Demodulation Techniques for Self-Oscillating Eddy-Current Displacement Sensor Interfaces: A Review

Chaturvedi, Vikram; Nabavi, M.R.; Vogel, Johan G.; Nihtianov, Stoyan

doi:10.1109/jsen.2017.2677526

Cited by 23 publications

(12 citation statements)

References 26 publications

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“…However, with continued developments on inductance measurement ICs in this area [43], fully integrated SITS with embedded electronics are achievable in the near future.…”

Section: Discussionmentioning

confidence: 99%

Robust and high-performance soft inductive tactile sensors based on the Eddy-current effect

Wang

Kow

Raske

et al. 2018

Sensors and Actuators A: Physical

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G.B.), m.ghajari@imperial.ac.uk (M.G.), r.hewson@imperial.ac.uk (R.H.), A.Alazmani@leeds.ac.uk (A.A.), P.R.Culmer@leeds.ac.uk (P.C.). AbstractTactile sensors are essential for robotic systems to interact safely and effectively with the external world, they also play a vital role in some smart healthcare systems. Despite advances in areas including materials/composites, electronics and fabrication techniques, it remains challenging to develop low cost, high performance, durable, robust, soft tactile sensors for realworld applications. This paper presents the first Soft Inductive Tactile Sensor (SITS) which exploits an inductance-transducer mechanism based on the eddy-current effect. SITSs measure the inductance variation caused by changes in AC magnetic field coupling between coils and conductive films. Design methodologies for SITSs are discussed by drawing on the underlying physics and computational models, which are used to develop a range of SITS prototypes. An exemplar prototype achieves a state-of-the-art resolution of 0.82 mN with a measurement range over 15 N. Further tests demonstrate that SITSs have low hysteresis, good repeatability, wide bandwidth, and an ability to operate in harsh environments. Moreover, they can be readily fabricated in a durable form and their design is inherently extensible as highlighted by a 4x4 SITS array prototype. These outcomes show the potential of SITS systems to further advance tactile sensing solutions for integration into demanding real-world applications.

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“…However, with continued developments on inductance measurement ICs in this area [43], fully integrated SITS with embedded electronics are achievable in the near future.…”

Section: Discussionmentioning

confidence: 99%

Robust and high-performance soft inductive tactile sensors based on the Eddy-current effect

Wang

Kow

Raske

et al. 2018

Sensors and Actuators A: Physical

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“…From one side, it allows for the use of several demodulation techniques to extract the displacement information. The pros and cons of each solution have been investigated and summarized in [24,25]. High-frequency excitation frequency signals are beneficial to improve the resolution and sensitivity of the ECDS, minimizing skin depth effects but, at the same time, are detrimental in terms of power consumption.…”

Section: Main Contributions Of This Workmentioning

confidence: 99%

Effects of the Target on the Performance of an Ultra-Low Power Eddy Current Displacement Sensor for Industrial Applications

2020

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The demand for smart, low-power, and low-cost sensors is rapidly increasing with the proliferation of industry automation. In this context, an Ultra-Low Power Eddy Current Displacement Sensor (ULP-ECDS) targeting common industrial applications and designed to be embedded in wireless Industrial Internet of Things (IIoT) devices is presented. A complete characterization of the realized ULP-ECDS operating with different metallic targets was carried out. The choice of the considered targets in terms of material and thickness was inspired by typical industrial scenarios. The experimental results show that the realized prototype works properly with extremely low supply voltages, allowing for obtaining an ultra-low power consumption, significantly lower than other state-of-the-art solutions. In particular, the proposed sensor reached the best resolution of 2 µm in case of a carbon steel target when operated with a supply voltage of 200 mV and with a power consumption of 150 µW. By accepting a resolution of 12 µm, it is possible to further reduce the power consumption of the sensor to less than 10 µW. The obtained results also demonstrate how the performances of the sensor are strongly dependent on both the target and the demodulation technique used to extract the displacement information. This allowed for defining some practical guidelines that can help the design of effective solutions considering application-specific constraints.

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“…These voltages are digitized and their ratio is calculated to compute D out = L sen /L ref , which gives the measure of the displacement. The amplitude is chosen as the carrier of the displacement information due to higher sensitivity when compared to the frequency or losses in the LC resonator [13]- [15].…”

Section: Introductionmentioning

confidence: 99%

A 19.8-mW Eddy-Current Displacement Sensor Interface With Sub-Nanometer Resolution

Chaturvedi¹,

Vogel

Makinwa

et al. 2018

IEEE J. Solid-State Circuits

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This paper presents an eddy-current sensor (ECS) interface intended for sub-nanometer displacement sensing in hitech applications. The interface employs a 126 MHz excitation frequency to mitigate the skin-effect, and achieve high resolution and stability. An efficient on-chip sensor-offset compensation scheme is introduced which removes sensor-offset proportional to the standoff distance. To assist in the ratiometric suppression of noise and drift of the excitation-oscillator, the ECS interface consists of a highly linear amplitude-demodulation scheme that employs passive capacitors for voltage-to-current conversion. Using a PCB-based pseudo-differential ECS, stability tests were performed which demonstrated a thermal drift of < 7.3 nm/ • C and long-term drift of only 29.5 nm over a period of 60 hours. The interface achieves an effective noise floor of 13.4 pm/ √ Hz which corresponds to a displacement resolution of 0.6 nm in a 2 kHz noise-bandwidth. The ECS interface is fabricated in TSMC 0.18 µm CMOS technology and dissipates only 19.8 mW from a 1.8 V supply.

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Demodulation Techniques for Self-Oscillating Eddy-Current Displacement Sensor Interfaces: A Review

Cited by 23 publications

References 26 publications

Robust and high-performance soft inductive tactile sensors based on the Eddy-current effect

Robust and high-performance soft inductive tactile sensors based on the Eddy-current effect

Effects of the Target on the Performance of an Ultra-Low Power Eddy Current Displacement Sensor for Industrial Applications

A 19.8-mW Eddy-Current Displacement Sensor Interface With Sub-Nanometer Resolution

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