Moving in z, x & y direction

Whenever a drone is stationary, it’s in alignment with World frame, meaning to say its Z axis is in same direction as World’s gravitational field. During such a case, if a drone wants to move upwards, it just needs to set proper propeller rotating speed and it can start moving in z direction according to equation total generated force — gravity. However, if it wants to move in x or y direction it first needs to orient itself (making required theta or phi angle). When that happens, total thrust generated by four propellers (F_thrust) has a component in z direction and in x/y direction as shown in above 2D figure. For above shown example, using basic trigonometry, we can find z and y directional force by following equation, where phi is angle made Drone’s body z axis with world Frame. F_y ​= F_thrust * ​sinϕ F_z ​= F_thrust * ​cosϕ