electric fuerte   Documentation Status

This package contains two main ROS nodes and two supporting scripts..

articulate_cart_server.py

This is the main node for performing articulation of a cart using both arms on the PR2.

Subscribed topics

cart_pushing/ready_pose_achieved (roslib/Header)

• Once the base achieves a ready pose, in which the robot's arms are in the position corresponding to the cart being at its initial position, with grippers open, a message will be sent on this topic (at a fixed rate).

~command_twist (geometry_msgs/TwistStamped)

• The desired twist for the reference point on the cart, relative to the base_footprint frame

Published topics

/r_cart/command_pose, /l_cart/command_pose (geometry_msgs/PoseStamped)

• Desired poses for the left and right gripper tool frames are sent on these topics

/r_cart/command_posture, /l_cart/command_posture (std_msg/Float64MultiArray)

• Since there is a degree of freedom remaining in the arm after specifying the gripper pose, we send a desired posture on this topic

invalid_pose (std_msgs/Empty)

• This is a debugging topic, on which a message is sent on this topic whenever a pose is requested that is outside the workspace bounds for the cart

Expected services

manipulation_transforms_server/LoadInitialTransforms (manipulation_transforms/LoadInitialTransforms)

• Used to tell the manipulation transforms server that the current pose is the one at which the cart is at its initial position

manipulation_transforms_server/MapObjectPoseToEffectors (manipulation_transforms/MapObjectPoseToEffectors)

• Used to get the effector poses corresponding to a desired cart pose

TF frames used

base_footprint

• Used as the base position and the reference for the cart

l_gripper_tool_frame, r_gripper_tool_frame

• Used as the locations of the grippers

Command line parameters

-g

• If specified, the initial pose of the robot (once the ready_pose_achieved message is received) is used as the reference position. If not, the reference position is read from the parameter server.

ROS parameters

cart_pushing/{x,y,t}_{min,max}

• Workspace bounds for the cart pose

cart_pushing/init_pose/position

• The initial position of the cart relative to the base; specified as [x, y, z]

cart_pushing/init_pose/orientation

• The initial orientation of the cart relative to the base; specified as [x, y, z, w]

fake_articulate_cart_server.py

This is for use in simulators in which gripper frames are not available. It provides the interface of articulate_cart_server.py. Additionally, it publishes transforms between base_footprint and l_gripper_tool_frame/r_gripper_tool_frame corresponding to the commands it receives on ~command_twist.

close_grippers.py

Once a message is received on move_base/goal, keeps the grippers closed by sending commands to {l,r}_gripper_controller/gripper_action.

switch_controllers.py

Once a message is received on cart_pushing/ready_pose_achieved, disables the {l,r}_arm_controller controllers and enables {l,r}_cart. Switches the controllers back before exiting.