Pub Date : 2026-01-15DOI: 10.1109/TIM.2026.3654702
Xi Wang;Letian Gao;Zihao Huang;Xin Xia;You Li;Guangcai Wang;Lu Xiong
The initial alignment of a vehicular inertial navigation system (INS) is a critical process, where accuracy and convergence speed represent the primary performance challenges. This article addresses initial attitude estimation errors resulting from unreliable aiding information and limited observation time in complex environments, such as during global navigation satellite system (GNSS) signal outages or wheel slippage. To mitigate these issues, a novel dynamic initial alignment strategy aided by light detection and ranging (LiDAR) is proposed to overcome the limitations inherent to conventional GNSS- or odometer (OD)-aided methods. Furthermore, to achieve fast, high-precision alignment with sparse observation data, a dynamic alignment model employing chronological optimization is developed. The proposed algorithm is validated through both simulations and real-world vehicle experiments. Results demonstrate that, compared with existing state-of-the-art methods, the proposed strategy exhibits superior environmental adaptability and faster convergence speed under dynamic conditions.
{"title":"Fast In-Motion Alignment for LiDAR–Inertial in Challenging Scenarios","authors":"Xi Wang;Letian Gao;Zihao Huang;Xin Xia;You Li;Guangcai Wang;Lu Xiong","doi":"10.1109/TIM.2026.3654702","DOIUrl":"https://doi.org/10.1109/TIM.2026.3654702","url":null,"abstract":"The initial alignment of a vehicular inertial navigation system (INS) is a critical process, where accuracy and convergence speed represent the primary performance challenges. This article addresses initial attitude estimation errors resulting from unreliable aiding information and limited observation time in complex environments, such as during global navigation satellite system (GNSS) signal outages or wheel slippage. To mitigate these issues, a novel dynamic initial alignment strategy aided by light detection and ranging (LiDAR) is proposed to overcome the limitations inherent to conventional GNSS- or odometer (OD)-aided methods. Furthermore, to achieve fast, high-precision alignment with sparse observation data, a dynamic alignment model employing chronological optimization is developed. The proposed algorithm is validated through both simulations and real-world vehicle experiments. Results demonstrate that, compared with existing state-of-the-art methods, the proposed strategy exhibits superior environmental adaptability and faster convergence speed under dynamic conditions.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-12"},"PeriodicalIF":5.9,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-15DOI: 10.1109/TIM.2026.3654717
Vikas Kumar Malav;Ashwani Sharma
The battery-free wireless sensor beacons (WSB) are essential for realizing a green and self-sustainable operation for power-constrained Internet of Things (IoT) applications. With increasing communication activities and availability, the radio frequency (RF) energy harvesting (EH) using a rectenna has become a reliable solution to energize the WSB wirelessly. Prior literary works indicate that the EH of a rectenna depends on the wave polarization between the rectenna and the transmitter to effectively capture the maximum incoming waves from any orientation, allowing the deployment of IoT nodes without requiring specific alignment. However, simultaneous effective EH and data transfer over a long distance at ultralow power is still an issue. Therefore, a novel RF-powered battery-free IoT beacon with a polarization-insensitive (PoI) feature is developed and demonstrated for ultralow-power IoT sensing applications. This WSB is completely integrated and miniaturized by implementing both wireless power and data transfer, which is developed on a multilayer printed circuit board (PCB). The WSB consists of a rectenna array operating at 5.2 GHz for wireless power, an integrated circuitry of a power management unit (PMU), and a Bluetooth low energy (BLE) module for data transfer. The WSB operates at a minimum received microwave power of −15.18 dBm. The results demonstrate the system to be wirelessly energized at a transfer range of 11 m away from the transmitter emitting 47.22 dBm power and realizing battery-free operation for IoT sensors. Thus, this design is suitable for orientation-independent WSB operations in IoT applications such as environmental monitoring and smart agriculture applications in remote areas.
