This paper presents a fault tolerant approach for a coaxial octorotor regarding rotor failures. A complete architecture including error detection, fault isolation and system recovery is presented. The diagnosis system is designed with a nonlinear observer to generate residuals and an inference model to evaluate them and isolate the faulty motor. Once the motor failure is diagnosed, a recovery algorithm is applied. It uses the built-in hardware redundancy of the octorotor and compensates the loss of the failing motor by controlling its dual to keep a stable flight that allows the multirotor to continue its mission. This architecture is validated on real flights.
SUMMARYThis paper presents a global stabilization of a chain of n integrators in cascade. The control strategy is obtained using the Lyapunov approach and separated saturation functions. Moreover, the stability analysis is obtained using the recurrence theorem. This generalized control law is designed in order to quickly implement it on a system, as choosing a degree n gives all conditions to have a stable system. Moreover, in the proposed controller the saturation function bound only one state. This allows us to easily tune the control parameters. Simulations and real-time experiments are presented for the VTOL platform represented as a chain of two and four integrators in cascade.
International audienceIn this work, an output-feedback scheme for the global stabilisation of the planar vertical take-off and landing aircraft with bounded inputs is developed taking into account the positive nature of the thrust. The global stabilisation objective is proven to be achieved avoiding input saturation and by exclusively considering the system positions in the feedback. To cope with the lack of velocity measurements, the proposed algorithm involves a finite-time observer. The generalised versions of the involved finite-time stabilisers have not only permitted to solve the output-feedback stabilisation problem avoiding input saturation, but also provide additional flexibility in the control design that may be used in aid of performance improvements. With respect to previous approaches, the developed finite-time observer-based scheme guarantees the global stabilisation objective disregarding velocity measurements in a bounded input context. Simulation tests corroborate the analytical developments. The study includes further experimental results on an actual flying device
Abstract-The problem of vision-based road following using a quad-rotor is addressed. The objective consists of estimating and tracking a road without a priori knowledge of such path. For this purpose, two operational regions are defined: one for the case when the road is detected, and the other one for when it is not. A switching between imaging and inertial sensors measurements allows estimating the required vehicle's parameters in both regions. Also, for dealing with both aforementioned cases, a switching control strategy which stabilizes the vehicle's lateral position is proposed. The performance of the proposed switching methodologies is tested in real time experiments.
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