Design, Dynamics and Active Control of Micro Interferometers for Low Noise Parallel Operation

2008 ◽  
Author(s):  
Omkar Karhade ◽  
Levent Degertekin ◽  
Thomas Kurfess
Keyword(s):  
Noise Reduction ◽  
Range Of Motion ◽  
Active Control ◽  
Control Algorithm ◽  
Cutoff Frequency ◽  
Low Noise ◽  
Experimental Results ◽  
Ambient Vibration ◽  
Limited Range Of Motion ◽  
Tunable Gratings

Micromachined Scanning Grating Interferometer (μSGI) array offers a viable solution to the high resolution, large bandwidth, non-contact and high throughput metrology. Parallel active control of μSGIs is necessary to reduce the effect of positioning errors and ambient vibration noise. To achieve individual control of the μSGIs, the gratings in the μSGI are micromachined on Silicon membranes, which can be electrostatically actuated. These tunable gratings are designed to have sufficient range of motion (∼400nm) and sufficient bandwidth (∼50kHz) for effective noise reduction. The tunable gratings are fabricated successfully using Silicon on Insulator wafers with a two mask process. A novel recurrent calibration based control algorithm is designed to actively control the tunable gratings. The novel algorithm is implemented digitally using FPGA on an array of μSGIs simultaneously. The algorithm compensates for the non-linearities of the actuator and problem due to limited range of motion. A system model is built to design and analyze the control algorithm and is verified by experimental results. Experimental results show 100 times noise reduction at low frequencies and 6.5kHz noise reduction cutoff frequency. A resolution of 1×10−4 nmrms/√Hz is achieved by implementation of this algorithm on μSGI.

The Use of Damping Based Semi-Active Control Algorithms in the Mechanical Smart-Spring System

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Wander Gustavo Rocha Vieira ◽  
Fred Nitzsche ◽  
Carlos De Marqui
Keyword(s):  
Active Control ◽  
Control Algorithm ◽  
Control Strategies ◽  
Vibration Reduction ◽  
Flow Analysis ◽  
Coupled Systems ◽  
Control Technique ◽  
Control Algorithms ◽  
Control Techniques ◽  
Spring Mechanism

In recent decades, semi-active control strategies have been investigated for vibration reduction. In general, these techniques provide enhanced control performance when compared to traditional passive techniques and lower energy consumption if compared to active control techniques. In semi-active concepts, vibration attenuation is achieved by modulating inertial, stiffness, or damping properties of a dynamic system. The smart spring is a mechanical device originally employed for the effective modulation of its stiffness through the use of semi-active control strategies. This device has been successfully tested to damp aeroelastic oscillations of fixed and rotary wings. In this paper, the modeling of the smart spring mechanism is presented and two semi-active control algorithms are employed to promote vibration reduction through enhanced damping effects. The first control technique is the smart-spring resetting (SSR), which resembles resetting control techniques developed for vibration reduction of civil structures as well as the piezoelectric synchronized switch damping on short (SSDS) technique. The second control algorithm is referred to as the smart-spring inversion (SSI), which presents some similarities with the synchronized switch damping (SSD) on inductor technique previously presented in the literature of electromechanically coupled systems. The effects of the SSR and SSI control algorithms on the free and forced responses of the smart-spring are investigated in time and frequency domains. An energy flow analysis is also presented in order to explain the enhanced damping behavior when the SSI control algorithm is employed.

scholarly journals Ambient Vibration Tests of an Arch Dam with Different Reservoir Water Levels: Experimental Results and Comparison with Finite Element Modelling

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Sergio Vincenzo Calcina ◽  
Laura Eltrudis ◽  
Luca Piroddi ◽  
Gaetano Ranieri
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Water Levels ◽  
Arch Dam ◽  
Experimental Results ◽  
Ambient Vibration ◽  
Reservoir Water ◽  
Ambient Vibration Tests ◽  
Vibration Properties ◽  
Vibration Tests

