A project to learn Java and create software for Mindstorms Robots using hardware supported by EV3Dev & the LeJOS way.
1. Introduction
Lego Mindstorms ecosystem is
a fantastic educational way to learn Java, Linux and Robotics to develop your creativity using your favourite Bricks.
In the the third generation of the product Lego Mindstorms EV3,
others companies like Dexter Industries
& Mindsensors has released boards combining the power of
Raspberry Pi 3 with the usage of Sensors & Actuators from Lego Mindstorms ecosystem.
The result is very healthy for the Community but… some questions appear in the air:
-
How to manage the hardware in an easy way?
-
How to continue using Java with all boards?
-
What happen with amazing LeJOS libraries about
local-navigationin this context?
The answer is this project, EV3Dev-lang-java.
2. Project architecture
The project has been designed with the following solution in mind:
| Layer | Option 1 | Option 2 |
|---|---|---|
ev3dev-lang-java |
0.7.0 |
2.4.16 |
Platforms |
BrickPi BrickPi3 PiStorms |
EV3 |
OS |
Debian Jessie |
Debian Jessie/Stretch |
JVM |
OpenJDK 11 |
OpenJDK JRI 11/12 ea |
EV3Dev Kernel |
4.4.47-19-ev3dev-ev3 4.4.47-19-ev3dev-rpi2 |
4.14.71-ev3dev-2.3.0-ev3 |
Note: At the moment, the whole solution is scalable until the next LEGO Mindstorms product estimated
for next January of 2020.
3. Features included
Java features
-
OpenJDK Java 11/12 ea support for EV3 Brick, Brickpi+/PiStorms + Raspberry Pi 3
-
Java profiling tools Support (Oracle mission control & JConsole)
-
Logging support based on SLF4J
-
Centralized logs with Kibana
Platform features
-
Support for EV3 Brick, PiStorms v1/v2, BrickPi+ & BrickPi 3
Lego Mindstorms features
-
Regulated Motor Support
-
Unregulated Motor Support
-
Sensor Support (EV3 sensors)
-
Sounds Support
-
EV3 LCD Support
Robotics
-
Automatic installation of OpenCV
-
eSpeak TTS (Text to speech) Support
-
LeJOS Sensor filter Support
-
LeJOS local navigation stack Support
-
RPLidar A1/A2 (2D Lidar) Support
4. Subprojects
Stable projects:
-
OpenJDK for EV3: A custom OpenJDK JRE build for EV3
-
EV3Dev-lang-java: Low level interation with EV3Dev
-
lejos-commons: LeJOS interfaces & utilities
-
Installer: A set of Bash scripts to automate some operations with your brick
-
Template project: A Gradle project ready to test the project
-
Examples: A repository with several examples about the usage of this project
Incubator projects:
-
lejos-navigation: LeJOS navigation stack
-
Usb Devices: A library to use Arduino, Grove Sensors, GPS, IMU, LIDAR, and more devices…
-
ROS: A library to publish Sensor data to ROS for SLAM purposes
5. Competitive advantages
The competitive advantages of this project are:
-
Development Java robots with modern Java versions
-
Support for Multiple Bricks like EV3 Brick, BrickPi & PiStorms
-
Support for
USBConnections for Sensors like 2D LIDARs, IMU & GPS &ArduinoBoards -
Usage of
LeJOSinterfaces
If you analyze the hardware, any EV3 Brick uses a
SoC: Sitara Processor AM1808 (from year 2010) to manage Sensors &
Actuators but now with the usage of a BrickPi/PiStorms unit, it is
possible to use the power of a Raspberry Pi 3 increasing the
possibilities to develop complex projects which require por
Computational consumption.
| Element | LEGO | Raspberry Pi 3 Model B+ |
|---|---|---|
Year |
2010 |
2018 |
Hardware |
EV3 Brick |
BrickPi+ BrickPi3 PiStorms |
SoC |
Sitara Processor AM1808 |
Broadcom BCM2837 RISC de 64 bits |
CPU |
ARM9 300MHz / 456 Mhz |
4× ARM Cortex-A53, 1.4GHz |
RAM |
16KB of Instruction Cache, 16KB of Data Cache, 8KB of RAM (Vector Table), 64KB of ROM |
1GB LPDDR2 (900 MHz) |
USB |
1x |
4x |
6. Timeline of the project
In 2015, EV3Dev was born to offer a solution to install a complete Linux Debian Operating System on EV3 Brick, BrickPi Series & PiStorms Series. The project provides an agnostic Linux interface to unify the way to interact with Mindstorms Hardware too.
At the end of the same year, EV3Dev-lang-java was born with the idea to continue developing Java robots
on Lego Mindstorms and providing a port of LeJOS libraries like the local-navigation stack.
In the future, we will add the remote support and ROS support.
7. Evolution of Java on Lego Mindstorms ecosystem
LeJOS project is the unique Open Source project available for every Lego Mindstorms generations of the product. In any generation, the project had to find a solution for the following layers:
-
Runtime
-
JVM
-
Robotics libraries
This premise was solved in every Mindstorms generation:
| Product | RCX | NXT | EV3 + LeJOS | EV3/BrickPi/PiStorms + EV3Dev-lang-java |
|---|---|---|---|---|
Last release |
17/12/2006 |
03/02/2015 |
16/11/2015 |
13/11/2018 |
Runtime |
Custom firmware |
Custom firmware |
Busybox + Native libraries |
Debian Jessie/Stretch |
JVM |
Custom JVM |
Custom JVM |
Oracle JRE 8 |
OpenJDK 11/12 ea |
Robotics libraries |
Initial libraries |
local-navigation, remote, ros |
local-navigation, remote |
local-navigation |