Filter Hardware Research Articles

Effective active vibration control of single link flexible manipulator with modified positive position feedback control in the presence of instrumentation phase lead/lag

Accurate trajectory regulation of flexible link manipulators is a challenging task. The presence of hardware filters with the cut-off frequency near the resonant frequency cause an additional closed loop instability problem in the control system. This problem can be solved using modified Kalman filters along with certain hardware circuits called compensators. A linear quadratic Gaussian controller has been used to control the hub position. A positive position feedback (PPF) controller has been used at the piezoelectric actuators at the flexible link in the present work to minimize the end-effector vibrations. Normally the design parameters (i.e. coefficients of the numerator and denominator polynomial) of the PPF controller are selected by hit and trial. Pattern search technique has been used as an efficient design method to design these controllers which otherwise have no systematic way to design.

The Lightning Current Measurement Based on Wavelet Transform

The current model of the lightning process is established and simulated in this article, and aiming at the disadvantage that the hardware filtering de-noising method adopted in the general lightning measurement system can not effectively separate signals and noises in same one frequency channel, this article uses the wavelet transform to replace the usual hardware filtering method in the lightning measurement system in order to overcome the disadvantage, and simulate this method. The result shows that this method is feasible and effective, with certain theoretical and practical values.

On the Potential of Least Squares Response Method for the Calibration of Superconducting Gravimeters

One of the most important operating procedures after the installation of a superconducting gravimeter (SG) is its calibration. The calibration process can identify and evaluate possible time variability in the scale factor and in the hardware anti-aliasing filter response. The SG installed in Cantley, Canada is calibrated using two absolute gravimeters and the data are analysed in the time and frequency domains to estimate the SG scale factor. In the time domain, we use the weighted linear regression method whereas in the frequency domain we use the least squares response method. Rigorous statistical procedures are applied to define data disturbances, outliers, and realistic data noise levels. Using data from JILA-2 and FG5-236 separately, the scale factor is estimated in the time and frequency domains as−78.374±0.012 μGal/V and−78.403±0.075 μGal/V, respectively. The relative accuracy in the time domain is 0.015%. We cannot identify any significant periodicity in the scale factor. The hardware anti-aliasing filter response is tested by injecting known waves into the control electronics of the system. Results show that the anti-aliasing filter response is stable and conforms to the global geodynamics project standards.

Comparison between the image qualities obtained with low energy high-resolution (LEHR) and LEGP collimators in single-photon emission computed tomography (SPECT) under implementation of different filters

The aim of a single-photon emission computed tomography (SPECT) filter is to use the sharpest filter/smooth combination consistent with getting quality images. Fourier filtering technique has been shown to greatly improve image quality in both the spatial and temporal domain. An optimal filter manipulates the image in such a way that the image quality is enhanced without losing the basic components of the input object. Many filters have been developed to recover resolution and suppress noise. Thus, the question of theoptimal filter selection has been the subject of this investigation. The selection of proper collimator in many application of SPBCT will contribute to optimal image quality and quantitative information within the characteristics of the imaging equipment. In this study, we compared the results obtained by utilization of low energy high-resolution (LEHR) and low energy general-purpose (LEGP) collimators, under implementation of various filters, to show effect of hardware and software filters on the image quality, and capability of mathematical tools to compensate for the hardware flaw. Key words: Single-photon emission computed tomography (SPECT), filter, low energy high-resolution (LEHR) collimator, low energy general-purpose (LEGP).

Design and Development of the Stiffness Test System for Car Body Based on Multifunction Data Acquisition Device

Based on the computer and multifunction data acquisition device, the stiffness test system for car body was developed by using Microsoft Visual Studio.Net 2008, which could manage the test process, test the stiffness automatically according to the test process, manage the template of test report, generate the test report automatically and etc. The high precision displacement transducer and the high accuracy multifunction data acquisition device were used to realize precise test of car body. In order to improve system reliability and test accuracy, the method including opt electric isolating, software and hardware filtering has been used. By practical application, it is proved that this system has some advantages such as high test precision, high test efficiency, and convenient operation.

