A Multisensor Baseline and Abstention Architecture for Low Voltage Rotating Machine Condition Assessment

Abstract

Condition assessment of small rotating machines is often demonstrated with a single sensor and a fixed threshold, although operating point, mounting and environment can alter measured signals. This paper presents NEXUS PRIME V1 as a documented design for a low voltage, ESP32 based bench instrument using device specific baselines, validity checks and corroborating channels. Its proposed rule set reports NORMAL when required measurements agree with calibrated healthy bands, ABNORMAL only for a coherent pattern in at least two independent condition channels, and INCONCLUSIVE when evidence is missing or contradictory. The design specifies vibration, current, voltage, temperature and RPM sensing, with distance serving primarily as a setup validity check; it also specifies local indication and a web dashboard. The supplied 71 page blueprint reports a design audit, including 18 distinct GPIO assignments and an estimated INR 1,894 parts budget. Hardware, firmware, diagnostic accuracy and reliability have not yet been measured. The contribution is an inspectable architecture and a preregisterable validation protocol, not an experimentally demonstrated diagnostic improvement.

Introduction

The text presents NEXUS PRIME V1, a proposed low-cost, multisensor condition-monitoring system designed to assess the health of a small DC rotating device and support maintenance decisions. The system aims to detect abnormal operating conditions by combining sensor readings, comparing them with a calibrated healthy baseline, and explicitly identifying situations where the available evidence is insufficient.

The proposed system uses an ESP32 DevKit V1 as its main controller, integrating an MPU6050 accelerometer for vibration, an INA219 sensor for motor current and supply voltage, a DS18B20 temperature sensor, an optical sensor for rotational speed (RPM), and an HC-SR04 ultrasonic sensor for distance or presence detection. An OLED display, RGB LED, buzzer, and local web dashboard provide status information, while a motor driver and servos support device operation and sensor positioning.

The core feature of NEXUS PRIME V1 is its three-state decision policy:

• NORMAL: Sensor readings remain within calibrated healthy limits, with sufficient confidence and no conflicting evidence.

• ABNORMAL: At least two independent condition indicators exceed their calibrated limits, form a physically consistent pattern, and satisfy the required confidence threshold.

• INCONCLUSIVE: Required sensors or baseline data are invalid, readings conflict, or the evidence is insufficient for a reliable decision.

This approach is intended to prevent isolated sensor fluctuations from being incorrectly classified as faults. However, the thresholds, confidence scores, sampling rates, and calibration parameters still need to be established through experiments.

The design also emphasizes electrical safety and affordability. It specifies a regulated 5 V, 3 A power supply, protection against reverse polarity, input fusing, appropriate signal-level conversion, and a proposed component budget of approximately INR 1,894. Nevertheless, actual power consumption, motor and servo current peaks, regulator capacity, and emergency-stop behavior require physical verification.

The proposed validation process includes sensor calibration, electrical testing, controlled fault simulations, sensor-dropout testing, and repeated healthy and abnormal operating trials. Performance should be evaluated using false-alarm rates, missed faults, inconclusive decisions, diagnostic coverage, and confidence intervals, with comparisons against a single-sensor baseline.

A major limitation is that NEXUS PRIME V1 remains at the design and documentation stage. No assembled prototype, implemented firmware, experimental dataset, or measured diagnostic performance is reported. Therefore, its accuracy, reliability, response time, and ability to detect real faults have not yet been established.

In conclusion, NEXUS PRIME V1 proposes an affordable and explainable approach to machine condition monitoring by combining multiple sensors, healthy-reference calibration, cross-sensor verification, and an explicit inconclusive state. Future work should focus on hardware implementation, electrical safety verification, baseline calibration, firmware development, and systematic experimental validation before making claims about diagnostic effectiveness or reliability.

Conclusion

NEXUS PRIME V1 specifies a low voltage rotating machine condition assessment architecture using device baselines, multiple physical signals and an INCONCLUSIVE state for weak or conflicting evidence. Its present contribution is a precise, testable design and evaluation plan. Design consistency checks are available, while the physical build, safety response, accuracy and reliability remain unverified. Publication as an experimental fault diagnosis result requires the planned hardware and held out validation data.

References

[1] NEXUS PRIME Engineering, NEXUS PRIME V1 Engineering Build Blueprint, ver. 1.0, hardware rev. A, software rev. 0.1, 30 Aug. 2026. Supplied project document. [2] A. K. S. Jardine, D. Lin and D. Banjevic, “A review on machinery diagnostics and prognostics implementing condition-based maintenance,” Mechanical Systems and Signal Processing, vol. 20, no. 7, pp. 1483–1510, 2006, doi: 10.1016/j.ymssp.2005.09.012. [3] M. A. F. Pimentel, D. A. Clifton, L. Clifton and L. Tarassenko, “A review of novelty detection,” Signal Processing, vol. 99, pp. 215–249, 2014, doi: 10.1016/j.sigpro.2013.12.026. [4] C. K. Chow, “On optimum recognition error and reject tradeoff,” IEEE Transactions on Information Theory, vol. 16, no. 1, pp. 41–46, 1970, doi: 10.1109/TIT.1970.1054406. [5] Texas Instruments, INA219 Zerø-Drift, Bidirectional Current/Power Monitor With I2C Interface, datasheet, rev. G, 2014. Available: https://www.ti.com/product/INA219 [6] Texas Instruments, DRV8833 Dual H-Bridge Motor Driver, datasheet, rev. E. Available: https://www.ti.com/lit/ds/symlink/drv8833.pdf [7] Espressif Systems, “GPIO & RTC GPIO,” ESP-IDF Programming Guide for ESP32. Available: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/gpio.html

Copyright

Copyright © 2026 Ms. Shraddha Raut, Shravya Bansod, Neil Sewak, Tahazain Sheikh, Omkar Parate, Armaan Shaikh, Vaibhav Pashine. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.