simple_local_planner

A controller based on pure pursuit path tracking has been extended to command velocities to the differential robot so as to follow the path smoothly. This path tracker runs at a frequency of 15Hz and has been extended to perform a collision detection checking similar to the Dynamic Windows Approach algorithm. If the forward projection of the robot movement given by the control law is detected as a possible collision, a valid command is tried to be found by sampling small variations of the given angular velocity. If a possible collision is still detected, a rotation in place in the correct direction is performed in order to avoid very close obstacles. Moreover, a linear decrease of the velocities when approaching the goal has been also added.

Parameters

• Robot Configuration Parameters

  • max_trans_acc. Maximum acceleration in translation (m/s^2).
  • max_rot_acc. Maximum acceleration in rotation (rad/s^2).
  • max_trans_vel. Maximum linear velocity (m/s).
  • min_trans_vel. Minimum linear velocity (m/s).
  • max_rot_vel. Maximum angular velocity (rad/s).
  • min_rot_vel. Minimum angular velocity (rad/s).
  • min_in_place_rot_vel. Angular velocity of rotations in place (rad/s).

• Goal Tolerance Parameters

  • yaw_goal_tolerance. Tolerance in angular distance (rad) to consider that the goal has been reached.
  • xy_goal_tolerance. Tolerance in euclidean distance (m) to consider that the goal has been reached.
  • wp_tolerance. Distance (m) from the robot to look for the point of the global plan to follow.

• Forward Simulation Parameters

  • sim_time. Time (seconds) to expand the robot movement and check for collisions. (default: 0.5).
  • sim_granularity. Resolution in meters to split the expanded trayectory and check for collisions (Default: 0.025).
  • angular_sim_granularity. Resolution in radians to split the expanded angular movement and check for collisions (Default: 0.025).
  • controller_freq. Frequency of execution in Hz (Default: 15.0).

The package is a work in progress used in research prototyping. Pull requests and/or issues are highly encouraged.