Building D-O, The Cone Face Droid

For many of us, movies are a great source of inspiration for projects, and the Star Wars films are a gift that just keeps giving. The D-O droid featured and the Rise of Skywalker is the equivalent of an abandoned puppy, and with the help of 3D printing, [Matt Denton] has brought it to life. (Video, embedded below.)

D-O is effectively a two-wheeled self-balancing robot, with two thin drive wheels on the outer edges of the main body. A wide flexible tire covers the space between the two wheels, where the electronics are housed, without actually forming part of the drive mechanism. The main drive motors are a pair of geared DC motors with encoders to allow closed-loop control down to very slow speeds. The brains of the operation is an Arduino MKR-W1010 GET on a stack that consists of a motor driver, shield, IMU shields, and prototyping shield. [Matt] did discover a design error on the motor driver board, which caused the main power switching MOSFET to burst into flames from excessive gate voltage. Fortunately he was able to work around this by simply removing the blown MOSFET and bridging the connection with a wire.

The head-on D-O is very expressive and [Matt] used four servos to control its motion, with another three to animate the three antennas on the back of its head. Getting all the mechanics to move smoothly without any slop took a few iterations to get right, and the end result looks and moves very well. Continue reading “Building D-O, The Cone Face Droid”

Pop A Wheelie With Your Electric Skateboard, The Hacker Way

Using a bit of tech to make up for a lack of skill is a time-honoured tradition, otherwise known as cheating among those who acquired the skill the hard way. Learning to wheelie manual a skateboard is usually paid for in bruises, but [blezalex] got around that by letting his electric skateboard handle the balancing act.

At first glance the board looks and rides like an average DIY electric skateboard, with an off-the-shelf  a dual hub motor truck, VESC speed controllers and a wireless throttle. The party trick appears when the front wheel is popped off the ground, which activates the secret self-balancing mode. At this point a STM32F401 dev board and MPU-6050 IMU take over control of the motors, which is in turn controlled by leaning forward or backwards, like a hoverboard. The remote throttle turns into a dead man switch, which cuts power to the motors when released.

[blezalex] says he has had less that an hour of skateboard time in his life before getting on this one, which is a good testament of just how well it works. The biggest challenge was in getting the board to turn while on two wheels, which was solved by sensing side-to-side tilt of the board with the IMU and applying proportional differential torque to the wheels. With a bit of practice it’s also possible to smoothly shift between riding modes while moving.

We think this is a really elegant cheat, now we need to build one of our own. Fortunately the STM32 firmware and instructions are all up on GitHub. Building your own electric skateboard has become really simple with the availability of off-the-shelf components. We’ve also seen a bicycle with a wheelie cheat device to prevent you falling on your back

Hackaday Links: January 5, 2020

It looks like the third decade of the 21st century is off to a bit of a weird start, at least in the middle of the United States. There, for the past several weeks, mysterious squads of multicopters have taken to the night sky for reasons unknown. Witnesses on the ground report seeing both solo aircraft and packs of them, mostly just hovering in the night sky. In mid-December when the nightly airshow started, the drones seemed to be moving in a grid-search pattern, but that seems to have changed since then. These are not racing drones, nor are they DJI Mavics; witnesses report them to be 6′ (2 meters) in diameter and capable of staying aloft for 90 minutes. These are serious professional machines, not kiddies on a lark. So far, none of the usual government entities have taken responsibility for the flights, so speculation is all anyone has as to their nature. We’d like to imagine someone from our community will get out there with radio direction finding gear to locate the operators and get some answers.

We all know that water and electricity don’t mix terribly well, but thanks to the seminal work of White, Pinkman et al (2009), we also know that magnets and hard drives are a bad combination. But that didn’t stop Luigo Rizzo from using a magnet to recover data from a hard drive. He reports that the SATA drive had been in continuous use for more than 11 years when it failed to recover after a power outage. The spindle would turn but the heads wouldn’t move, despite several rounds of percussive maintenance. Reasoning that the moving coil head mechanism might need a magnetic jump-start, he probed the hard drive case with a magnetic parts holder until the head started moving again. He was then able to recover the data and retire the drive. Seems like a great tip to file away for a bad day.

It seems like we’re getting closer to a Star Trek future every day. No, we probably won’t get warp drives or transporters anytime soon, and if we’re lucky velour tunics and Spandex unitards won’t be making a fashion statement either. But we may get something like Dr. McCoy’s medical scanner thanks to work out of MIT using lasers to conduct a non-contact medical ultrasound study. Ultrasound exams usually require a transducer to send sound waves into the body and pick up the echoes from different structures, with the sound coupled to the body through an impedance-matching gel. The non-contact method uses pulsed IR lasers to penetrate the skin and interact with blood vessels. The pulses rapidly heat and expand the blood vessels, effectively turning them into ultrasonic transducers. The sound waves bounce off of other structures and head back to the surface, where they cause vibrations that can be detected by a second laser that’s essentially a sophisticated motion sensor. There’s still plenty of work to do to refine the technique, but it’s an exciting development in medical imaging.

