There’s A LEGO Suspension Dyno Now

June 16, 2022 by Lewin Day 1 Comment

When it comes to the development and testing of performance suspension, it’s helpful to have a test apparatus that lets you recreate certain conditions reliably. This LEGO suspension dyno does just that, and it’s clearly a big help for those doing R&D on minifig motorcycle suspension.

The build relies on four motors to overcome the resistance of turning a chunky conveyor belt, which acts as a rolling road. As the belt is built out of Technic beams, various LEGO blocks can be added to the conveyor to act as bumps or perturbations for testing suspension.

The video demonstrates the use of the dynamometer, showing how a simple LEGO motorbike design deals with bumps of various sizes. It’s easy to swap out forks and springs and change the geometry to tune the suspension, and the changes can be easily seen when running it through the same test conditions.

While we don’t imagine there are too many people working in this particular field, the lessons being taught here are valuable. This setup allows one to quickly visualize how changing vehicle parameters affects handling. It’s hard to imagine a better teaching tool for vehicle dynamics than something like this that lets you see directly what’s really going on!

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The blue LEGO brick described, with the OLED inside shining through the 3D-printed and subsequently cast brick body. The picture on the small OLED imitates the lines of text shown on the brick that this is an imitation of.

Computer-Shaped LEGO Brick Brought To Life

June 8, 2022 by Arya Voronova 26 Comments

In childhood, many of us wondered — wouldn’t it be cool if our miniature toys had “real” functions? Say, that our toy cars actually were able to drive, or at least, that the headlights could light up. [James Brown] captures some of this childhood expectation of magic, recreating the 2×2 45°-sloped Lego bricks with computer screens and panels drawn on them by building a LEGO brick (thread, nitter) with an actual display inside of it.

This is possible thanks to an exceptionally small OLED display and a microcontroller board that’s not much larger. It’s designed to plug onto a LEGO platform that has an internal 9V battery, with power exposed on the brick’s studs. [James] has taken care building this — the brick was built with help of a tiny 3D-printed form, and then, further given shape by casting in what appears to be silicone or resin.

We’ve yet to hear more details like the microcontroller used — at least, the displays look similar to the ones used in a different project of [James]’, a keyboard where every keycap has a display in it (thread, nitter). Nevertheless, it is lovely to witness this feat of micro-engineering and fabrication. It reminds us of an another impressive build we covered recently — a 1/87 scale miniature Smart Car that’s as functional as you can get!

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Slow Races On A Pinewood Derby Track Built From Scratch

May 20, 2022 by Lewin Day 18 Comments

Pinewood derby racing is a popular pastime for scouting groups and many others besides. [Mr Coster] whipped up his own track with the assistance of some 3D printed parts, and used it to run a competition with a fun twist on the usual theme.

The track starts with a pair of MDF panels, on to which some strips are placed to act as guides for the racers. There’s also a release mechanism built with hinges and a pair of dowels that ensures both racers start the competition at exactly the same time. To give the track a nice transition from the downward slope to the horizontal, a series of curved transition pieces were designed in Fusion 360, 3D printed, and added to the course.

As for the competition, [Mr Coster] decided to eschew the usual focus on outright speed. Instead, students were charged with building the slowest possible car that could still complete the course. Just for the fun of it, though, the kids were then given one day to modify their slowest cars to compete in a more typical fastest-wins event. It gives the students a great lesson in optimizing for different performance parameters.

You might be old-school, though, and want to ruin the fun by taking it all way too seriously. Those competitors may wish to consider some of the advanced equipment we’ve featured before. Alternatively, you could run a no-holds-barred cheater’s version of the contest. Video after the break.

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PCB Linear Motors For Model Trains

May 19, 2022 by Anne Ogborn 34 Comments

Modeling a railroad is hard. Railroads are large, linear pieces of civil engineering. So many modelers are drawn to the smallest scale they can use. Recently a new scale, named T, at 1:450 has been pushing this barrier. But fitting a reliable mechanical drive mechanism and MCU board in a package this size is a challenge. In practice, even more of a problem is getting reliable electrical contact through a metal wheel on metal track (about the worst possible design for a contact).