{"title":"EcoSense: An Autonomous Polarization-Insensitive Wireless-Powered Battery-Free IoT Beacon for Live Environmental Sensing","authors":"Vikas Kumar Malav;Ashwani Sharma","doi":"10.1109/TIM.2026.3654717","DOIUrl":"https://doi.org/10.1109/TIM.2026.3654717","url":null,"abstract":"The battery-free wireless sensor beacons (WSB) are essential for realizing a green and self-sustainable operation for power-constrained Internet of Things (IoT) applications. With increasing communication activities and availability, the radio frequency (RF) energy harvesting (EH) using a rectenna has become a reliable solution to energize the WSB wirelessly. Prior literary works indicate that the EH of a rectenna depends on the wave polarization between the rectenna and the transmitter to effectively capture the maximum incoming waves from any orientation, allowing the deployment of IoT nodes without requiring specific alignment. However, simultaneous effective EH and data transfer over a long distance at ultralow power is still an issue. Therefore, a novel RF-powered battery-free IoT beacon with a polarization-insensitive (PoI) feature is developed and demonstrated for ultralow-power IoT sensing applications. This WSB is completely integrated and miniaturized by implementing both wireless power and data transfer, which is developed on a multilayer printed circuit board (PCB). The WSB consists of a rectenna array operating at 5.2 GHz for wireless power, an integrated circuitry of a power management unit (PMU), and a Bluetooth low energy (BLE) module for data transfer. The WSB operates at a minimum received microwave power of −15.18 dBm. The results demonstrate the system to be wirelessly energized at a transfer range of 11 m away from the transmitter emitting 47.22 dBm power and realizing battery-free operation for IoT sensors. Thus, this design is suitable for orientation-independent WSB operations in IoT applications such as environmental monitoring and smart agriculture applications in remote areas.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-12"},"PeriodicalIF":5.9,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-15DOI: 10.1109/TIM.2026.3652713
R. Akash;R. Sarathi;Manu Haddad;Bannur Nanjunda Shivananju
One of the major failure mechanisms in outdoor polymeric insulators is tracking. This article presents a novel dual-optical measurement system that combines fluorescent fiber sensing and optical emission spectroscopy (OES) for early detection of tracking in insulators. The proposed system captures both the time-dependent temporal features and the wavelength dependent spectral energy of the discharges simultaneously. The analysis was conducted with a large dataset of more than 1000 fluorescence pulses and 3000 spectral acquisitions during IEC 60587 tests. The progressive shift is observed in the photon emission energy from ~3.75 eV during the initial surface discharge to ~1.37 eV during the tracking stage. In addition, the stage-dependent progression of the fluorescence-based temporal features, such as rise time, pulsewidth, and energy, has also been investigated. By unsupervised t-distributed stochastic neighbor embedding (t-SNE) clustering, clear separability of degradation stages was visualized, with a silhouette score of 0.72 and 0.88 for OES and fluorescence, respectively. Field representative validation carried out on a polluted 11 kV insulator confirmed that these optical signatures remain consistent under practical conditions. The proposed method is non-contact, immune to electromagnetic interference, and suitable for automated field monitoring.
{"title":"Dual Optical Measurement for Early Detection of Tracking in Polymeric Insulators Using Fluorescent Fiber and Emission Spectroscopy","authors":"R. Akash;R. Sarathi;Manu Haddad;Bannur Nanjunda Shivananju","doi":"10.1109/TIM.2026.3652713","DOIUrl":"https://doi.org/10.1109/TIM.2026.3652713","url":null,"abstract":"One of the major failure mechanisms in outdoor polymeric insulators is tracking. This article presents a novel dual-optical measurement system that combines fluorescent fiber sensing and optical emission spectroscopy (OES) for early detection of tracking in insulators. The proposed system captures both the time-dependent temporal features and the wavelength dependent spectral energy of the discharges simultaneously. The analysis was conducted with a large dataset of more than 1000 fluorescence pulses and 3000 spectral acquisitions during IEC 60587 tests. The progressive shift is observed in the photon emission energy from ~3.75 eV during the initial surface discharge to ~1.37 eV during the tracking stage. In addition, the stage-dependent progression of the fluorescence-based temporal features, such as rise time, pulsewidth, and energy, has also been investigated. By unsupervised t-distributed stochastic neighbor embedding (t-SNE) clustering, clear separability of degradation stages was visualized, with a silhouette score of 0.72 and 0.88 for OES and fluorescence, respectively. Field representative validation carried out on a polluted 11 kV insulator confirmed that these optical signatures remain consistent under practical conditions. The proposed method is non-contact, immune to electromagnetic interference, and suitable for automated field monitoring.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-10"},"PeriodicalIF":5.9,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TIM.2025.3648088
Weixiao Tuo;Guanhao Liu;Xingfei Li;Tianyu Wang
In-orbit microangular vibration has been recognized as a key contributor to the satellite-borne optical communication system. A magnetohydrodynamic (MHD) angular rate sensor with extremely low noise and high frequency is the most suitable instrument for microangular vibration measurement. However, it exhibits poor near-dc sensitivity due to the influence of viscous force and electromagnetic force. The Kalman algorithm has been verified to be an effective method to extend the sensor bandwidth by fusing with other sensors. However, the traditional Kalman algorithm cannot deal with the unpredictable dynamics of the system due to its invariant parameters over time. In this work, an adaptive sequential Kalman algorithm is proposed. The high-dimensional measurement updates are reduced to multiple low-dimensional measurement updates. The covariance matrix of the measurement noise is set to be adaptively updated and computed in segments. The process noise covariance matrix is derived via weighted coefficient analysis by minimizing the mean square error. The computing time of the proposed method is proven to be a 38.39% reduction compared to the traditional Kalman method. The proposed method is realized in real-time to experimentally verify the frequency response and noise characteristics of the composite sensor. Results show that the bandwidth can achieve 0.1–700 Hz with a maximum amplitude fluctuation of 1.34 dB. The equivalent noise angular rate is 0.1523°/s root mean square (RMS). Allan variance analysis indicates that the bias instability and angle random walk of the composite sensor are both better than the other methods.
