Distributed Control of Truss Structures

2003 ◽  
Vol 9 (1-2) ◽  
pp. 7-23
Author(s):  
Sandrine Kevorkian ◽  
Madeleine Pascal
Keyword(s):  
Modal Analysis ◽  
Active Control ◽  
Distributed Control ◽  
Transfer Matrix ◽  
Closed Loop ◽  
Feedback Controller ◽  
Truss Structures ◽  
Flexible Beams ◽  
Performance Predictions

Continuous element methods have frequently been used in the modal analysis of structures modeled as flexible beams, extensible strings and rods, but only rarely for purposes of control. In this paper, we define a strategy of active control using the exact transfer matrix of a two-cell planar truss. The closed-loop performance predictions of both collocated and non-collocated controllers are compared as a function of feedback controller parameters.

Active Control of Multi-Mode Rotor-Bearing Systems Using HSFDs

1997 ◽  
Vol 119 (1) ◽  
pp. 49-56 ◽  
Author(s):  
J. P. Hathout ◽  
A. El-Shafei ◽  
R. Youssef
Keyword(s):  
Modal Analysis ◽  
Active Control ◽  
Closed Loop ◽  
Open Loop ◽  
Rotor System ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Multiple Modes ◽  
Inertia Effects ◽  
Modeling And Control

This paper summarizes the modeling and control of hybrid squeeze film dampers (HSFDs) for active control of vibration of rotors exhibiting multiple modes. In a recent paper (El-Shafei and Hathout, 1994), it was shown that the automatically controlled HSFD based on feedback on rotor speed can be a very efficient device for active control of rotor vibration. It was shown that this closed-loop, on-off control strategy results in a much improved behavior of the rotor system. The previous investigation was performed on a Jeffcott rotor model. The model was simple and fluid inertia effects were not taken into consideration. In this paper, major strides were made in both the modeling of the rotor and the HSFD. Modal analysis was implemented in the dynamic analysis of the squeeze film damper supported rotor in a novel and unique manner of performing modal analysis on nonlinear rotor systems. This allowed the modeling of any number of modes using modal analysis and hence to verify the capability of the HSFD to control multiple modes. Also, fluid inertia forces were considered in our model for the HSFD due to their direct influence in changing the behavior of the damper (El-Shafei and Crandall, 1991). A complete mathematical model of this open-loop system is developed and is implemented on a digital computer. Finally, based on the feedback on speed, the closed-loop behavior was studied from both steady-state and transient points of view and showed an overall enhanced behavior for the rotor system.

Feedback Control of Truss Structures With Distributed Flexibility

2001 ◽  
Author(s):  
Sandrine Kevorkian ◽  
Madeleine Pascal
Keyword(s):  
Feedback Control ◽  
Active Control ◽  
Closed Loop ◽  
Truss Structures ◽  
Actual System ◽  
Space Applications ◽  
Infinite Dimensional ◽  
The Past ◽  
Flexible Behavior ◽  
Flexible Arms

Abstract Among other applications, truss structures are used for space applications and several strategies of active control are studied, including recently the use of piezoelectric actuators. However, the standard method for designing active control of structures is to use modal approximation for distributed flexibility. The actual system is infinite-dimensional and the modes describing its flexible behavior depend on the feedback control. Very few attempts to use the continuous elements method for purposes of control were proposed in the past and concern only manipulators composed of one or two flexible arms. In this work, a strategy of active control using the exact transfer matrix of a two-cells planar truss is defined. Both collocated and non collocated control are considered. For both cases, the closed-loop pole locations are compared as a function of feedback controller parameters.

PI Control of HSFDs for Active Control of Rotor-Bearing Systems

1997 ◽  
Vol 119 (3) ◽  
pp. 658-667 ◽  
Author(s):  
J. P. Hathout ◽  
A. El-Shafei
Keyword(s):  
Vibration Control ◽  
Active Control ◽  
Closed Loop ◽  
Rotating Machinery ◽  
Loop System ◽  
Pi Control ◽  
Closed Loop System ◽  
Transient Vibration ◽  
Critical Speeds ◽  
Rotor Bearing

This paper describes the proportional integral (PI) control of hybrid squeeze film dampers (HSFDS) for active control of rotor vibrations. Recently it was shown that the automatically controlled HSFD based on feedback of rotor speed can be a very efficient device for active control of rotor vibration when passing through critical speeds. Although considerable effort has been put into the study of steady-state vibration control, there are few methods in the literature applicable to transient vibration control of rotor-bearing systems. Rotating machinery may experience dangerously high dynamic loading due to the sudden mass unbalance that could be associated with blade loss. Transient run-up and coast down through critical speeds when starting up or shutting down rotating machinery induces excessive bearing loads at criticals. In this paper, PI control is proposed as a regulator for the HSFD system to attenuate transient vibration for both sudden unbalance and transient runup through critical speeds. A complete mathematical model of this closed-loop system is simulated on a digital computer. Results show an overall enhanced behavior for the closed-loop rotor system. Gain scheduling of both the integral gain and the reference input is incorporated into the closed-loop system with the PI regulator and results in an enhanced behavior of the controlled system.

