## repository: https://code.ros.org/svn/wg-ros-pkg
<<PackageHeader(pr2_gripper_sensor_controller)>>
<<TOC(4)>>

== Introduction ==

The [[pr2_gripper_sensor_controller]] package is a real-time controller that is intended to support the [[pr2_gripper_sensor_action]] interface and allow it to:

 a. Act as a fully compatible replacement for the simpler [[pr2_gripper_action]] interface.
 a. Provide new functionality to allow more complex gripper actions in real-time that are able to delicately and sensitively control the gripper position and force, as well as provide a wealth of sensory feedback.

'''Currently the [[pr2_gripper_sensor_controller]] can only be accessed over the [[pr2_gripper_sensor_action]] action interface. There is no other API support at this time. Please refer to the [[pr2_gripper_sensor_action]] wiki page for usage and feature information.'''

{{attachment:wiki_control_flow_diagram_controller.png|alt text|width=780}}

The [[pr2_gripper_sensor_controller]] package continuously publishes several messages defined in the [[pr2_gripper_sensor_msgs]] package, which are intended for use in the action servers of [[pr2_gripper_sensor_action]] and not for normal user usage, but can provide useful information for more advanced users.

== Hardware Dependecies ==
The [[pr2_gripper_sensor_controller]] '''requires''' two important PR2 sensors to be available:

 *A [[ethercat_hardware/Tutorials/GripperAccelerometer|palm-mounted accelerometer]], which should exist on all modern PR2 robots.

 * [[pr2_hardware_interface|Pressure-sensitive fingertips]], which are an optional hardware add-on for all modern PR2 that require a brief installation procedure [installation link?].

A simple test to check if these sensors exist is to run the command {{{rostopic list}}} and check to make sure the {{{/accelerometer}}} and {{{/pressure}}} fields are present.

== Running the Controller ==

=== Compiling ===
If you are not using a prebuilt installation you may have to compile the [[pr2_gripper_sensor_controller]] package. Since the [[pr2_gripper_sensor_controller]] package is a real-time controller, it is important to remember to compile the package '''before''' launching your robot, otherwise it will fail to register and load correctly with [[pluginlib]]. Compiling can be done simply by typing:
{{{
rosmake pr2_gripper_sensor_controller
}}}

Or by building any of the higher-level packages (such as [[pr2_gripper_sensor_action]] which depend on this package) '''before''' launching your robot.

=== Launching ===
See the [[pr2_gripper_sensor_action]] launch instructions, which will automatically launch the [[pr2_gripper_sensor_controller]] package for both the left and right PR2 grippers. Specific left/right launch files are available in the [[pr2_gripper_sensor_controller]] package, but it is unecessary for the end user to launch them independently.

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