손가락 동작과 힘 추정 시스템

This presents a motion and force estimation system of human fingers by using an Electromyography (EMG) sensor module and a data glove system to be proposed in this paper. Both EMG sensor module and data glove system are developed in such a way to minimize the number of hardware filters in acquiring the signals as well as to reduce their sizes for the wearable. Since the onset of EMG precedes the onset of actual finger movement by dozens to hundreds milliseconds, we show that it is possible to predict the pattern of finger movement before actual movement by using the suggested system. Also, we are to suggest how to estimate the grasping force of hand based on the relationship between RMS taken EMG signal and the applied load. Finally we show the effectiveness of the suggested estimation system through several experiments.

Trajectories in parallel optics

In our previous work we showed the ability to improve the optical system's matrix condition by optical design, thereby improving its robustness to noise. It was shown that by using singular value decomposition, a target point-spread function (PSF) matrix can be defined for an auxiliary optical system, which works parallel to the original system to achieve such an improvement. In this paper, after briefly introducing the all optics implementation of the auxiliary system, we show a method to decompose the target PSF matrix. This is done through a series of shifted responses of auxiliary optics (named trajectories), where a complicated hardware filter is replaced by postprocessing. This process manipulates the pixel confined PSF response of simple auxiliary optics, which in turn creates an auxiliary system with the required PSF matrix. This method is simulated on two space variant systems and reduces their system condition number from 18,598 to 197 and from 87,640 to 5.75, respectively. We perform a study of the latter result and show significant improvement in image restoration performance, in comparison to a system without auxiliary optics and to other previously suggested hybrid solutions. Image restoration results show that in a range of low signal-to-noise ratio values, the trajectories method gives a significant advantage over alternative approaches. A third space invariant study case is explored only briefly, and we present a significant improvement in the matrix condition number from 1.9160e+013 to 34,526.

Energy reduction techniques for H.264 deblocking filter hardware

In this paper, we propose pixel equality and pixel similarity based techniques for reducing the amount of computations performed by H.264 Deblocking Filter (DBF) algorithm, and therefore reducing the energy consumption of H.264 DBF hardware. These techniques avoid unnecessary calculations in H.264 DBF algorithm by exploiting the equality and similarity of the pixels used in DBF equations. The proposed techniques reduce the amount of addition and shift operations performed by H.264 DBF algorithm up to 52% and 67% respectively with a small comparison overhead. The pixel equality based technique does not affect PSNR. The pixel similarity based technique does not affect the PSNR for some video frames, but it decreases the PSNR slightly for some video frames. We also implemented an efficient H.264 DBF hardware including the proposed techniques using Verilog HDL. The proposed pixel equality and pixel similarity based techniques reduced the energy consumption of this H.264 DBF hardware up to 35% and 39%, respectively. Therefore, they can be used in portable consumer electronics products that require real-time video compression.

Development of ECG beat segmentation method by combining lowpass filter and irregular R–R interval checkup strategy

