Do a circuit loop with a mobile M3 node

Difficulty: Intermediate

Duration: 20 minutes

Prerequisites: Configure SSH Access / Experiment CLI client / Nodes Serial Link Aggregation

Description: The aim of this tutorial is to submit an experiment with a mobile M3 node and interact with it. A mobile node is a node embedded on a robot with predefined trajectories. You will book one mobile M3 node, set it up with a sample firmware file. Once the experiment running, you will interact with the firmware running on the node and graph IMU sensors values. After the experiment, you can plot the mobile node trajectory.
Since robots features are not yet included in the webportal, you will use here the cli-tools.

Launch the experiment

1. Choose your node:
   • Click on Activity
   • Filter resources by choosing mobile only in the list
   • Choose a node available and keep its node id
   • Note: Try to take a node which was inactive the last two hours (to be sure to have enough battery).

   

2. Choose your circuit, within the list returned by iotlab-robot:

   iotlab-robot get -l

3. Download the simple_robot.elf firmware binary for m3 nodes. For information, you can have a look at the firmware code.
4. Submit an experiment with cli-tools, either from an SSH frontend or from your computer. In this example, we chose the m3-258 from Lille doing the square1 circuit:

   iotlab-experiment submit -d 20 -n simple_robot_tutorial -l lille,m3,258,simple_robot.elf,mobility=square1

   Or you may also let the scheduler choose the node just by describing node properties:

   iotlab-experiment submit -d 20 -n simple_robot_tutorial -l 1,archi=m3:at86rf231+mobile=1+site=lille,simple_robot.elf,mobility=square1

   You get an experiment id.

Interact during experiment

1. In a terminal on your computer, give access as a tcp socket (explanation in Advanced usage section of Nodes Serial Link Aggregation tutorial) :

   socat tcp-listen:20000,fork,reuseaddr "exec:ssh <login>@<site>.iot-lab.info 'serial_aggregator'"

2. In another terminal on your computer, download the live_imu.py script from our Openlab repository on GitHub.
   Note: you need to have a working Python with Matplotlib installed.
3. Launch the script with the following parameters. Use the right TCP port configured with socat before. Use the right nodeid (e.g. m3-258) in order to filter incoming traffic from the serial_aggregator. Avalaible values for the sensor option are Gyr (gyrometer), Acc (accelerometer), Mag (magnetometer).

   python ./live_imu.py --port 20000 --sensor Gyr --nodeid m3-258

   

4. Close the trajectory plot and stop the socat command with Ctrl-C.

Mobile node’s trajectory

1. Stop your experiment

   iotlab-experiment stop

2. Connect to the SSH fronted of Lille with X11 forwarding

   ssh -X <login>@lille.iot-lab.info

3. The mobile node trajectory is copied at the end of the experiment in your home folder in .oml files.

   <login>@lille:~$ less ~/.iot-lab/<experiment id>/robot/m3-258.oml
   protocol: 4
   domain: 39738
   start-time: 1459778452
   sender-id: m3-258
   app-name: robot_position_measures
   schema: 0 _experiment_metadata subject:string key:string value:string
   schema: 10 robot_pose timestamp_s:uint32 timestamp_us:uint32 x:double y:double theta:double
   content: text
   
   10.298170       10      1       1459778462      878753  2.526062        0.129655        -1.563731
   10.398204       10      2       1459778462      978787  2.526062        0.129655        -1.563731
   10.498178       10      3       1459778463      078761  2.526062        0.129655        -1.563731
   ....
   

   Trajectory Measure Table

   Measure	Unit
   x, y z th	meters, cartesian coordinates meters, altitude which is a constant radians, orientation around z axis

4. Plot your file using the oml_plot_tools:

   <login>@lille:~$ plot_oml_traj -i ~/.iot-lab/<experiment id>/robot/m3-258.oml

   You can use --circuit-name and --circuit-file options to observe the mobile node trajectory respectively with the planned circuit and the site map.