This paper studies the attitude tracking control for an uncertain 2-degrees of freedom helicopter system where the inputs and the states are quantized. An adaptive backstepping based control scheme is proposed to handle the effect of quantization for tracking of reference angles for pitch and yaw. All closed-loop signals are ensured uniformly bounded and the tracking errors will converge to a compact set containing the origin. Experiments on the helicopter system illustrate the proposed control scheme.Paper D. Adaptive Backstepping Control of a 2-DOF Helicopter System in the Presence of Quantization utilize quantized states, and this problem is being addressed.• The attitude, i.e. orientation, of a MIMO 2-DOF helicopter system is to be controlled, where the system has challenges due to uncertain parameters, there is a coupling between the inputs and the outputs that makes control more complicated, and quantization of both the inputs and the states introduce errors that need to be handled in the control design and in the stability analysis.We propose an adaptive control algorithm using the backstepping technique to deal with these problems.The paper is organized as follows. In Section D.2, the system model, problem statement and the considered quantizer are presented. Section D.3 presents the adaptive control design based on backstepping technique. In Section D.4 a stability analysis is given, Section D.5 presents the results from experiment before a conclusion is given in Section D.6.
D.2 Dynamical Model and Problem Formulation
D.2.1 NotationsVectors are denoted by small bold letters and matrices with capitalized bold letters. λ max (•) and λ min (•) denotes the maximum and minimum eigenvalue of the matrix (•), and ∥•∥ denotes the L 2 -norm and induced L 2 -norm for vectors and matrices, respectively.