The backstepping and related block control principle is a widely used methods of robust control. In these methods, it is standard to use linear feedback in both the controller and observer, which may contribute to overshooting. The aim of this paper is to develop an approach free of this problem to control the Euler angles and altitude of a quadcopter in the presence of uncertainties in the plant model. To achieve this goal, we propose a block control principle with smooth and bounded nonlinear feedback in the form of a hyperbolic tangent. In this control law, we introduce acceleration-related parts to reduce the oscillations of the state variables. We present the numerical simulation results of the proposed algorithms and their comparison with standard algorithms with linear controls.