Search Results (365)

Human kinematic analysis is an increasingly important tool in biomechanics, human performance, and wearable sensing research. Many emerging sensing modalities utilize custom sensors requiring accurate temporal alignment with ground-truth biomechanical movement data. Optical motion capture systems provide high-fidelity kinematic measurements but operate as closed, self-contained systems, making time synchronization with external sensor data non-trivial, particularly in wireless and mobile contexts. This work presents a wireless analog interface system built using commercially available components that enables alignment between analog sensor data (e.g., from custom wearables and Internet-of-Things devices) and a commercial motion capture system. The proposed architecture consists of a wearable data acquisition node and a receiver node interfaced directly with an optical motion capture system, allowing synchronized recording of analog sensor signals alongside kinematic data. Notably, the system reconstructs signals into the commercial hardware interface rather than relying on triggers or sync outputs, resulting in a single data file containing kinematics and sensor readings. Benchtop testing demonstrated a mean end-to-end frame delay of ~6 ms, with 95% of the sample exhibiting delay within 15 ms. Accounting for the typical offset, this leaves a standard deviation of 4 ms, within one motion capture frame of the true timestamp (at 100 Hz). Voltage reconstruction accuracy was within 30 mV across the tested conditions, with gain compression below 2.7%. Adjacent channel crosstalk remained below −83 dB across all test conditions. The use of commercial off-the-shelf components supports replication and adaptation by other research groups and integration with different optical motion capture systems. Full article

Private Networks or Standalone Non-Public Networks (SNPNs) are essential for Industry 4.0 and enterprise connectivity. However, most existing studies rely on simulations, evaluate only a single radio access technology, or report raw key performance indicators (KPIs) without an interpretable quality assessment framework. In practical deployment, operators require measurement-driven evidence to assess the performance and feasibility of 4G LTE and 5G SNPN solutions. This study presents a controlled experimental comparison of software-defined radio (SDR)-based 4G LTE and 5G SNPNs using the same Universal Software Radio Peripheral (USRP) platform, Open5GS, srsRAN, and commercial off-the-shelf user equipment (COTS-UE). The evaluation was conducted in an indoor environment under line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. Experimental iPerf3 results show that the SDR-based 5G SNPN achieves higher downlink and uplink throughput than the SDR-based 4G LTE SNPN across all tested scenarios. The 5G deployment reaches up to 55 Mbps downlink and 40.5 Mbps uplink under LOS conditions, while maintaining 42 Mbps downlink and 28 Mbps uplink under NLOS conditions. Furthermore, 5G achieves lower latency than 4G LTE, with average values ranging from 21 ms to 31 ms. To provide interpretable network quality assessment, a Mamdani fuzzy logic-based Network Quality Index (NQI) with 81 inference rules is proposed to map signal-to-interference-plus-noise ratio (SINR), throughput, latency, and jitter into linguistic quality levels. The proposed approach enables nonlinear integration of heterogeneous KPIs and provides a technology-agnostic framework for practical SNPN deployment. Full article

