Yajie Ma

Actuator failure compensation and attitude control for rigid satellite by adaptive control using quaternion feedback

Abstract The attitude control problem of a rigid satellite with actuator failure uncertainties and external disturbance is addressed using adaptive control method. A discontinuous adaptive failure compensation controller, using unit quaternion and angular velocities feedback, is designed to accommodate the external disturbance and actuator failures which are uncertain in time instants, values and patterns. A common approximate function is used to avoid system chattering caused by such discontinuous control laws. The parameters of external disturbance and failure uncertainties are estimated directly by adaptive laws, and the desired stability and output tracking properties of the adaptive control system are analyzed. Finally, simulation results of a rigid satellite with six reaction wheels are presented to illustrate the performance of the proposed adaptive actuator failure compensation scheme.

A direct adaptive actuator failure compensation scheme for satellite attitude control systems

A new direct adaptive failure compensation approach is developed for satellite attitude control systems in the presence of uncertain failures of redundant actuators. The adaptive failure compensation controller is designed via a backstepping design, which can accommodate uncertainties in actuator failure time instants, values, and patterns. The failure uncertainties are estimated directly by adaptive laws and the adaptive satellite attitude control system with actuator failures is analyzed, to show its desired stability and asymptotic tracking properties. Finally, simulation results of a satellite attitude control system with redundant reaction wheels are presented to demonstrate the effectiveness of the proposed adaptive failure compensation scheme.

Uncertainty decomposition-based fault-tolerant adaptive control of flexible spacecraft

A fault-tolerant adaptive control scheme is developed for attitude tracking of flexible spacecraft with unknown inertia parameters, external disturbance, and actuator faults. The uncertainties of flexibility and dynamics are parameterized, and the control gain matrix uncertainty is handled using an uncertainty decomposition. The control scheme, with adaptive laws of the overall system uncertain parameter estimates, guarantees the system stability and asymptotic attitude tracking properties. Simulation results illustrate the effectiveness of the proposed control scheme.

Adaptive actuator failure compensation design for spacecraft attitude control

An adaptive actuator failure and disturbance compensation scheme is developed for attitude tracking control of spacecraft. The proposed scheme consists of a composite parameter adaptation design that incorporates an adaptive backstepping feedback control law and an adaptive feedforward actuator failure compensator; it can guarantee the overall closed-loop system stability and asymptotic tracking. Illustrative simulation results of an application to a spacecraft model show that the designed actuator failure compensation controller ensures system stability and tracking performance.

Multiple-Model Adaptive Control for Spacecraft Under Sign Errors in Actuator Response

This paper addresses the attitude tracking control problem for spacecraft with unknown inertia parameters and sign errors in actuator response that are uncertain in occurring time instants and patterns. Either a software or hardware error may cause actuation sign errors, which may lead spacecraft to fail. A new multiple-model adaptive control scheme is developed to compensate the uncertainties of actuation sign errors and inertia parameters, which ensures the desired system global stability and asymptotic attitude tracking properties. Such a control scheme employs a set of adaptive estimators to generate parameter estimates, estimator states, and estimation errors, in which the uncertainties of inertia parameters are parameterized. Then, a set of control signals are designed by using such estimates and estimation errors, and a switching mechanism is established based on calculating multiple cost functions from the estimation errors to select the most appropriate control signal with the minimum cost functi...

Adaptive Actuator Failure Identification for Microsatellites Under Closed-Loop Control

This paper addresses the actuator failure identification problem of microsatellites in a stabilized feedback framework. An adaptive failure identification scheme is developed using multiple estimators and cost functions to identify the failed actuators for understanding vehicle health and protecting microsatellites. For the implementation of failure identification, an adaptive failure compensation scheme is developed using an uncertainty decomposition to guarantee the system stability and asymptotic tracking properties, and a special reference motion is also provided using a linearly independent condition. After some actuators have failed, both identification and control are applied, and the control, while stabilizing the system, makes the microsatellite engage in the provided special motion so that the failed actuators can be identified by the identification algorithm. Simulation results illustrate the effectiveness of the proposed adaptive failure identification and compensation schemes.

An adaptive actuator failure compensation scheme for spacecraft with unknown inertia parameters

An adaptive actuator failure compensation scheme is developed for attitude tracking control of a spacecraft with unknown inertia parameters. The proposed scheme employs a composite parameter adaptation design which incorporates an adaptive backstepping feedback control law and an adaptive feedforward actuator failure compensator and guarantees the overall closed-loop system stability and asymptotic tracking. A new feature of this adaptive control scheme is the adaptation of the failure pattern parameter estimates, together with that of the failure signal parameter estimates, for direct adaptive actuator failure compensation. Illustrative simulation results of an application to a spacecraft model show that the desired properties are achieved in the presence of the unknown inertia matrix and uncertain actuator failures.

Multiple-model based adaptive compensation of actuation sign uncertainty using an error transformation

This paper develops a new multiple-model based adaptive control scheme to compensate actuation sign uncertainty, which employs three steps: (1) design multiple estimators; (2) design multiple controllers using an error transformation relating to the output tracking error, the estimation error, and a virtual tracking error between the estimator state and the reference signal; and (3) design a control switching mechanism to select the most appropriate controller to generate the applied control signal. Such a control scheme is first deigned for single-degree of freedom bodies with a control gain that is unknown in both sign and magnitude, to introduce and illustrate this approach. Then, the full scheme is developed for three-axis rigid microsatellites with unknown inertia parameters and uncertain actuation signs. The proposed multiple-model based adaptive control scheme ensures the desired system stability and asymptotic tracking properties. Simulation results verify its effectiveness.

Adaptive failure identification for near space vehicles under closed-loop control

This paper develops an adaptive actuator failure identification scheme for near space vehicles (NSVs) in a stabilized feedback framework. For the implementation of failure identification, an adaptive failure compensation scheme is developed, and a special reference motion is provided by employing a linearly independent condition. When some actuators have failed, both identification and control are applied, and the control, while guaranteeing the system stability, makes NSVs engage in the designed reference motion so that the failed actuators can be found out by the failure identification algorithm. Simulation results verify the effectiveness of the proposed adaptive failure identification strategy.

Multiple-model control for spacecraft under actuation sign errors

This paper addresses the attitude tracking control problem of spacecraft in the presence of sign errors in actuator response which are uncertain in occurring time instants and patterns. Either a software or hardware fault may cause such an actuation sign error which will lead to the system instability even loss of spacecraft. A multiple-model control scheme, consisted of a bank of controllers and a control switching mechanism, is developed to compensate such actuation sign errors and to ensure the system stability and asymptotic attitude tracking properties. Simulation results are presented to verify the performance of the proposed multiple-model control scheme.