GP 2: Action-Based Goal Navigation

Overview

Due Date	April 24, 2026, 11:59 PM EST
Total Points	50 points
Submission	Canvas (zip the ~/enpm605_ws/src/gp2/ folder and submit as group<N>_gp2.zip)
Collaboration	Groups of 2 (or 3).
Late Policy	10% deduction per calendar day, up to 3 days. Zero after 3 days.
Peer Review	Final grade: 60% assignment grade + 40% peer review score.

Description

This is a group project (2 or 3 students per group). You will wrap the two-phase proportional controller from Lecture 11 inside a ROS 2 action server, and drive a simulated rosbot to three goals sequentially using an action client. The controller logic (position + orientation, 20 Hz control loop) is already written for you in ~/enpm605_ws/src/lecture11/robot_control_demo. Your job is to port it into an action server, wire it to a client, and submit the result.

Learning Objectives

Custom Action Interfaces

Define a .action file with goal, feedback, and result sections. Generate Python bindings via rosidl_generate_interfaces in a CMake package.

Action Servers

Implement a long-running goal with an ActionServer: accept/reject logic, cancellation support, periodic feedback publishing, and a final result on success or failure.

Action Clients

Use an ActionClient to send goals asynchronously, handle goal-response, feedback, and result callbacks, and chain multiple goals sequentially (wait for each result before sending the next).

Embedded Control Logic

Port the two-phase proportional controller (position then orientation) into the action server’s execution callback so that goal progress and tolerance checks drive the feedback/result lifecycle.

Parameter Configuration

Load three goal poses (x, y, final_heading) from a YAML parameter file at launch time, organized as named blocks (goal1, goal2, goal3) and accessed via dot-namespaced parameter names.

Launch File Integration

Write a Python launch file that starts the action server and the action client together, loads the goals YAML file into the client node, and exposes launch arguments for the controller gains and tolerances.

Suggested Timeline

You have one week (April 16 → April 23). The schedule below is a suggestion; adjust based on your group’s pace.

Period	Duration	Tasks
Days 1 to 2	2 days	Read the assignment carefully. Review Lecture 10 (action_demo, parameters_demo) and Lecture 11 (robot_control_demo/p_controller_demo). Launch the GP2 world (rosbot_gazebo gp2_world.launch.py) and confirm the three floor markers are visible. Create the two package skeletons. Define and build group<N>_gp2_interfaces.
Days 3 to 4	2 days	Implement the action server: port the two-phase P-controller into the execute_callback. Test with a hardcoded goal using ros2 action send_goal from the CLI.
Days 5 to 6	2 days	Implement the action client: read goals from parameters, send goals sequentially, handle feedback and results. Write the launch file. Test the full pipeline end to end.
Day 7	1 day	Write README.md. Code quality pass (docstrings, type hints, comments, Ruff). Remove cache directories. Package and submit.

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