Hackaday Prize 2022: MasterPi Is A Capable Robot With Fancy Wheels

July 1, 2022 by Lewin Day 2 Comments

When it comes to building a mobile robot, often maneuverability is more important than outright speed. The MasterPi robot demonstrates this well, using fancy wheels to help it slide and skate in any direction needed.

Four DC gear-motors are fitted to a metal chassis, each one driving a mecanum wheel. These are special wheels with rollers fitted around their circumference at an angle that allows the robot to move in all directions and rotate in various ways depending on how each wheel is driven.

On top of this highly maneuverable chassis is placed a 5-degree-of-freedom robotic arm. The robot also gets a ultrasonic sensor for avoiding objects, as well as a camera for line-following duties. The camera also allows the robot to pick up blocks and identify their color, and it can then sort them into boxes. It’s all powered by a Raspberry Pi, running a bunch of Python code to make everything happen.

It’s a neat project that shows off just how capable a robot can be with some smart design choices and modern computing hardware on board. We’ve seen some other smart block sorters before, too. Continue reading “Hackaday Prize 2022: MasterPi Is A Capable Robot With Fancy Wheels” →

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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Lego Car Demonstrates Proper Use Of Ball Wheels

March 23, 2022 by Lewin Day 22 Comments

Wheels are typically just simple cylinders, though fans of I, Robot (2004) may have admired the handsome vehicle featuring ball wheels that was driven by the protagonist. YouTuber [Brick Technology] decided to evaluate the use of spherical wheels with a Lego car design.

The benefit of ball wheels is that they can turn in multiple directions when driven on different axes, with the benefit of improved maneuverability. With a set of drive rollers spring loaded with rubber bands pushing against the 52mm Duplo spheres, the ball wheels can be rotated both forward and back as well as left and right. This gives the Lego car a rather neat strafing ability, as well as the ability to spin on the spot or steer in a more traditional fashion. The car is controlled via smartphone, thanks to BuWizz modules that allow remote control of the Lego motors.

Ball wheels are unlikely to catch on in mainstream automobiles; the mechanical complexity required to drive them makes such designs impractical for cars. However, omniwheels and similar designs have found some applications on forklifts and other such slow-speed applications where the ability to move in any direction is very useful. Video after the break.

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Really Robotic Robot Costume Will Probably Win The Contest

October 28, 2021 by Kristina Panos 8 Comments

Still don’t have anything to wear to that Halloween party this weekend? Or worse, your kid hasn’t decided on a costume that you both can agree on? Well, look no further than [Natasha Dzurny]’s Sally Servo the Really Robotic Robot Costume and accompanying multi-part build guide. You might want to start by raiding that recycle bin for cardboard, because you’re going to need a lot of it.

What you won’t need a lot of is hard-to-source parts, at least if you build it the [Natasha] and Brown Dog Gadgets way. Even so, there are a ton of cool moving and blinking bits and bobs to be made with servos, LEDs, and RGB LEDs connected up to something kid-friendly like the Micro:bit and the Brown Dog Gadgets Bit Board — that’s a base for the :bit that lets users connect components via LEGO and conductive tape.

Between Sally’s robotic googly eyes and her light-up belt, there are plenty of ideas here to steal and make your own, and each one is packaged in a great-looking guide complete with paper printing templates.

Our favorite part has to be the infinity mirror heart, which appears to be beating thanks to clever programming. That, and the costume details, like the waist-area wires running between the upper and lower pieces.

Is the party at your house? There’s probably still enough time to put together a projector-based stomping game for the driveway.

New Part Day: Raspberry Pi LEGO HAT

October 21, 2021 by Dave Rowntree 18 Comments

The Raspberry Pi Foundation have been busy little bees for the last couple of years producing their own silicon, new boards and now in collaboration with the LEGO Education team a new HAT to connect to the LEGO SPIKE education platform. This new HAT board will work with every Raspberry Pi board with a 40-pin GPIO header.

Based on the RPI2040 microcontroller, it makes an interesting detour away from dumb slave boards, although it looks like the firmware is closed (for now) so you’ll have to make do with the pre-baked capabilities and talk to it with the supplied python library.

According to the documentation, the communication between the Pi and the RPI2040 nestled beneath the HAT PCB is plaintext-over-serial, freeing up the majority of the GPIO pins for other uses. The board uses a surface mount pass-through type header which allows pins from the Pi to protrude through the PCB, allowing stacking more HATs on top. Curiously they decided to mount the PCB with active parts facing down, giving a flat rear surface to park things on. We suspect that decision was made to improve access to the LPF2 connectors, especially if they were surface mount parts.

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Wild Lego-Bot Pronks About Your Patio

October 2, 2021 by Sonya Vasquez 10 Comments

Legged robots span all sorts of shapes and sizes. From the paradigm-setting quadrupeds built from a pit-crew of grad students to the Kickstarter canines that are sure to entertain your junior hackers, the entry point is far and wide. Not one to simply watch from the sidelines, though, [Oracid] wanted to get in on the quadruped-building fun and take us all with him. The result is 5BQE2, a spry budget quadruped that can pronk around the patio at a proper 1 meter-per-second clip.

Without a tether, weight becomes a premium for getting such a creature to move around at a respectable rate. Part of what makes that possible is [Oracid’s] lightweight legs. Designing the legs around a five-bar linkage tucks the otherwise-heavy actuators out of the leg and into the body, resulting in a limb that’s capable of faster movement. What’s more, 5BQE2 is made from the LEGO plastic building bricks of our heydays. And with a full bill-of-materials, we’re just about ready to head over to our parents’ garage and dust off those parts for a second life.

For some action shots of 5BQE2, have a look at the video after the break. And since no set would be complete without the building instructions, stay tuned through the full video to walk through the assembly process step-by-step.

Here at Hackaday, we’re certainly no stranger to walking automatons, but not all robots use their legs for walking. For a trip down memory lane, have a look at [Carl Bugeja’s] buzzing Vibro-bots and UC Berkeley’s leaping Salto.

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LEGO Pole Climbers Are Great Study In What It Takes To Go Vertically Upwards

July 23, 2021 by Lewin Day 3 Comments

Climbing a pole with a robot might sound complicated and hard, but it doesn’t have to be. This video from [Brick Experiment Channel] demonstrates multiple methods of doing the job while keeping things simple from a mechanical perspective. (Video, embedded below.)

The first method uses a gravity locking design, where the weight of the battery pack is placed on a lever arm to increase the normal force on the wheels gripping the pole. Increasing the length of the lever arm, reducing the angle of the crawler, or adding grippier tyres can all be used to increase the grip with this design. The final design of this type is able to climb most of the way up an 8 meter flagpole without too much trouble.

The next version uses rubber bands to help add tension to grip the pole. This too works well and makes it to the top of the flagpole. The final build is a circulating design that looks truly wild in action, and winds its way to the top of the flagpole as well.

It’s great to see the experimental method of designing these Lego creations, as well as seeing how they do in the wild. [Brick Experiment Channel] has been featured here before, too.

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