scholarly journals COMPARE THE EFFICIENCY OF CONTROLLED STIFFNESS DAMPER WITH VARIABLE FRICTION DAMPER FOR SEISMIC PROTECTION OF BUILDING

2009 ◽  
Vol 12 (8) ◽  
pp. 81-89
Author(s):  
Phuc Quang Bao Nguyen ◽  
Hoa Nhan Pham ◽  
Thang Quoc Chu
Keyword(s):  
Control Method ◽  
Seismic Protection ◽  
Control Law ◽  
Modal Control ◽  
Clamping Force ◽  
Friction Damper ◽  
Vibration Mitigation ◽  
Friction Dampers ◽  
Advantages And Disadvantages ◽  
Variable Friction

The implementation of variable friction dampers (VFD) for vibration mitigation of seismic structures generally requires an efficient semi-active control law. In this paper, a semi-active modal control method is proposed to determine the controllable clamping force of a variable friction damper. A comparative study was performed on a multiple DOF structure controlled by passive friction dampers, variable friction dampers in subsection numerical examples. Finally, this paper also provides preliminary conclusions about the advantages and disadvantages for friction dissipators.

scholarly journals THE USE OF MOBILE CONTROL METHODS FOR STABILIZATION OF A SPACECRAFT WITH AEROMAGNETIC DEORBITING SYSTEM

2019 ◽  
Vol 6 (125) ◽  
pp. 41-54
Author(s):  
Anatolii Alpatov ◽  
Erik Lapkhanov
Keyword(s):  
Executive Control ◽  
Permanent Magnets ◽  
Control Method ◽  
Electrical Energy ◽  
Angular Motion ◽  
Control Law ◽  
Control Methods ◽  
Advantages And Disadvantages ◽  
Electromagnetic Control ◽  
Control Devices

The search for optimal control algorithms for spacecrafts is one of the key areas in rocket and space technology. Taking into account certain restrictions and requirements in a specific space mission, the selection of certain executive devices of the spacecraft is carried out and the corresponding control law is synthesized. One of such space missions is the providing of angular motion stabilization of a utilized spacecraft with aeromagnetic deorbiting system. The stabilization of spacecraft angular motion is needed for the orientation of aerodynamic element perpendicular to the vector of atmosphere dynamic flux with the aim of increasing of aerodynamic braking force. In this mission, the main optimization criterion is the minimization of the on-board electrical energy consumption which is needed for the control of angular motion. The original construction of the aeromagnetic deorbiting system consists of aerodynamic flat sails element and executive control devices with permanent magnets. However, not all spacecraft can be equipped with additional executive control devices with permanent magnets. That’s why with the aim of expansion of aeromagnetic deorbiting system application, using extra source of electromagnetic control executive devices is proposed in this research.The purpose of the article is the search of the control law which provides minimal consumption of electrical on-board energy by electromagnetic control executive devices during long-term deorbiting mission. For satisfying this criterion of optimization using of mobile control methods to orientate the spacecraft with aeromagnetic deorbiting system are proposed in this investigation. Computer modeling of orbital motion of spacecraft with aeromagnetic deorbiting system show the efficiency of using proposed mobile methods for angular motion control which realized by electromagnetic devices – magnetorquers. It has been showed that because of using mobile control method consumption of on-board electrical energy significantly less than with classical approach. The advantages and disadvantages have been determined.

scholarly journals Numerical evaluation of a novel passive variable friction damper for vibration mitigation

2020 ◽  
Vol 220 ◽  
pp. 110920
Author(s):  
Vahid Barzegar ◽  
Simon Laflamme ◽  
Austin Downey ◽  
Meng Li ◽  
Chao Hu
Keyword(s):  
Numerical Evaluation ◽  
Friction Damper ◽  
Vibration Mitigation ◽  
Variable Friction

Optimization of Interblade Friction Damper Design

2000 ◽  
Author(s):  
Lars Panning ◽  
Walter Sextro ◽  
Karl Popp
Keyword(s):  
Equations Of Motion ◽  
Turbine Blades ◽  
Relative Displacement ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Computation Method ◽  
Friction Damper ◽  
Friction Dampers ◽  
Advantages And Disadvantages ◽  
Bladed Disk

