A versatile test bench setup for characterization of tolerance sensitivity and propagation delay of inductive rotary position sensors

Abstract

We present a highly accurate measurement setup and related methods for the efficient characterization of inductive rotary position sensors. The test bench is designed to measure analog sine/cosine output signals of the device under test (DUT) under nominal conditions as well as deliberate misalignment, such as center offset and tilt tolerances – enabling analysis of DUT performance w.r.t. the angle deviation, the harmonic decomposition, and tolerance sensitivities. We further propose a method to emulate tolerances of a target on the rotary axis, such as on-axis target tilt (skew) or eccentricity (wobble), utilizing only a nominal target by modeling these tolerances as equivalent angle-dependent DUT alignment tolerances. This method is validated with precision reference targets. With laser-guided positioning, the printed circuit board (PCB) of the DUT is automatically positioned relative to the rotary axis (runout ±5 μm) in airgap and radial direction (repeatability 5 μm, total deviation 30 μm). The setup is capable of high-speed measurements at a rotation speed of at least 5,000 min ⁻¹ which allows precise measurement of the DUT propagation delay (repeatability 14 ns, total deviation ∼200 ns). The proposed measurement setup enables fast and automated characterization of the DUT angle deviation with excellent accuracy better than  10 ″ (0.003°).