Franka Panda

in Blog / Robotics on Config
Franka Panda

Configured Franka Panda, 3D-Connexion teleoperation from scratch while working at MiLab and utilized them to conduct research on manipulation. You can find the repo here !

Franka Panda robotic arm flow The construction process of the hardware platform.

⚙️ Important Things

to Grab before Starting

🤔 Franka Control Interface (FCI)

Franka Control Interface is a real-time control framework provided by Franka Emika for the Panda robotic arm. It enables developers to achieve high-performance control by directly interfacing with the robot at a low level. -> manual

  • High Frequency Control: Operates at up to 1 kHz, allowing precise control for advanced applications like force control and trajectory optimization.
  • Low-level Access: Users can directly control joint positions, velocities, torques, or end-effector forces and poses.
  • Real-time Feedback: Provides detailed robot states, such as joint positions, forces, external torques, and end-effector status.
  • Customization: Through the libfranka C++ library, users can create their own control algorithms.

🤔 Difference between Franka and UR

FeatureFranka FCIUR RTDE
Real-time CapabilityHigh (1 kHz)Medium (2 ms update frequency)
Control AbilitySupports low-level control (joint force, velocity, position)Supports joint or end-effector position and velocity control
State FeedbackHigh precision (joints, forces, end-effector states)Customizable feedback, fairly comprehensive
Development ComplexityHigh (requires real-time kernel and low-level programming)Lower (TCP/IP communication, standard system compatible)
Typical ApplicationsForce control tasks, advanced trajectory planning, research tasksIndustrial automation tasks, monitoring, and logging
Supported LanguagesC++ (libfranka), third-party library extensions neededMulti-language support (Python, C++, Java, etc.)
Hardware RequirementsReal-time kernel system, direct communication with the robot armStandard system, communicates with the robot via TCP/IP
Target UsersResearchers, advanced developersEngineers, industrial automation developers

🤔 Meanings of Different Colors

  • White: Interactive
  • Blue: Activated
  • Cyan: Initiating motion
  • Yellow: Locked
  • Red: Error
  • Pink: Conflict
  • Green: Automatic execution

🤔 IP address connection

Connect the control panel through 192.168.3.20\desk (IP address of the robot arm). And we can control the panda through 192.168.3.20.

🤔 libfranka

A C++ library that provides low-level control of Franka Robotics research robots. Its source code is available at here. Documentation is available at here.

🤔 franka_ros

the ROS integration for Franka Robotics research robots, including support for ROS Control and MoveIt. It also contains franka_description, a collection of URDF models and 3D meshes that can be useful outside of ROS. The repository is available at here. Documentation is available at here. And the order is as following: $\text{PC} \Rightarrow \text{franka}_\text{ros} \Rightarrow \text{libfranka} \Rightarrow \text{Franka Control Interface(FCI)} \Rightarrow \text{Robot Arm}$

🤔 Frankapy

This is a software package used for controlling and learning skills on the Franka Emika Panda Research Robot Arm. And it’s based on libfranka and franka-interface, which is a C++ Library for Interfacing with libfranka and Frankapy. Installation Instructions and Network Configuration Instructions are also available here. And it’s provided from IAM Lab.

🤔 serl_franka_controllers

serl_franka_controllers is a ROS package designed to control Franka Emika Robot through libfranka and franka_ros. This package provides a compliant yet accurate Cartesian Impedance Controller for safe online reinforcement learning algorithms, as well as a Joint Position Controller for resetting arm. It’s provided from RAIL.

⚙️ Setting

basically we can control the robot through libfranka and franka_ros from Franka. while there exists a number of third-party suites for off-the-shelf controllers like serl_franka_controllers from here.

📒 Prerequisite

  • Ubuntu 20.04
  • ROS Noetic
  • libfranka and franka_ros ( both $\geq$ 0.8.0 )
  • controllers chosen according to specific requirements

🛠️ Franka Installation

🔧 Install Noetic for Ubuntu 20.04

set download source

sudo sh -c '. /etc/lsb-release && echo "deb http://mirrors.ustc.edu.cn/ros/ubuntu/ `lsb_release -cs` main" > /etc/apt/sources.list.d/ros-latest.list'

add ros-key

sudo apt install curl 
curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -

download noetic package

sudo apt update
sudo apt install ros-noetic-desktop-full

set global environment

echo "source /opt/ros/noetic/setup.bash" >> ~/.bashrc 
source ~/.bashrc

install tools for ros

sudo apt install python3-rosdep python3-rosinstall python3-rosinstall generator python3-wstool build-essential

check the installation

roscore
rosrun turtlesim turtlesim_node
rosrun turtlesim turtle_teleop_key

🔧 Install libfranka and franka_ros

build from the ROS repositories, and please refer to here to check the version-match between the franka system and the softwares’

sudo apt-get update
sudo apt-get install ros-noetic-libfranka ros-noetic-franka-ros

build from source

🔧 Build serl_franka_controllers

mkdir -p catkin_ws/src
cd catkin_ws/src
git clone git@github.com:rail-berkeley/serl_franka_controllers.git
cd catkin_ws
catkin_make -DPYTHON_EXECUTABLE=/usr/bin/python3 --pkg serl_franka_controllers
cd ..
source catkin_ws/devel/setup.bash

