This repo includes packages needed to control the KUKA Robots with a modular interface. (i.e. as a seperate "KUKA" bridge mode) in ROS with robot-toolkit.

###Dependencies

• robot-toolkit (from epfl-lasa)
• motion-generators (from epfl-lasa)

###Funcionality

This package offers a bridge control interface for the KUKA robot using robot-toolkit. This way, instead of having your controllers implemented within the lwr-interface framework (as most robot-toolkit examples do), we facilitate a modular architecture, where control policies/motion planners/joint contollers can be implemented in a seperate node and the kuka_fri_bridge deals with setting the control modes and bi-directional communication with the robot. It provides two types of control modes for your convenience.

####1. Joint Impedance Control Mode:

The joint impedance control mode has two control interfaces: position and velocity. Following is a diagram of the control flow.

From your own node you have to publish joint commands which can be position+stiffness or velocity+stiffness. The bridge will then publish the current joint state to the standard sensor_msgs/JointState message with topic name /joint_states which includes positions/velocities/effort.

If you want to read the joint stiffness as well, you can subscribed to the topic named /joint_imp_states, which is of our custom type kuka_fri_bridge/JointStateImpedance and includes all the measurements from former message + joint stiffnesses.

Similarly, there are two message options for the joint commands:

1. A sensor_msgs/JointState message type which has to be published to /KUKA/joint_cmd. With this message you can only set position/velcoties. The stiffness will be set with the default values (500 Nm/rad).
2. A kuka_fri_bridge/JointStateImpedance message type which has to be published to /KUKA/joint_imp_cmd. With this message you have to set position/velocity and stiffness.

To configure the bridge for either position or velocity control interface, you have to modify one line in the /kuka_fri_bridge/config/KUKABridge.xml:

<Options>
            <CtrlInterface> velocity </CtrlInterface>
</Options>

rosrun kuka_fri_bridge run_lwr.sh

Once this is done, run the script in the teach pad correctly until you get the message FRI Succesfully opened, then you must press the ```PageDown`` key twice and afterwords type:

KUKA> control 1

in the kuka_fri_bridge terminal. The bridge will now be waiting for the script to run on the teachpad. Keep clicking on the green button until JOINTIMPEDANCE control mode is set.

####2. Cartesian Impedance Control Mode:

This control mode has only 1 interface posibility and it is by sending pose (position/orientation), forces/torques and stiffness values for the end-effector, these are expected to be published in the following topics:

/KUKA/des_ee_pose
/KUKA/des_ee_ft
/KUKA/des_ee_stiff

As seen in the diagram, besides the joint state message described above, the bridge will also publish cartesian state messages:

/KUKA/Pose
/KUKA/FT
/KUKA/STiff

The names are self-explanatory.

rosrun kuka_fri_bridge run_lwr.sh

Run the script in the teach pad correctly until you get the message FRI Succesfully opened, the you must type the ```PageDown`` key twice and afterwords type:

KUKA> control 2

in the kuka_fri_bridge terminal. The bridge will now be waiting for the script to run on the teachpad. Keep clicking on the green button until CARTESIANIMPEDANCE control mode is set.

NOTE: If you decide to use this control mode, the robot might do some unexpected behaviors since the IK/ID is being computed in the KUKA control box. One way to be safe is to check your next cartesian command with an IK/ID solver OR if you wish to trust the robot blindly it's on you, just try not to break it or any walls.