We have developed a long-term cardiorespiratory sensor system that includes a wearable sensor probe with adaptive hardware filters and data processing algorithms ( Choi & Jiang, 2006, 2008). However, the data processing algorithm proposed for the R–R interval (RRI) information extraction did not work well in the case of ECG signals with baseline shifts or muscle artifacts. Furthermore, many false ECG beats were extracted due to a weak decision-making scheme. Then, those false beats produced irregular RRI information and erroneous heart rate variability results. Modification of data processing algorithm was strongly needed. Therefore, this work presented an efficient ECG beat segmentation method using an irregular RRI checkup strategy into five sequential RRI patterns. This algorithm was comprised of signal processing stage and ECG beat detector stage. The signal processing included the wavelet denoising, the baseline shift elimination by 20 Hz lowpass filter and the envelope curve extraction by a single degree of freedom analytical model. The ECG beat detector included the candidate ECG beat detection and segmentation by one threshold and by irregular RRI checkup strategy, respectively. In particular, four abnormal RRI patterns were proposed to find out false ECG beats. The MIT-BIH arrhythmia database was selected as the dataset for testing the proposed algorithm. The proposed irregular RRI checkup strategy estimated 5463 beats to the suspected false beats and succeeded in segmenting 96.19% (5255 beats) of them. The performance results showed that our algorithm had very good results such as the detection error of 0.54%, sensitivity of 99.66% and positive predictivity of 99.80%. Furthermore, our algorithm showed very high accuracy as the mean time error between the beat annotations of the database and our obtained beat occurence times was 7.75 ms.

A MEG investigation of cortical and subcortical networks involved in human voluntary saccades and smooth pursuit eye movements

Event Abstract Back to Event A MEG investigation of cortical and subcortical networks involved in human voluntary saccades and smooth pursuit eye movements Andreas A. Ioannides1*, Peter B. Fenwick1 and Lichan Liu1 1 AAI Scientific Cultural Services Ltd., Lab. for Human Brain Dynamics, Cyprus There is no consensus yet about either the precise location of the human eye fields or the way the underlying neural network is recruited for saccades and smooth pursuit eye movements. We designed a protocol to separate activity related to decision, planning and the command to execute the eye movements. We used this protocol to record the MEG signal while subjects performed saccadic and smooth pursue eye movements. Magnetic Field Tomography (MFT) allowed us to identify the positions of frontal and parietal eye fields and eye movement related activity in the cerebellum and brainstem during planning and just before the execution of voluntary saccades and smooth tracking. Activity in these areas (both in the time and frequency domains) was compared between saccades, smooth tracking and during blinking. The time domain analysis showed a very complex pattern of activity, with distinct features when the solutions were aligned to the cues and the eye movement onset. The analysis in the frequency domain showed significant changes in activity over a very wide spectrum of frequencies extending to the highest frequencies (~600 Hz) allowed by the hardware filters. The blink analysis, confirmed the prediction of strong eye field activation just anterior to the central sulcus, and showed also activity in the more anterior FEFs bilaterally, and in parietal areas. A striking feature of our results was the rather asymmetric activity associated with saccades to the left and right. We identified the expected preponderance of contralateral cortical and ipsilateral brainstem and cerebellum activities. In addition we observed more left frontal cortex activity (including left FEF) associated with the (presumably conscious) control of saccade execution and a more right frontal cortex activity (including right FEF) for the early (possibly unconscious) planning of saccades. Some of these results were best over a very wide frequency range and hence in the data obtained with fast sampling. Conference: Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010. Presentation Type: Poster Presentation Topic: Sensory Processing and Functional Connectivity Citation: Ioannides AA, Fenwick PB and Liu L (2010). A MEG investigation of cortical and subcortical networks involved in human voluntary saccades and smooth pursuit eye movements. Front. Neurosci. Conference Abstract: Biomag 2010 - 17th International Conference on Biomagnetism . doi: 10.3389/conf.fnins.2010.06.00160 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 26 Mar 2010; Published Online: 26 Mar 2010. * Correspondence: Andreas A Ioannides, AAI Scientific Cultural Services Ltd., Lab. for Human Brain Dynamics, Nicosia, Cyprus, a.ioannides@humanbraindynamics.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Andreas A Ioannides Peter B Fenwick Lichan Liu Google Andreas A Ioannides Peter B Fenwick Lichan Liu Google Scholar Andreas A Ioannides Peter B Fenwick Lichan Liu PubMed Andreas A Ioannides Peter B Fenwick Lichan Liu Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Radiofrequency ablation of small liver malignancies under magnetic resonance guidance: progress in targeting and preliminary observations with temperature monitoring

