Quadcopter Stability: the Effects of CoM, Dihedral Angle and Its Uncertainty

Since quadcopters are hugely limited by their short flight duration, it is of significant importance to employ an optimal design for the structure of the vehicle in order to reduce energy costs. Tilting-rotor quadcopter designs have shown promise in high speed maneuvers. However, the effects of different structural parameters on the stability of quadcopters have not been thoroughly investigated. In this paper, the effects of the Center of Mass (CoM) location and the inward tilting of rotors (dihedral angle) are analyzed. Additionally, a formula for the optimal selection of the dihedral angle based on the CoM position is derived. Furthermore, the effects of uncertainties in the dihedral angle on the quadcopter’s behavior are studied. The results indicate that increasing the dihedral angle makes the robot more sensitive to small uncertainties in adjusting the dihedral angle of different rotors. By considering these analyses during the design phase of a new quadcopter, a more optimal structure can be proposed to achieve the most efficient behavior.