Sliding mode fault‐tolerant control of an octorotor using linear parameter varying‐based schemes

Abstract

Abstract-This paper presents two fault tolerant control (FTC) schemes for an octorotor UAV. The FTC schemes are based on an LPV system representation and utilizes a combination of sliding mode ideas and control allocation in order to take full advantage of the available redundant rotors in the octorotor configuration. A detailed synthesis procedure for the design of the two FTC schemes in the presence of uncertainty, as well as faults/failures, is presented. The first scheme is based on an online control allocation methodology where knowledge of the rotor effectiveness level has been used to redistribute the control signals to the healthy rotors. The second scheme assumes that this information is not available and uses a fixed control allocation structure even in the event of faults/failures. Although the synthesis process for the two schemes is different and they use different strategies to redistribute the control signals when faults/failures occur, both schemes involved the same 'baseline' (sliding mode) controller which does not need to be reconfigured. The difference is in the final physical control law where the control allocation matrix is defined. Simulation results on the full nonlinear octorotor model are presented for the two different schemes in the presence of uncertainty, sensor noise as well as faults/failures. The simulation results for various fault/failure scenarios show no visible degradation in state tracking performance, highlighting the potential of the proposed schemes.

Comparative study of self tuning, adaptive and multiplexing FTC strategies for successive failures in an Octorotor UAV

“…Another work [20] suggests a fault-tolerant control strategy using cooperation between a radial based function neural network, fuzzy logic control and sliding mode control (SMC) technique in presence of actuator faults, to alleviate the chattering and to maintain good tracking of the system. In [21], two FTC schemes using linear parameter varying system representation, with a combination of SMC theory and control allocation, are developed and tested in the presence of uncertainty, as well as faults and failures. In the first scheme, the knowledge of the rotor effectiveness is required in order to apply an online control allocation methodology, and to redistribute the control signal to working motors, but in the second scheme this knowledge is not necessary.…”

“…2) is presented. This configuration was developed in [32] and will be used to test the FTC schemes, since it has many advantages over the star-shaped configuration [21] regarding stability and size factors. First, for design purposes, some assumptions are made:…”

An adaptive sliding mode actuator fault tolerant control scheme for octorotor system

“…FTC schemes considering ISMC have been recently proposed for state feedback and output feedback in the literatures. [27][28][29] All these techniques require FDI scheme, wherein FDI scheme was used to estimate the effectiveness levels of the actuators because this information was explicitly used. Recently in Zhong et al, 30 an overview of the tilt rotor UAV was presented where the concept and some typical platforms while focusing on various control techniques is discussed.…”

Active versus passive fault-tolerant control of a redundant multirotor UAV

“…The fault tolerant control of this type of vehicles has been recently studied and different strategies have been proposed: Linear Parametric Varying-(LPV-) based sliding mode control allocation (7) , neural network interval type-2 fuzzy sliding mode controller (8) , integral sliding mode scheme combined with fixed control allocation (9) , and cascade inverse method of control allocation (10) .…”