The latest version of Lego’s popular robotics kit, Mindstorms EV3, was released in late September and I have finally had time to play with it! Our grade 8 students already make use of Lego’s previous generation of robots, the Mindstorms NXT 2.0, in their Mars explorer project, and our grade 11 ITGS students use them as part of the Higher Level Artificial Intelligence, Robotics, and Expert Systems topic. This year I want to expand the use of these kits with IB students so we were interested to see what the new EV3 package offers.
NXT versus EV3
At first glance a lot of the EV3 kit appears to be very similar to the NXT 2.0 kit: the bricks are of course all standard Lego Technic parts, the sensors (EV3 includes touch, colour, and infrared sensors) look familiar and use the same interface cables as the NXT robots, and even the box art and the standard robotic model (the only one for which paper instructions are included) are essentially the same as those in the NXT kit.
Of course, this similarity to NXT 2.0 is not necessarily a bad thing, especially if you have a mix of kits in your classroom (the older NXT 2.0 kits have been very hard to find since the announcement of EV3). Indeed, all NXT 2.0 sensors are compatible with the new EV3 brick (but the opposite is not true) and the servo motors are 100% interchangeable between kit versions. This is clearly a benefit for those of us who have invested in the NXT robots.
Some changes from NXT 2.0:
- The colour sensor has better background light protection (this was sometimes a big problem with the NXT colour sensor)
- Sensors now respond faster (every 1/1000 sec rather than 1/333 sec)
- An InfraRed sensor replaces the ultrasonic sensor (and can be used for essentially the same tasks)
- An InfraRed beacon is included
- WiFi and BlueTooth support
- Where NXT 2.0 featured three large motors, the EV3 kit features only two, plus a third smaller motor
- No software CD is included: the NXT-G programming software must be downloaded. The Mac and Windows versions are about 600MB each.
- There is no paper “test pad” as there was in NXT 2.0. This is not much of a loss in the classroom as these pads quickly became dog-eared and damaged
- The NXT-G software (now just called Lego Mindstorms Software ) has some useful new features
- Mobile phone apps for Android and iOS allow remote control of EV3 robots
Lego have advertised the WiFi features of the EV3 Lego brick, but are a bit quieter about the fact that this needs a WiFi dongle, which must be purchased separately. Once this is acquired, EV3 bricks can be programmed without the need of a USB cable to attach them to a computer. However, this WiFi connectivity is not used to control the robots using the smartphone apps (see below), or to enable multiple robots to communicate with each other. To achieve the latter, with up to four EV3 bricks daisy-chained together, you must use USB cables (not supplied).
The graphical Mindstorms programming software has a variety of interesting new features, and can be used to create programs for NXT and EV3 robots (though programs for the former will lack some of the new EV3 features).Note that although the Robot Commander app allows control of robots from an Android or iOS smartphone, it does not allow them to be programmed using your phone.
Personally I am a fan of the third party Bricx Command Center (BricxCC) and the NXC (Not eXactly C) programming language, which my students and I find more powerful than the NXT-G interface. The BricxCC software has been updated to support EV3, but the install process is now somewhat more complicated and although I have successfully compiled code I have not yet managed to get it working on the robot. This is rather frustrating because I really do not like graphical programming environments, but the situation should improve soon. The LeJOS tools used to write Mindstorms code in Java are in a similar state of flux.
The EV3 kit is clearly an improvement over the NXT kit with better, digital sensors, a more powerful brick, and improved programming software – although the changes are really evolutionary rather than revolutionary. However, the NXT versus EV3 debate is a short one simply because the NXT kits are no longer generally available. At the price – around $349.99 in the US and about £249 in the UK- the Mindstorms kit is not cheap by any standard, and a teacher is likely to need several sets to make effective use with a class of students. However, they remain an extremely accessible entry point into robotics and programming for students of all ages, with no technical fuss or configuration required. Younger students will find the graphical programming environment user-friendly, while older students can push the limits of the hardware with additional sensors, third party programming languages, and data logging tools available in the educational version.
Versions: Retail and Education
Lego Mindstorms EV3 Retail version (Set 31313) is the version reviewed here. It features over 550 Lego pieces, 3 motors (2 large, 1 medium), a touch sensor, InfraRed sensor, and colour sensor. The programming software is available for download but does not include the data logging functionality found in the education version. Extras such as gyro sensors and rechargeable batteries are available separately.
Lego Mindstorms Education EV3 Core Set (Set 45554) has some useful additions for the classroom, including an extra touch sensor, a gyro sensor, a ‘brick organiser’ tray, and a rechargeable battery (the standard brick requires 6 AA batteries). The software in the educational version also has data logging functionality, which could be useful in several subject areas. The education version does have fewer bricks than the retail edition though.