Active damping of rotating platforms using integral force feedback

peer reviewedThis paper investigates the use of Integral Force Feedback (IFF) for the active damping of rotating mechanical systems. Guaranteed stability, typical benefit of IFF, is lost as soon as the system is rotating due to gyroscopic effects. To overcome this issue, two modifications of the classical IFF control scheme are proposed. The first consists of slightly modifying the control law while the second consists of adding springs in parallel with the force sensors. Conditions for stability and optimal parameters are derived. The results reveal that, despite their different implementations, both modified IFF control scheme have almost identical damping authority on the suspension modes

Designing negative derivative feedback controller based on maximum damping and H 2method

peer reviewedIn this paper, a straightforward procedure is presented for optimal design of negative derivative feedback (NDF) controller with maximum damping and H2 optimization method. NDF is a controller, which works as a band-pass filter, cutting off the control action far from the natural frequencies associated with the controlled modes and reducing spillover effect. Since it is a bandpass filter, it can effectively control the lower or higher frequency disturbances. It is also implementable on vibration mitigation applications with high performance. For this end, a simple one degree of freedom system is considered and afterward, the controller parameters are extracted dependent on closed loop damping. The H2 method is used to calculate the optimal value of closed loop damping. The effect of changing the controller parameters on the system response are evaluated and discussed in detail. Also, the control effort for various closed loop damping has been calculated and compared with performance index of controller. A detailed comparison between performance and control effort are also presented. The results show high impact of NDF controller on vibration mitigation and its applicability to employ on various systems

Optimal negative derivative feedback controller design for collocated systems based on H2 and H∞ method

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Active Damping of Rotating Platforms using Integral Force Feedback

This paper investigates the use of Integral Force Feedback (IFF) for the active damping of rotating mechanical systems. Guaranteed stability, typical benefit of IFF, is lost as soon as the system is rotating due to gyroscopic effects. To overcome this issue, two modifications of the classical IFF control scheme are proposed. The first consists of slightly modifying the control law while the second consists of adding springs in parallel with the force sensors. Conditions for stability and optimal parameters are derived. The results reveal that, despite their different implementations, both modified IFF control scheme have almost identical damping authority on suspension modes

Determination of optimal sensor-actuator position for active vibration damping in collocated SISO systems using a pole-zero distance criterion for fast convergence of the search algorithm

The position of the transducers in active control architectures is critical to ensure the performance and has consequently been studied during the last few decades. However, the placement criteria often require the use of extensive search algorithms that demand numerous iterations, leading to prohibitive computational time for large and/or complex structures. To overcome this limitation, this paper investigates the use of the pole-zero (PZ) distance placement criterion as the starting point for a simple gradient algorithm. This open-loop criterion is based on the direct link between the PZ distance and the maximum reachable damping: the obtained position locates in the vicinity of a high damping area which ensures the convergence of the search algorithm, for fewer iterations. A numerical simulation is performed to assess the performance of the proposed approach and compared to a genetic algorithm optimization. A significant reduction of the processing time is observed while the solution shows an improved robustness to transducers misplacement

Mechatronics Approach for the Development of a Nano-Active-Stabilization-System

With the growing number of fourth generation light sources, there is an increased need of fast positioning end-stations with nanometric precision. Such systems are usually including dedicated control strategies, and many factors may limit their performances. In order to design such complex systems in a predictive way, a mechatronic design approach also known as "model based design", may be utilized. In this paper, we present how this mechatronic design approach was used for the development of a nano-hexapod for the ESRF ID31 beamline. The chosen design approach consists of using models of the mechatronic system (including sensors, actuators and control strategies) to predict its behavior. Based on this behavior and closed-loop simulations, the elements that are limiting the performances can be identified and re-designed accordingly. This allows to make adequate choices concerning the design of the nano-hexapod and the overall mechatronic architecture early in the project and save precious time and resources. Several test benches were used to validate the models and to gain confidence on the predictability of the final system's performances. Measured nano-hexapod's dynamics was shown to be in very good agreement with the models. Further tests should be done in order to confirm that the performances of the system match the predicted one. The presented development approach is foreseen to be applied more frequently to future mechatronic system design at the ESRF.NAS

Einstein Telescope Euregio-Meuse-rhin Site and Technology

Presentation of the E-TEST and SILENT projects, covering the development of a high-resolution optical accelerometer, a 6-D inertially controlled isolation system and a high-performance Absolute Quantum Gravimeter

Optically targeted search for gravitational waves emitted by core-collapse supernovae during the first and second observing runs of advanced LIGO and advanced Virgo

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Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network

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