Inertial measurement unit
=========================


This sensor emulates an Inertial Measurement Unit (IMU), measuring
the angular velocity and linear acceleration including acceleration
due to gravity.
For the magnetic field part, refer to the documentation of
:doc:`./magnetometer`.

If the robot has a physics controller, the velocities are directly
read from it's properties ``localAngularVelocity`` and
``worldLinearVelocity``. Otherwise the velocities are calculated by
simple differentiation. Linear acceleration is always computed by
differentiation of the linear velocity. The measurements are given
in the IMU coordinate system, so the location and rotation of the
IMU with respect to the robot is taken into account.


.. cssclass:: properties morse-section

Configuration parameters for Inertial measurement unit
------------------------------------------------------


You can set these properties in your scripts with ``<component>.properties(<property1>=..., <property2>=...)``.

- ``ComputationMode`` (string, default: ``"Automatic"``)
	Kind of computation, can be one of ['Velocity', 'Position']. Only robot with dynamic and Velocity control can choose Velocity computation. Default choice is Velocity for robot with physics, and Position for others


.. cssclass:: fields morse-section

Data fields
-----------


This sensor exports these datafields at each simulation step:

- ``timestamp`` (float, initial value: ``0.0``)
	number of seconds in simulated time
- ``angular_velocity`` (vec3<float>, initial value: ``[0.0, 0.0, 0.0]``)
	rates in IMU x, y, z axes (in radian . sec ^ -1)
- ``linear_acceleration`` (vec3<float>, initial value: ``[0.0, 0.0, 0.0]``)
	acceleration in IMU x, y, z axes (in m . sec ^ -2)
- ``magnetic_field`` (vec3<float>, initial value: ``[0.0, 0.0, 0.0]``)
	magnetic field along x, y, z axes (in nT)

*Interface support:*

- :tag:`moos`  as IMUNotifier (:py:mod:`morse.middleware.moos.imu.IMUNotifier`)
- :tag:`ros`  as `sensor_msgs/Imu <http://ros.org/doc/api/sensor_msgs/html/msg/Imu.html>`_ (:py:mod:`morse.middleware.ros.imu.ImuPublisher`)
- :tag:`socket`  as straight JSON serialization (:py:mod:`morse.middleware.socket_datastream.SocketPublisher`)
- :tag:`yarp`  as yarp::Bottle (:py:mod:`morse.middleware.yarp_datastream.YarpPublisher`)
- :tag:`text`  as key = value format with timestamp and index value (:py:mod:`morse.middleware.text_datastream.Publisher`)


.. cssclass:: services morse-section

Services for Inertial measurement unit
--------------------------------------

- ``get_properties()`` (blocking)
    Returns the properties of a component.
    
    
  - Return value

    a dictionary of the current component's properties  

- ``get_local_data()`` (blocking)
    Returns the current data stored in the sensor.
    
    
  - Return value

    a dictionary of the current sensor's data 

- ``set_property(prop_name, prop_val)`` (blocking)
    Modify one property on a component
    
    
  - Parameters

    - ``prop_name``: the name of the property to modify (as shown the documentation)
    - ``prop_val``: the new value of the property. Note that there is no checking about the type of the value so be careful

  - Return value

    nothing 

- ``get_configurations()`` (blocking)
    Returns the configurations of a component (parsed from the properties).
    
    
  - Return value

    a dictionary of the current component's configurations  



.. cssclass:: examples morse-section

Examples
--------


The following examples show how to use this component in a *Builder* script:

.. code-block:: python


    from morse.builder import *
    
    # adds a default robot (the MORSE mascott!)
    robot = Morsy()
    
    # creates a new instance of the sensor
    imu = IMU()

    # place your component at the correct location
    imu.translate(<x>, <y>, <z>)
    imu.rotate(<rx>, <ry>, <rz>)
    
    robot.append(imu)
    
    # define one or several communication interface, like 'socket'
    imu.add_interface(<interface>)

    env = Environment('empty')
    

.. cssclass:: files morse-section

Other sources of examples
+++++++++++++++++++++++++

- `Source code <../../_modules/morse/sensors/imu.html>`_
- `Unit-test <../../_modules/base/imu_testing.html>`_




*(This page has been auto-generated from MORSE module morse.sensors.imu.)*