{"title":"Extended-Bandwidth Spacecraft Attitude Jitter Detection Based on Adaptive Sequential Kalman Algorithm","authors":"Weixiao Tuo;Guanhao Liu;Xingfei Li;Tianyu Wang","doi":"10.1109/TIM.2025.3648088","DOIUrl":"https://doi.org/10.1109/TIM.2025.3648088","url":null,"abstract":"In-orbit microangular vibration has been recognized as a key contributor to the satellite-borne optical communication system. A magnetohydrodynamic (MHD) angular rate sensor with extremely low noise and high frequency is the most suitable instrument for microangular vibration measurement. However, it exhibits poor near-dc sensitivity due to the influence of viscous force and electromagnetic force. The Kalman algorithm has been verified to be an effective method to extend the sensor bandwidth by fusing with other sensors. However, the traditional Kalman algorithm cannot deal with the unpredictable dynamics of the system due to its invariant parameters over time. In this work, an adaptive sequential Kalman algorithm is proposed. The high-dimensional measurement updates are reduced to multiple low-dimensional measurement updates. The covariance matrix of the measurement noise is set to be adaptively updated and computed in segments. The process noise covariance matrix is derived via weighted coefficient analysis by minimizing the mean square error. The computing time of the proposed method is proven to be a 38.39% reduction compared to the traditional Kalman method. The proposed method is realized in real-time to experimentally verify the frequency response and noise characteristics of the composite sensor. Results show that the bandwidth can achieve 0.1–700 Hz with a maximum amplitude fluctuation of 1.34 dB. The equivalent noise angular rate is 0.1523°/s root mean square (RMS). Allan variance analysis indicates that the bias instability and angle random walk of the composite sensor are both better than the other methods.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-10"},"PeriodicalIF":5.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TIM.2026.3652753
Koustav Dey;Rony Kumer Saha;Bohong Zhang;S. Narasimman;Farhan Mumtaz;Jeffrey D. Smith;Rex E. Gerald;Ronald J. O'Malley;Jie Huang
Metal-coated optical fibers are widely employed in sensing applications owing to their superior mechanical strength and corrosion resistance. However, their calibration at elevated temperatures is hindered by hysteresis, manifested as discrepancies between heating and cooling cycles, primarily caused by residual strain from mismatched thermal expansion coefficients (TECs) between the metal coating and silica cladding. This research introduces an optimal heat-treatment procedure aimed at minimizing the impact of the mismatch in TECs between the cladding and the coating materials that causes the residual strain in gold (Au) and copper (Cu) coated fibers for achieving reliable distributed high-temperature sensing up to $500~^{circ }$ C using optical frequency domain reflectometry (OFDR) technology. The treatment facilitates stress relaxation and microstructural modifications, including surface diffusion, grain growth, and oxidation (for Cu coatings), which collectively induce partial interfacial delamination and thereby suppress hysteresis. This work presents the first comprehensive experimental study to systematically investigate and demonstrate the mitigation of hysteresis through an optimized heat-treatment process and its underlying mechanisms in metal-coated fibers, supported by microstructural insights. The identified treatment range of $25~^{circ }$ C–$300~^{circ }$ C achieves substantial reductions in residual strain, lowering hysteresis effects by approximately 90.2% in Cu-coated fibers and 86.6% in Au-coated fibers. Furthermore, Au-coated fibers exhibit a consistently lower degree of hysteresis than Cu-coated fibers under comparable thermal conditions. Heat treatment also enhances temperature sensitivity, with improvements of approximately 28.9% for Cu-coated fibers and 6.6% for Au-coated fibers. Posttreatment strain analysis confirms maximum sustainable strain limits of $sim!!!6000~mu varepsilon $ for Au-coated fibers and ~12 $000~mu varepsilon $ for Cu-coated fibers. Both fiber types also demonstrated excellent thermal stability, maintaining consistent performance across three heating cycles between $25~^{circ }$ C and $300~^{circ }$ C over a 20-h period. Collectively, the findings not only advance the scientific understanding of residual strain relaxation mechanisms but also provide a practical route toward robust, precise, and reliable distributed sensing for demanding industrial environments such as the steel, oil, and gas sectors.
