robotSensor

Sensor for robot scenario

Since R2022a

Description

The robotSensor object creates a sensor that is rigidly attached to a robot platform, specified as a robotPlatform object. You can specify different mounting positions and orientations. Configure this object to automatically generate readings at fixed rate from a sensor specified as an gpsSensor, insSensor, or robotLidarPointCloudGenerator System object™ or robotics.SensorAdaptor class.

Creation

Syntax

sensor = robotSensor(name,platform,sensormodel)

sensor = robotSensor(___,Name=Value)

Description

sensor = robotSensor(name,platform,sensormodel) creates a sensor with the specified name name and sensor model sensormodel, which set the Name and SensorModel properties respectively. The sensor is added to the platform platform specified as a robotPlatform object. The platform argument sets the MountingBodyName property.

sensor = robotSensor(___,Name=Value) sets properties using one or more name-value pair arguments in addition to the input arguments in the previous syntax. You can specify the MountingLocation, MountingAngles, or UpdateRate properties as name-value pairs.

Properties

Name — Sensor name

string scalar

Sensor name, specified as a string scalar. Choose a name to identify this specific sensor.

Data Types: char | string

SensorModel — Sensor model for generating readings

gpsSensor System object | insSensor System object | robotLidarPointCloudGenerator System object

Sensor model for generating readings, specified as an gpsSensor, insSensor, or robotLidarPointCloudGenerator System object.

MountingBodyName — Name of sensor mounted platform body

robotPlatform.Name (default) | string scalar

Name of the sensor mounted platform body, specified as a string scalar. The rigidBodyTree based robot platform can have multiple bodies, any valid body can be selected to mount sensor.

Data Types: char | string

MountingLocation — Sensor position on platform

[0 0 0] (default) | vector of form [x y z]

Sensor position on platform, specified as a vector of the form [x y z] in the platform frame. Units are in meters.

Data Types: single | double

MountingAngles — Sensor orientation on platform

[0 0 0] (default) | vector of form [z y x]

Sensor orientation on platform, specified as a vector of the form [z y x] where z, y, and x are rotations about the z-axis, y-axis, and x-axis, sequentially, in degrees. The orientation is relative to the platform body frame.

Data Types: single | double

UpdateRate — Update rate of sensor

positive scalar

Update rate of the sensor, specified as a positive scalar in Hz. By default, the object uses the UpdateRate property of the specified sensor model object.

The sensor update interval (1/UpdateRate) must be a multiple of the update interval for the associated robotScenario object.

Data Types: single | double

Object Functions

read	Gather latest reading from robot sensor

Examples

Create and Simulate Robot Scenario

Create a robot scenario.

scenario = robotScenario(UpdateRate=100,StopTime=1);

Add the ground plane and a box as meshes.

addMesh(scenario,"Plane",Size=[3 3],Color=[0.7 0.7 0.7]);
addMesh(scenario,"Box",Size=[0.5 0.5 0.5],Position=[0 0 0.25], ...
        Color=[0 1 0])

Create a waypoint trajectory for the robot platform using an ENU reference frame.

waypoint = [0 -1 0; 1 0 0; -1 1 0; 0 -1 0];
toa = linspace(0,1,length(waypoint));
traj = waypointTrajectory("Waypoints",waypoint, ...
                          "TimeOfArrival",toa, ...
                          "ReferenceFrame","ENU");

Create a rigidBodyTree object of the TurtleBot 3 Waffle Pi robot with loadrobot.

robotRBT = loadrobot("robotisTurtleBot3WafflePi");

Create a robot platform with trajectory.

platform = robotPlatform("TurtleBot",scenario, ...
                         BaseTrajectory=traj);

Set up platform mesh with the rigidBodyTree object.

updateMesh(platform,"RigidBodyTree",Object=robotRBT)

Create an INS sensor object and attach the sensor to the platform.

ins = robotSensor("INS",platform,insSensor("RollAccuracy",0), ...
                  UpdateRate=scenario.UpdateRate);

Visualize the scenario.

[ax,plotFrames] = show3D(scenario);
axis equal
hold on

In a loop, step through the trajectory to output the position, orientation, velocity, acceleration, and angular velocity.

count = 1;
while ~isDone(traj)
    [Position(count,:),Orientation(count,:),Velocity(count,:), ...
     Acceleration(count,:),AngularVelocity(count,:)] = traj();
    count = count+1;
end

Create a line plot for the trajectory. First create the plot with plot3, then manually modify the data source properties of the plot. This improves the performance of the plotting.

trajPlot = plot3(nan,nan,nan,"Color",[1 1 1],"LineWidth",2);
trajPlot.XDataSource = "Position(:,1)";
trajPlot.YDataSource = "Position(:,2)";
trajPlot.ZDataSource = "Position(:,3)";

Set up the simulation. Then, iterate through the positions and show the scene each time the INS sensor updates. Advance the scene, move the robot platform, and update the sensors.

setup(scenario)
for idx = 1:count-1
    % Read sensor readings.
    [isUpdated,insTimestamp(idx,1),sensorReadings(idx)] = read(ins);
    if isUpdated
        % Use fast update to move platform visualization frames.
        show3D(scenario,FastUpdate=true,Parent=ax);
        % Refresh all plot data and visualize.
        refreshdata
        drawnow limitrate
    end
    % Advance scenario simulation time.
    advance(scenario);
    % Update all sensors in the scene.
    updateSensors(scenario)
end
hold off

Version History

Introduced in R2022a