Robot Operating System Cookbook

Hover and upward and downward motion

Let us look at some conditions of the motion of the quadcopter; first, how the quadcopter can hover in the air! As the quadcopter is steady in the air, it must be in equilibrium. All the forces must be balanced. The total thrusts F₁, F₂, F₃, and F₄ produced by the propellers must be equal to the weight of the quacopter. And, all the Moments produced must be zero:

Condition for hovering:

Equation of motion: ...