金属包覆光纤由于其优异的机械强度和耐腐蚀性，在传感领域得到了广泛的应用。然而，它们在高温下的校准受到滞后的阻碍，滞后表现为加热和冷却循环之间的差异，主要是由金属涂层和硅包层之间不匹配的热膨胀系数（TECs）造成的残余应变造成的。本研究介绍了一种最佳热处理工艺，旨在最大限度地减少包层和涂层材料之间tec不匹配的影响，这种不匹配会导致金（Au）和铜（Cu）涂层光纤中的残余应变，从而使用光频域反射（OFDR）技术实现高达$500~^{circ }$ C的可靠分布式高温传感。该处理促进了应力松弛和微观结构的改变，包括表面扩散、晶粒生长和氧化（对于Cu涂层），这些共同诱导了部分界面分层，从而抑制了滞后。这项工作提出了第一个全面的实验研究，系统地调查和证明了通过优化的热处理工艺及其在金属涂层纤维中的潜在机制，并得到微观结构见解的支持。确定的$25~^{circ }$ C - $300~^{circ }$ C处理范围内，残余应变显著降低，迟滞效应降低约90.2% in Cu-coated fibers and 86.6% in Au-coated fibers. Furthermore, Au-coated fibers exhibit a consistently lower degree of hysteresis than Cu-coated fibers under comparable thermal conditions. Heat treatment also enhances temperature sensitivity, with improvements of approximately 28.9% for Cu-coated fibers and 6.6% for Au-coated fibers. Posttreatment strain analysis confirms maximum sustainable strain limits of $sim!!!6000~mu varepsilon $ for Au-coated fibers and ~12 $000~mu varepsilon $ for Cu-coated fibers. Both fiber types also demonstrated excellent thermal stability, maintaining consistent performance across three heating cycles between $25~^{circ }$ C and $300~^{circ }$ C over a 20-h period. Collectively, the findings not only advance the scientific understanding of residual strain relaxation mechanisms but also provide a practical route toward robust, precise, and reliable distributed sensing for demanding industrial environments such as the steel, oil, and gas sectors.
{"title":"Mitigating Hysteresis in Metal-Coated Fibers via Optimized Thermal Treatment for Advanced Distributed High-Temperature Sensing Applications","authors":"Koustav Dey;Rony Kumer Saha;Bohong Zhang;S. Narasimman;Farhan Mumtaz;Jeffrey D. Smith;Rex E. Gerald;Ronald J. O'Malley;Jie Huang","doi":"10.1109/TIM.2026.3652753","DOIUrl":"https://doi.org/10.1109/TIM.2026.3652753","url":null,"abstract":"Metal-coated optical fibers are widely employed in sensing applications owing to their superior mechanical strength and corrosion resistance. However, their calibration at elevated temperatures is hindered by hysteresis, manifested as discrepancies between heating and cooling cycles, primarily caused by residual strain from mismatched thermal expansion coefficients (TECs) between the metal coating and silica cladding. This research introduces an optimal heat-treatment procedure aimed at minimizing the impact of the mismatch in TECs between the cladding and the coating materials that causes the residual strain in gold (Au) and copper (Cu) coated fibers for achieving reliable distributed high-temperature sensing up to <inline-formula> <tex-math>$500~^{circ }$ </tex-math></inline-formula>C using optical frequency domain reflectometry (OFDR) technology. The treatment facilitates stress relaxation and microstructural modifications, including surface diffusion, grain growth, and oxidation (for Cu coatings), which collectively induce partial interfacial delamination and thereby suppress hysteresis. This work presents the first comprehensive experimental study to systematically investigate and demonstrate the mitigation of hysteresis through an optimized heat-treatment process and its underlying mechanisms in metal-coated fibers, supported by