Little Quadruped Uses Many Servos

July 26, 2021 by Lewin Day 12 Comments

Walking robots were once the purview of major corporations spending huge dollars on research programs. Now, they’re something you can experiment with at home. [Technovation] has been doing just that with his micro quadruped build.

The build runs twelve servos – three per leg – to enable for a great range of movement for each limb. The servos are all controlled by an Arduino Uno fitted with an Arduino Sensor Shield. Everything is fitted together with a 3D printed chassis and limb segments that bolt directly on to the servo output shafts. This is a common way of building quick, easy, lightweight assemblies with servos, and it works great here. Inverse kinematics is used to calculate the required motions of each joint, and the robot can take steps from 1 to 4cm long in a variety of gaits.

We’d love to see a few sensors and a battery pack added on to allow the ‘bot to explore further in an untethered fashion. [Technovation] has left some provision to mount extra hardware, so we look forward to seeing what comes next.

We’ve seen bigger quadrupeds do great things, too. Video after the break.

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Why Make Coffee When You’re Tired? Let A Robot Do It For You

July 25, 2021 by Kristina Panos 9 Comments

Like us, [Alberto] doesn’t compromise when it comes to a good cup of coffee. We figure that if he went to an office in the Before Times, he was the type of coworker to bring in their own coffee equipment so as not to suffer the office brew. Or perhaps he volunteered to order the office supplies and therefore got to decide for everyone else. Yep, that’s definitely one way to do it.

But like many of us, he is now operating out of a home office. Even so, he’s got better things to do than stand around pouring the perfect cup of coffee every morning. See, that’s where we differ, [Alberto]. But we do love Cafeino, your automated pour-over machine. It’s so sleek and lovely, and we’re sure it does a much better job than we do by hand — although we enjoy doing the pouring ourselves.

Cafeino is designed to mimic the movements of a trained barista’s hand, because evidently you’re supposed to pour the water in slow, deliberate swirls to evenly cover the grounds. (Our kettle has a chunky spout, so we just sort of wing it.) Cafeino does this by pumping water from an electric kettle and pouring a thin stream of it in circles with the help of two servos.

The three buttons each represent a different recipe setting, which specifies the amount of water, the hand pouring pattern, and the resting times between blooming the grounds and actually pouring the bulk of the water. These recipes are set using the accompanying web app via an ESP32, although the main brain barista is an Arduino Nano. Grab a cup and check out the demo after the break.

Got an old but modern coffee robot lying around? You could turn it into a planter with automated watering.

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Monowheel Balancing Robot Can’t Turn (Yet)

July 24, 2021 by Danie Conradie 21 Comments

Self-balancing robots have become a common hobby project, and they usually require two wheels to work. [James Bruton] has managed to single wheel balancing robot by adding gyroscopic stabilization.

[James] has done other self-balancing robots, like his Sonic robot, but recently started experimenting with gyroscopic stabilization. In that project, he proposed the idea of combining the two stabilization methods to create a monowheel robot, and he followed through on that idea. The wheel is powered by a brushless motor and is stabilized conventionally around the wheel’s axis. Side to side balancing is achieved using a phenomenon known as gyroscopic precession, by tilting a pair of heavy spinning wheels. This is not to be confused with reaction wheels, which use rotational inertia for control. It appears the actuating the gyroscopes also affects the front-to-back stabilization, so at the moment the robots won’t stay on one spot. [James] plans to implement a second observation controller in software to solve this.

Another challenge with this robot is that it cannot turn at the moment. The gyroscopes are not in the correct orientation to effect rotation around the vertical axis, and changing their orientation would cause other problems. A fan, which works like a helicopter’s tail rotor is one option, and a reaction wheel on top might also work. We’re partial to the reaction wheel idea. Having a different mechanical control mechanism for each axis would make it quite an interesting robot.

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Tardygrade Walker Is A Lesson In 3D Printed Design

July 23, 2021 by Danie Conradie 12 Comments

The ability to quickly create complex parts with 3D printers has created a platform to show off mechanical design skills. This is true in the case of [Dejan Ristic]’s capable little Tardygrade walking robot, which uses only two servos and a bunch of clever 3D printed parts.

The robot’s chassis is split into two subassemblies, each with a pair of feet on diagonal corners. As one pair of feet lifts the robot, the other section of the robot can rotate before coming back down, allowing the robot to turn. One servo handles the actuation of the feet, while the other rotates the body as required. An ESP32 based controller creates a web server user interface, and power comes from a lipo cell.

