Xidong Tang

Adaptive actuator failure compensation for nonlinear MIMO systems with an aircraft control application

A direct adaptive approach is developed for control of a class of multi-input multi-output (MIMO) nonlinear systems in the presence of uncertain failures of redundant actuators. An adaptive failure compensation controller is designed which is capable of accommodating uncertainties in actuator failure time instants, values and patterns. A realistic situation is studied with fixed grouping of actuators and proportional actuation within actuator groups. The adaptive control system is analyzed, to show its desired stability and asymptotic tracking properties in the presence of actuator failure uncertainties. As an application, such an adaptive controller is used for actuator failure compensation of a twin otter aircraft longitudinal model, with design conditions verified and control structure and adaptive laws developed for a nonlinear aircraft dynamic model. The effectiveness of adaptive failure compensation is demonstrated by simulation results.

Brief Adaptive actuator failure compensation for parametric strict feedback systems and an aircraft application

Adaptive actuator failure compensation for parametric-strict-feedback systems is studied under different system structure conditions. Adaptive state feedback control schemes are developed, which ensure asymptotic output tracking and closed-loop signal boundedness. An adaptive control scheme is applied to a twin otter aircraft longitudinal nonlinear dynamics model in the presence of unknown failures in a two-segment elevator servomechanism. Simulation results verify the effectiveness of adaptive actuator failure compensation for desired system performance.

Robust and adaptive actuator failure compensation designs for a rocket fairing structural-acoustic model

The actuator failure compensation problem is formulated for active vibration control of a rocket fairing structural-acoustic model with unknown actuator failures. Performance of a nominal optimal control scheme in the presence of actuator failures is studied to show the need of effective failure compensation. A robust control scheme and two adaptive control schemes are developed, which are able to ensure the closed-loop system signal boundedness in the presence of actuator failures whose failure pattern and values are unknown. The adaptive scheme for parameterizable failures ensures asymptotic stability despite failure uncertainties. Simulation results verified their failure compensation effectiveness.

Virtual Grouping based adaptive actuator failure compensation for MIMO nonlinear systems

A new control design technique called virtual grouping is presented to handle actuator redundancy and failures for multiple-input-mutliple-output (MIMO) systems, enlarging the set of compensable actuator failures. An adaptive compensation scheme is thus developed for a class of nonlinear MIMO systems to ensure closed-loop signal boundedness and asymptotic output tracking despite unknown actuator failures. Simulation results are given to show the effectiveness of the adaptive design.

Adaptive Compensation of Aircraft Actuation Failures Using an Engine Differential Model

This paper investigates actuator failure compensation for aircraft flight control in a novel framework. A general failure compensation scheme for asymptotic tracking is developed based on a direct adaptive control approach. This control scheme is capable of utilizing the remaining control authority to achieve the desired performance in the presence of unknown and uncertain constant actuator failures occurring at unknown time instants. A nonlinear aircraft model that incorporates independently adjustable engine throttles and ailerons is employed and linearized to describe the aircrafts longitudinal and lateral motion. This model captures the key features of aircraft flight dynamics when in the engine differential mode. The proposed control scheme is applied to a transport aircraft model in the presence of three types of failures during operation: rudder failure, aileron failure, and engine malfunction. Simulation results are presented to assess the effectiveness of this adaptive failure compensation design.

AN ADAPTIVE CONTROL SCHEME FOR OUTPUT FEEDBACK NONLINEAR SYSTEMS WITH ACTUATOR FAILURES

An adaptive control scheme to achieve stability and output tracking is presented for the output-feedback nonlinear plant with unknown actuator failures. A state observer is designed for estimating the unavailable plant states, based on a chosen control strategy, in the presence of actuator failures with unknown failure values, time instants and pattern. An adaptive controller is developed by employing the backstepping technique, for which parameter update laws are derived to ensure asymptotic output tracking and signal boundedness of the closed-loop system, as shown by detailed stability analysis.

State Feedback Designs for State Tracking

In this chapter, we solve the adaptive actuator failure compensation problems for linear time-invariant systems with unknown actuator failures and unknown dynamics, using state feedback for state tracking. In Section 2.1, the plant-model state matching conditions, controller structure, and adaptive designs are presented for a linear time-invariant system with up to m − 1 (where m is the total number of actuators) actuator failures characterized by some of the plant inputs being stuck at some unknown fixed or varying values that cannot be influenced by control action, for example, the “lock-inplace” type of actuator failures. Adaptive actuator failure designs for systems with up to m − 1 parametrizable time-varying failures and up to m − 1 unparametrizable time-varying failures are developed in Section 2.2 and Section 2.3, respectively. In Section 2.4, parametrization and design results such as plant-model matching and adaptive controller structure are extended to the case when the state reference model system has multiple inputs, which allows more freedom in characterizing desired system behavior. In Section 2.5, necessary and sufficient plant-model matching conditions, and adaptive control designs for systems with up to m − q, 1 ≤ q ≤ m − 1, lock-in-place actuator failures are derived and the effectiveness of adaptive compensation is verified by simulation results from Boeing 747 lateral control.

Adaptive output feedback actuator failure compensation for a class of state-dependent nonlinear systems

This paper develops an adaptive output feedback control scheme for a class of nonlinear systems with state-dependent nonlinearities in the presence of unknown actuator failures. A robust backstepping feedback control law is derived to effectively handle the state estimation error due to such uncertain nonlinearities. An adaptive actuator failure compensation scheme is designed to ensure closed-loop signal boundedness and desired output tracking performance. An application to controlling the angle of attack of a nonlinear aircraft model in the presence of elevator segment failures is studied and simulation results are presented to illustrate the effectiveness of the adaptive actuator failure compensation design.

Output tracking actuator failure compensation control

Controller parametrization is crucial for control of systems with actuator failures. Certain conditions on the controlled system are needed for a parametrization suitable for meeting a given control objective. For actuator failure compensation, it is desirable to use less restrictive conditions which mean that larger classes of systems can be candled with a fixed or adaptive compensation controller. In this paper, a minimal necessary and sufficient condition for stable plant-model output matching is derived, with analytical proof, for two actuator failure models: failures with fixed or variant values. An adaptive control scheme is developed for systems with unknown dynamics parameters and actuator failure parameters including failure values, times and patterns.

Adaptive failure compensation for aircraft tracking control using engine differential based model

An aircraft model that incorporates independently adjustable engine throttles and ailerons is employed to develop an adaptive control scheme in the presence of actuator failures. This model captures the key features of aircraft flight dynamics when in the engine differential mode. Based on this model an adaptive feedback control scheme for asymptotic state tracking is developed and applied to a transport aircraft model in the presence of two types of failures during operation, rudder failure and aileron failure. Simulation results are presented to demonstrate the adaptive failure compensation scheme