microstructural insights. The identified treatment range of <inline-formula> <tex-math>$25~^{circ }$ </tex-math></inline-formula>C–<inline-formula> <tex-math>$300~^{circ }$ </tex-math></inline-formula>C achieves substantial reductions in residual strain, lowering hysteresis effects by approximately 90.2% in Cu-coated fibers and 86.6% in Au-coated fibers. Furthermore, Au-coated fibers exhibit a consistently lower degree of hysteresis than Cu-coated fibers under comparable thermal conditions. Heat treatment also enhances temperature sensitivity, with improvements of approximately 28.9% for Cu-coated fibers and 6.6% for Au-coated fibers. Posttreatment strain analysis confirms maximum sustainable strain limits of <inline-formula> <tex-math>$sim!!!6000~mu varepsilon $ </tex-math></inline-formula> for Au-coated fibers and ~12 <inline-formula> <tex-math>$000~mu varepsilon $ </tex-math></inline-formula> for Cu-coated fibers. Both fiber types also demonstrated excellent thermal stability, maintaining consistent performance across three heating cycles between <inline-formula> <tex-math>$25~^{circ }$ </tex-math></inline-formula>C and <inline-formula> <tex-math>$300~^{circ }$ </tex-math></inline-formula>C over a 20-h period. Collectively, the findings not only advance the scientific understanding of residual strain relaxation mechanisms but also provide a practical route toward robust, precise, and reliable distributed sensing for demanding industrial environments such as the steel, oil, and gas sectors.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-18"},"PeriodicalIF":5.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TIM.2026.3652758
Jian Zhang;Haotian Zhou;Aohui Li;Gaoyu Han;Zhengkai Zhu;Jiehu Kang;Bin Wu;Jun Wang;Tianliang Li
The simultaneous monitoring of intracranial pressure (ICP) and intracranial temperature (ICT) is an essential process for assessing neurocritical conditions and preventing secondary brain injury. This study develops a medical monitor employing the optical fiber sensing technique, with a wavelength–phase hybrid coding approach, to simultaneously measure pressure and temperature. The optical fiber sensor is configured with a Fabry–Pérot (F-P) cavity and a fiber Bragg grating (FBG). The F-P cavity is fabricated through precision cutting and polishing, showing the advantages of controllable performance and low cost. Aiming at the multifeature spectrum demodulation, this work combined the discrete Fourier transform with a centroid peak detection technique to propose a wavelength–phase calculation strategy. Experimentally measuring range of the designed monitor is $- 300sim 300$ mmHg with a sensitivity of 248.67 pm/mmHg. The error of pressure was reduced to a lower level of 2.48% by using temperature compensation. In addition, the study constructed ex vivo tissue and in vivo animal experiments designed to test the monitor’s performance. The results show that the monitor can accurately measure ICP and brain temperature, and it exhibits rapid response characteristics compared to commercial monitors. Such merits show the great potential of the monitor in the diagnosis and surveillance of neurocritical care patients.
