I have defined a quadcopter that I control with a PID controller. The dynamics that define it are such.
$T=mg+m\ddot{z}$
$\theta=\frac{\ddot{x}}{-9.82}$
$\phi=\frac{\ddot{y}}{9.82}$
As you can see I always need acceleration to actuate so I have defined a trajectory that allows via points that I took from a robot manipulator book and applied it to the quadcopter. The trajectories give me a position for PID and an acceleration for dynamics actuating. However, those trajectories (cubic polynomials) do not look good in the 3d world as you can see on the figure. So what trajectory should I use on a quadcopter?
On the figure, I tried to make a reference trajectory to look like a circle but the blends "ruins" it. There are 10 via points here.