Differential Driver Actuator:             Linear and angular speed (V, W) actuator
==================================================================================


This actuator reads the values of linear and angular speed and
applies them to the robot as speeds for the wheels. It only works
with robots of the type ``WheeledRobot``, such as the :doc:`Segway
RMP 400 <../robots/segwayrmp400>` and the :doc:`Pioneer 3-DX
<../robots/pioneer3dx>`.  The movement of the robot is more
realistic, but also depends on more factors, such as the friction
between the wheels and the surface.

The speeds for the left and right wheels are calculated as:

        left_speed = (v - e w) / R
        right_speed = (v + e w) / R

where:

    - **v** is the linear velocity given as parameter
    - **w** is the angular velocity given as parameter
    - **e** is half of the distance between the left and
    right wheels
    - **R** is the radius of the wheels



.. cssclass:: properties morse-section

Configuration parameters for differential driver actuator:             linear and angular speed (v, w) actuator
---------------------------------------------------------------------------------------------------------------

*No configurable parameter.*

.. cssclass:: fields morse-section

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


This actuator reads these datafields at each simulation step:

- ``v`` (float, initial value: ``0.0``)
	linear velocity in x direction (forward movement) (m/s)
- ``w`` (float, initial value: ``0.0``)
	angular velocity (rad/s)

*Interface support:*

- :tag:`ros`  as TwistReader (:py:mod:`morse.middleware.ros.motion_vw.TwistReader`)
- :tag:`moos`  as db entries (:py:mod:`morse.middleware.moos.motion.MotionReader`)
- :tag:`pocolibs`  as `GENPOS_CART_SPEED <http://trac.laas.fr/git/genPos-genom/tree/genPosStruct.h#n90>`_ (:py:mod:`morse.middleware.pocolibs.actuators.genpos.GenPosPoster`)
- :tag:`socket`  as straight JSON deserialization (:py:mod:`morse.middleware.socket_datastream.SocketReader`)
- :tag:`yarp`  as yarp::Bottle (:py:mod:`morse.middleware.yarp_datastream.YarpReader`)


.. cssclass:: services morse-section

Services for Differential Driver Actuator:             Linear and angular speed (V, W) actuator
-----------------------------------------------------------------------------------------------

- ``stop()`` (blocking)
    Stop the robot
    
    Internally, it sets (v, w) to (0.0, 0.0)
    
- ``set_speed(v, w)`` (blocking)
    Modifies v and w according to the parameters
    
    
  - Parameters

    - ``v``: desired linear velocity (meter by second)
    - ``w``: desired angular velocity (radian by second)

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

    a dictionary of the current component's properties  

- ``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 *
    
    robot = ATRV()
    
    # creates a new instance of the actuator
    motionvwdiff = MotionVWDiff()

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

    env = Environment('empty')
    

.. cssclass:: files morse-section

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

- `Source code <../../_modules/morse/actuators/v_omega_diff_drive.html>`_
- `Unit-test <../../_modules/base/v_omega_diff_drive_testing.html>`_




*(This page has been auto-generated from MORSE module morse.actuators.v_omega_diff_drive.)*
