easynav_simple_controller

Easy Navigation: Simple Controller package.

README

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
jazzy
kilted
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
`max_linear_speed`	`double`	`1.0`	Maximum linear speed (m/s).
`max_angular_speed`	`double`	`1.0`	Maximum angular speed (rad/s).
`max_linear_acc`	`double`	`0.3`	Maximum linear acceleration (m/s²).
`max_angular_acc`	`double`	`0.3`	Maximum angular acceleration (rad/s²).
`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.

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