodynamic as a brick. Unless all its motors are turning and the control electronics are doing their thing, most UAVs are quickly destined to become UGVs, and generally in spectacular fashion. But by switching up things a bit, it’s possible to make a multi-rotor drone that keeps on flying even without two-thirds of its motors running.

We’ve been keeping a close eye on [Nick Rehm]’s cool spinning drone project, which basically eschews a rigid airframe for a set of three airfoils joined to a central hub. The collective pitch of the blades can be controlled via a servo in the hub, and the whole thing can be made to rotate and provide lift thanks to the thrust of tip-mounted motors and props. We’ve seen [Nick] manage to get this contraption airborne, and hovering is pretty straightforward. The video below covers the next step: getting pitch, roll, and yaw control over the spinning blades of doom.

The problem isn’t trivial. First off, [Nick] had to decide what the front of a spinning aircraft even means. Through the clever uses of LED strips mounted to the airfoils and some POV magic, he was able to visually indicate a reference axis. From there he was able to come up with a scheme to vary the power to each motor as it moves relative to the reference axis, modulating it in either a sine or cosine function to achieve roll and pitch control. This basically imitates the cyclic pitch control of a classic helicopter — a sort of virtual swashplate.

The results of all this are impressive, if a bit terrifying. [Nick] clearly has control of the aircraft even though it’s spinning at 250 RPM, but even cooler is the bit where he kills first one then two motors. It struggles, but it’s still controllable enough for a bumpy but safe landing.

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Mini Falcon 9 Uses NASA Software

July 26, 2022 by 17 Comments

[T-Zero Systems] has been working on his model Falcon 9 rocket for a while now. It’s an impressive model, complete with thrust vectoring, a microcontroller which follows a predetermined flight plan, a working launch pad, and even legs to attempt vertical landings. During his first tests of his model, though, there were some issues with the control system software that he wrote so he’s back with a new system that borrows software from the Space Shuttle.

The first problem to solve is gimbal lock, a problem that arises when two axes of rotation line up during flight, causing erratic motion. This is especially difficult because this model has no ability to control roll. Solving this using quaternion instead of Euler angles involves a lot of math, provided by libraries developed for use on the Space Shuttle, but with the extra efficiency improvements the new software runs at a much faster rate than it did previously. Unfortunately, the new software had a bug which prevented the parachute from opening, which wasn’t discovered until after launch.

There’s a lot going on in this build behind-the-scenes, too, like the test rocket motor used for testing the control system, which is actually two counter-rotating propellers that can be used to model the thrust of a motor without actually lighting anything on fire. There’s also a separate video describing a test method which validates new hardware with data from prior launches. And, if you want to take your model rocketry further in a different direction, it’s always possible to make your own fuel as well.

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OpenCV Brings Pinch To Zoom Into The Real World

March 24, 2022 by 11 Comments

Gesture controls arrived in the public consciousness a little over a decade ago as touchpads and touchscreens became more popular. The main limitation to gesture controls, a least as far as [Norbert] is concerned, is that they can only control objects in a virtual space. He was hoping to use gestures to control a real-world object instead, and created this device which uses gestures to control an actual picture.

In this unique augmented reality device, not only is the object being controlled in the real world but the gestures are being monitored there as well, thanks to a computer vision system watching his hand which is running OpenCV. The position data is fed into an algorithm which controls a physical picture mounted on a slender robotic arm. Now, when [Norbert] “pinches to zoom”, the servo attached to the picture physically brings it closer to or further from his field of view. He can also use other gestures to move the picture around.

While this gesture-controlled machine is certainly a proof-of-concept, there are plenty of other uses for gesture controls of real-world objects. Any robotics platform could benefit from an interface like this, or even something slightly more mundane like an office PowerPoint presentation. Opportunity abounds, but if you need a primer for OpenCV take a look at this build which tracks a hand in minute detail.

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IR Translator Makes Truly Universal Remote

February 10, 2022 by 19 Comments

Universal remotes are a handy tool to have around if you have many devices that would all otherwise have their own remote controls. Merging them all into a single device leads to less clutter and less frustration, but they are often not truly “universal” as some of them may not support every infrared device that has ever been built. If you’re in a situation like that it’s possible to build a truly universal remote instead, provided you have a microcontroller and a few infrared LEDs on hand.

This was the situation that [Matt] found himself in when his Amazon Fire TV equipment control feature didn’t support his model of speakers. To get around this he programmed an Arduino to essentially translate the IR codes from the remote and output a compatible set of codes to the speakers.This requires both an IR photodiode and an IR LED but little else other than the codes for the remote and the equipment in question. With that all set up and programmed into the Aruino, [Matt]’s remote is one step closer to being truly “universal”.