T always seemed to us a long way out on the bleeding edge. But all that may have changed. In a recent Hackaday.io writeup, author [Martin] describes a PCB technology based linear motor system to externally drive T scale locomotives.

The system uses 4mm planar coils. The underside of the PCB has another coil, so the effective pitch is 2mm. With microstepping, a step of 0.25mm is possible, and trains run smoothly. Current is 3-400mA. Continue reading “PCB Linear Motors For Model Trains” →

Verbot Goes To The Dark Side

May 9, 2022 by Adam Fabio 14 Comments

What happens to old, neglected 1980s toy robots? According to the [Randi Rain], they turn to the dark side! Way back in the ’80s, Tomy had an entire line of robots — from keychain wind-up toys to rolling, talking machines almost 2 feet tall. Tucked into the middle of this line was Verbot. Verbot’s claim to fame is that it is a voice-controlled robot. More than that, it was speaker-dependent. Train the robot with commands like “go forward” and then watch as it responds to your every command.

As you might guess, the speech recognition wasn’t great by today’s standards. Recognition was handled by a Microcontroller — a Mitsubishi product that was possibly a mask programmed 8051 variant. Pretty novel for an 80s toy — in fact, there’s a patent for it.

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Building Reaction Wheels With Python And LEGO

April 27, 2022 by Lewin Day 3 Comments

Reaction wheels are useful things, typically used by satellites to keep themselves oriented the right way up in space. Turning the reaction wheel creates an equal and opposite torque in the spacecraft, allowing it to point and rotate itself accurately. The same technique also works here on Earth, and [Brick Experiment Channel] decided to build one out of LEGO to control an inverted pendulum.

The initial design using a small LEGO wheel on an inverted pendulum was only able to work reliably over a 4-degree angle from the vertical. Upgrading the wheel to a larger, heavier one enabled the wheel to instead work over a 28-degree range instead.

A MPU9250 inertial measurement unit was pressed into service for control of the reaction wheel, fitted to the base of the pendulum and read by a Raspberry Pi. The Pi takes accelerometer and gyroscope readings, and then controls the motor on the pendulum with a PID controller to keep the inverted pendulum upright.

The video goes into a great deal of detail on what it takes to make the pendulum run smoothly. From changes to the control coefficients to measuring the motor’s back EMF, [Brick Experiment Channel] demonstrates everything required to make the pendulum robust to outside perturbances.

The inverted pendulum is a great way to learn about control theory, as we’ve seen time and again.

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2022 Sci-Fi Contest: A Star Wars Mouse Droid Of Your Very Own

April 21, 2022 by Lewin Day 5 Comments

The show-stealing droids of Star Wars, R2-D2 and C-3PO, are quite challenging to replicate at home, due to their size and complexity. [curiousmarc] had built the former, with much work going into drawing and design. The more humble Mouse Droid, as seen skittering about the halls of the Death Star, is a considerably easier build — especially with this somewhat improvised approach.

The build relies on reject parts from [curiousmarc]’s R2-D2 build, and other stuff laying around the house, like a toy eggbeater, a VFD, and other electronic bits and pieces. An RC car chassis was placed in the droid’s vacuum-formed shell in order to provide propulsion, with much of the rest of the work being decoration of the housing with various sci-fi ephemera. There’s also a pair of Arduinos inside, controlling the VFD, sound output, and the movable antenna dish on top.

It’s a build with a lot of personality. The sounds, flickering display, and moving antenna do a lot to imbue this droid with a soul, something Lucasfilm readily achieved with many of the robots in the series. It’s something we’ve also seen in robot companion builds from [Jorvon Moss], which are quite sci-fi in their own way, too. Video after the break.

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