offboard_velocity_control(PID)

OFFBOARD control is dangerous.

If you are operating on a real vehicle be sure to have a way of gaining back manual control in case something goes wrong.

Installation

git clone https://github.com/ducanh1699/offboard_control.git

Getting started

1. Launch a quadrotor with px4 and mavros in gazebo

roslaunch px4 mavros_posix_sitl.launch 

2. Run the offboard_velocity_control

rosrun offboard_control offb_node
rosrun offboard_control setmode_offb

PID Controller

Basis theory

PID controller is a proportional–integral–derivative controller (PID controller or three-term controller) is a control loop mechanism employing feedback loop.

This based on the current position and target position to have velocity to control UAV.

  x----------------------------x
current                      target

To understand clearly, you can refer to the wiki: https://en.wikipedia.org/wiki/PID_controller

And watch the video: https://www.youtube.com/watch?v=wkfEZmsQqiA&ab_channel=MATLAB

Necessary library include:

#include "offboard_control/pid_controller_base.h"

1. set-up PID coefficient

double kp = 0.4, ki = 0.0, kd = 3.4;

2. create pid command and pass the values above

PidControllerBase pid_cmd(kp, ki, kd);

Note: each pid_command have only use in one axis

3. set-up max and min the velocity to fly UAV

pid_cmd.setUMax(max_v);
pid_cmd.setUMin(min_v);