It's been 7 years since the LEGO Mindstorms 31313 EV3 set was released, which was a huge hit. It's use in schools and competitions is very wide-spread. Now, LEGO have retired the EV3 set so you can no longer buy it from them. Can the new Robot Inventor replacement live up to it's predecessor's success?
The new Mindstorms set 51515 Robot Inventor has unfortunately moved away from catchy 3-character names (RCX, NXT, EV3). Although maybe we can come up with something better - RI5? This annoyed me considerably while writing this review, so I decided to just call it 51515 :)
7 years is a long gap between sets, much longer than previous iterations. Although back in 2017 we saw the release of the 17101 Boost Creative Toolbox set which contained a new programmable hub using the new Powered Up system that was aimed at younger kids. It was cute, and a decent try at getting younger kids interested in programmable robotics but it completely failed on my kids (then 8 and 9 years old), and wasn't customisable enough to get it into mainstream teaching/competitions.
We also saw the 45678 SPIKE Prime set (who comes up with these set numbers?) released earlier this year which is the education version of 51515. Historically, you can't buy these education sets unless you are representing a school, but due to Covid it has been made available to the general public for home schooling purposes.
Box & Contents
The box measures 48 x 37 x 7cm (and I forgot to weight it before building).
There are no building instructions included in the set unfortunately. More on that later.
Other than the new Mindstorms parts, there are a lot of new parts in Dark Turquoise which is nice. There are also a nice assortment of technic frames to make building robots easy, and the new large 11x19 base frame only previously seen in the Spike set.
When I bought the 51515 the gift-with-purchase set was coincidentally(?) the 40413 Mini Robots which is a small-scale reproduction of the 5 robots you can build in 51515. And they can all be built at once too.
New Mindstorms Parts
Since the EV3, we have seen Power Functions replaced by Powered Up so it's no surprise to find them in use here. The hub has 6 i/o ports, 3 on either side.
It's not really apparent in my photos, but the top of the hub has a 5x5 pixel display. Each pixel can vary in brightness but they are all orange. The primary button and smaller bluetooth buttons can be lit up in different colors. The video at the end of this review shows off the capabilities of the display a bit better.
Thankfully it comes with a 2100mAh Li-Ion rechargeable battery, unlike the EV3 which used AAs. Although it's charged via a micro-USB cable... would a USB-C port have been that hard??? I'm not sure how long a charge lasts yet, but I didn't have to recharge it once for this review after the initial charge.
It comes with 4 identical medium motors, one light/color sensor, and one distance sensor which I assume uses ultra-sonics. Unlike the EV3, the cables are all integrated into the devices. I'm not sure if that's a good thing or a bad thing yet.
The 51515 hub is much smaller than it's predecessors. As are the motors, although I'm not sure of their relative torque/power capabilities.
The Mindstorms App
Since there are no building instructions included in the set, there is a small booklet with a URL for the digital building instructions. Which is kind of confusing because the URL actually leads to the Mindstorms app download page. It is supported by a variety of OSs: iOS, macOS, Android, Windows and even Fire OS. Ummm... where's Linux? I work on a Linux desktop (I know, old school) and have an Android phone. Sigh... I guess I have to use my phone for this.
When starting the app, it displays the five robots you can build. For the EV3 there were a number of smaller robots building up to the obvious main one at the end. Here, it seems like they are more or less all equal. So I picked Charlie to start with.
Building Charlie is broken down into 4 steps, with tests after each step to make sure things are working and slowly introduce you to what the tools offer.
The building instructions are within the app and are tiny on my phone. I was constantly zooming and scrolling around on each build step just to see what was happening. There are also links in the app to PDF versions of the instructions too which is nice, but not much better when viewing on a phone.
The program looks very much like what we've seen before in apps like Scratch. The control blocks are color coded, and have dropdown selections for choosing things like colors, i/o port numbers, specifying constants, or choosing saved animations/sounds etc. This thing really needs at least a tablet to be used properly (ideally my dual screen desktop, grrrr).
