lgmath

lgmath is a C++ library for handling geometry in state estimation problems in robotics. It is used to store, manipulate, and apply three-dimensional rotations and transformations and their associated uncertainties.

There are no minimal, constraint-free, singularity-free representations for these quantities, so lgmath exploits two different representations for the nominal and noisy parts of the uncertain random variable.

• Nominal rotations and transformations are represented using their composable, singularity-free matrix Lie groups, SO(3) and SE(3).
• Their uncertainties are represented as multiplicative perturbations on the minimal, constraint-free vectorspaces of their Lie algebras, *so**(3)* and *se**(3)*.

This library uses concepts and mathematics described in Timothy D. Barfoot’s book State Estimation for Robotics. It is used for robotics research at the Autonomous Space Robotics Lab; most notably in the STEAM Engine, a library for Simultaneous Trajectory Estimation and Mapping.

Installation

Dependencies

• Compiler with C++17 support
• CMake (>=3.16)
• Eigen (>=3.3.7)
• (Optional) ROS2 Foxy or later (colcon+ament_cmake)

Install c++ compiler and cmake

sudo apt -q -y install build-essential cmake

Install Eigen (>=3.3.7)

# using APT
sudo apt -q -y install libeigen3-dev

# OR from source
WORKSPACE=~/workspace  # choose your own workspace directory
mkdir -p ${WORKSPACE}/eigen && cd $_
git clone https://gitlab.com/libeigen/eigen.git . && git checkout 3.3.7
mkdir build && cd $_
cmake .. && make install # default install location is /usr/local/

• Note: if installed from source to a custom location then make sure cmake can find it.

Build and install lgmath using cmake

WORKSPACE=~/workspace  # choose your own workspace directory
# clone
mkdir -p ${WORKSPACE}/lgmath && cd $_
git clone https://github.com/utiasASRL/lgmath.git .
# build and install
mkdir -p build && cd $_
cmake ..
cmake --build .
cmake --install . # (optional) install, default location is /usr/local/
make doc  # (optional) generate documentation in ./doc

Note: lgmathConfig.cmake will be generated in both build/ and <install prefix>/lib/cmake/lgmath/ to be included in other projects.

Build and install lgmath using ROS2(colcon+ament_cmake)

WORKSPACE=~/workspace  # choose your own workspace directory

mkdir -p ${WORKSPACE}/lgmath && cd $_
git clone https://github.com/utiasASRL/lgmath.git .

source <your ROS2 worspace>
colcon build --symlink-install --cmake-args "-DUSE_AMENT=ON"
colcon build --symlink-install --cmake-args "-DUSE_AMENT=ON" --cmake-target doc  # (optional) generate documentation in ./build/doc

License