And finally, it may actually be that the future is less Star Trek more WALL-E in the unlikely event that Segway’s new S-Pod personal vehicle becomes popular. The two-wheel self-balancing personal mobility device is somewhat like a sitting Segway, except that instead of leaning to steer it, the operator uses a joystick. Said to be inspired by the decidedly not Tyrannosaurus rex-proof “Gyrosphere” from Jurassic World, the vehicle tops out at 24 miles per hour (39 km/h). We’re not sure what potential market for these things would need performance like that – it seems a bit fast for the getting around the supermarket and a bit slow for keeping up with city traffic. So it’s a little puzzling, although it’s clearly easier to fully automate than a stand-up Segway.

Augmented Arthropod Gets A Self-Balancing Ride

There are many people who find being around insects uncomfortable. This is understandable, and only likely to get worse as technology gives these multi-legged critters augmented bodies to roam around with. [tech_support], for one, welcomes our new arthropod overlords, and has even built them a sweet new ride to get around in.

The build follows the usual hallmarks of a self-balancing bot, with a couple of interesting twists. There’s twin brushed motors for drive, an an Arduino Uno running the show. Instead of the more usual pedestrian IMUs however, this rig employs the Bosch BNO055 Absolute Orientation Sensor. This combines a magnetometer, gyroscope, and accelerometer all on a single die, and handles all the complicated sensor fusion maths onboard. This allows it to output simpler and more readily usable orientation data.

The real party piece is even more interesting, however. Rather than radio control or a line following algorithm, this self-balancer instead gets its very own insect pilot. The insect is placed in a small chamber with ultrasonic sensors used to determine its position. The insect may then control the movement of the bot by moving around this chamber itself. The team have even developed a variety of codes to dial in the sensor system for different types of insect.

It’s not the first time we’ve seen insects augmented with robotic hardware, and we doubt it will be the last. If you’re working on a mad science project of your own, drop us a line. Video after the break.

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This Two-Wheeled RC Car Is Rather Quick

Radio control cars have always been fun, it’s true. With that said, it’s hard to deny that true speed was unlocked when lithium polymer batteries and brushless motors came to the fore. [Gear Down For What?] built himself a speedy RC car of his own design, and it’s only got two wheels to boot (Youtube link, embedded below).

The design is of the self-balancing type – if you’re thinking of an angry unmanned Segway with a point to prove, you’re in the ballpark. The brains of the machine come thanks to a Teensy 3.6, which runs the PID loops for balancing and control. An MPU6050 gyroscope & accelerometer provide the necessary sensing to enable the ‘bot to keep itself upright in varied conditions. Performance is impressive, with the car reaching speeds in excess of 40 MPH and managing to handle simple ramps and bumps with ease. It’s all wrapped up in a 3D printed frame which held up surprisingly well to many crashes into tripods and tarmac.

Such builds are not just fun; they’re an excellent way to learn useful control skills that can serve you well in industry and your own projects. You can pick up the finer details of control systems in a university engineering course, or you could give our primer a whirl. When you’ve whipped up your first awesome project, we’d love to hear about it. Video after the break.

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Balancing Robots From Off-The-Shelf Parts

In this day and age, we are truly blessed as far as the electronics hobby is concerned. Advanced modules such as gyros and motor controllers are readily available, not just as individual parts, but as pre-soldered modules that can be wired together with a minimum of fuss and at low cost. This simple balancing robot is a great example of what can be done with such parts (Google Translate link).

The robot has an ESP32 running the show, which provides both the processing power required, as well as the WiFi interface used to control the ‘bot from a smartphone. This is achieved using an app from JJRobots, an open-source robotics teaching resource. Stepper motors are controlled by DRV8825 modules sourced from amazon, and an MPU6050 gyro rounds out the major components. Naturally, source code is available on GitHub for your reading pleasure.

It’s remarkable that in this day and age, it’s possible to build such a project with little to no soldering required at all. With a credit card and a healthy supply of patch leads, it’s possible to whip up complex digital projects quite quickly. We’ve seen a similar approach before, too. Video after the break.

[Thanks to Baldpower for the tip!]
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3000W Unicycle’s Only Limitation Is “Personal Courage”

Electric vehicles are fertile ground for innovation because the availability of suitable motors, controllers, and power sources makes experimentation accessible even to hobbyists. Even so, [John Dingley] has been working on such vehicles since about 2009, and his latest self-balancing electric unicycle really raises the bar by multiple notches. It sports a monstrous 3000 Watt brushless hub motor intended for an electric motorcycle, and [John] was able to add numerous touches such as voice feedback and 1950’s styling using surplus aircraft and motorcycle parts. To steer, the frame changes shape slightly with help of the handlebars to allow the driver’s center of gravity to shift towards one or the other outer rims of the wheel. In a test drive at a deserted beach, [John] tells us that the bike never went above 20% power; the device’s limitations are entirely by personal courage. Watch the video of the test, embedded below.

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