This paper deals with the ambient vibration tests performed in an arch dam in two different working conditions in order to assess the effect produced by two different reservoir water levels on the structural vibration properties. The study consists of an experimental part and a numerical part. The experimental tests were carried out in two different periods of the year, at the beginning of autumn (October 2012) and at the end of winter (March 2013), respectively. The measurements were performed using a fast technique based on asynchronous records of microtremor time-series. In-contact single-station measurements were done by means of one single high resolution triaxial tromometer and two low-frequency seismometers, placed in different points of the structure. The Standard Spectral Ratio method has been used to evaluate the natural frequencies of vibration of the structure. A 3D finite element model of the arch dam-reservoir-foundation system has been developed to verify analytically determined vibration properties, such as natural frequencies and mode shapes, and their changes linked to water level with the experimental results.

Frequency Shaped Semi-Active Control for Magnetorheological Fluid-Based Vibration Control Systems

2013 ◽  
Author(s):  
Young-Tai Choi ◽  
Norman M. Wereley ◽  
Gregory J. Hiemenz
Keyword(s):  
Vibration Control ◽  
Control Systems ◽  
Active Control ◽  
Control Algorithm ◽  
Active Vibration Control ◽  
Control Algorithms ◽  
Model Parameters ◽  
Mr Fluid ◽  
Control Current ◽  
Active Vibration

Novel semi-active vibration controllers are developed in this study for magnetorheological (MR) fluid-based vibration control systems, including: (1) a band-pass frequency shaped semi-active control algorithm, (2) a narrow-band frequency shaped semi-active control algorithm. These semi-active vibration control algorithms designed without resorting to the implementation of an active vibration control algorithms upon which is superposed the energy dissipation constraint. These new Frequency Shaped Semi-active Control (FSSC) algorithms require neither an accurate damper (or actuator) model, nor system identification of damper model parameters for determining control current input. In the design procedure for the FSSC algorithms, the semi-active MR damper is not treated as an active force producing actuator, but rather is treated in the design process as a semi-active dissipative device. The control signal from the FSSC algorithms is a control current, and not a control force as is typically done for active controllers. In this study, two FSSC algorithms are formulated and performance of each is assessed via simulation. Performance of the FSSC vibration controllers is evaluated using a single-degree-of-freedom (DOF) MR fluid-based engine mount system. To better understand the control characteristics and advantages of the two FSSC algorithms, the vibration mitigation performance of a semi-active skyhook control algorithm, which is the classical semi-active controller used in base excitation problems, is compared to the two FSSC algorithms.

Comparison of Times of Synchronization of Chaotic Burke-Shaw Attractor with Active Control and Integer and Optimum Fractional-Order Pecaro Carroll Method

2021 ◽  
Author(s):  
Ali Durdu ◽  
Yılmaz Uyaroğlu
Keyword(s):  
Active Control ◽  
Fractional Order ◽  
Chaotic Attractor ◽  
Secure Communication ◽  
Chaotic Systems ◽  
Control Method ◽  
Initial Conditions ◽  
Data Communication ◽  
Experimental Results ◽  
Active Control Method

Abstract Many studies have been introduced in the literature showing that two identical chaotic systems can be synchronized with different initial conditions. Secure data communication applications have also been made using synchronization methods. In the study, synchronization times of two popular synchronization methods are compared, which is an important issue for communication. Among the synchronization methods, active control, integer, and fractional-order Pecaro Carroll (P-C) method was used to synchronize the Burke-Shaw chaotic attractor. The experimental results showed that the P-C method with optimum fractional-order is synchronized in 2.35 times shorter time than the active control method. This shows that the P-C method using fractional-order creates less delay in synchronization and is more convenient to use in secure communication applications.

Profile Measurement of a Curved Workpiece by the Fuzzy Control of Sensor Positioning

1999 ◽  
Author(s):  
Masatake Shiraishi ◽  
Gongjun Yang
Keyword(s):  
Fuzzy Control ◽  
Control Algorithm ◽  
Experimental Results ◽  
Measuring System ◽  
Displacement Sensor ◽  
Profile Measurement ◽  
Laser Displacement Sensor ◽  
Inclination Angles ◽  
Fuzzy Control Algorithm ◽  
Sensor Positioning

Abstract A laser displacement sensor which has a resolution of 0.5 μm was used to determine the measurement of a curved workpiece profile in turning. This sensor is attached to a specially designed stage and is operated by three motors which are controlled by a fuzzy control algorithm. The experimental results show that the measuring system can be applied to workpieces having inclination angles of up to around 45°. The proposed measuring system has a practical measuring accuracy to within ten micrometers.