{"title":"Wavelength–Phase Hybrid Coding Optical Fiber Medical Monitor With Intracranial Pressure and Temperature Dynamic Self-Decoupling","authors":"Jian Zhang;Haotian Zhou;Aohui Li;Gaoyu Han;Zhengkai Zhu;Jiehu Kang;Bin Wu;Jun Wang;Tianliang Li","doi":"10.1109/TIM.2026.3652758","DOIUrl":"https://doi.org/10.1109/TIM.2026.3652758","url":null,"abstract":"The simultaneous monitoring of intracranial pressure (ICP) and intracranial temperature (ICT) is an essential process for assessing neurocritical conditions and preventing secondary brain injury. This study develops a medical monitor employing the optical fiber sensing technique, with a wavelength–phase hybrid coding approach, to simultaneously measure pressure and temperature. The optical fiber sensor is configured with a Fabry–Pérot (F-P) cavity and a fiber Bragg grating (FBG). The F-P cavity is fabricated through precision cutting and polishing, showing the advantages of controllable performance and low cost. Aiming at the multifeature spectrum demodulation, this work combined the discrete Fourier transform with a centroid peak detection technique to propose a wavelength–phase calculation strategy. Experimentally measuring range of the designed monitor is <inline-formula> <tex-math>$- 300sim 300$ </tex-math></inline-formula> mmHg with a sensitivity of 248.67 pm/mmHg. The error of pressure was reduced to a lower level of 2.48% by using temperature compensation. In addition, the study constructed ex vivo tissue and in vivo animal experiments designed to test the monitor’s performance. The results show that the monitor can accurately measure ICP and brain temperature, and it exhibits rapid response characteristics compared to commercial monitors. Such merits show the great potential of the monitor in the diagnosis and surveillance of neurocritical care patients.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-12"},"PeriodicalIF":5.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Driving fatigue is a major contributing factor to road traffic accidents, particularly under prolonged driving conditions where it significantly impairs attention and reaction capabilities. Electroencephalogram (EEG) signals, due to their high sensitivity to mental states, have been widely adopted for fatigue detection and assessment. However, existing methods still struggle to jointly model discriminative spectral patterns and multiscale temporal dependencies. To address these limitations, we propose dual-branch spectral-temporal attention fusion network (STAFNet) for EEG-based driving fatigue detection. The spectral branch uses frequency-band convolution and squeeze-and-excitation (SE) attention to extract key rhythms, while the temporal branch employs multiscale convolution, bidirectional gated recurrent unit (Bi-GRU), and temporal attention to capture fatigue-related temporal dynamics. Semantic-level feature fusion is then performed to integrate the two branches collaboratively. Extensive Experiments conducted on a self-constructed 64-channel EEG dataset comprising 40 participants demonstrate that STAFNet outperforms mainstream baseline methods in terms of classification performance and achieves strong cross-subject generalization ability. Ablation studies confirm the contribution of each module, and frequency importance analysis highlights the dominant role of alpha and theta bands in fatigue representation. Moreover, cross-dataset evaluation on the public SEED-VIG dataset further confirms its robustness. These results suggest that STAFNet provides a robust and effective signal processing framework for real-time fatigue monitoring in driving scenarios.
{"title":"A Dual-Branch Spectral–Temporal Attention Fusion Network for EEG-Based Driving Fatigue Detection","authors":"Xianhui Wu;Zhuoxi Jiang;Chaojie Fan;Chenxi Li;Zhongjing Xia;Ziteng Zhang;Yong Peng","doi":"10.1109/TIM.2026.3652735","DOIUrl":"https://doi.org/10.1109/TIM.2026.3652735","url":null,"abstract":"Driving fatigue is a major contributing factor to road traffic accidents, particularly under prolonged driving conditions where it significantly impairs attention and reaction capabilities. Electroencephalogram (EEG) signals, due to their high sensitivity to mental states, have been widely adopted for fatigue detection and assessment. However, existing methods still struggle to jointly model discriminative spectral patterns and multiscale temporal dependencies. To address these limitations, we propose dual-branch spectral-temporal attention fusion network (STAFNet) for EEG-based driving fatigue detection. The spectral branch uses frequency-band convolution and squeeze-and-excitation (SE) attention to extract key rhythms, while the temporal branch employs multiscale convolution, bidirectional gated recurrent unit (Bi-GRU), and temporal attention to capture fatigue-related temporal dynamics. Semantic-level feature fusion is then performed to integrate the two branches collaboratively. Extensive Experiments conducted on a self-constructed 64-channel EEG dataset comprising 40 participants demonstrate that STAFNet outperforms mainstream baseline methods in terms of classification performance and achieves strong cross-subject generalization ability. Ablation studies confirm the contribution of each module, and frequency importance analysis highlights the dominant role of alpha and theta bands in fatigue representation. Moreover, cross-dataset evaluation on the public SEED-VIG dataset further confirms its robustness. These results suggest that STAFNet provides a robust and effective signal processing framework for real-time fatigue monitoring in driving scenarios.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-13"},"PeriodicalIF":5.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TIM.2025.3650255
Yaoguang Shi;Xiaozhou Lü;Zhuolun Li;Haoning Chu;Chao Yuan;Weimin Bao
Flexible skins with active thermal protection systems have attracted considerable attention owing to their role as essential enabling technologies for morphing high-speed vehicles. Temperature sensors integrated into flexible skin can help regulate and optimize coolant consumption. However, it is often difficult to obtain strain-insensitive temperature measurements under multidirectional deformations of flexible skin. Therefore, this study investigates a novel multidirectional strain-insensitive stretchable temperature sensor (STS) based on a hexagram structure. A sensor prototype was fabricated with a measurement range of $200~^{circ }$ C and a temperature coefficient of resistance (TCR) of 0.30%/°C. Furthermore, it achieved hysteresis and repeatability errors of 0.83% and 1.79%, respectively. The proposed sensor exhibited a resistance variation of less than 1% under a multidirectional uniaxial tensile strain of 0%–80%, indicating its effective strain decoupling capability. Finally, real-time surface temperature distribution detection was successfully achieved under a heat flux of 202 kW/m2 by integrating the sensor array on an active thermal protection flexible skin, demonstrating the potential application of morphing high-speed vehicles.
