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zitongbai / bipedal_control

Bipedal robot control using ocs2
BSD 3-Clause "New" or "Revised" License
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bipedal_control

bipedal_control is an NMPC framework for bipedal robot depending on OCS2

Installation

Preparation

Before installation, make sure you have ROS noetic installed in Ubuntu 20.04.

Install catkin tools to use catkin build instead of catkin_make.

sudo apt-get install python3-catkin-tools

Create a catkin workspace: 

mkdir -p ~/bipedal_ws/src
cd ~/bipedal_ws/src

others:

sudo apt install ros-noetic-effort-controllers

OCS2

OCS2 is a huge monorepo; DO NOT try to compile the whole repo. You only need to compile ocs2_legged_robot_ros and its dependencies following the step below.

  1. You are supposed to clone the OCS2, pinocchio, and hpp-fcl as described in the documentation of OCS2. 
    # Under the src directory of your catkin workspace
# Clone OCS2
git clone git@github.com:leggedrobotics/ocs2.git
# Clone pinocchio
git clone --recurse-submodules https://github.com/leggedrobotics/pinocchio.git
# Clone hpp-fcl
git clone --recurse-submodules https://github.com/leggedrobotics/hpp-fcl.git
# Clone ocs2_robotic_assets
git clone https://github.com/leggedrobotics/ocs2_robotic_assets.git
# Install dependencies
sudo apt install liburdfdom-dev liboctomap-dev libassimp-dev
sudo apt install ros-noetic-grid-map-rviz-plugin
  2. Compile the ocs2_legged_robot_ros package with catkin tools instead of catkin_make. It will take you several minutes. 
    # Under catkin workspace
cd ~/bipedal_ws
catkin config -DCMAKE_BUILD_TYPE=RelWithDebInfo
catkin build ocs2_legged_robot_ros ocs2_self_collision_visualization

  3. Launch the example to test whether ocs2 is installed correctly.

    # Under catkin workspace
# Source workspace
source devel/setup.bash
# Launch the example for DDP
roslaunch ocs2_legged_robot_ros legged_robot_ddp.launch

    Ensure you can command the ANYmal as shown in the document and below.

Build

Clone the repository to the src folder of your catkin workspace.

cd ~/bipedal_ws/src
git clone https://github.com/zitongbai/bipedal_control.git

Build the source code of bipedal_control.

cd ~/bipedal_ws
catkin build ocs2_bipedal_robot_ros

Implemente your own robot

For implementation of your own robot, here are some steps to follow:

  1. Create a folder under bipedal_robot_example to store some ROS packages specific to your robot. (e.g., bipedal_robot_example/unitree_h1)

  2. Create a ROS package for the urdf model of your robot, or you can copy the out-of-the-box package containing the urdf model to here. (e.g., bipedal_robot_example/unitree_h1/h1_description). Make sure the urdf model is correct (you can use check_urdf) and can be visualized in RViz.

  3. Create a ROS package for the configuration of ocs2 for your robot. (e.g., bipedal_robot_example/unitree_h1/h1_ocs2_config). It should contain the following contents:

    • gait.info: the gait information of the robot, including several mode templates and the corresponding mode sequences.
    • reference.info: the reference information of the robot, it would be used in your command.
    • task.info

    You can copy these files from bipedal_robot_example/unitree_h1/h1_ocs2_config and modify them according to your robot. Details would be explained later.

    You can also create the launch file in this package to start bipedal interface node and a dummy node to test the MPC trajectory planner. (you can refer to bipedal_robot_example/unitree_h1/h1_ocs2_config/launch/bipedal_robot_sqp.launch)

  4. If your robot does not have links in the sole, add virtual links to the urdf model of your robot. These links are used to construct contact constraints in MPC. You can refer to right_sole_1_link, etc. in bipedal_robot_example/unitree_h1/h1_description/urdf/h1_with_sole.urdf for an example.

  5. Modify jointNames in task.info to match ONLY the revolute legged joint names of your robot. Upper body joints should not be included.

  6. Modify contactNames3DoF in task.info to match the contact points (links defined in 4) of your robot.

  7. Modify initialState in task.info and defaultJointState in reference.info to set the initial state of your robot.

  8. Create a launch file like /bipedal_robot_example/unitree_h1/h1_ocs2_config/launch/bipedal_robot_sqp.launch to launch the bipedal interface node and a dummy node to test the MPC trajectory planner.

  9. Modify torqueLimitsTask in task.info

Acknowledgement

TODO