Velocity
========


This sensor returns the linear and angular velocity of the sensor,
both in robot frame and in world frame. Linear velocities are
expressed in meter . sec ^ -1 while angular velocities are expressed
in radian . sec ^ -1.

The sensor expects that the associated robot has a physics controller.


.. cssclass:: properties morse-section

Configuration parameters for Velocity
-------------------------------------


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
- ``linear_velocity`` (vec3<float>, initial value: ``[0.0, 0.0, 0.0]``)
	velocity in sensor x, y, z axes (in meter . sec ^ -1)
- ``angular_velocity`` (vec3<float>, initial value: ``[0.0, 0.0, 0.0]``)
	rates in sensor x, y, z axes (in radian . sec ^ -1)
- ``world_linear_velocity`` (vec3<float>, initial value: ``[0.0, 0.0, 0.0]``)
	velocity in world x, y, z axes (in meter . sec ^ -1)

*Interface support:*

- :tag:`text`  as key = value format with timestamp and index value (:py:mod:`morse.middleware.text_datastream.Publisher`)
- :tag:`ros`  as `geometry_msgs/TwistStamped <http://ros.org/doc/api/geometry_msgs/html/msg/TwistStamped.html>`_ (:py:mod:`morse.middleware.ros.velocity.TwistStampedPublisher`)
- :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:`moos`  as StringPublisher (:py:mod:`morse.middleware.moos.abstract_moos.StringPublisher`)


.. cssclass:: services morse-section

Services for Velocity
---------------------

- ``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
    velocity = Velocity()

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

    env = Environment('empty')
    

.. cssclass:: files morse-section

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

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




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