To evaluate the feasibility and effectiveness of magnetic resonance (MR)-guided radiofrequency (RF) ablation for small liver tumours with poor conspicuity on both contrast-enhanced ultrasonography (US) and computed tomography (CT), using fast navigation and temperature monitoring. Sixteen malignant liver nodules (long-axis diameter, 0.6-2.4 cm) were treated with multipolar RF ablation on a 1.5-T wide-bore MR system in ten patients. Targeting was performed interactively, using a fast steady-state free precession sequence. Real-time MR-based temperature mapping was performed, using gradient echo-echo planar imaging (GRE-EPI) and hardware filtering. MR-specific treatment data were recorded. The mean follow-up time was 19 +/- 7 months. Correct placement of RF electrodes was obtained in all procedures (image update, <500 ms; mean targeting time, 21 +/- 11 min). MR thermometry was available for 14 of 16 nodules (88%) with an accuracy of 1.6 degrees C in a non-heated region. No correlation was found between the size of the lethal thermal dose and the ablation zone at follow-up imaging. The primary and secondary effectiveness rates were 100% and 91%, respectively. RF ablation of small liver tumours can be planned, targeted, monitored and controlled with MR imaging within acceptable procedure times. Temperature mapping is technically feasible, but the clinical benefit remains to be proven.

Digital control of force microscope cantilevers using a field programmable gate array

This report describes a cantilever controller for magnetic resonance force microscopy based on a field programmable gate array, along with the hardware and software used to integrate the controller into an experiment. The controller is assembled from a low-cost commercially available software defined radio device and libraries of open-source software. The controller includes a digital filter comprising two cascaded second-order sections ("biquads"), which together can implement transfer functions for optimal cantilever controllers. An appendix in this report shows how to calculate filter coefficients for an optimal controller from measured cantilever characteristics. The controller also includes an input multiplexer and adder used in calibration protocols. Filter coefficients and multiplexer settings can be set and adjusted by control software while an experiment is running. The input is sampled at 64 MHz; the sampling frequency in the filters can be divided down under software control to achieve a good match with filter characteristics. Data reported here were sampled at 500 kHz, chosen for acoustic cantilevers with resonant frequencies near 8 kHz. Inputs are digitized with 12 bit resolution, and outputs are digitized with 14 bits. The experiment software is organized as a client and server to make it easy to adapt the controller to different experiments. The server encapsulates the details of controller hardware organization, connection technology, filter architecture, and number representation. The same server could be used in any experiment, while a different client encodes the particulars of each experiment.

Fabrication of C&lt;sub&gt;sf&lt;/sub&gt;/Mg Composites Using Extrusion Directly Following Vacuum Infiltration - Part 1: Monitoring and Acquiring of Process Parameters

Many process parameters are involved during the fabrication of Csf/Mg composites using extrusion directly following vacuum infiltration. The selection of suitable process parameters is important for the successful fabrication of composites. This will require a continuous monitoring and collecting system of process parameters. This paper describes how this is performed. The monitoring and collecting system is developed to monitor and control the forming process successfully. The hardware was built with data acquisition (DAQ) card based on PCI and various sensors for temperature, pressure, displacement. The industrial computer is used to process the data collected from the sensors. The data acquisition card is the bridge between the computer and sensors. In order to reduce the signal noise from sensors, the hardware filter circuit is designed. The data acquisition card can not work by connecting the computer and sensors through it simply. It must be operated through the self-developed software. The data colletcing software is developed in this paper. It can realize the parameter monitoring and collecting easily by setting up the hardware through the user friendly interface. The curves of parameters can be displayed on the computer screen and the data can be saved into the database for post-processing. The software also supplies the warning function. When the parameters (for example the temperature of mold) arrives the set value, the computer can sound a note of warning to tell the worker to operate the press. It is demonstrated that the main parameters, such as temperature of mold and liquid metal, the loaded pressure and the displacement of punch, can be monitored and collected in real-time by use of this system. This paper found the base for the further selection of optimized process parameters.

