Hybrid Magnetic–Inductive Angular Sensor with 360° Range and Stray-Field Immunity

Brajon, Bruno; Lugani, Lorenzo; Close, Gael F.

doi:10.3390/s22062153

Cited by 8 publications

(5 citation statements)

References 11 publications

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“…Consequently, we expect this benchmark to evolve. To streamline further benchmarking by the magnetics community, we released a computational notebook online [50]. Our computational notebook reproduces an interactive version of Figure 6, that can be expanded as new devices become available.…”

Section: Discussionmentioning

confidence: 99%

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A Benchmark of Integrated Magnetometers and Magnetic Gradiometers

2023

Preprint

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<p>This survey paper compiles and benchmarks the performance of integrated magnetic sensors, in terms of their noise and full-scale magnetic field. In total, we collected performance metrics of 31 sensors realized in various technologies. For each sensor, we derived a noise model to estimate the noise under the same conditions. We obtained a comprehensive benchmark with a focus on integrated devices. We also measured the noise spectrum of 11 of those sensors to confirm our noise model. Given that for many emerging applications, such as tactile, current, torque and biomagnetic sensing, the signal of interest is the field gradient to reject magnetic stray fields, we extended the benchmark to gradiometers. We developed a low-noise measurement setup and a low-field gradient (full scale: 10 μT/mm) generation setup to characterize magnetic gradiometers in this regime. The paper discusses the key sensor trade-off between precision and range, and summarizes the technology trends graphically on a trade-off curve, providing broad insight.</p>

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Section: Discussionmentioning

confidence: 99%

“…In this section, we explain the key aspects of our Python implementation, but don't cover the details. This is because the code and data for our noise models is available online on Code Ocean [50].…”

Section: Notementioning

confidence: 99%

A Benchmark of Integrated Magnetometers and Magnetic Gradiometers

2023

Preprint

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“…Inductive angular sensors are significantly simpler, cheaper, and more compact than traditional resolvers, of which they share the same basic working principle (angledependent magnetic coupling) and are tolerant with respect to mounting errors in the same way. In addition, Brajon et al [5] proposed a design that combines inductive angular sensors with Hall-effect instruments to improve the measurement accuracy and achieve the immunity to stray fields and stray metals.…”

Section: Introductionmentioning

confidence: 99%

Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method

Dalboni

Soldati

2023

IEEE Trans. Instrum. Meas.

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Driving synchronous machines requires early and accurate knowledge of the absolute position of the rotor; current solutions based on resolvers, sin-cos or absolute encoders are complex, bulky and costly. Hence, in this work two variants of absolute rotary encoder based on Vernier method are analyzed. One, already discussed in the literature, displays the Vernier scale across the whole circumference (full-Vernier), the other shows half Vernier traces over the entire perimeter (half-Vernier), which is an original feature. Both implementations are characterized by only two tracks and as many sensors: the proposed conditioning algorithms provide the absolute angular position as a function of the time delays between the wave edges generated by the two traces, thus being of easy implementation on low-cost MCUs. The Vernier encoders are also compared with state-of-the-art absolute and relative solutions, i.e. incremental, binary and Graycode encoders. Experimental tests are carried out to assess the accuracy of the proposed sensors. The investigation shows that (i) the full-Vernier cannot provide, in practice, a reliable estimate of the direction of rotation and of the actual angular sector without resorting to a third sensor; (ii) the half-Vernier produces a trusty measurement of the absolute angle and velocity and (iii) can give a reliable position result with less than 30°shaft turn, but (iv) it can suffer from marginal performance degradation at low velocities in conjunction with high accelerations. Compared to the Gray encoder, the half-Vernier provides a simpler and more compact hardware for a given resolution, similar to that of an incremental encoder, at the expense of a small accuracy reduction at low speed.

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“…Because fail-safe operational systems use redundant system functions in an architecture that allows transition to a backup system if a malfunction occurs in the primary system, global IC component suppliers are beginning to offer double and triple dies within a single package to support the need for redundancy without occupying more physical space [ 13 , 14 ]. Additionally, they try to offer a safety function IC for the external magnetic field [ 7 , 12 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

ISO26262-Compliant Inductive Long-Stroke Linear-Position Sensors as an Alternative to Hall-Based Sensors for Automotive Applications

Lim

Kim

2022

Sensors

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To ensure safety, vehicle companies require position sensors that maintain accuracy and avoid target loss even in harsh automotive environments. Most vehicle position sensors are Hall-based, but even improved gradiometric 3D Hall sensors using the arctangent operation are vulnerable to external magnetic fields (EXMFs) and encounter difficulty at long-stroke (LS) positions. An ISO26262-compliant inductive position sensor (IPS) employing a 3.5 MHz-induced magnetic field source (much higher in frequency than vehicle–environment EXMFs) is proposed in this study as an alternative. To meet the safety goal, a threshold LS distance of 12 mm was set. Then the IPS was compared to existing Hall-based sensors. The B field of the existing 3D sensor was weak at LS and the airgap between sensor face and magnet target caused a large error in accuracy, whereas the IPS was not affected by LS. Because of its high excitation frequency, the IPS was also largely unaffected by EXMFs, as was demonstrated by ISO11452-8 and 0.1 T immunity tests. The proposed IPS outperformed existing 3D Hall sensors, achieving stable accuracy within ±0.85% for different airgaps (1.5–2.5 mm) and proving robust to magnetic and LS effects.

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Hybrid Magnetic–Inductive Angular Sensor with 360° Range and Stray-Field Immunity

Cited by 8 publications

References 11 publications

A Benchmark of Integrated Magnetometers and Magnetic Gradiometers

A Benchmark of Integrated Magnetometers and Magnetic Gradiometers

Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method

ISO26262-Compliant Inductive Long-Stroke Linear-Position Sensors as an Alternative to Hall-Based Sensors for Automotive Applications

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