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The imperative need to advance the development of more efficient electric motors requires the meticulous measurement of small increments while minimizing the associated uncertainty in dynamometer tests. One of the key variables in such tests is the angular speed, which is typically obtained based on encoder measurements. This paper proposes a systematic measurement uncertainty assessment method based on the Guide to the Expression of Uncertainty for the two most widely used methods for angular speed measurement, namely, the frequency and period methods. In addition, the impact of the angular speed calculation method on the efficiency test uncertainty is assessed using an automatic test rig for electric motors. Our experimental results consider both steady-state and dynamic analyses. The results show that the period measurement method provides measurements with lower uncertainty for the encoders typically used in such test rigs, about 30 times less than the uncertainty determined for the frequency measurement method. Based on these results, the choice of a proper method can drastically decrease the angular speed uncertainty, and consequently the motor efficiency uncertainty, without increasing instrumentation cost.

Rod pumping systems typically require the analysis of dynamometer cards for fault diagnosis. While external instrumentation assists in obtaining these cards, it simultaneously raises monitoring costs and complexity. To address this issue, this paper introduces a parameter estimator that integrates the equivalent circuit model of an induction motor with the beam pumping unit model. We have compared the performance of two practical estimators, utilizing the terminal quantities of the driving motor as inputs. The results demonstrate surface dynamometer cards under varying operational conditions of the oil well. By augmenting the estimator’s input variables, the estimated cards align more closely with the actual ones. This practical application proposes an alternative method for acquiring the surface dynamometer card, which can function as a supplementary approach in fault diagnostics and contribute to informed maintenance decisions for the pumping unit.

Objectives. The purpose of the study is to develop dynamometric equipment for measuring the components of cutting forces when processing materials with an axial tool in a dynamic mode.Methods. The study is based on the application of electrical methods using piezoelectric and strain gauge transducers, whose main advantage is the ability to register and record fast-moving dynamic processes.Results. Based on an analysis of existing dynamometers, the necessity of developing a new modern dynamometer device, which would allow the oscillations of the cutting force components to be registered and recorded in dynamic mode, is justified. The advantages of using strain sensors for a dynamometer are described. An analysis of the selected dynamometer design indicated that the sensors for measuring the axial forces and torque are located on one elastic element, which affects the accuracy of their measurement due to their mutual influence. Therefore, it was necessary to place them on different elastic elements. The developed and manufactured dynamometric equipment for carrying out the research work in the field of axial tools for processing materials is presented. The relative measurement error is calculated.Conclusion. The dynamometric equipment makes it possible to record the periodic and quasiperiodic oscillations of two components of the cutting forces without distortion for various tapping, drilling and countersinking processes, occurring at a frequency of up to 1500 Hz in real time mode, and can be used to optimise the cutting parameters. Using the dynamometric equipment, it is possible to register the signals from up to 8 force sensors in real time, amplify signals, transform the signal from analogue to digital, visualise data and print out the results of experimental data. The equipment is suitable for use in research laboratories of machine-building enterprises, universities and other scientific institutions.

A novel neural network algorithm for indirect measurement of the polished rod load of the beam-pumping unit is proposed. The dynamometer card is a two-dimension graph of polished rod load versus horse head position, and it is widely used for working state monitoring of pumping unit. The drift problem of load sensor makes the direct measurement of polished rod load not economical and practical, so indirect measurement of polished rod load is crucial. Through the analysis of the mechanical characteristics of the pumping unit, a neural network with physical meaning (physical network) is designed. The experiment shows that the physical network can simulate the energy transfer process properly with only 18 training data items, which is about 1% of other data-driven models, and maintains good performance under different down-hole conditions.

The aim of the present study was to provide alternative means of measurement and evaluation of muscle strength in rehabilitation practice and diagnostics. In the last few years many electronic devices for evaluation of muscle strength have developed. Contemporary studies have shown that in addition to the standard manual muscle testing muscle strength can be assessed more objectively and analytically using electronic dynamometers and equipment. The strain gauges are used as a tool of precision in the industry that allows measurement of mechanical loads by dynamometers. By using these tools is possible to obtain continuous digital measurement and recording of muscle strength.