I know that designing a flight controller for an aerial vehicle (multirotor) using Linear Quadratic Regulator (LQR) control is a complex task that involves several steps. As a beginner I need the community’s help to direct a pipeline or a pathway to proceed the project and recommend some resource materials. I also recommend your suggestions in LQR or other control algorithms.
I wouldn’t be able to help with this, but perhaps these questions should be asked on https://robotics.stackexchange.com/. ROS discourse is more about news and discussion.
Check out the ROS support guidelines here : Support - ROS Wiki
Also if your question is not ROS related but related to an autopilot program, it is better to use their associated support channels.