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Jan
31

Raspberry Pi robot and hobby kit robot guide part 1

by Linux User team

Discover the best robotics kits around for both Raspberry Pi and Arduino

The rise of our robot overlords is well underway – give it another five years and we’ll all be watched over by Pi-powered machines of loving grace. In the meantime, though, we’ve rounded up the very best DIY robotics kits available to buy right now that are designed to work with your Raspberry Pi, so you can get a head start on the inevitable revolution. Whether they’re Arduino or Raspberry Pi-based, we’re getting all of our robots to listen to our master Pi controller and showing you how to do the same with your kit. We’ll also be scoring these robotics kits to identify their strengths and weaknesses in terms of their build quality, functionality out of the box, the construction process and of course their programmability, to help show you which kit is right for you and where you can get hold of your own.

And what then? Well, we thought we’d put our robots to the test with a series of challenges inspired by the Cambridge Raspberry Jam’s Pi Wars event (www.piwars. org). Super senpai Rob Zwetsloot will be your compère for a weekend of a robot-building mayhem, and he has cut code capable of rendering these robots skillful enough to breeze through a line-following challenge, a proximity alert test, a tricky obstacle course and a three-point turn examination. Not content to stop there, though, Rob also reveals how he got one of our robots to play a damned fine round of golf (for an automaton) and another two to battle each other (sumo style).

So it’s time to introduce you to our hand- picked team of robots – some of whom you might recognise from previous issues of Linux User & Developer. Over the next few pages you’ll meet Rapiro, our most humanoid and delightfully articulate Gundamesque robot; GoPiGo and Pi2Go, two nippy little two-wheel tricars with ball-bearing casters for stability at the rear; Frindo, the sensor-loaded, open source mobile robotics platform; Rover 5, the rugged two-track tank with a Seeeduino brain and an inexorable top speed of 1km/s; and Hexy, the six-legged, crab-walking, Thriller-dancing force of robotic nature.

Rover 5 Seeeduino

A relative monstrosity, the Seeeduino is fully kitted out and makes a great gift

Technical specs

Manufacturer: Dawn Robotics
Height: 170 mm
Width and depth: 225x235mm
Weight: 1.05 kg
Power: 9 volts from 6 AA batteries
Control board: Seeeduino Arduino (ATmega 328P)
Form of locomotion: Two treads powered by four motors
Sensors: Ultrasonic and four corner-mounted infrared sensors

The completed Rover 5 Seeeduino is large and full of potential
The completed Rover 5 Seeeduino is large and full of potential

If you recall issue 132, where we made our first robot, you’ll remember that the kit we used to build it was from Dawn Robotics – the Rover 5 is sort of a successor to that kit. The Rover 5 is obviously a lot larger and generally has a few more functions than that particular Raspberry Pi robot. Said Raspberry Pi is not needed for the Rover 5 as it is fully powered by the Seeeduino, another ATmega 328P.

Construction is not the easiest and requires an extra hand at times. There’s no soldering involved but there are an enormous amount of wires that connect up the board. Couple this with some extremely fiddly nuts and bolts, a manual that is sometimes a bit unhelpful, the odd cheap screw and you get a few problems that take a bit of lateral thinking in order to find a solution. The whole kit is a mixture of different components manufactured separately, which explains some of the discrepancies in the screws and how cobbled together the entire thing actually is.

The big board sits on top of the Rover 5 and is quite well suited for the kit, but it does contribute to the DIY, mashed-together look of the Rover 5 with all the wires flying around.

Programming it is slightly harder than other robots due to using pure Arduino rather than having serial commands or Python functions. You’ll need to get right into the code to start programming, however there are some preset tutorial scripts that give pointers on how to create your own code. With the sensors on each corner of the Rover 5, the board and robot can react to almost any obstacle thanks to their coverage, not to mention the ultrasonic sensor also attached to it.