Also a big annoyance for me was that the standard Android back button did nothing in the app. I was constantly trying to change screens with it to no avail.
Another annoying property of using a phone app is that it never remembers where you are up to. If I turn my phone off or start using other apps, it will quickly forget and send you back to the starting screen when you open it up again.
Charlie
Step 1 is simply Charlie's head. It includes a program with a sound and display animation.
The first time you connect to the hub (via bluetooth), I had to update it's firmware. This was a 10-15 min process which I of course started right before having to go out. Stopping firmware updates in progress is never a good idea, so I was late :)
I never got my phone and hub to reconnect automatically though. Every time I turned on the hub I had to manually connect to it from the app again. Not sure if that's just my phone or how the hub works.
The built-in program is downloaded to the hub and run locally. There is also an option to stream the programs as well to save storage space I guess. It might also provide some kind of debugging capabilities but I couldn't see anything like breakpoints etc. At this point you are prompted to try different sounds and animations and basically explore how the programming works. My daughter spent about 20 mins trying all the different options before getting bored of it.
Step 2 adds the wheel base - two motorised wheels to turn/move and front and back trolley wheels to stop it falling over.
The relatively new 49283 Wire Clip parts come in very handy here.
Step 3 adds some arms. Nothing terribly exciting here.
Step 4 finishes the body work.
He's a simple build but still has plenty of character. The main Charlie program expands on the smaller demo programs shown throughout the build. Here it is in action:
Here is a video of the startup which is pretty fast, and shutdown. I turned off the photography lights to make the 5x5 matrix easier to see.
Further Activities
After the main build, there are a bunch of other activities included (10 for Charlie). These include additional accessories and programs to go with them, some of which are shown below.
Activity - My Favourite Color
This is a simple addition of the color sensor. Waving the different colors in front of the sensor triggers different reactions from Charlie. The program shows some new things like broadcasting values to other blocks of code, the same way as is done in Scratch.
It's not apparent from the below photo, but the color sensor shines a bright white light from the ring around the sensor. It must pulse the light as when viewed through the camera you can see the flickering and the photo actually misses the pulse.
Activity - Drum Solo
This is actually two activities but is definitely one of the more interesting looking ones, even if not very complicated programming wise.
Here's a video of the program in action, it makes for a pretty fun demonstration of what can be done:
Programming
The actual programming is pretty easy to understand. You drag the various blocks around and they automatically connect with each other. Although doing that on a phone is hard and I am constantly breaking links accidentally just while trying to scroll around. I imagine a tablet would have the same problem but at least has more open areas to use for scrolling. A mouse and desktop is much preferred (Linux support please LEGO!).
There are many blocks provided separated into different categories eg Movement, Light, Sound, etc. And of course you can create your own custom blocks for reuse.
There are 20 program slots available (because 19 is the largest number the 5x5 matrix can display). You can move them around and delete them from the app. It shows how much storage each program uses but I couldn't find anywhere that indicated what the total available storage is or a % used.
The app can show you the current value of all sensors connected to it, as well as the built-in sensors in the hub in one easy to use screen (last image shown above). The hub has many built-in sensors that the EV3 never had, but are now pretty common place in any phone: Title angle (yaw, pitch, roll), Orientation (6 different values), Gyro (x, y, z), and Acceleration (x, y, z).
Motors
The motors provide input values for position (degrees), speed (0-100), power (%) and degrees counted. You can control all these values and there are blocks that simplify things for you. You can indicate which motors are controlling movement and then use blocks like "move forward 10cm" and "turn shortest path to position X" which figure out the correct ports/settings to use for you.
Lights
You can control the 5x5 display one pixel at a time, and each pixel has a brightness of 0-100% although I tested it with a simple loop and the actual brightness seemed to increment in 8 steps from what I could see rather than a linear gradient.
