Plot Turtlebot Odometry

Connect to TurtleBot

Description of first code block

ipaddress = '192.168.192.130'; % IP address of your robot
tbot = turtlebot(ipaddress,11311);
tbot.Velocity.TopicName = '/cmd_vel';

Get Odometry Data

Use getOdometry to get a single odometry point off the TurtleBot. The function returns the position and orientation as [x y z] coordinates and [yaw pitch roll] angles.

odom = getOdometry(tbot)

odom = struct with fields:
       Position: [4.3772 1.4580 -0.0010]
    Orientation: [-2.2936 0.0032 7.8259e-06]

Send velocity commands to change the position of the robot. To note the change in position, reset the odometry first. Use setVelocity to drive the robot forward for 2 seconds and wait for the robot to execute this command.

resetOdometry(tbot)
setVelocity(tbot,0.5,'Time',2)

Get the odometry after the velocity command is sent. The x-coordinate of odom.Position reflects the change in position. A velocity of 0.5 m/s for 2 seconds yields a displacement of 1m in the x direction as expected.

odom = getOdometry(tbot)

odom = struct with fields:
       Position: [3.2717 0.7216 -0.0010]
    Orientation: [-2.6151 0.0032 -1.5861e-05]

Plot Odometry Data Points

You can store odometry data to get a full trajectory of a robot path as it navigates through its environment.

Start a loop to store the odometry position and then send a velocity command. This loop runs 20 times to create a basic two-turn trajectory. Plot the trajectory.

odomList = zeros(20,2);
resetOdometry(tbot)

for i = 1:20
    odom = getOdometry(tbot);
    odomList(i,:) = [odom.Position(1) odom.Position(2)];
    
    if i < 10
        setVelocity(tbot,0.25,0.15)
    else
        setVelocity(tbot,0.25,-0.15)
    end
    pause(1);
end

plot(odomList(:,1),odomList(:,2))