Automated Design Space Exploration for DSP Applications

We present a performance analysis framework that efficiently generates and analyzes hardware designs for computationally intensive signal processing applications. Our framework synthesizes designs from a high level of abstraction into well-constructed and recognizable hardware structures that perform well in terms of area, throughput and power dissipation. Cost functions provided by our framework allow the user to reduce the design space to a set of efficient hardware implementations that meet performance constraints. We utilize our framework to estimate hardware performance using a set of pre-synthesized mathematical cores which expedites the synthesis process by approximately 14 fold. This reduces the architectural generation and hardware synthesis process from days to several hours for complex designs. Our work aims at performing hardware optimizations at the architectural and arithmetic levels, relieving the user from manually describing the designs at the register transfer level and iteratively varying the hardware structures. We illustrate the efficiency and accuracy of our framework by generating finite impulse response filter structures used in several signal processing applications such as adaptive equalizers and quadrature mirror filters. The results show that hardware filter structures generated by our framework can achieve, on average, a 3 fold increase in power efficiency when compared to manually constructed designs.

Low power H.264 deblocking filter hardware implementations

In this paper, we present two efficient and low power H.264 deblocking filter (DBF) hardware implementations that can be used as part of an H.264 video encoder or decoder for portable applications. The first implementation (DBF_4times4) starts filtering the available edges as soon as a new 4times4 block is ready by using a novel edge filtering order to overlap the execution of DBF module with other modules in the H.264 encoder/decoder. Overlapping the execution of DBF hardware with the execution of the other modules in the H.264 encoder/decoder improves the performance of the H.264 encoder/decoder. The second implementation (DBF_16times16) starts filtering the available edges after a new 16times16 macroblock is ready. Both DBF hardware architectures are implemented in Verilog HDL and both implementations are synthesized to 0.18 mum UMC standard cell library. Both DBF implementations can work at 200 MHz and they can process 30 VGA (640times480) frames per second. DBF_4times4 and DBF_16times16 hardware implementations, excluding on-chip memories, are synthesized to 7.4 K and 5.3 K gates respectively. These gate counts are the lowest among the H.264 DBF hardware implementations presented in the literature. Our hardware implementations are more cost effective solutions for portable applications. DBF_16times16 has 36% less power consumption than DBF_4times4 on a Xilinx Virtex II FPGA on an Arm Versatile PB926EJ-S development board. Therefore, DBF_4times4 hardware can be used in an H.264 encoder or decoder for which the performance is more important, whereas DBF_16times16 hardware can be used in an H.264 encoder or decoder for which the power consumption is more important.

Improving detection sensitivity for partial discharge monitoring of high voltage equipment

Partial discharge (PD) measurements are an important technique for assessing the health of power apparatus. Previous published research by the authors has shown that an electro-optic system can be used for PD measurement of oil-filled power transformers. A PD signal generated within an oil-filled power transformer may reach a winding and then travel along the winding to the bushing core bar. The bushing, acting like a capacitor, can transfer the high frequency components of the partial discharge signal to its earthed tap point. Therefore, an effective PD current measurement can be implemented at the bushing tap by using a radio frequency current transducer around the bushing-tap earth connection. In addition, the use of an optical transmission technique not only improves the electrical noise immunity and provides the possibility of remote measurement but also realizes electrical isolation and enhances safety for operators. However, the bushing core bar can act as an aerial and in addition noise induced by the electro-optic modulation system may influence overall measurement sensitivity. This paper reports on a machine learning technique, namely the use of a support vector machine (SVM), to improve the detection sensitivity of the system. Comparison between the signal extraction performances of a passive hardware filter and the SVM technique has been assessed. The results obtained from the laboratory-based experiment have been analysed and indicate that the SVM approach provides better performance than the passive hardware filter and it can reliably detect discharge signals with apparent charge greater than 30 pC.