Comparison of Noise Reduction Performance Evaluation Methods for Low-Noise Pavement in Korea- Part

2021 ◽  
Vol 263 (4) ◽  
pp. 2930-2939
Author(s):  
Byungchae Kim ◽  
Hyunjin Kim ◽  
Wonuk Kang
Keyword(s):  
Noise Reduction ◽  
Noise Level ◽  
Measurement Method ◽  
Road Traffic ◽  
Low Noise ◽  
Management Standards ◽  
Close Proximity ◽  
Porous Pavement ◽  
Reduction Effect ◽  
Measurement Location

In Korea, road noise is assessed as a measurement method of exterior noise emitted by road vehicle for management standards by the National Institute of Environmental Sciences. In this method, the noise felt at the actual pickup point is measured as LAeq (the roadside equivalent noise level). Recently, to clarify the standard for measuring noise on low-noise pavements, the CPX (ISO11819-2; Close-proximity method) was first introduced in the Porous Pavement Guidelines of the Ministry of Land, Infrastructure and Transport. According to ISO, the CPX adopts the side microphone as a mandatory measurement location, and the rear optional. The side location has been a mandatory due to its high correlation with SPB (ISO 11819-1, Statistical Pass-by method). However, according to our previous study on the correlation evaluation between L and CPX rear microphone noise level, both noise reduction effect was about 9-12 dB(A) showed a high correlation in Korea where heavy road traffic is common. The following study aims to show the consistent correlation between the L and CPX rear noise level. Furthermore, it is intended to be helpful in selecting the location of the CPX microphone that can most effectively represent the actual noise on the low-noise pavement in Korea.

Simulated Compensatory Motion of Transradial Prostheses

2008 ◽  
Author(s):  
Derek Lura ◽  
Rajiv Dubey ◽  
Stephanie L. Carey ◽  
M. Jason Highsmith
Keyword(s):  
Range Of Motion ◽  
Shoulder Joint ◽  
Degrees Of Freedom ◽  
Biomechanical Model ◽  
Elbow Flexion ◽  
Limited Range ◽  
Joint Movement ◽  
Range Of Movement ◽  
Limited Range Of Motion ◽  
Compensatory Motion

The prostheses used by the majority of persons with hand/arm amputations today have a very limited range of motion. Transradial (below the elbow) amputees lose the three degrees of freedom provided by the wrist and forearm. Some myoeletric prostheses currently allow for forearm pronation and supination (rotation about an axis parallel to the forearm) and the operation of a powered prosthetic hand. Older body-powered prostheses, incorporating hooks and other cable driven terminal devices, have even fewer degrees of freedom. In order to perform activities of daily living (ADL), a person with amputation(s) must use a greater than normal range of movement from other body joints to compensate for the loss of movement caused by the amputation. By studying the compensatory motion of prosthetic users we can understand the mechanics of how they adapt to the loss of range of motion in a given limb for select tasks. The purpose of this study is to create a biomechanical model that can predict the compensatory motion using given subject data. The simulation can then be used to select the best prosthesis for a given user, or to design prostheses that are more effective at selected tasks, once enough data has been analyzed. Joint locations necessary to accomplish the task with a given configuration are calculated by the simulation for a set of prostheses and tasks. The simulation contains a set of prosthetic configurations that are represented by parameters that consist of the degrees of freedom provided by the selected prosthesis. The simulation also contains a set of task information that includes joint constraints, and trajectories which the hand or prosthesis follows to perform the task. The simulation allows for movement in the wrist and forearm, which is dependent on the prosthetic configuration, elbow flexion, three degrees of rotation at the shoulder joint, movement of the shoulder joint about the sternoclavicular joint, and translation and rotation of the torso. All joints have definable restrictions determined by the prosthesis, and task.

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