Integration of Franka Panda arm into Orocos

Besides an Orocos toolchain, this project requires libfranka built from source for compilation. Installation instructions can be found at https://frankaemika.github.io/docs/installation.html. libfranka apparently needs a kernel compiled with the PREEMPT_RT patchset, so you can either build your own kernel as stated in the official documentation or simply install one of the lowlatency kernels included with recent versions of Ubuntu:

sudo apt install linux-image-lowlatency

With <libfranka> as your location of the libfranka sources, use

mkdir build && cd build
cmake -DFranka_DIR=<libfranka>/build ..
cmake --build .

to build an Orocos component from the code.

To control the Franka Panda arm from Orocos, make sure your machine booted a kernel including the PREMPT_RT patch and is connected to the controller hardware as written in the official documentation. Additional, you will need the URDF and SRDF of the manipulator (available for example here, originally taken from the franka_ros package).

If those prerequisites are fulfilled, you can load and use a component called franka::franka_robot from the deployer:

# Import typekits and OS library for convenience
import("eigen_typekit")
import("rst-rt_typekit")
require("os")
    
# Import rtt-franka-hardware-integration
import("rtt-franka-hardware-integration")

# Assume URDF and SRDF files are in $GAZEBO_MODEL_PATH/franka
var string model_path = os.getenv("GAZEBO_MODEL_PATH") + "/franka"

# Load component and schedule it really fast (event driven) with high priority
loadComponent("franka", "franka::franka_robot")
setActivity("franka", 0, 90, ORO_SCHED_RT)

# Initialize kinematic chain using URDF and SRDF files
franka.addChain("franka", "172.16.0.2", model_path + "model.urdf", model_path + "model.srdf")

# Set control mode and start component!
franka.setControlMode("franka", "JointTorqueCtrl")
franka.configure()
franka.start()

# TODO
# Connect your own component to the feedback and command ports of franka and control the robot!

• Control modes
  • Joint velocity (JointVelocityCtrl)
  • Joint torque (JointTorqueCtrl)
  • Joint impedance (JointIpedanceCtrl)
• Joint state feedback
  • Position
  • Velocity
  • Torque
• Dynamic feedback
  • Manipulator jacobian
  • Inertia/mass matrix
  • Gravity vector
  • Coriolis vector

• Joint position control (JointPositionCtrl)
  Robot reports errors due to joint velocity and acceleration discontinuities even in case clearly smooth trajectories are commanded and handed to libfranka. Root cause of this problem is unkown up to now.

See HACKING.md for information about code structure and implementation details.