This category contains 10 posts


SLAM (Simultaneous Localisation And Mapping) is the process of building a map by sensing the environment surrounding a robot and at the same time using that map to locate the robot and navigate it. This topic has been something of a hot item in robotics research for many years and is a core technology used … Continue reading

GyroBoy in JAVA – leJOS EV3

GyroBoy is a self-balancing robot created by LEGO as a demonstration of what you can build with the EV3 LEGO Mindstorms education kit. The kit includes building instructions as well as a control program for GyroBoy developed in LEGO´s so called block-programming language. In this article I will present a similar control program developed in Java using the leJOS EV3 class library. Continue reading

Line following with openCV

In a previous article I built a simple line following robot. I had intended to follow this article up with more about building cooperating systems, but I’m afraid I got distracted! In particular I spent some time adding openCV (the open source image processing project) to leJOS. As a result I wanted a project to explore what … Continue reading

EV3 LIDAR Sensor

I had planned that my next article would be part two of the series on line following (part one is here), however a new sensor from a company call PULSEDLIGHT (http://pulsedlight3d.com/) caught my attention. Basically this sensor (the LIDAR-Lite) provides a relatively low cost laser based range finder that provides centimetre resolution with a maximum distance … Continue reading

Line Following & Cooperating Robots (part 1)

Following on from the series of articles about EV3 to EV3 communications I wanted to build some actual robots and have them cooperate, but I wanted to keep things simple and avoid the complexities of navigation and dealing with the environment as much as possible. I wanted to be able to concentrate on the cooperation side … Continue reading

MIDI controlled robots

When I was a young kid we had the most intriguing device in our local warehouse. It was a glass box with monkeys in it. Not real monkeys, but to me they seemed alive. Each monkey had an instrument, flute, banjo drums, etc. and they sat in a nice scenery with palm trees. Every time you … Continue reading

Using the PCF8574 IO expander with the EV3

Mindsensors sell a breadboard sensor making kit with a PCF8574 for the NXT. I bought one a long time ago, and I thought I would try it on the EV3, after seeing some interest in the chip on the leJOS forums. I am using the sensor in read mode to read a set of buttons. … Continue reading

Homemade IMU

Here is an example of a more useful homemade EV3 UART sensor. It is an IMU that uses an MPU-9150 breakout board that can be bought cheaply on ebay. I am usinh a cheap Arduino Nano clone. The sensor supports 4 modes: Temperature, Compass, Gyro and Acceleration. The last three are all 3D, and have … Continue reading

Uart Sensor using Sparkfun Pro Micro

Here is an example of an EV3 UART sensor based a Sparkfun Pro Micro Arduino clone and a Dexter Industries breadboard adapter. It uses the EV3UARTEmulationHard library. This could be used with a variety of cheap sensors. It is shown with an MQ-2 gas sensor. There is also a Bluetooth serial adapter. This could be … Continue reading

UART Compass Sensor

This is an example of a homemade EV3 UART sensor using an HMC5883L compass module, which can be bought cheaply from ebay or amazon. I am using an Arduino Uno, but a smaller device like an Arduino Nano or a Sparkfun Arduino Pro Micro would be better. The code below implements two modes: the raw … Continue reading

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