Adaptive Fault–Tolerant Position Control of a Hexacopter Subject to an Unknown Motor Failure

Abstract

This paper presents a fault tolerant position tracking controller for a hexarotor system. The proposed controller has a cascaded structure composed of a position and an attitude control loop. The nominal controller is augmented by an adaptive control allocation which compensates for faults and failures within the propulsion system without reconfiguration of the controller. Simultaneously, it is able to implement a degraded control strategy which prioritizes specific control directions in the case of extreme degradation. The main contribution is a controller that is a step closer to application scenarios by including outdoor GPS-based flight tests, onboard computation and the handling of unknown degradation and failure of any rotor.

Asymptotic tracking position control with active oscillation damping of a multibody Mars vehicle using two artificial augmentation approaches

“…To solve objective (i), the flight controller is designed using a nonlinear cascaded control design model (CDM) which is inspired by [26] and [49].…”

“…(54), we use the I-frame as reference frame while applying Euler's classical treatment of vector analysis [39] which yields For a more compact notation of Eq. (55), the thrust vector dynamics can be reformulated into a matrix-vector form of notation [49] which includes T ∈ ℝ 3×3 , the thrustmagnitude matrix, as well as T ∈ ℝ 3×3 , the reduced thrust-magnitude matrix:…”

“…Based on the CDM of Sect. 3, a flight controller for the Mars vehicle can be derived which is primarily inspired by [26] and [49]. The flight controller is a cascaded version of a backstepping-based attitude controller nestling inside a superior position controller which is based on Feedback Linearization [52].…”

“…Since the overall controller testbed is treated as a modelin-the-loop (MIL) simulation, the controller states are initialized through the plant state vector x P . Feasible reference trajectories, indicated by the subscript r, are not only provided by linear first-and second-order reference models (PT1 and PT2 filters), but also by a second-order nonlinear reference model [49], to define the controllers' tracking objectives.…”

Control Strategies and Novel Techniques for Autonomous Rotorcraft Unmanned Aerial Vehicles: A Review

“…The robustness and durability of the planned strategy were shown in improving the reference tracking capability and AFEO was found to have faster estimation speed and estimation accuracy. Falconi et al [199] presented, numerically and practically, an adaptive fault-tolerant controller to control position tracking of a hexacopter model. The results revealed the efficacy of the proposed strategy in dealing with any unknown degradation and failure of any rotor.…”