While [Matt] was able to make use of existing codes in the Arduino library, it is also possible to capture the codes required manually by pointing a remote at a photodiode and programming a microcontroller to capture the codes that you need. [Matt] used a Raspberry Pi to do this when debugging this project, but we’ve also seen this method used with a similar build which uses an ESP8266 to control an air conditioner via its infrared remote control capabilities.

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Random Robot Makes Random Art

May 14, 2021 by 4 Comments

For the price of a toothbrush and a small motor with an offset weight, a bristlebot is essentially the cheapest robot that can be built. The motor shakes the toothbrush and the bristle pattern allows the robot to move, albeit in a completely random pattern. While this might not seem like a true robot that can interact with its environment in any meaningful way, [scanlime] shows just how versatile this robot – which appears to only move randomly – can actually be used to make art in non-random ways.

Instead of using a single bristlebot for the project, three of them are built into one 3D printed flexible case where each are offset by 120°, and which can hold a pen in the opening in the center. This allows them to have some control on the robot’s direction of movement. From there, custom software attempts to wrangle the randomness of the bristlebot to produce a given image. Of course, as a bristlebot it is easily subjected to the whims of its external environment such as the leveling of the table and even the small force exerted by the power/communications tether.

With some iterations of the design such as modifying the arms and control systems, she has an interesting art-producing robot that is fairly reliable for its inherently random movements. For those who want to give something like this a try, the code for running the robot and CAD files for 3D printing the parts are all available on the project’s GitHub page. If you’re looking for other bristlebot-style robots that do more than wander around a desktop, be sure to take a look at this line-following bristlebot too.

Thanks to [johnowhitaker] for the tip!

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Magnetic Angle Sensor Mods Make Encoder Better For Blasting

March 5, 2021 by 12 Comments

Most of the hacks we see around these parts have to do with taking existing components and cobbling them together in interesting new ways. It’s less often that we see existing components gutted and repurposed, but when it happens, like with this reimagined rotary encoder, it certainly grabs our attention.

You may recall [Chris G] from his recent laser-based Asteroids game. If not you should really check it out — the build was pretty sweet. One small problem with the build was in the controls, where the off-the-shelf rotary encoder he was using didn’t have nearly enough resolution for the job. Rather than choosing a commodity replacement part, [Chris] rolled his own from the mechanical parts of the original encoder, like the shaft and panel bushing, and an AS5048A sensor board. The magnetic angle sensor has 14 bits of resolution, and with a small neodymium ring magnet glued to the bottom of the original shaft, the modified encoder offers far greater resolution than the original contact-based encoder.

The sensor breakout board is just the right size for this job; all that [Chris] needed to do to get the two pieces together was to 3D-print a small adapter. We have to admit that when we first saw this on Hackaday.io, we failed to see what the hack was — the modified part looks pretty much like a run-of-the-mill encoder. The video below shows the design and build process with a little precision rock blasting.

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Reverse-Engineering An Elevator Control Panel Results In Clicky Goodness

February 4, 2021 by 9 Comments

We have to admit that in the hardware hacking universe, there aren’t generally too many chances to hack elevators. Well, at least not opportunities that don’t also include the risk of incarceration. But fortune favors the bold, and when he found the remains of an elevator control panel in an abandoned Croatian resort hotel, [Davor Cihlar] undertook an extensive and instructive reverse-engineering of the panel.

The video below highlights his efforts, which were considerable given the age and state of the panel. This is a relay-only control panel, after all, with most of the relays missing and a rat’s nest of wires connecting the sockets. So [Davor] put his “RevIng” concept to work. This uses a custom PCB with a microcontroller on-board that plugs into each relay socket and probes the connections between it and every other socket. Very clever stuff, and it presented him with the data needed to develop a ladder-logic diagram of the board, with the help of some custom software.

With the original logic in hand, [Davor] set about building a simulator for the panel. It’s a lovely piece of work, with buttons and lights to mimic the control panel inside the elevator car, as well as the call stations that would have graced each lobby of the hotel. Interestingly, he found logic that prevented the elevator from being called to some floors from anywhere but inside the car. The reason remains a mystery, but we suppose that a hotel built by Penthouse publisher [Bob Guccione] would have plenty of secrets.

We love the supremely satisfying clickiness of this build, and the reverse engineering prowess on display, but we can’t find much practical use for something like this. Then again, DIY elevators are a thing.

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