Pololu Zumo Arduino Compatible Robot Kit Review

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Here at BreakoutBros we are doing a series on Robot Kit Reviews. Last week we looked at the Elegoo Smart Car Robot Kit and today we are looking at the Pololu Zumo 32U4. Zumo is an Arduino compatible, palm sized, tread driven robot platform that’s equipped with tons of sensors and surprisingly fast. It has 5 downward pointing IR sensors for line following, 5 IR range finders, a 3 axis accelerometer, compass, gyroscope, motor encoders, 3 selection buttons, a buzzer, and an LCD screen.

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Zumo comes in several different forms based around the general concept of a 10 cm by 10 cm mini sumo bot with treads.  All versions have a 4 AA battery compartment. You can buy Zumo in three controller configurations including just the chassis with no controller or motors. The next step up is the Zumo for Arduino that makes the whole robot an upside down Arduino Shield. Or you can buy the Zumo 32U4 that includes the controller and the most I/O. These last 2 versions come either assembled or as kits that you build. The assembled Zumo for Arduino only comes with 75:1 motors and the Zumo 32U4 comes with your choice of 50:1, 75:1, or 100:1 motors.

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Quarter for scale, Pololu does not include one.

I built the 32U4 Arduino compatible kit with 75:1 motors. This is not a kit I would recommend for beginners or the faint of heart. There are some tiny parts and putting the thing together took the better part of an afternoon. Don’t get me wrong, everything is solid and fits together like a glove but unless you have some experience with solder and the proper equipment, it would be best to buy it assembled. By the right equipment I mean at the minimum you need an adjustable temperature iron with a fine tip and some very thin diameter solder. Something like this Weller and this .6mm solder would be perfect. The good news is everything is through hole so while you avoid surface mount issues, you still need to solder several two row headers which can be tricky. Adjustable temperature helps when going from the headers and tiny motor leads to the battery connection pads that need rather large globs.

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Don’t be like me, use good quality soldering tools.

Full disclosure: I did all the soldering with a 25W fixed temperature Weller with a medium tip and some solder I had on hand that was far too thick and I managed to not mess anything up. But I have been soldering with cheap equipment for over a decade, so don’t expect the same results if this is your first soldering project. If you have the ability to solder this kit correctly, you will most likely have access to the right equipment.  If you are on the fence I’d suggest a practice soldering kit like this or this. I do need to give credit to Pololu on their resources though. Zumo’s assembly instructions are top notch. They are well written and the pictures are great. I also reached out to Pololu’s product support and received helpful answers to my questions quickly.  The other great thing is Pololu has a forum on their website where users can ask questions and employees answer them for the whole community.

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Once Zumo was put together I was rather impressed with the heft. The kit is mostly a battery compartment and PCB but with 4 AA’s and the wheels and motors installed it feels solid. More like a little rolling brick than a robot. Everything fits together really tightly and you can tell Pololu really took tolerances seriously. It reminds me more of industrial equipment than a toy and with the metal gears and plow I’m not afraid of it bumping or crashing into walls or other robots.

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Zumo ships with a demo program that lets you go through and test each sensor and output to confirm everything works. This was a huge relief after spending all that time putting it together. This also gives you a neat look at how the screen and buttons can be used to set operating modes and display graphically what the robot’s sensors “see.” To get my own program on Zumo I had to go back to Pololu’s website and download the drivers for the 32U4 controller. Once complete I was able to open up the Arduino IDE and  load Blink to Zumo. Next I wanted to see some more advanced examples so I installed the Zumo 32U4 Library from the Arduino IDE. You do this by going to Sketch>Include Library> Manage Libraries, search for Zumo, and dowloaded the library by Pololu.20161119_202132

I was able to quickly install this:



This line follower is great for a few reasons. This floor is awful for line following. It has a pattern and divots. The line is electrical tape so the curves aren’t smooth and it just ends. Most line followers would either be slow and jagged following this line or fast and lose it on the ends. Zumo does neither. It stays pretty fast and smooth and when it does reaches the end, it doesn’t overshoot and can make it back to the line.

Really the only thing I can fault this kit with is the limits to hardware expandability. Pololu has chocked this thing so full of I/O devices that you actually have to start removing things if you want to add anything else. The crazy thing is they have a guide for just that. It tells you exactly what pins you gain from removing different parts of the robot. However if you know this is a route you are interested in from the beginning, I would just go with the Arduino version of Zumo as it has less sensors, no screen, and you can more easily mount things to the flat surface that is the top of your Uno board. The other thing that is mildly bothersome is the way to switch between the optional line followers and range finders. Zumo actually had more I/O than the Atmel A-Star 32U4 can handle. To deal with this Pololu has included jumpers to enable either the range finders or the outer line followers on the downward facing board. To move these Jumpers the downward facing board must be removed from the header. This is a clever way to solve this problem but I’d prefer if the jumpers were available without having to remove the board. 20161119_202253

This would be a great kit to build a high school or university robotics class around. With a set of these you can be confident that all of them are going to be identical and solid (just don’t let your students build them.) You could teach segments about robot navigation like line or wall following, gradient measuring, ramp climbing, and dead reckoning with motor encoders.  You could even use the multiple output modes like the screen, buzzer, and LED’s to provide feedback so student’s understand what and how robots can “see.” You could work in lessons on obstacle avoidance or tracking and hold competitions like maze following, ball collecting, and Sumo. I am confident the Zumo would not only hold up but give a ton of coding customization on standardized hardware due to it’s many sensors. For any hobbyist trying to learn robotics that doesn’t have an exact project in mind I would definitely recommend the Zumo for it’s sturdy base, compact size, and many sensors. You can buy the Zumo for Arduino on Amazon and the Zumo 32U4 directly from Pololu. I hope you enjoyed looking at the Zumo with me and please consider Subscribing to see the rest of the robot reviews.

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