Katsunori Shida

Steady-state analysis of a plain gradient algorithm for a second-order adaptive IIR notch filter with constrained poles and zeros

Gradient-type algorithms for adaptive infinite-impulse response (IIR) notch filters are very attractive in terms of performance and computation cost. However, it is generally quite difficult to assess their performances analytically. There are several trials to analyze adaptive algorithms, such as the sign and the plain gradient algorithms for some types of adaptive IIR notch filters, but the analysis techniques used cannot be directly applied to different types of adaptive IIR notch filters. This brief presents closed form expressions for steady-state estimation bias and mean square error (MSE) of a well known plain gradient (LMS-like) second-order adaptive IIR notch filter with constrained poles and zeros. First, theoretical expressions for output signals of the notch filter and its corresponding gradient filter at their steady states are developed based on the Taylor series expansions of transfer functions of these two filters in the vicinity of the sinusoidal signal frequency difference equations for convergences in the mean and mean square are then established by using these output signals, from which the steady-state bias and MSE of the algorithm are derived. Stability bound of the algorithm is also investigated based on the difference equations. Extensive simulations are provided to support the analytical findings.

A simple interface circuit to measure very small capacitance changes in capacitive sensors

This paper presents an easy-to-design interface circuit to measure very small-percentage capacitance variations in capacitive sensors, especially suitable for industrial measurements. A computer-controlled 24-bit A/D converter is employed to obtain a higher resolution. This interface circuit can be used with various types of capacitive sensors. The most interesting thing is, that the measurement results through this interface circuit are independent of the initial capacitance of the sensor. In addition, the double differential operating principle used here minimizes the error caused by coupling and stray capacitance of sensor probes. The operating principle of the designed interface circuit, the major assumptions made, test data, and possible future developments are discussed.

Design and Implementation of a Self-Validating Pressure Sensor

A new prototype of self-validating pressure sensor is described, including structure design of the transducer, fault detection and diagnosis method and signal transmitter based on double digital signal processors (DSPs) system. The elastic body of the transducer is based on circular-flat diaphragm structure. Eight groups of strain gauges are distributed on the diaphragm. One group of metal strain gauge with little temperature drift is used as primary pressure sensor, the other seven groups of semiconductor strain gauges with high sensitivity are used as calibration references. Consistency checking of the measured data is used to detect sensor fault. The outputs of self-validating pressure sensor including validated measurement value (VMV) of pressure, validated uncertainty (VU) of pressure, and measurement value status (MVS) of pressure are calculated using the high consistency data. A new fault diagnosis method based on wavelet packet decomposition feature extraction and support vector machine multiclassification is used to identify six sensor fault status. A double DSPs system is implemented using TMS 320 F 2812 and TMS 320 C 6713 to acquire the output signal and complete fault detection, diagnosis, and self-validating parameters calculating. The experiment results show that the designed pressure sensor prototype implements the self-validating function. It can detect fault in real-time and identify sensor status with high accuracy.

A new multifunctional tactile sensing technique by selective data processing

To obtain three parameter tactile information, (contact force, temperature change, and contact situation) using two sensor output signals of a tactile sensor consisting of a mono-material sensing device, a new multifunctional tactile sensing technique using selective data processing is proposed. A pressure-conductive rubber tactile sensor with temperature dependency, which compared with one of the minute sense receptors of the human skin, was experimentally made to confirm the proposed sensing technique. The ability of the sensor was tested under various contact conditions. As experimental results, the usefulness of the proposed multi functional tactile sensing technique was confirmed.

Tracking properties of a gradient-based second-order adaptive IIR notch filter with constrained poles and zeros

Gradient-type adaptive IIR notch filters have many attractive merits for various real-life applications since they require a small number of computations and yet demonstrate practical performance. However, it is generally quite difficult to assess their performance analytically. Their tracking properties, in particular, have not yet been investigated. In this paper, the tracking performance of a plain gradient (PG) algorithm is analyzed in detail for a second-order adaptive IIR notch filter with constrained poles and zeros, which takes a linear chirp signal as its input. First, two sets of difference equations for the frequency tracking error and mean square error (MSE) are established in the sense of convergence in the mean and convergence in the mean square, respectively. Closed-form expressions for the asymptotic tracking error and MSE are then derived from these difference equations. An optimum step-size parameter for the algorithm is also evaluated based on the minimization of the asymptotic tracking error or the tracking MSE. It is discovered that the asymptotic tracking error may be driven to zero for a positive chirp rate by selecting a proper step size, which is an interesting property for a real-valued adaptive filtering algorithm. Extensive simulations are performed to support the analytical findings.