{"title":"Multidirectional Strain-Insensitive Stretchable Temperature Sensor for Active Thermal Protection Flexible Skin","authors":"Yaoguang Shi;Xiaozhou Lü;Zhuolun Li;Haoning Chu;Chao Yuan;Weimin Bao","doi":"10.1109/TIM.2025.3650255","DOIUrl":"https://doi.org/10.1109/TIM.2025.3650255","url":null,"abstract":"Flexible skins with active thermal protection systems have attracted considerable attention owing to their role as essential enabling technologies for morphing high-speed vehicles. Temperature sensors integrated into flexible skin can help regulate and optimize coolant consumption. However, it is often difficult to obtain strain-insensitive temperature measurements under multidirectional deformations of flexible skin. Therefore, this study investigates a novel multidirectional strain-insensitive stretchable temperature sensor (STS) based on a hexagram structure. A sensor prototype was fabricated with a measurement range of <inline-formula> <tex-math>$200~^{circ }$ </tex-math></inline-formula>C and a temperature coefficient of resistance (TCR) of 0.30%/°C. Furthermore, it achieved hysteresis and repeatability errors of 0.83% and 1.79%, respectively. The proposed sensor exhibited a resistance variation of less than 1% under a multidirectional uniaxial tensile strain of 0%–80%, indicating its effective strain decoupling capability. Finally, real-time surface temperature distribution detection was successfully achieved under a heat flux of 202 kW/m<sup>2</sup> by integrating the sensor array on an active thermal protection flexible skin, demonstrating the potential application of morphing high-speed vehicles.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-10"},"PeriodicalIF":5.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TIM.2025.3648096
Shiyuan Zhao;Jiwen Cui;Zhanjun Wu
Optical frequency domain reflectometry (OFDR) distributed optical fiber sensing technology has become a critical technique for structural health monitoring due to its exceptional spatial sensing resolution. Current state-of-the-art OFDR sensing systems predominantly use external-cavity tunable lasers (ECTLs) as their light sources to detect the Rayleigh backscattering spectra (RBS) over wavelength ranges spanning several tens of nanometers. However, the significant challenges posed by ECTLs in terms of size, weight, power consumption, and cost (SWaP-C) have constrained the large-scale industrial deployment of OFDR sensing technology. This study introduces a novel multiband multiplexed OFDR distributed optical fiber sensing approach that replaces the conventional single-shot optical frequency modulation light injection detection strategy with time-division segmented spectral detection. Both theoretical analyses and experimental validations demonstrate that sensing capabilities equivalent to those of ECTLs can be achieved via this sequential spectral acquisition approach. To implement this methodology, the correlation of the RBS from a characteristic fiber segment (CFS) within the optical frequency overlap region of the main interferometer is used to determine the stitching positions of adjacent frequency band measurement signals, enabling precise picometer-level wavelength stitching. By adopting a commercial distributed feedback (DFB) laser array as the system’s light source and using segmented modulation with precision stitching, an RBS detection range of 35.013 nm is achieved, and has the potential for further expansion. Leveraging this architecture, an OFDR distributed optical fiber sensing system is developed, and it demonstrates an 8-mm spatial sensing resolution and a 10 000-$mu varepsilon $ measurement range. This innovative approach provides a new design paradigm for OFDR systems. The proposed OFDR distributed optical fiber sensing system demonstrates performance metrics comparable to those of conventional systems while offering significant advantages in terms of SWaP-C, holding significant promise for advancing the industrialization of this technology.
