2026 ASEE Annual Conference & Exposition

Currently, there are thousands of proximity probe series, part numbers, types, and cable lengths available across the industry. This vast variety makes the selection and ordering process challenging for users who must identify the correct configuration for their application. The objective of this senior design project is to develop a universal inductive proximity probe (UNI-PROBE) that can be mounted into any machine casing, remain backward compatible with standard proximity probe drivers, and utilize a new, low-cost body, cable, and connector system to simplify ordering and installation.

This project was completed as an industry partnership with Machine Saver, Inc. by an interdisciplinary team of Engineering Technology students specializing in both Mechanical and Electronics and Computer Engineering Technology disciplines. The UNI-PROBE is designed to comply with the American Petroleum Institute (API) Standard 670, making it suitable for global machinery protection systems. It can be applied to a wide range of vibration measurement scenarios, including radial shaft vibration, shaft axial position, piston rod drop, and similar applications. Implementing the design was certainly a challenge. In the earlier preliminary planning discussion with one of the senior engineers, it was brought to the concern that the twisted shielded pair cable varied too much in inductance and capacitance as the length was varied. To test this theory, multiple cable lengths were tested with an LCR meter to determine the capacitance per foot and to determine how much variation was seen between the different distances. Circuit diagrams, functional block diagrams, and test results will be provided in the full paper.

The UNI-PROBE eliminates the need for users to select among numerous probe series and configurations. Since it is designed to be backward compatible with existing systems, customers will only need to choose between metric or standard threading, dramatically simplifying the ordering process. The probe body is engineered to fit most machine casings, while the cable and connector interface are compatible with current industry hardware standards.

Meeting the stringent API 670 requirements is a key design objective. Equipment used in hazardous areas must ensure electrical safety and avoid ignition of flammable gases due to potential electrical sparks. This standard also specifies acceptable materials for use in such environments, requiring research and selection of an appropriate sensor body material that offers both safety and durability.

Key Design Challenges:

Universal Mounting: Designing a probe body that can fit into various rotating machine casings while allowing accurate shaft travel measurement.

Inductive Coil Design: Developing an inductive coil that reliably generates the eddy current needed to detect target material displacement.

Cable Compatibility: Integrating a low-cost three-wire cable alternative while maintaining seamless functionality with standard coaxial connectors.

Connector Durability: Selecting and sourcing an electrical connector capable of withstanding corrosive industrial environments and extreme temperatures.

The resulting UNI-PROBE solution simplifies the purchasing process by removing the complexity of selecting part numbers, probe lengths, cable types, and system series. Customers need only specify the thread type of their machine, making the process efficient and error-free. Additionally, the design ensures compatibility with existing industry-standard systems, allowing straightforward integration with previously installed hardware.

This project aligns with the ABET-ETAC-accredited Engineering Technology Program’s Student Learning Outcomes (SLOs), specifically addressing the outcome “Design systems, components, or processes meeting specified needs for broadly defined engineering problems appropriate to the ECET discipline.” Assessment results for this outcome, along with related Key Performance Indicators (KPIs), will be presented in the full paper.