The 5x5 display is a big change from the EV3's LCD screen, and typical programmers who use displays to output debug information might be disappointed with this change. However, you can still display text on it in a scrolling fashion though via the "Write" block. Not as good obviously, but a nice trick.
You can also save patterns and animations which cycle through patterns. The animation editor is pretty easy to use, and my kids had fun playing with it.
Sounds
You can record your own sound clips directly in the app, and even edit them afterwards. However, all the sounds I tried played through my phone and not the hub. I'm not sure if there's something I'm doing wrong or the hub speaker is really limited to the ones provided which sound low quality.
There is also a volume setting from 0 to 100% you can control.
Sensors
The light sensor can detect from 8 different preset colors, or the % of reflected light. The hub shows levels for each RGB values but there doesn't seem to be a way to read them programmatically via the Scratch interface.
The ultra-sonic distance sensor works from 4cm to 200cm, which should be much more reliable than the EV3's infra-red method. There is also a ring of white light around each sensor and you can turn on the top and bottom halves of each separately to make cool eye effects.
The hub's built in sensors can be accessed individually, or use the provided blocks to detect things like "shaken", "tapped", or "falling".
Compatibility
Just for fun I tested the Boost color sensor and motor. The color sensor showd up on the hub status display as "0UNIT" and the motor did not show up at all.
I tried reading the color sensor with a test for red but it didn't trigger. I then tried turning the motor and it worked! However, it doesn't seem to be able to read it's position at all.
TobyMac tested Control+ and Train motors with the same result. So, the 51515 devices are obviously instrumented just for this hub, which makes sense but is a bit disappointing.
I would guess the Spike sensors/motors would work with the 51515. The Spike set has an extra touch sensor we don't get here, although given the hub has an accelerometer you could still do bump detection if the hub is moving.
Python Support
When creating a new project you have the option to use the "Word Blocks" shown above or using Python which is labelled BETA.
This is awesome and totally changes how this set might be perceived. The Scratch-like environment is great for younger coders without much experience, but is not really suitable for more complicated programs. Python is perfect (and my favourite language of all time!).
An empty program is created for you with some default imports, and a simple demo to make a beep sound. There is a help guide provided to give advice on how to use the provided Python libraries too. It all seems pretty comprehensive and I'm keen to give it a try later on, but the thought of coding on my phone gives me a headache.
I couldn't find the Python libraries on Github or anywhere else unfortunately. I'd much rather be able to code in my own environment (PyCharm ftw!), and download to the robot from there. Hopefully they can release that to the public eventually. But a desktop based Mindstorms app would do just as well I guess (Linux support please!!!).
Next Steps
There are many other activities to try out with Charlie which I will probably build next. Looking through the other robots and their various activities, the kids found an obvious next one to build - the Blast robot has one called "Guard my Room" and is armed with dual canons :)
I might write a shorter review of that one when the time comes.
Conclusion
Well, I'm certainly impressed with what LEGO have released here. Compared to the EV3, the 51515 (RI5?) is definitely easier to use and get working on straight away.
The provided robots are fun and demonstrate many ways to use the motors and sensors. They also made interesting characters that are fun to interact with, and keep kids' interest.
The Python support provided within the app also makes this a very customisable robotics platform. I wasn't sure how well this set would be viewed by the various robotics programs eg FLL, but given the ease and flexibility of the Scratch-like programming and support for Python I think this will take off big time with both younger and older coders. Compared to the previous EV3 software, this is a breeze to use.
My only real criticism is the lack of Linux support for the Mindstorms app. Considering it's aimed at programmers, I think this is strange.
It is an expensive set at AU$550, USD$360, €350, but in line with the previous Mindstorms sets. For fans of the series, this is a clear must buy in my opinion. I bought it the first day it was released and it looks to be out of stock in several countries already.
The recent poll we had about this set indicated that of those who were interested in the theme, many of you were unsure. I hope this review has helped answer some of the uncertainty you may have had, if not please ask in the comments below this post and I will try to answer questions if I can.
