The requirements for the control performances of space manipulators, especially stability and accuracy attitude systems base spacecrafts, are ever increasing during target capturing tasks. However, system uncertainties caused by parameter variations will degrade severely. This paper investigates precise fast trajectory tracking problem free-flying manipulator, after a with uncertain mass. To compensate uncertainty complex dynamics, novel adaptive sliding mode disturbance observer (ASMDO) is...

Multiple disturbances are the main constraints that hinder high-performance velocity tracking of gimbal servo system in control moment gyro. This article presents a non-cascade structured velocity-tracking controller based on refined disturbance observer for handling multiple and improve performance. Specifically, is designed to estimate imbalance disturbance, which can be represented by an exogenous system. The cannot modeled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML"...

This article proposes a safety control scheme for quadrotor unmanned aerial vehicle (UAV) to counteract ground effect and blade damage. The impacts of damage are quantitatively analyzed in the established model. proposed consists position attitude loops. Specifically, proportional derivative controller is designed as baseline with acceleration feedforward loop. A disturbance observer (DO) using measured Euler angles exploited estimate lumped forces. developed DO can effectively mitigate...

State estimation has long been a fundamental problem in signal processing and control areas. The main challenge is to design filters with ability reject or attenuate various disturbances. With the arrival of big data era, disturbances complicated systems are physically multi-source, mathematically heterogenous, affecting system dynamics via isomeric (additive, multiplicative, recessive) channels, deeply coupled each other. In traditional filtering schemes, multi-source heterogenous usually...

For a practical engineering system, disturbances usually have negative impact on system performance. Especially, when the physical constraints (e.g., actuator amplitude saturation and input channel constraint) are present, study for antidisturbance controllability (ADC) is of paramount importance. This article presents concepts disturbance estimability, compensability, an enhanced control (EADC). From viewpoint design, example spacecraft attitude given. The multiple explicitly analyzed sake...

High-precision and fast-response attitude control of launch vehicles plays an increasingly important role in numerous space missions, ensuring the efficiency transportation. However, disturbances caused by liquid sloshing external environments degrade performances seriously. Because complicated coupling with inputs angular acceleration, dynamics disturbance are highly uncertain. Therefore, it is urgent to develop novel estimation methods for thoroughly analyzing dynamics. In this paper,...

This brief investigates the high-precision trajectory tracking control of space manipulator after capturing an unknown target. The neutral uncertainty induced by parameter variation poses great challenges to controller design. Moreover, existence actuator deadzone nonlinearity makes situation more complicated. In order address aforementioned difficulties, a novel scheme is proposed in this brief. First, reduce conservativeness descriptions uncertainties, dynamic described uncertain system...

The rendezvous and proximity operations with respect to a tumbling non-cooperative target pose high requirement for the position attitude control accuracy of servicing spacecraft. However, multiple disturbances including parametric uncertainties, flexible vibration, unknown nonlinear dynamics degrade performance significantly. In order enhance system anti-disturbance ability, this paper proposes composite law spacecraft tracking. Firstly, relative dynamic models are established, where...

High-precision and safety control in face of disturbances uncertainties is a challenging issue both theoretical practical importance. In this article, new adaptive anti-disturbance schemes are proposed for class uncertain nonlinear systems with composite disturbances, including additive multiplicative actuator faults, implicit deeply coupled system states. Both the cases known unknown control/fault directions investigated. By properly fusing techniques disturbance observers compensation, it...

In this paper, a composite velocity-tracking control scheme is presented for improving dynamics response and accuracy of the flexible gimbal system in moment gyro (CMG). Specifically, an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H}_{\infty } $ </tex-math></inline-formula> optimal vibration controller (HOVC) developed to weigh multi-performance system, such as stability, fast-tracking performance,...

The high-precision and fast-response safety proximity control for servicing spacecrafts is affected by dynamic obstacle constraints multiple disturbances, such as actuator deviations flexible vibration. To address this challenge, an adaptive fixed-time disturbance observer (AFTDO)-based composite scheme proposed the to achieve effective avoidance position tracking. Because disturbances are coupled with system physical variables (e.g., input relative position) exhibit complicated dynamics,...

Abstract A wide range of practical control systems such as robot manipulators and spacecrafts can be modeled by Euler–Lagrange systems. On one hand, the requirements for system accuracy, response speed, robustness are ever increasing. other performances inevitably degraded multiple disturbances. In this paper, a novel finite‐time composite law is proposed class subject to heterogeneous disturbances including neutrally stable disturbance norm‐bounded disturbance. More specifically, refined...

The safety and high-precision attitude control of launch vehicles are threatened by degradation fault multiple disturbances (such as model uncertainty, uncertain inertia, external disturbance) during the reentry stage. To address these challenges, an adaptive sliding mode observer (ASMO)-based composite scheme is proposed in this article for to achieve simultaneous compensation suppression disturbances. Since mismatched uncertainty that coupled with system state exhibits strong ASMO designed...

The proportional-integral (PI) controller has proven to be a remarkably effective control strategy in the servo field. However, it is difficult for PI handle problem of multiple disturbances degrading velocity-tracking capability gimbal system moment gyro (CMG). In this article, we propose solution while preserving advantages from an engineering standpoint. Starting refined disturbance analysis based on 5 Nms CMG experimental tests, can classified according frequency distribution terms 0...

The high-precision alignment of spacecrafts subject to multiple composite disturbances [e.g., axle frictions and back electromotive force (EMF)] mandatory pointing constraints is an extremely challenging issue for both theoretically practically. To address this challenge, a refined deep coupled control scheme proposed in article. First, model spacecraft based on the dynamics reaction wheel actuator established, which reveals influence disturbances, such as EMF system, separates into...

Attaining microradian control accuracy within seconds is essential for the coarse pointing assembly (CPA) to establish and maintain intersatellite laser link under multiple disturbances. In response requirements challenges, this article proposed a fixed-time refined disturbance observer-based composite (FTRDOBC) scheme. First, periscope-type CPA model established, incorporating gimbal coupling torque, friction, satellite-transmitted vibration characterize operational environment. Second, by...

The actuator of attitude control system (ACS) plays an important role in providing the necessary torque for spacecraft missions, such as orbital maneuvering and high-precision stabilization. In complex space environment under long-term working loads, is more likely to degrade fail compared other components. This makes it significant assess its reliability state predict remaining useful life (RUL). To overcome drawback that traditional RUL prediction methods are based on indirect external...