Diagnosing Dangerous Arrhythmia of Patients by Automatic Detecting of QRS Complexes in ECG

Abstract — In this paper, an automatic detecting algorithm for QRS complex detecting was applied for analyzing ECG recordings and five criteria for dangerous arrh ythmia diagnosing are applied for a protocol type of automatic arrhythmia diagnosing system. The automatic detecting algorithm applied in this paper detected the distribution of QRS complexes in ECG recordings and related information, such as heart rate and RR interval. In this investigation, twenty sampled ECG recordings of patients with different pathologic conditions were collected for off-line analysis. A combinative application of four digital filters for bettering ECG signals and promoting detecting rate for QRS complex was proposed as pre-processing. Both of hardware filters and digital filters were applied to eliminate different types of noises mixed with ECG recordings. Then, an automatic detecting algorithm of QRS complex was applied for verifying the distribution of QRS complex. Finally, the quantitative clinic criteria for diagnosing arrhythmia were programmed in a practical application for automatic arrhythmia diagnosing as a post-processor. The results of diagnoses by automatic dangerous arrhythmia diagnosing were compared with the results of off-line diagnoses by experienced clinic physicians. The results of comparison showed the application of automatic dangerous arrhythmia diagnosis performed a matching rate of 95% compared with an experienced physician’s diagnoses.

A wearable cardiorespiratory sensor system for analyzing the sleep condition

This paper describes a long-term cardiorespiratory sensor system, which is supposed to be used for monitoring sleep condition at home environment. This system consists of belt sensor probe, data acquisition and communication devices, and the data processing algorithms. New wearable sensor probe with a couple of conductive fabric sheets material and a PVDF film material is developed. To obtain clear cardiorespiratory responses from the belt sensor probe, adaptive hardware filters with signal conditioners are designed and further software data processing algorithms are proposed for extraction of the relative cardiorespiratory information, such as respiratory cycle (RC) and RR interval (RRI). These simple and powerful data processing algorithms for extraction of the proposed RC and RRI information are described and testified in detail. And two commercial sensor devices such as thermistor-type pneumography sensor and 3-lead electrocardiogram sensor are used simultaneously to validate the performance and efficiency of the proposed sensor system. Furthermore, the belt type sensor demonstrated that PVDF film and conductive fabric sensors can complement each other, especially in RRI extraction. Finally, for a case study, the sleep conditions are estimated experimentally by analyzing the heart rate variability (HRV) from the extracted RRI information.

Post Filtering Technique for High-Resolution Magnetic Image of an HTS Scanning SQUID Microscope

We have developed a post filtering technique by the numerical analysis program in MATLAB to improve the high-resolution magnetic image of an HTS scanning SQUID microscope. The SQUID has a high-permeability flux guide protruded to a sample in air at room temperature. Software filtering has an advantage that an object to analyze can be freely selected in comparison with hardware filters. The magnetic image of such a high-resolution as we can discriminate the magnetic microstructure of a few micron-size magnetic particles was obtained by means of our post filtering processing. It took only 38 seconds in case of our PC with a 2GHz processor.

Optimal Hardware and Software Design of an Image-Based System for Capturing Dynamic Movements

In contrast to conventional image-capture systems, which attempt to minimize the amount of data collected during capture, typically by using hardware filters, the more general condition of using all information captured on a camera sensor is much more challenging and requires rigorous consideration of the hardware and software pipelines to obtain accurate tracking results. In this paper, this issue is specifically addressed by describing a unique hardware and software design implemented for use as a fully image-based capture system. An attempt is made to minimize the cost of this system by maximizing hardware control through software implementation. The hardware and software requirements are described in the context of the desired high-speed capture suitable for earthquake motions or other dynamic movements in a scene. Experiments are conducted and presented illustrating the good performance and stability of the system. This system is deemed suitable for the general condition of a building interior.