Research on a Robust Backstepping Attitude Controller for Multi-rotor Plant Protection UAV

The plant protection UAV is an important application equipment for precision spraying technology. However, in the process of spraying, the change of its own load will lead to the decline of control performance and disturbance rejection ability. In order to improve the control performance of the plant protection UAV, the application research of robust backstepping control strategy is carried out, and the Robust Backstepping Attitude Controller (RBAC) is designed to force the quadrotor to follow the desired attitude. Through simulation experiments, the control effect of RBAC and the Backstepping Terminal Sliding Mode Controller (BTSMC) in the literature are compared and analysed. The simulation results show that: RBAC can improve the dynamic performance of the system. The average settling time of the system is shortened by 404.663ms, which is 24.85% faster than that of the BTSMC system. Simultaneously, the system is insensitive to external unknown disturbance and has strong robustness.

An Adaptive Observer Design for Nonlinear Systems Affected by Unknown Disturbance with Simultaneous Actuator and Sensor Faults. Application to a CSTR

Continuous Stirred Tank Reactor (CSTR) is an important system in the chemical and biological industries. It's characterized by a complex nonlinear behavior and is usually affected by faults and disturbances. Therefore, the states and faults estimation of a CSTR is always a challenging task for automated process researchers and engineers. This paper proposes an adaptive observer. This paper proposes an adaptive observer in order to estimate states and actuator and sensor faults simultaneously under unknown disturbance. Firstly, the approach of the Takagi-Sugeno multi-model is proposed to transform the complex nonlinear model into several simple linear sub-models. However, the states of the considered isotherm CSTR are not completely measurable, so the multi-model is represented with non-measurable premise variables. Then, in order to transform the considered system into a system with an unknown input, a mathematical transformation is introduced to describe the sensor faults as actuator faults. The proposed observer is designed, and the exponential stability conditions are studied with the Lyapunov theory and L2 optimization and formulated in terms of linear matrix inequalities. Finally, to improve the effectiveness of the proposed observer, a numerical simulation is carried out on a CSTR.

Bearing-Only Adaptive Formation Control Using Back-Stepping Method

In this paper, the bearing-only formation control problem of a class of second-order system with unknown disturbance is investigated, where the control law merely depends on the relative bearings between neighboring agents. In order to offset the effect of unknown disturbance on the system, adaptive estimation is introduced. In the design of the control law, the back-stepping design method and the negative gradient method are used. The Barbalat’s lemma is used to prove the global stability of the system. The simulation results prove the effectiveness of the proposed formation control algorithm.