The interesting part of this robot is in how [Dejan] designed it for printing and assembly. All the parts can print without support, and in the correct orientation to optimize strength. There are only six screws in the assembly holding the servo and servo horns, while everything else uses snap fits or short pieces of filament. Take a look at the videos after the break to gain some appreciation of the design effort and attention to detail that went into this robot. Even the contact surfaces of the feet were carefully designed for optimum walking over flat surfaces and small obstacles.

This reminds us of [gzumwalt]’s little 3D printed creations, like the fridge crawler and mechanical edge-avoiding robot.

Rover Uses Different Kind Of Tracks

July 22, 2021 by Danie Conradie 7 Comments

Tracked robots usually require at least two wheels inside to work properly. However, [James Bruton] discovered a curious tractor design from the 1940s, the Fordson Rotaped, which only uses a single sprocket wheel inside each track. Being [James], he built a self-balancing robot around the rotaped concept.

Instead of a lot of short track sections, the Rotaped uses six long sections of track, about the same length as the wheel’s diameter. To keep the track on the wheel, a series of chains or an oval frame is used on the inside of the track.

As is usual for [James]’ projects, most of the mechanical parts are 3D printed. To hold the tracks in place, he stretches a bungee cord loop around three points on each side of the track. To make things more interesting, he made the robot balanced on the tracks. This took a bit of PID tuning to get working without oscillations, since the wheels experience a slight cogging effect inside the tracks. The wheels are driven by a pair of brushless motors with O-Drive controllers. The balancing is handled by an Arduino Mega, which reads processed position values from an Arduino Pro Mini connected to an MPU6050 IMU.

This might be a viable alternative to conventional tracks for certain applications, and the reduced part count is certainly an advantage. Let us know in the comments if it spawns any ideas. [James] has previously built another tracked rover, which uses flexible 3D printed track sections. By far, the biggest 3D printed tracked vehicle we’ve seen was [Ivan Miranda]’s ridable tank.

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ZeroBug: From Simulation To Smooth Walking

July 21, 2021 by Danie Conradie 9 Comments

Thanks to 3D printing and cheap hobby servos, building you’re own small walking robot is not particularly difficult, but getting them to walk smoothly can be an entirely different story. Knowing this from experience, [Max.K] tackled the software side first by creating a virtual simulation of his ZeroBug hexapod, before building it.

Learning from his previous experience building a quadruped, ZeroBug started life in Processing as a simple stick figure, which gradually increased in complexity as [Max.K] figured out how to make it walk properly. He first developed the required movement sequence for the tip of each leg, and then added joints and calculated the actuator movements using reverse kinematics. Using the results of the simulations, he designed the mechanics and pulled it back into the simulation for final validation.

Each leg uses three micro servos which are controlled by an STM32F103 on a custom PCB, which handles all the motion calculations. It receives commands over UART from a python script running on a Raspberry Pi Zero. This allows for user control over a web interface using WiFi, or from a gamepad using a Bluetooth connection. [Max.K] also added a pincer to the front to allow it to interact with its environment. Video after the break.

The final product moves a lot smoother than most other servo-driven hexapods we’ve seen, and the entire project is well documented. The electronics and software are available on GitHub and the mechanics on Thingiverse.

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Giving Control Of A Smartphone Robot To A Raspberry Pi

July 21, 2021 by Danie Conradie 3 Comments

Most gadgets that interface with smartphones have a rather short lifespan and inevitably end up as E-waste. Unless hackers give them a second life, as is the case with the Romo, a little smartphone-controlled robot. [David Goeken] has successfully reverse-engineered the communication protocol to allow the Romo to controlled Raspberry Pi (or microcontroller)

The Romo was a little iPhone-controlled robot brought to market with a Kickstarter campaign back in 2013. It originally used the audio jack from the iPhone for the control interface, but was quickly followed by an updated version that used iPhone 4’s 30 pin connector and later the Lightning port. Romotive, the company behind Romo, eventually went out of business, but fortunately, they open-sourced the IOS app and the firmware. This has led to a few third-party apps currently on the app store.

[David] wanted to use other hardware for control, so he set about reverse-engineering the protocol using the open-source software and a logic analyzer. Unsurprisingly, it uses a serial interface to send and receive commands, with two additional pins to detect the connection and wake up the Romo. After breaking out the interface header on the board, he was able to modify the Romo to mount a Raspberry Pi Zero, and power it using the internal battery.

[David] has not made his code public yet, but it sounds like he plans to. It looks like Romo’s can be a fun little experimentation platform, and they can be found for cheap on eBay. We covered another cool Romo hack back in 2014, which used a projector and vision system to create a Mariokart-like game. For a completely open-source smartphone robot, check out the OpenBot.