The vibration amplitudes of bladed disk assemblies can be reduced significantly by means of friction damping devices such as shrouds, damping wires and interblade friction dampers. In practice, interblade friction dampers are applied in rotating arrangements with various geometries showing curved or flat surfaces like so-called wedge-shaped dampers. This paper is focusing on a computation method to predict the dynamical behaviour of turbine blades with friction dampers including both, curved and wedge-shaped dampers with Hertzian and non-Hertzian contact conditions, respectively. The presented computation method uses a 3D contact model to calculate the contact forces, including normal and tangential stiffnesses, roughness and microslip effects. The relative displacements in the contact area can be expressed by means of 6 DOF of the blade platforms and 6 rigid body DOF of the damper including translational and rotational displacements. The relative displacement of the friction damper with respect to the adjacent blades can be derived from the contact kinematics of the blade-damper-blade system and the equations of motion of the friction damper. Thus, the model can be applied to investigate spatial motions of the bladed disk assembly including bending and torsional vibrations. A comparison of different friction damper designs with respect to an optimal damper geometry and damper mass is presented. The advantages and disadvantages of each design will be discussed. Experimental results are shown to validate the developed computation method.

scholarly journals Disturbance compensation-based output feedback adaptive control for shape memory alloy actuator system

2021 ◽  
Vol 18 (1) ◽  
pp. 172988142199399
Author(s):  
Xiaoguang Li ◽  
Bi Zhang ◽  
Daohui Zhang ◽  
Xingang Zhao ◽  
Jianda Han
Keyword(s):  
Adaptive Control ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Control Method ◽  
Control Law ◽  
Reference Trajectory ◽  
Disturbance Compensation ◽  
Comparison Results ◽  
Control Scheme ◽  
Actuator System

Shape memory alloy (SMA) has been utilized as the material of smart actuators due to the miniaturization and lightweight. However, the nonlinearity and hysteresis of SMA material seriously affect the precise control. In this article, a novel disturbance compensation-based adaptive control scheme is developed to improve the control performance of SMA actuator system. Firstly, the nominal model is constructed based on the physical process. Next, an estimator is developed to online update not only the unmeasured system states but also the total disturbance. Then, the novel adaptive controller, which is composed of the nominal control law and the compensation control law, is designed. Finally, the proposed scheme is evaluated in the SMA experimental setup. The comparison results have demonstrated that the proposed control method can track reference trajectory accurately, reject load variations and stochastic disturbances timely, and exhibit satisfactory robust stability. The proposed control scheme is system independent and has some potential in other types of SMA-actuated systems.

Robust adaptive tracking control for uncertain nonholonomic mobile manipulator

2021 ◽  
pp. 095965182110277
Author(s):  
Abdelkrim Brahmi ◽  
Maarouf Saad ◽  
Brahim Brahmi ◽  
Ibrahim El Bojairami ◽  
Guy Gauthier ◽  
...  
Keyword(s):  
Control Method ◽  
Sliding Mode ◽  
Robust Adaptive Control ◽  
Convergence Time ◽  
Adaptive Sliding Mode Control ◽  
Mobile Manipulator ◽  
Control Law ◽  
Adaptive Tracking Control ◽  
Robust Adaptive ◽  
Manipulator Robot

In the research put forth, a robust adaptive control method for a nonholonomic mobile manipulator robot, with unknown inertia parameters and disturbances, was proposed. First, the description of the robot’s dynamics model was developed. Thereafter, a novel adaptive sliding mode control was designed, to which all parameters describing involved uncertainties and disturbances were estimated by the adaptive update technique. The proposed control ensures a relatively good system tracking, with all errors converging to zero. Unlike conventional sliding mode controls, the suggested is able to achieve superb performance, without resulting in any chattering problems, along with an extremely fast system trajectories convergence time to equilibrium. The aforementioned characteristics were attainable upon using an innovative reaching law based on potential functions. Furthermore, the Lyapunov approach was used to design the control law and to conduct a global stability analysis. Finally, experimental results and comparative study collected via a 05-DoF mobile manipulator robot, to track a given trajectory, showing the superior efficiency of the proposed control law.

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