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easynav_simple_controller

Description

Simple path-following controller that uses PID controllers and a look-ahead reference pose to follow a planned path. It produces velocity commands (cmd_vel) based on the reference pose sampled at a look-ahead distance and limits linear/angular speeds and accelerations.

Authors and Maintainers

  • Authors: Intelligent Robotics Lab
  • Maintainers: Francisco Martín Rico fmrico@gmail.com

Supported ROS 2 Distributions

Distribution Status
humble kilted
jazzy kilted
kilted kilted
rolling rolling

Plugin (pluginlib)

  • Plugin Name: easynav_simple_controller/SimpleController
  • Type: easynav::SimpleController
  • Base Class: easynav::ControllerMethodBase
  • Library: easynav_simple_controller
  • Description: Path-following controller using PID (linear and angular) and a look-ahead strategy.

Parameters

All parameters are declared under the plugin namespace, i.e., /<node_fqn>/easynav_simple_controller/SimpleController/....

This plugin derives from easynav::ControllerMethodBase.
See that section for shared collision-checking parameters and debug markers common to all controllers.

Name Type Default Description
— — — Velocity and acceleration limits are not this plugin's: they are the robot limits of controller_node (robot_limits.max_linear_vel, min_linear_vel, max_angular_vel, max_linear_acc, max_linear_decel, max_angular_acc, max_angular_decel), queried with ControllerMethodBase::get_robot_limits() and also enforced by ControllerNode's velocity smoother.
look_ahead_dist double 1.0 Look-ahead distance to sample the reference pose on the path (m).
tolerance_dist double 0.05 Distance threshold to switch to pure orientation tracking (m).
final_goal_angle_tolerance double 0.1 Angular tolerance (rad) used to decide final-goal arrival.
k_rot double 0.5 Gain used to reduce linear speed based on angular velocity (higher: stronger reduction while turning).
linear_kp double 0.95 Proportional gain for the linear PID controller.
linear_ki double 0.03 Integral gain for the linear PID controller.
linear_kd double 0.08 Derivative gain for the linear PID controller.
angular_kp double 1.5 Proportional gain for the angular PID controller.
angular_ki double 0.03 Integral gain for the angular PID controller.
angular_kd double 0.08 Derivative gain for the angular PID controller.

Deprecated: this plugin's former limit parameters (max_linear_speed, max_angular_speed, max_linear_acc, max_angular_acc, under the plugin's name) still apply, with a warning, where controller_node.robot_limits.* does not set that limit. They will stop working soon: move them to robot_limits.

Interfaces (NavState, Topics and Services)

NavState

This controller uses the shared NavState bag provided by the easynav_core framework. The following keys are used at runtime by SimpleController:

Key Type Access Notes
robot_pose nav_msgs::msg::Odometry Read Current robot odometry used to compute the robot pose and yaw.
path nav_msgs::msg::Path Read Planned path to follow. The controller samples a reference pose at look_ahead_dist along this path.
cmd_vel geometry_msgs::msg::TwistStamped Write Output velocity command. Header.frame_id is set to path.header.frame_id when available and stamp to the controller node clock.

Topics / Services

The controller itself does not create ROS publishers/subscribers or service servers. It interacts via the NavState abstraction; how NavState is exposed (topics or other IPC mechanisms) depends on the integrating node.

TF Frames

This controller reads pose from nav_msgs/Odometry (NavState key robot_pose). TF is not directly used in this plugin.

License

Apache-2.0