state_lattice_planner

Overview

TBW

The API documantation is here.

Enviornment

• Ubuntu 20.04, ROS noetic

Install and Build

cd catkin_workspace/src
git clone https://github.com/amslabtech/state_lattice_planner.git
cd ..
catkin_make

Nodes

state_lattice_planner

• local planner node

Published topics

• /cmd_vel (geometry_msgs/Twist)
• ~/candidate_trajectoryies (visualization_msgs/MarkerArray)
  • for visualization
• ~/candidate_trajectoryies/no_collision (visualization_msgs/MarkerArray)
  • for visualization

Subscribed topics

• /local_goal (geometry_msgs/PoseStamped)
  • the local goal must be in the local map
• /local_map (nav_msgs/OccupancyGrid)
  • robot-centered costmap
• /odom (nav_msgs/Odometry)
  • robot odometry

Parameters

• HZ
  • main loop rate (default: 20[Hz])
• ROBOT_FRAME
  • robot's coordinate frame (default: base_link)
• N_P
  • number of terminal state sampling for x-y position (default: 10)
• N_H
  • number of terminal state sampling for heading direction (default: 3)
• MAX_ALPHA
  • max terminal state sampling direction (default: M_PI/3.0[rad/s])
• MAX_PSI
  • max heading direction at terminal state (default: M_PI/6.0[rad/s])
• N_S
  • parameter for globally guided sampling (default: 1000)
• MAX_ACCELERATION
  • max acceleration of robot (absolute value)(default: 1.0[m/ss])
• TARGET_VELOCITY
  • max velocity of robot's target velocity (default: 0.8[m/s])
• LOOKUP_TABLE_FILE_NAME
  • absolute path of lookup table (default: $HOME/lookup_table.csv)
• MAX_ITERATION
  • max number of iteration (default: 100)
• OPTIMIZATION_TOLERANCE
  • when the cost becomes lower than this parameter, optimization loop is finished (default: 0.1)
• MAX_CURVATURE
  • max trajectory curvature (default: 1.0[rad/m])
• MAX_D_CURVATURE
  • max time derivative of trajectory curvature (default: 2.0[rad/ms]
• MAX_YAWRATE
  • max robot's yawrate (default: 0.8[rad/s])

Runtime requirement

• TF (from /odom to /base_link) is required

lookup_table_generator

• this node is a tool for generating a lookup table, not for planning. so this node doesn't publish or subscribe topics.

Parameters

• MIN_X
  • target state sampling parameter (default: 1.0[m])
• MAX_X
  • target state sampling parameter (default: 7.0[m])
• DELTA_X
  • target state sampling parameter (default: 1.0[m])
• MAX_Y
  • target state sampling parameter (default: 3.0[m])
• DELTA_Y
  • target state sampling parameter (default: 1.0[m])
• MAX_YAW
  • target state sampling parameter (default: 1.0471975[rad])
• DELTA_YAW
  • target state sampling parameter (default: 1.0471975[rad])
• LOOKUP_TABLE_FILE_NAME
  • full path of lookup_table.csv
• MIN_V
  • initial velocity sampling parameter (default: 0.1[m/s])
• MAX_V
  • initial velocity sampling parameter (default: 0.8[m/s])
• DELTA_V
  • initial velocity sampling parameter (default: 0.1[m/s])
• MAX_KAPPA
  • initial curvature sampling parameter (default: 1.0[rad/m])
• DELTA_KAPPA
  • initial curvature sampling parameter (default: 0.2[rad/m])
• MAX_ACCELERATION
  • max acceleration of robot (default: 1.0[m/ss])
• MAX_CURVATURE
  • max trajectory curvature (default: 1.0[rad/m])
• MAX_D_CURVATURE
  • max time derivative of trajectory curvature (default: 2.0[rad/ms])
• MAX_YAWRATE
  • max yawrate of robot (default: 0.8[rad/s])

How to Use

• for generating lookup table

roslaunch state_lattice_planner generate_lookup_table.launch

• for local path planning

roslaunch state_lattice_planner local_planner.launch

References

• https://www.ri.cmu.edu/publications/state-space-sampling-of-feasible-motions-for-high-performance-mobile-robot-navigation-in-complex-environments/
• https://github.com/AtsushiSakai/PythonRobotics/tree/master/PathPlanning/StateLatticePlanner