Loss Calculation of Reactor Connected to Inverter Power Supply Taking Account of Eddy Currents in Laminated Steel Core

A method of magnetic field analysis which takes eddy currents into account in laminated steel core is extended into loss calculation to investigate the loss reduction of reactor connected to inverter power supply. In the proposed method, the iron loss in the laminated core can be calculated considering the flux and eddy current distributions in steel plate affected by harmonic components. The proposed method is applied to a single-phase model of reactor connected to inverter power supply and the loss distributions are demonstrated in detail. Moreover, in order to reduce the loss, the shape configurations of core and plate are improved. Finally, the experiments using three-phase reactors are carried out to verify the calculation and investigate the effectiveness of the proposed shape configuration.

Automated measurement system for 1-/spl Omega/ standard resistors using a modified Wheatstone bridge

A modified Wheatstone bridge that has four detectors to sense the imbalances in the circuit and a digitally controlled feedback system to balance it automatically with a resolution of a few parts in 10/sup 9/ is described, and its operating principle is briefly explained. The performance of the fully automated measurement system using the bridge is examined. Data were taken with a measuring current of 50 mA through each resistor. The total integration time of 120 s for each feedback cycle corresponds to an effective noise bandwidth of 3.3 mHz, so that the estimated voltage resolution is 35 pV using the experimentally determined noise power spectrum of 0.61 nV/ square root Hz. Combining this with the voltage drop of 50 mV at each resistor, a resolution of 1.43 n Omega is expected for each feedback cycle, and 0.28 n Omega for each relative resistance ratio. The average standard deviation from the linear fits is 0.31 n Omega , which is in good agreement with the estimated value and is only a factor of four larger than the ultimate sensitivity determined by thermal noise of 1- Omega standard resistors. >

A Modified Wheatstone Bridge for High-Precision Automated Resistance Measurement

A modified Wheatstone bridge has been developed which auto-balances using a digitally controlled feedback system. The bridge has four detectors to sense the imbalance in the circuit, and a resolution of better than 0.01 ppm with nearly maintenance-free operation.

Multilayer sensing and aggregation approach to environmental perception with one multifunctional sensor

This paper presents a novel approach to perception of a specified environment for intelligent system or robotics applications in which high-level information must be extracted from multi-sensors data. A CdS and Fe/sub 3/O/sub 4/ material based multifunction sensor has been developed to measure temperature, humidity and brightness. The sensor focuses on the processing of the multifunctional information in a multilayer framework, which is more attractive in terms of system simplicity, performance, and compact structure. Further along, quantity creditability tactics (QCT), one multisensing data fusion method, is approached, with which quantities are sequentially aggregated to generate a general perception about the sensed environment. Different from the popular fusion strategies, the proposed algorithm also works in a step-by-step framework, and proves to be more practical and more effective when there are more variables for calculation.

Non-contact multi-sensing technique for the precise measurement of concentration of electrolytic solution

Abstract A new approach for the precise measurement of low concentration of electrolytic solutions using multi-sensing technique is presented in this paper. For achieving this multi-functional sensing function, a novel structure is proposed for the multi-functional sensor. Two sensing functions, namely, the inductive and the capacitive sensing functions, can be realized by this sensor. From the two types of sensing two databases are created and then the unknown concentration is precisely determined by comparing with the two databases. Experimental results using the sensor on various solutions of low concentration of NaCl, K2SO4 and Pb(NO3)2 electrolytes show distinct response to various concentrations as well as to different solutions. A concentration as low as 1 ppm of solution is possible to measure by this sensor.