🔧 Build virtual env

build miniforge if you don’t have it

cd /path/you/want/to/locate/
curl -L -O "https://github.com/conda-forge/miniforge/releases/latest/download/Miniforge3-$(uname)-$(uname -m).sh"
bash Miniforge3-$(uname)-$(uname -m).sh
source /path/to/your/miniforge3/bin/activate

build the corresponding environment

cd robot_infra
conda create -n robot_infra python=3.9
conda activate robot_infra
pip install -e .

check the path of each package in the env

python
import _package_to_test_
print(_package_to_test_.__file__)

🚗 Franka Run

  • initialization
    source /home/franka/jeffrey/miniforge3/bin/activate
conda activate robot_infra
cd /home/franka/jeffrey/Franka_Robot_Arm
  • run
    source catkin_ws/devel/setup.bash
python franka_ctrl/test.py --robot_ip=192.168.3.20
  • close
    killall -9 roscore
killall -9 rosmaster

🛠️ Others Installation

🖱️ SpaceMouse

install the packages for SpaceMouse (3Dconnexion)

pip install numpy termcolor atomics scipy
pip install git+https://github.com/cheng-chi/spnav
sudo apt install libspnav-dev spacenavd
sudo systemctl start spacenavd

🍀 Ubuntu Install w/ real-time Kernel

🔧 Download Source

download the source from here

# build foler
mkdir franka_env
cd franka_env
# download corresponding packages
curl -SLO https://www.kernel.org/pub/linux/kernel/v5.x/linux-5.15.76.tar.gz
curl -SLO https://www.kernel.org/pub/linux/kernel/projects/rt/5.15/older/patch-5.15.76-rt53.patch.gz
# unzip
tar xvzf linux-5.15.76.tar.gz
gunzip patch-5.15.76-rt53.patch.gz
# extract source code and insert the patch
cd linux-5.15.76
patch -p1 < ../patch-5.15.76-rt53.patch

🔧 Build Source

build the kernel from now on (refer to here or here)

# download neccessary packages
sudo apt-get install build-essential bc curl ca-certificates gnupg2 libssl-dev lsb-release libelf-dev bison flex dwarves zstd libncurses-dev
# borrow the config setting from current kernel
make olddefconfig

update the config of current kernel

make menuconig
  • General Setup -> Preemption Model -> Fully Preemptible Kernel (Real-Time)
  • Cryptographic API -> Certificates for signature checking -> Provide system-wide ring of trusted keys -> Additional X.509 keys for default system keyring -> remove “debian/canonical-certs.pem” -> save to .config open .config for further update
    gedit .config
# change the following old commands
CONFIG_SYSTEM_TRUSTED_KEYS="debian/canonical-certs.pem"
CONFIG_SYSTEM_REVOCATION_KEYS="debian/canonical-revoked-certs.pem"
CONFIG_DEBUG_INFO_BTF=y
# to the following new commands
CONFIG_SYSTEM_TRUSTED_KEYS=""
CONFIG_SYSTEM_REVOCATION_KEYS=""
CONFIG_DEBUG_INFO_BTF=n

begin to build kernel locally

fakeroot make -j24 deb-pkg

🔧 Install Source

finally, install the built kernel with patch

# install
sudo dpkg -i ../linux-headers-5.15.76-rt53*.deb ../linux-image-5.15.76-rt53*.deb
# re-start the computer
sudo reboot
# check
uname -msr

🔧 Add realtime permission

build a group for realtime command

sudo addgroup realtime
sudo usermod -a -G realtime $(whoami)

add the following limits into /etc/security/limits.conf, which is set for realtime group

@realtime soft rtprio 99
@realtime soft priority 99
@realtime soft memlock 102400
@realtime hard rtprio 99
@realtime hard priority 99
@realtime hard memlock 102400

finally, re-start your computer to apply it

reboot

⚙️ TroubleShooting

🔪 End-effector not initialized

  • unclear problem -> it can be solved after several minutes

🔪 Pilot mode in /desk

Switching between desk control and end effector control

  • desk control: Control through the Desk interface using high-level actions or predefined tasks.
  • end effector control: Direct control of the robot’s end-effector (the hand or gripper).

🔪 libfranka： Move command aborted by reflex!["communication_constraints_violation"] control_command_success_rate: 0,78

  • the problem mainly comes from the communication delay between the PC and the franka, and you can check the following reasons: 1) overload PC (limited CPU recourses) 2) unsuitable network card 3) inactivated real-time kernel 3) network issues from cable

🔪 Robot error: joint limit reached

  • the error comes from the abnormal recovery of franka arm, which is unknown about the reason, and what we can do is move the robot arm several times and wait a moment