Vision Augmented 3 DoF Quadrotor Control using a Non-singular Fast-terminal Sliding Mode Modified Super-twisting Controller

This paper proposes a novel 3 DoF vision augmented Quadrotor model for visual servoing. The proposed model eliminates the necessity of deploying a separate visual-servoing controller and a robot controller, thereby reducing the on-board computational load drastically. The proposed model, as opposed to the conventional PBVS and IBVS approaches, helps in the use of torque control strategies. To utilize this feature of the model, a non-singular fast-terminal sliding mode modified super-twisting controller (NSFTSM-MSTC) is proposed. The non-singular fast-terminal sliding manifold ensures the fast and finite time convergence of the error between the desired and actual points of interest, while ensuring smoother transitions in the quadrotor states. The modified super-twisting reaching law ensures that the control input is continuous thereby ensuring chattering attenuation. The overall system stability is presented using Lyapunov's stability criteria and an expression for convergence time is also derived. The proposed theory is validated using numerical simulations and is compared with the existing conventional sliding mode based visual servoing approach (CSMVS).