{"title":"Equivalent Broadband Optical Frequency Domain Reflectometry via Multiband Laser Injection and Signal Stitching for Distributed Fiber Sensing","authors":"Shiyuan Zhao;Jiwen Cui;Zhanjun Wu","doi":"10.1109/TIM.2025.3648096","DOIUrl":"https://doi.org/10.1109/TIM.2025.3648096","url":null,"abstract":"Optical frequency domain reflectometry (OFDR) distributed optical fiber sensing technology has become a critical technique for structural health monitoring due to its exceptional spatial sensing resolution. Current state-of-the-art OFDR sensing systems predominantly use external-cavity tunable lasers (ECTLs) as their light sources to detect the Rayleigh backscattering spectra (RBS) over wavelength ranges spanning several tens of nanometers. However, the significant challenges posed by ECTLs in terms of size, weight, power consumption, and cost (SWaP-C) have constrained the large-scale industrial deployment of OFDR sensing technology. This study introduces a novel multiband multiplexed OFDR distributed optical fiber sensing approach that replaces the conventional single-shot optical frequency modulation light injection detection strategy with time-division segmented spectral detection. Both theoretical analyses and experimental validations demonstrate that sensing capabilities equivalent to those of ECTLs can be achieved via this sequential spectral acquisition approach. To implement this methodology, the correlation of the RBS from a characteristic fiber segment (CFS) within the optical frequency overlap region of the main interferometer is used to determine the stitching positions of adjacent frequency band measurement signals, enabling precise picometer-level wavelength stitching. By adopting a commercial distributed feedback (DFB) laser array as the system’s light source and using segmented modulation with precision stitching, an RBS detection range of 35.013 nm is achieved, and has the potential for further expansion. Leveraging this architecture, an OFDR distributed optical fiber sensing system is developed, and it demonstrates an 8-mm spatial sensing resolution and a 10 000-<inline-formula> <tex-math>$mu varepsilon $ </tex-math></inline-formula> measurement range. This innovative approach provides a new design paradigm for OFDR systems. The proposed OFDR distributed optical fiber sensing system demonstrates performance metrics comparable to those of conventional systems while offering significant advantages in terms of SWaP-C, holding significant promise for advancing the industrialization of this technology.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-9"},"PeriodicalIF":5.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article presents a novel ultrasonic acetic acid concentration detection system based on capacitive micromachined ultrasonic transducers (CMUTs). The system utilizes CMUTs as the core sensing components to perform both signal transmission and reception. A temperature sensor is integrated to continuously monitor temperature variations in the test liquid, thereby ensuring measurement accuracy. Under the temperature compensation mechanism, the system continuously analyzes the acquired signals to accurately determine the ultrasonic time-of-flight (TOF) and propagation velocity in the liquid. A quantitative model correlating sound velocity with temperature and acetic acid concentration was established and experimentally validated, demonstrating excellent stability and high sensitivity. The system achieves a measurement accuracy of 0.35% and a resolution of 0.1%. Benefiting from the miniaturized design of CMUTs, the system can be developed into a compact probe, offering an efficient and convenient solution for real-time acetic acid concentration monitoring during vinegar production and distribution.
{"title":"A Novel Real-Time Acetic Acid Concentration Detection System Based on Capacitive Micromachined Ultrasonic Transducers","authors":"Jiaqi Chen;Yunbin Huang;Jiali Sun;Zhihao Wang;Zhaodong Li;Xiangcheng Zeng;Licheng Jia;Changde He;Yuhua Yang;Jiangong Cui;Guojun Zhang;Wendong Zhang;Renxin Wang","doi":"10.1109/TIM.2025.3647998","DOIUrl":"https://doi.org/10.1109/TIM.2025.3647998","url":null,"abstract":"This article presents a novel ultrasonic acetic acid concentration detection system based on capacitive micromachined ultrasonic transducers (CMUTs). The system utilizes CMUTs as the core sensing components to perform both signal transmission and reception. A temperature sensor is integrated to continuously monitor temperature variations in the test liquid, thereby ensuring measurement accuracy. Under the temperature compensation mechanism, the system continuously analyzes the acquired signals to accurately determine the ultrasonic time-of-flight (TOF) and propagation velocity in the liquid. A quantitative model correlating sound velocity with temperature and acetic acid concentration was established and experimentally validated, demonstrating excellent stability and high sensitivity. The system achieves a measurement accuracy of 0.35% and a resolution of 0.1%. Benefiting from the miniaturized design of CMUTs, the system can be developed into a compact probe, offering an efficient and convenient solution for real-time acetic acid concentration monitoring during vinegar production and distribution.","PeriodicalId":13341,"journal":{"name":"IEEE Transactions on Instrumentation and Measurement","volume":"75 ","pages":"1-11"},"PeriodicalIF":5.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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