Schwingungsanalyse an Industrierobotern*/Vibration analysis of industrial robots

2019 ◽  
Vol 109 (09) ◽  
pp. 656-661
Author(s):  
A. Karim ◽  
C. Michalkowski ◽  
A. Lechler ◽  
A. Verl
Keyword(s):  
Modal Analysis ◽  
Active Control ◽  
Normal Mode ◽  
Vibration Analysis ◽  
Industrial Robots ◽  
Vibration Exciter ◽  
Dynamic Vibration ◽  
Vibration Behavior ◽  
Working Space ◽  
Electromagnetic Vibration

Dieser Beitrag untersucht experimentell das dynamische Schwingverhalten eines „KR-500–3 MT“ von Kuka mittels eines elektromagnetischen Schwingerregers (Shaker) an insgesamt 28 Messposen im Arbeitsraum. Diese Untersuchungsmethode ist neuartig, da die Ergebnisse mit einer Modalanalyse mit Impulshammeranregung verglichen werden. Ab der vierten Eigenmode entstehen Unterschiede aufgrund der Anregungsform. Zudem wird an jeder Pose eine Messung mit angezogener Motorbremse und eine mit aktiver Regelung durchgeführt und miteinander verglichen.   This paper explores experimentally the dynamic vibration behavior of a Kuka KR-500 MT, using an electromagnetic vibration exciter (shaker) on a total of 28 measuring poses in the working space. As such studies are not known, the results are compared to a modal analysis with impulse hammer excitation. Starting from the fourth normal mode, differences arise due to the form of excitation. Both measurements are performed and compared with each other on each pose with brakes applied as well as with active control.

Material Handling Throughput Using a Track Based Multihead Robot

Manufacturing ◽  
2002 ◽  
Author(s):  
Stephen J. Derby ◽  
John McFadden
Keyword(s):  
Control System ◽  
Distributed Control ◽  
Material Handling ◽  
Closed Loop ◽  
Distributed Control System ◽  
System Configuration ◽  
Drive Chain ◽  
Return Path ◽  
Loop Track

A novel closed loop track based multi-head robot has been developed to increase material handing throughput. This robot allows for waves of robot heads to move materials in the working path by eliminating the traditional return path. Programmable clutching of a constant moving drive chain supplies the source of motion around the loop. This paper discusses the design and impact of such a system configuration, and looks at the required distributed control system.

Combined Feedforward–Feedback Active Control of Road Noise Inside a Vehicle Cabin

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Jie Duan ◽  
Mingfeng Li ◽  
Teik C. Lim ◽  
Ming-Ran Lee ◽  
Ming-Te Cheng ◽  
...  
Keyword(s):  
Active Control ◽  
Feedforward Control ◽  
Reference Signal ◽  
Active Noise Control ◽  
Internal Model Control ◽  
Feedback Controller ◽  
Road Noise ◽  
Vehicle Cabin ◽  
Model Control ◽  
Fxlms Algorithm

Conventional active control of road noise inside a vehicle cabin generally uses a pure feedforward control system with the conventional filtered-x least mean square (FXLMS) algorithm. While it can yield satisfactory noise reduction when the reference signal is well correlated with the targeted noise, in practice, it is not always possible to obtain a reference signal that is highly coherent with a broadband response typically seen in road noise. To address this problem, an active noise control (ANC) system with a combined feedforward–feedback controller is proposed to improve the performance of attenuating road noise. To take full advantage of the feedforward control, a subband (SFXLMS) algorithm, which can achieve more noise attenuation over a broad frequency range, is used to replace the conventional FXLMS algorithm. Meanwhile, a feedback controller, based on internal model control (IMC) architecture, is introduced to reduce the road noise components that have strong response but are poorly correlated with the reference signals. The proposed combined feedforward–feedback ANC system has been demonstrated by a simulation model with six reference accelerometers, two control loudspeakers and one error microphone, using actual data measured from a test vehicle. Results show that the performance of the proposed combined controller is significantly better than using either a feedforward controller only or a feedback controller only, and is able to achieve about 4 dBA of overall sound pressure level reduction.

scholarly journals Nonlinear feedback controller for the synchronization of (chaotic) systems with known parameters

2020 ◽  
Vol 23 (02) ◽  
pp. 124-135
Author(s):  
Muhammad Haris ◽  
Muhammad Shafiq ◽  
Adyda Ibrahim ◽  
Masnita Misiran
Keyword(s):  
Closed Loop ◽  
Lyapunov Stability Theory ◽  
Feedback Controller ◽  
Control Signal ◽  
Stability And Convergence ◽  
Nonlinear Feedback ◽  
Nonlinear Part ◽  
Synchronization Errors ◽  
Novel Structure ◽  
Linear And Nonlinear

This paper proposes, designs, and analyses a novel nonlinear feedback controller that realizes fast, and oscillation free convergence of the synchronization error to the equilibrium point. Oscillation free convergence lowers the failure chances of a closed-loop system due to the reduced chattering phenomenon in the actuator motion, which is a consequence of low energy sm ooth control signal. The proposed controller has a novel structure. This controller does not cancel nonlinear terms of the plant in the closed-loop; this attribute improves the robustness of the loop. The controller consists of linear and nonlinear parts; each part executes a specific task. The linear term in the controller keeps the closed-loop stable, while the nonlinear part of the controller facilitates the fast convergence of the error signal to the vicinity of the origin. Then the linear controller synthesizes a smooth control signal that moves the error signals to zero without oscillations. The nonlinear term of the controller does not contribute to this synthesis. The collaborative combination of linear and nonlinear controllers that drive the synchronization errors to zero is innovative. The paper establishes proof of global stability and convergence behavior by describing a detailed analysis based on the Lyapunov stability theory. Computer simulation results of two numerical examples verify the performance of the proposed controller approach. The paper also provides a comparative study with state-of-the-art controllers.

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