Claptrap, a room mapping robot

Presentation
Links
Source code and instructions
Claptrap specifications
Code architecture
Algorithms
Work division
Videos and Pictures

Presentation

Claptrap is a robot based on the LEGO MINDSTORMS EV3, whose purpose is to map a previously unknown room. It has been designed by Nathan Biette, Erwan Culerier and Olivier Roques for the OS fall course 2017 at EURECOM.

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Source code and instructions

Source code is available on our repository. Follow these steps to run our algorithm on your Lego Mindstorms EV3:

Set-up the robot and connect to it via ssh.

Update the robot with the latest packages:

sudo apt-get update && sudo apt-get upgrade

Install extra packages you will need for the project:
```
sudo apt-get install gcc make libbluetooth-dev
```

Install the development environment on the robot:

GIT_SSL_NO_VERIFY=true git clone https://github.com/in4lio/ev3dev-c.git
cd ~/ev3dev-c/source/ev3
make
sudo make install

Clone our repository on the robot and compile the source:

cd ~
git clone https://github.com/ojroques/OSproject-Claptrap.git
cd OSproject-Claptrap/src/
make main

Install the server on a computer:

git clone https://gitlab.eurecom.fr/ludovic.apvrille/OS_Robot_Project_Fall2017.git
cd OS_Robot_Project_Fall2017/server
make server

On the robot, change SERV_ADDR in src/client.h with your server bluetooth adress.

On your server, create a file with 14 lines. Each line of this file must correspond to a robot following this format:

1 BLUETOOTH_ADDR ROBOT_NAME

You can copy-paste this example in a file called claptrap to use only Claptrap as robot (the team ID of Claptrap is 7, you can change it in config.h):

00:00:00:00:00:00 Team01
00:00:00:00:00:00 Team02
00:00:00:00:00:00 Team03
00:00:00:00:00:00 Team04
00:00:00:00:00:00 Team05
00:00:00:00:00:00 Team06
a0:e6:f8:dc:96:79 Claptrap  <-- Use your own bluetooth address here
00:00:00:00:00:00 Team07
00:00:00:00:00:00 Team08
00:00:00:00:00:00 Team09
00:00:00:00:00:00 Team10
00:00:00:00:00:00 Team11
00:00:00:00:00:00 Team12
00:00:00:00:00:00 Team13

Launch the server with the previously created file:
```
./server claptrap
```
You can now run the program on your robot:
```
cd OSproject-Claptrap/src/
make run
```

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Claptrap specifications

Sensors

Claptrap uses 4 sensors:

Tachos

Claptrap uses 4 tachos:

Two large tachos for both wheels
One large tacho in its back for the obstacle carrier
One medium tacho to control the rotation of the ultrasonic sensor

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Code architecture

The repository contains 3 folders:

docs : website content
src : the project source code
tests : general tests for sensors and tachos

src structure

The source code is split into 8 parts:

main.c and main.h : the main algorithm
client.c and client.h : client-server communications
config.c and config.h : Claptrap initialization (tachos, sensors, network, image) and uninitialization
image.c and image.h : map functions
position.c and position.h : position thread and functions
sensors.c and sensors.h : to use the sensors
tachos.c and tachos.h : to control the tachos
const.h : general constants

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Algorithms

Claptrap is initialized with a map of arbitrary size filled with 0 (unexplored) and a starting position, as well as a timer (4 minutes).

The exploration algorithm

An infinite loop is started. There are two parts to this loop:

First, the center of the largest unexplored area is given to Claptrap, which then tries to go there. Once arrived or if it encounters an obstacle, it stops and go to the next step. This part aims to maximize the surface explored.
The area exploration procedure is then executed 4 times.

Area exploration

This second part is split into 5 sections:

ANALYSE :
- Claptrap faces one direction (North for instance)
- If it detects an object at less than 25cm, it calls the procedure obstacle_type detailed below
- If there is in fact an unmovable object, we update the map accordingly
- In any cases, we save the sonar value for the current direction (North here)
- Claptrap rotate by 90 deg.
- We start over until each direction has been analyzed
DECISION :
- Claptrap selects the direction with largest leeway and greater than 15cm (to allow it to move without bumping into obstacles)
- If this direction would result in a loop (Claptrap goes back and forth), it is ignored
- The chosen direction is saved (if there is one)
MOVEMENT :
- Claptrap turns to face the chosen direction
- It goes forward until an obstacle is detected
LOOPING AND STOPPING CONDITIONS
- Claptrap restarts at analyse
- Exploration is stopped when time is up or Claptrap is stuck (no direction available)
MAPPING
- The map is sent to the server: 0 indicates free area, 1 indicates obstacles

OBSTACLE_TYPE procedure

This function returns the type of obstacle Claptrap is currently facing:

Claptrap moves closer to the object (typically at 3cm from the object to make color detection possible and reliable)
The color is analyzed: red indicates a movable obstacle
Claptrap moves backward to its previous position
An integer is returned indicating the obstacle type or if there is none

Position thread

In parallel of the main algorithm, a thread updates Claptrap position. This position is then sent to the server every 1.5s.

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Work division

You can check our repository activity here.

Olivier Roques

Main algorithm: procedures for room exploration and mapping
Client / Server communications
Map and image: initialization, manipulation and transmission
Website
Integration
Robot configuration in config.c regarding the server and the image

Nathan Biette

Robot architecture: building the LEGO robot
Sensors: tests, initialization, getters
Robot movements: release of an obstacle, controlling the tacho to rotate the head, rotation of the robot using the gyro, translation calibration, updating the robot position
Robot configuration in config.c regarding the sensors