Autonomous assembly with collision avoidance of a fleet of flexible spacecraft based on disturbance observer

In this paper, a composite attitude control approach for orbiting spacecraft with rigid central hubs and flexible appendages is presented. The established attitude control model consists of the vibration modes excited by the rigid body, the space environment disturbances, the measurement noises, and the model uncertainty. The model is formulated into a dynamic system with two types of disturbance inputs. A composite control law with the simultaneous disturbance attenuation and rejection performance is presented for the flexible spacecraft system subject to multiple disturbances. The disturbance-observer-based control is designed for feedforward compensation of the elastic vibration. The H∞ state-feedback controller is designed to perform the robust attitude control in the presence of the space environment disturbances, measurement noises, and the model uncertainty. Numerical simulations show that the performance of the attitude control systems can be improved by combining the disturbance observer with H∞ state-feedback control.

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A fast finite-time convergent guidance law with nonlinear disturbance observer for unmanned aerial vehicles collision avoidance

Aerospace Science and Technology ◽

10.1016/j.ast.2019.01.021 ◽

2019 ◽

Vol 86 ◽

pp. 204-214 ◽

Cited By ~ 12

Author(s):

Ning Zhang ◽

Wendong Gai ◽

Maiying Zhong ◽

Jing Zhang

Keyword(s):

Unmanned Aerial Vehicles ◽

Collision Avoidance ◽

Finite Time ◽

Disturbance Observer ◽

Nonlinear Disturbance Observer ◽

Guidance Law ◽

Aerial Vehicles ◽

Nonlinear Disturbance

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Extended harmonic disturbance observer-based attitude control for flexible spacecraft with control moment gyroscopes

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410019842503 ◽

2019 ◽

Vol 233 (14) ◽

pp. 5331-5346

Author(s):

Liya Huang ◽

Zhong Wu

Keyword(s):

Attitude Control ◽

Disturbance Observer ◽

Wide Frequency Range ◽

Flexible Spacecraft ◽

Space Environment ◽

Harmonic Model ◽

External Disturbances ◽

Control Moment ◽

Control Moment Gyroscopes ◽

Rotor Dynamic

In the flexible spacecraft with control moment gyroscopes, there are multiple disturbances including not only internal disturbances from actuators and flexible appendages, but also external disturbances from space environment. These disturbances are characterized by a wide frequency range and may degrade attitude control performance to a great extent. In this paper, the lumped disturbance is modeled as a harmonic plus a polynomial model, and an extended harmonic disturbance observer (EHDO) is proposed to estimate the total disturbance. Since the rotor dynamic imbalance disturbance from control moment gyroscopes is described by an internal harmonic model, the lumped disturbance can be estimated precisely via EHDO even with a lower bandwidth. Afterwards, a backstepping-based composite controller is designed to compensate the disturbances by combining the output of EHDO and realize high-precision attitude control for flexible spacecraft with control moment gyroscopes. Simulation results are presented to demonstrate the effectiveness of the proposed method.

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