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Co-simulation for adaptive vibration isolation system with the piezoelectric stack actuator is done by employing ADAMS and SIMULINK. The structure and properties of the piezoelectric stack actuator is analyzed, and the actuator is simplified to the stiffness-damping model to obtain the mechanical equation. Then the virtual prototype of the piezoelectric stack actuator is established in ADAMS, meanwhile,...
In order to accommodate actuator failures which are uncertain in time, pattern and value, the finite-time stable nonsmooth control method is applied to suppress the vibration, which overcomes the shortcomings of the traditional control method neglecting the influence of actuator. According to theory of Lyapnov stability, the designed control method is proved that can realize the stability of building...
This study is concerned with the circular orbital spacecraft rendezvous by the delayed output feedback (DOF). Considering that the rendezvous system is subjected to actuator delay and the relative velocity is difficult to be measured actually in practice, the DOF controller is constructed by just using the present and past inputs and outputs to predict the future state, which is then used to form...
This paper proposes a novel dynamics model of the twisted and coiled polymer actuator (TCPA) which is one of the artificial muscles recently discovered. It can be driven by Joule heating and can contract up to 25%. Most of the conventional works employed the linear model of TCPA which represents the relationships between the input voltage, the temperature, and the displacement, but the real TCPA shows...
Micro/nano-manipulation systems have been developed and utilized for decades due to their irreplaceable roles in fields such as MEMS/NEMS fabrication and biological studies. Generally, the motion precision of a micro/nano-manipulator highly depends on its actuator, whose performance can be enhanced by proper control strategies. To design satisfactory controllers, an accurate plant model is ideal....
A fault detection, identification, estimation and state estimation (FDIESE) problem involves joint decision and estimation (JDE). Decision contains detection and identification, while estimation is for fault severeness and system state. Both detection and identification are highly coupled with estimation and a fault is identified after detection. To solve this problem, an approach named nested joint...
With advent of wireless standards for real-time control, such as WirelessHART and ISA100.11a, Wireless Control Systems (WCSs) have been widely deployed in many application areas. However, due to limited bandwidth, the reliability of transmission is still a problem, which directly deteriorates control performance. In this paper, we consider a WirelessHART network consisting of multiple actuators and...
In this work, an adaptive fault tolerant control method is proposed to address the problem of attitude tracking for stratospheric airship with both multiplicative and additive actuator faults. Input saturation for control surfaces are also considered and an auxiliary system is designed to deal with the saturation. Both multiplicative and additive actuator faults are estimated by a specific adaption...
Adaptive structures are engineering structures with the ability to modify their response to external loads. This includes active damping of externally induced vibrations. The controller design is usually based on reduced order models that comprise the most important vibration modes of the structure. This can lead to unwanted excitation of the neglected modes, known as control spillover. One means...
This paper presents the design, mathematical model, and evaluation of a novel variant of a variable stiffness actuator. The actuator combines a cam and a variable lever mechanism. The lever length changes through the rotation of the follower and results in the change of the mechanism stiffness. The design of the actuator results in a nearly linear torque-deflection characteristic, earning it its name:...
A novel modified Preisach model is proposed to identify and simulate the hysteresis phenomena observed in a piezoelectric stack actuator. Further, an open-loop controller is incorporated to eliminate hysteresis influence. The proposed approach with a continuous, analytical distribution function performs very well when considering the low amount of parameters. In contrast to the classical and discrete...
This paper presents the mechanical design of a novel 3-PSS (P and S represent the prismatic and spherical joints, respectively) parallel-kinematic flexure nanopositioning stage. This stage provides a high-precision motion driven by three piezoelectric actuators. By employing the compound displacement amplifier and 3-PSS parallel mechanism, the flexure nanopositioning stage can deliver two rotational...
In this paper, cyber physical system is analyzed from security perspective. A double closed-loop security control structure and algorithm with defense functions is proposed. From this structure, the features of several cyber attacks are considered respectively. By this structure, the models of information disclosure, denial-of-service (DoS) and Man-in-the-Middle Attack (MITM) are proposed. According...
Aiming at the nonlinear transmission problem resulting from movement conversion of line transmission products in aircraft electric serve system, in order to define the serve system states all the time, and then improve the precision of the mathematical model. With fork structure and rocker arm structure as the research objects, firstly, applying speed synthesis theory and structure force balance theory,...
This article describes the design and characterization of a new dual-stage, three-axis hybrid parallel-serial-kinematic nanopositioner; this platform incorporates a novel non-orthogonal mechanical amplifying mechanism for the long-range low-speed stage to mitigate parasitic motion in the lateral scanning directions. A five-bar linkage model is proposed to model the cross-coupling effects of the long-range...
Inflatable manipulators open new trends in robotic applications. In this paper, a new inflatable actuator to articulate a long-range inflatable robotic arm, is presented. Completely made of high strength fabric, its low mass leads to large force-weight ratios and a stroke almost equal to twice its overall length. The operation principle, as well as the relations among the displacement, the pressure...
Single-winged rotating aerial vehicles such as monocopters have recently gained popularity, due to the development of small and powerful mechanical actuators and lightweight electronic sensors. Even though monocopters have to rely on their single wings for the total lift generation, few have looked into an efficient wing design for monocopters. In this paper, a chordwise optimization of wing design...
Reaction wheel assembly (RWA) is an attitude control actuator for spacecraft. Its induced micro vibration will have a harsh effect on the performance of sensitive payloads. In this paper, a compact four-legged vibration isolation system for RWA is designed and investigated. Piezoelectric stack actuators (PSA) are chosen and dynamic equations are derived by Newton-Euler approach. Moreover, to identify...
This paper describes an analytical study undertaken on an electromagnetic actuator design with a displacement amplification mechanism by explaining the physical modeling and formulizing the actuation time of the actuator in terms of physical model variables. This is followed by an experimental investigation on the actuation time of the electromagnetic actuator. Increasing the gap between the electromagnet...
This paper proposes the modeling and control design of an electro-hydraulic actuator for the variable-geometry suspension system. The purpose of this novel suspension type is to guarantee trajectory tracking through the variation of the camber angle. The motion of the wheel is realized by the electro-hydraulic actuator, whose elements are the cylinder and the electric valve. Thus, the trajectory tracking...
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