towr: A C++ repository from JaFeKl

A light-weight and extensible C++ library for trajectory optimization for legged robots.

A base-set of variables, costs and constraints that can be combined and extended to formulate trajectory optimization problems for legged systems. These implementations have been used to generate a variety of motions such as monoped hopping, biped walking, or a complete quadruped trotting cycle, while optimizing over the gait and step durations in less than 100ms (paper).

Features:
✔️ Inuitive and efficient formulation of variables, cost and constraints using Eigen.
✔️ ifopt enables using the high-performance solvers Ipopt and Snopt.
✔️ Elegant rviz visualization of motion plans using xpp.
✔️ ROS/catkin integration (optional).
✔️ Light-weight (~6k lines of code) makes it easy to use and extend.

Install

The easiest way to install is through the ROS binaries:

sudo apt-get install ros-<ros-distro>-towr_ros

In case these don't yet exist for your distro, there are two ways to build this code from source:

Option 1: core library and hopper-example with pure CMake.
Option 2 (recommended): core library & GUI & ROS-rviz-visualization built with catkin and ROS.

Building with CMake

Install dependencies CMake, Eigen, Ipopt:
```
sudo apt-get install cmake libeigen3-dev coinor-libipopt-dev
```
Install ifopt, by cloning the repo and then: cmake .. && make install on your system.

Build towr:

git clone https://github.com/ethz-adrl/towr.git && cd towr/towr
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make
sudo make install # copies files in this folder to /usr/local/*
# sudo xargs rm < install_manifest.txt # in case you want to uninstall the above

Test (hopper_example.cc): Generates a motion for a one-legged hopper using Ipopt
```
./towr-example # or ./towr-test if gtest was found
```

Use: You can easily customize and add your own constraints and variables to the optimization problem. Herefore, add the following to your CMakeLists.txt:

find_package(towr 1.2 REQUIRED)
add_executable(main main.cpp) # Your custom variables, costs and constraints added to TOWR
target_link_libraries(main PUBLIC towr::towr) # adds include directories and libraries

Building with catkin

We provide a ROS-wrapper for the pure cmake towr library, which adds a keyboard interface to modify goal state and motion types as well as visualizes the produces motions plans in rviz using xpp.

Install dependencies CMake, catkin, Eigen, Ipopt, ROS, xpp, ncurses, xterm:

sudo apt-get install cmake libeigen3-dev coinor-libipopt-dev libncurses5-dev xterm
sudo apt-get install ros-<ros-distro>-desktop-full ros-<ros-distro>-xpp

Build workspace:

cd catkin_workspace/src
git clone https://github.com/ethz-adrl/ifopt.git
git clone https://github.com/ethz-adrl/towr.git
cd ..
catkin_make_isolated -DCMAKE_BUILD_TYPE=Release # or `catkin build`
source ./devel/setup.bash

Use: Include in your catkin project by adding to your CMakeLists.txt

find_package(catkin COMPONENTS towr) 
include_directories(${catkin_INCLUDE_DIRS})
target_link_libraries(foo ${catkin_LIBRARIES})

Add the following to your package.xml:

<package>
  <depend>towr</depend>
</package>

Run / Develop

Launch the program using

roslaunch towr_ros towr_ros.launch

Click in the xterm terminal and hit 'o'.

Understand how to tune the parameters according to your problem and other useful information for developers:
➡️ doxygen documentation.

Publications

The theory behind this code can be found in this paper:

A. W. Winkler, D. Bellicoso, M. Hutter, J. Buchli, Gait and Trajectory Optimization for Legged Systems through Phase-based End-Effector Parameterization, IEEE Robotics and Automation Letters (RA-L), 2018:

@article{winkler18,
  author    = {Winkler, Alexander W and Bellicoso, Dario C and 
               Hutter, Marco and Buchli, Jonas},
  title     = {Gait and Trajectory Optimization for Legged Systems 
               through Phase-based End-Effector Parameterization},
  journal   = {IEEE Robotics and Automation Letters (RA-L)},
  year      = {2018},
  month     = {July},
  pages     = {1560-1567},
  volume    = {3},
  doi       = {10.1109/LRA.2018.2798285},
}

Authors

Alexander W. Winkler - Initial Work/Maintainer

The work was carried out at the following institutions:

Contributing

We love pull request, whether its new constraint formulations, additional robot models, bug fixes, unit tests or updating the documentation. Please have a look at CONTRIBUTING.md for more information.
See here the list of contributors who participated in this project.

Bugs & Feature Requests

To report bugs, request features or ask questions, please have a look at CONTRIBUTING.md.

JaFeKl/towr