Score

Assembly: A little tricky in practise but still quite solid, 3/5
Build quality: Generally fine but some of the screws are a little cheap, 4/5
Programmability: For those without Arduino experience it can be a little confusing, 3/5
Functionality: Great traction, great control and aware of its surroundings, 5/5

Best for: big projects

Pi2Go Lite

One of the smallest robots in our test, yet the Pi2Go has a few tricks

Technical specs

Manufacturer: 4tronix

Height: 90 mm
Width and depth: 130 x 145 mm
Weight: 0.40 kg
Power: 9 volts from 6 AA batteries
Control board: Raspberry Pi
Form of locomotion: Two-wheel drive
Sensors: Ultrasonic sensor, two line sensors and two IR obstacle sensors

The tiny Pi2Go is incredibly featurefull
The tiny Pi2Go is incredibly featurefull

The Pi2Go Lite is a very interesting little bit of kit. Coming in a tiny little box and utilising no chassis, in favour of construction via its PCBs, you’d think it would be a super simple robot that follows commands and doesn’t really react much to the environment. It makes it sound like a remote control novelty more than anything else. That couldn’t be further than the truth, as the Pi2Go is probably the most featureful robot in this feature.

All this functionality comes at a price though, as it’s the only robot that requires a lot of soldering and pre-preparation before construction. You’ll need to be a bit handy with a soldering iron to do it, although you don’t need to strip any wires and such. There are about 50 components to fit, possibly more, and it can be a little time-consuming. The instructions are not extremely helpful, but the individual components are actually listed on the PCB as a rough guide to where things should be fitted. Once the soldering is done though, you just need to put the few parts together to complete it. The website lists a 90 minute construction time, but we found it took somewhat longer – it was no longer than any of the bigger or more complicated robots on the other pages though.

It’s a sturdy, compact little thing and it’s powered purely by the Raspberry Pi via a custom Python library. Sensing, turning on the LEDs, activating the motors and other physical functions have their own corresponding Python function. It lets you create scripts that can make it fully autonomous, as long as the autonomy only requires distance, line and proximity sensing to operate. At least it can take extra timed or web information from the Raspberry Pi if that’s set up correctly.

For the price, functionality and relative ease of programming, it’s a fantastic piece of kit that’s great for getting into starter-level robotics and slightly beyond. Some soldering skills required though.

Score

Assembly: Soldering the kit together is time-consuming and not easy, 3/5
Build quality: It’s perfectly stable, but the chassis is its circuit boards, 3/5
Programmability: A custom Python library makes it fairly easy to program, 4/5
Functionality: For its size and price it has an absurd amount of features, 5/5

Best for: makers

Hexy the Hexapod

The Kickstarter success story with six legs, 19 servos and some mad dance moves

Technical specs

Manufacturer: ArcBotics
Height: 100-140 mm
Width and depth: 300-400 x 200mm approx (depending on stance)
Weight: 0.90 kg
Power: 6 or 7.5 volts from 4 or 5 AA batteries
Control board: Arduino
Form of locomotion: Legs x6
Sensors: Ultrasonic sensor

This is how we assume the Replicators from Stargate started
This is how we assume the Replicators from Stargate started

We were really impressed by this all-in-one kit that lives up to its Kickstarter promise of being easy to assemble for people of any skill level, including absolute beginners. Everything is neatly packaged in the box and there’s even a tiny screwdriver – meaning you don’t need any other tools (though to be fair, those servo horns ended up breaking ours, but more on that later).

For the most part the instructions are excellent but there were a couple of occasions where a slight lack of clarity meant that we just followed the images instead, though they were generally spot-on and very useful. You can really see the thought that’s gone into it, from the strong and lightweight plastic material to their razor-sharp design. The wiring instructions are perfect and the software tutorials are really useful – you can get an Arduino IDE set up and also dive straight into PoMoCo, ArcBotics’ position and motor controller software that’s already preloaded with actions (including dance moves) for you to play with.

There’s only one real criticism of this kit – the screws are all wrong. There is a big bag of various size screws provided but you don’t even use a quarter of them, instead being forced to open each individually packaged servo and borrow the medium screws from them instead because the small holes on the servo horns are far too tiny for the recommended medium screws. The slightly smaller ones from the servo packs fit, so we used those, but you still have to widen those pinholes with brute force. It brings the otherwise speedy build process to a total halt, but all in all, we have to say that Hexy is absolutely worth the trouble.

Score

Assembly: Fairly straightforward, but the wide array of screws doesn’t help, 3/5
Build quality: Generally quite solid, but not consistent due to the screws, 4/5
Programmability: PoMoCo gives full control over Hexy using visual aids and sliders, 5/5
Functionality: Movement capabilities are incredible enough, but it does more, 5/5

Best for: mobility

Part two is now available.

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