LAUSR

Reliable and accurate position measurement in harsh, high-temperature environments remains a major challenge in industrial automation. Linear variable differential transformers (LVDTs) are highly sensitive and robust against environmental influences. However, temperature-dependent variations in magnetic permeability, electrical conductivity, and component geometry can cause significant position errors. Existing countermeasures, such as geometric modifications, compensation techniques, or high-grade materials, increase cost and complexity with limited success. This article presents a temperature-insensitive LVDT achieved through three complementary design measures: 1) a coil configuration where the sensing coils are placed outside the excitation coil to minimize the influence of temperature-induced magnetic-field redistributions on the sensing voltages; 2) high-frequency operation (up to 100 kHz) to reduce penetration depth and temperature sensitivity; and 3) a nonmagnetic ceramic coil carrier with negligible electrical conductivity that does not disturb the excitation field. Temperature experiments up to 180 °C show a 20-fold reduction in temperature-induced errors at 30 and 100 kHz, compared to 1 kHz, even without compensation. Position errors are reduced to below 0.8% full-scale (FS) over ±70 mm (30 kHz) and below 1% FS from −50 to 70 mm (100 kHz). Active compensation could further reduce errors. The proposed design uses off-the-shelf components that allow integration into standard LVDT constructions, enhancing reliability in high-temperature applications.