Nodes

Node	Method
local_map_creator	Ray casting update
localization	emcl: mcl with expansion resetting
global_path_planner	A* search algorithm
local_path_planner	DWA: Dynamic Window Approach

How to run

export TURTLEBOT3_MODEL=burger
roslaunch system_ros demo.launch

rosrun rosserial_python serial_node.py /dev/ttyACM0

mqtt transmit

Step 1: Install Mosquitto as the MQTT broker (Raspberry Pi)

sudo apt install mosquitto mosquitto-clients
sudo systemctl enable mosquitto
sudo systemctl start mosquitto

• Check the status of Mosquitto:

sudo systemctl status mosquito

If it’s running, see something like:

Active: active (running) ...

Step 2: Configure Mosquitto

sudo nano /etc/mosquitto/mosquitto.conf

Enable password authentication by adding this line to the config file:

listener <port_number>
allow_anonymous false
password_file /etc/mosquitto/pwfile

Set password by:

sudo mosquitto_passwd -c /etc/mosquitto/pwfile <username>
sudo chmod 644 /etc/mosquitto/pwfile

Replace <username> with the name you want to use. You will be prompted to set a password.

Verify that the password file exists:

cat /etc/mosquitto/pwfile

Should see something like this (hashed password): <username>:$6$xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

(Optional) Enable TLS (for secure connections): If you want to enable encryption (TLS) for MQTT communication:

cafile /etc/mosquitto/certs/ca.crt
certfile /etc/mosquitto/certs/server.crt
keyfile /etc/mosquitto/certs/server.key

You would need to generate or obtain SSL/TLS certificates for this, which can be self-signed or from a certificate authority.

Restart Mosquitto for the changes to take effect:

sudo systemctl restart mosquitto
mosquitto -c /etc/mosquitto/mosquitto.conf -v #to check if have issue

Step 3: Install MQTT Client Tools on PCs (Clients)

1. Install Mosquitto Clients

sudo apt install mosquitto-clients
sudo apt install libmosquitto-dev

Step 4: Test the Connection between PCs (Clients) and Raspberry Pi (Broker)

Test MQTT Publish from the PC1 (Client):

mosquitto_pub -h <broker_ip> -t "test/topic" -m "Hello from PC!" -u <username> -P <password>

Replace <broker_ip> with the actual IP address of your Raspberry Pi.

Test MQTT Subscribe from the PC2 (Client):

Open another terminal and subscribe to the same topic:

mosquitto_sub -h <broker_ip> -t "test/topic" -u <username> -P <password>

Should see the message Hello from PC! appear in the terminal of the subscribing client.

Ref: https://mosquitto.org/api/files/mosquitto-h.html