Test Frequency Selection Research Articles

Soft fault diagnosis in linear circuits: Test selection and non-iterative identification procedure

The paper deals with the diagnosis of soft faults in linear electronic circuits. Circuits containing operational amplifiers operating at low frequencies are considered. A method for identifying single and double faults in the AC domain is proposed. The method is non-iterative and relies on certain relations derived from the modified nodal description of the circuit. An essential part of the paper is a procedure enabling the selection of measurement nodes and test frequencies. The algorithm considers the AC sensitivities, the measurement accuracy, and the diagnostic method applied. The effectiveness of both methods was verified on several electronic circuits. The simulation and laboratory tests were done. Considering parameter tolerances and measurement uncertainties leads to determining intervals of parameter values covering the actual faults.

Test Frequency Selection Using Particle Swarm Optimization

The paper deals with the problem of test frequency selection for multi-frequency parametric fault diagnosis of analog linear circuits. An appropriate set of test frequencies is determined by minimizing the conditionality of the sensitivity matrix based on the system of fault equations using a global stochastic optimization. A novel method based on the Particle Swarm Optimization, which provides more accurate results and improves the convergence rate, is described. The paper provides several practical examples of its application to test frequency selection for active RC filters. A comparison of the results obtained by the proposed method and by the Genetic Algorithm is also presented.

Optimal Dual-Tone Frequency Selection for ADC Sine-Wave Tests

An automated frequency selection algorithm for dual-tone analog-to-digital converter sine-wave test that guarantees optimal test coverage in the phase-plane is presented. The proposed method relaxes some constraints of the existing phase-space design methodology. This enables wider application of the phase-space method in test frequency selection. The proposed algorithm also extends the previous works by generating a good frequency pair while taking into account various hardware constraints in the production environment. Quality measures for phase-plane coverage is proposed and evaluated, followed by the theoretical analysis and description of the phase-plane uniformity. Extensive computer simulation is carried out to validate the proposed technique.

A Method for the Automatic Selection of Test Frequencies in Analog Fault Diagnosis

A new procedure for the selection of test frequencies in the parametric fault diagnosis of analog circuits is presented. It is based on the evaluation of algebraic indices, as the condition number and the norm of the inverse, of a sensitivity matrix of the circuit under test. This matrix is obtained starting from the testability analysis of the circuit. A test index (T.I.) that permits the selection of the set of frequencies that better leads to locating parametric faults in analog circuits is defined. By exploiting symbolic analysis techniques, a program that implements the proposed procedure has been developed. It yields the requested set of frequencies by means of an optimization procedure based on a genetic algorithm that minimizes the T.I. Examples of the application of the proposed procedure are also included.

Effects of curing time and frequency on ultrasonic wave velocity in grouted rock bolts

Grouted rock bolts are widely used to reinforce excavated ground in mining and civil engineering structures. To date, opportunities for testing the quality of the grout in grouted rock bolts have been limited to the pull-out tests and the over-coring methods. Both these methods are destructive, time-consuming and costly. These deficiencies have fueled research into the use of ultrasonic methods for testing the quality of the grout in rock bolts. However, only partial success has been achieved in these efforts chiefly due to inadequate knowledge of the ultrasonic wave characteristics such as wave velocity in grouted rock bolts. This paper presents results of an experimental study into the effects of curing time and testing frequency on the velocity of ultrasonic waves propagating along rock bolts grouted in concrete. A substantial wave velocity decrease, as much as 47.7% at certain frequencies, was recorded in rock bolts grouted in fully cured concrete in comparison to non-grouted bolts. The results demonstrate the importance of optimizing the selection of test frequencies as well as suggesting the possibility of a new approach based on wave velocity decrease for testing the grout quality of rock bolts.

Automated Selection of Test Frequencies for Fault Diagnosis in Analog Electronic Circuits

This paper suggests three novel methods for selecting the frequencies of sinusoidal test signals to be used in fault diagnosis of analog electronic circuits. The first and second methods are based on a sensitivity analysis and show to be particularly effective in linear circuits where a priori information and designer experience can be exploited. Conversely, the third method selects the input frequencies to be used for diagnostic purposes without requiring any hypothesis about the circuit or testing design background. As such, the method is particularly appealing in complex -possibly nonlinear - circuits where the designer experience is of little value and an effective blind approach saves both designer and testing time. The suggested frequency selection methods are then contrasted to each other against performance and computational complexity.

Symbolic Techniques for the Selection of Test Frequencies in Analog Fault Diagnosis

In this work symbolic methods are used for implementing a procedure for the selection of test frequencies in multifrequency parametric fault diagnosis of analog linear circuits. The proposed approach is based on the evaluation of the condition number and the norm of a sensitivity matrix of the circuit under test. This matrix is determined by exploiting the testability and ambiguity group concepts. A Test Error Index (T.E.I.) is obtained which permits to select the set of frequencies which better leads to locate parametric faults in analog linear circuits. A program implementing the proposed procedure has been realized by using symbolic techniques. Examples of application are also included.

Computer aided feature selection for enhanced analogue system fault location

A digital computer based technique for the selection of optimum test frequencies for fault diagnosis of analogue systems is presented. Gain and phase deviations from the nominal system response for changes in component values are evaluated and the recognition matrix is established which in turn is normalized and made sparse. The heuristic optimization technique developed is applied to the sparse recognition matrix to select the best subset of features via a discriminatory index of measurement points by adding or discarding features until the optimum is found. The efficiency of the selected feature set is measured by the confidence level formally incorporated in the algorithm and which is found to correlate well with the actual diagnosability of faults for a simulation of varying fault levels and including varying production tolerances for the non-faulty components. Actual fault location is implemented using the nearest neighbour rule, which is complimentary to the feature selection technique. Only three measurements are found to be sufficient to achieve a high level of diagnosability. The simulation of 91,000 faulty 7 component passive circuits has been undertaken to verify the procedure, which may now be applied equally well to larger scale systems using input-output measurements only, or, alternatively on sub-systems of comparable size to the sample circuit which have been isolated by special electronic partitioning devices as recently proposed for the fault location in television receivers during the manufacturing process.