Designing low-voltage (LV) power distribution systems for mass-sensitive electric vehicles involves several unresolved technical challenges, including parasitic $I^{2}R$ losses, excessive mass of commercial off-the-shelf distribution units, and difficulties in isolating thermal phenomena during vehicle operation. In dynamic racing conditions, temperature measurements of LV components are strongly influenced by external heat sources such as traction batteries, motors, and inverters, complicating accurate assessment of conductor self-heating and distribution losses. This work presents a load-driven methodology for the specification, implementation, and validation of LV architectures, demonstrated using a Formula Student electric race car. The proposed approach combines harness current mapping, resistive loss modeling, and component-level topology optimization to support the development of lightweight and electrically robust systems. Within this framework, a mass-optimized programmable solid-state power distribution unit (PDU), an auxiliary battery system with a battery management system (BMS), and an optimized LV wiring harness were developed and experimentally validated through controlled subsystem tests and in-vehicle operation. The proposed methodology enabled reduction in PDU mass by 40–80% relative to commercially available solutions while maintaining programmable protection, integrated current sensing, and stable thermal operation under representative racing loads. This reduction was achieved through load-driven conductor sizing, application-specific protection threshold optimization, and elimination of redundant protection and interconnection hardware. The developed PDU achieved a mass of 155 g with measured channel resistances of 40–70 m$\mathsf{\Omega }$. The auxiliary battery pack exhibited an average internal resistance of 64.2 m$\mathsf{\Omega }$ at a total mass of 2190 g, while the optimized harness demonstrated resistivity in the range of 14.72–33.98 m$\mathsf{\Omega }$/m. Experimental validation confirmed stable operation below critical thermal limits under both nominal and off-nominal load conditions. The obtained results demonstrate that the proposed methodology enables measurable reductions in both system mass and resistive power losses through application-specific optimization of the LV architecture. However, the presented approach is primarily suited for motorsport and other highly mass-constrained applications, where reduced packaging volume, efficiency, and weight justify the increased design complexity and lower universality compared to commercial off-the-shelf solutions. Full article

This paper presents the field deployment and performance evaluation of a New Radio Vehicle-to-Everything (NR-V2X) Cooperative Intelligent Transportation System (C-ITS) test corridor over a 5G stand-alone (SA) private network, implemented on a 40 km highway in Istanbul, Turkey. The deployment integrates 19 dual-sector gNBs, commercial off-the-shelf (COTS) core network components, and an O-RAN-compatible Rel. 17 architecture and evaluates six ETSI-compliant C-ITS scenarios under a systematic 3 × 3 experimental matrix spanning three vehicle speeds and three traffic density categories. Key quantitative findings include the following: (i) 98.9% of the corridor achieves the target RSRP of −110 dBm, confirming coverage viability; (ii) five of the six scenarios satisfy ETSI end-to-end latency requirements across all tested conditions, with the packet delivery ratio remaining above 94% throughout; and (iii) the Emergency Vehicle Approaching (EVA) scenario meets its stringent 20 ms latency requirement exclusively under free-flow conditions (μ = 14.7 ms) and progressively exceeds it under medium- and high-density traffic (μ = 26.6 ms and μ = 40.1 ms, respectively). These results provide quantitative evidence that MEC integration is a necessary architectural complement to the 5G SA private network for ultra-low-latency safety services and establish a reproducible reference architecture for public highway C-ITS deployments. Full article

Wireless networks are increasingly considered for industrial and time-critical applications, where flexible deployment must be reconciled with predictable communication behaviour. IEEE 802.11ax introduces mechanisms such as Orthogonal Frequency Division Multiple Access (OFDMA), Trigger-based Uplink Access (TUA), and Target Wake Time (TWT) as part of ongoing efforts to support bounded latency and deterministic transmissions in Wi-Fi networks. However, the practical behaviour of these mechanisms depends not only on the standard, but also on what commercial devices expose, how access points implement scheduling decisions, and how trigger-based access, RU assignment, and timing control can be configured in real deployments. This paper therefore focuses on the practical implementation and experimental assessment of OFDMA-based deterministic operation using Wi-Fi 6 commercial off-the-shelf (COTS) hardware. The proposed configuration combines driver-level enabling of high-efficiency mechanisms with controlled testbed measurements and complementary simulations, allowing OFDMA operation to be compared against conventional single-user OFDM under realistic traffic and interference conditions. The results show that coordinated OFDMA operation on COTS devices improves temporal stability, reducing jitter by up to 23% and latency by approximately 44% with respect to single-user OFDM operation. The experiments also reveal practical effects that are central to deterministic-oriented Wi-Fi: simultaneous RU-based transmissions reduce contention-driven variability, TWT-based activity windows improve temporal alignment, and RU subdivision introduces a throughput trade-off that must be considered when dimensioning industrial traffic. Overall, the study provides empirical evidence that Wi-Fi 6 can support deterministic-oriented industrial communication when OFDMA, trigger-based access, and timing mechanisms are jointly configured, while also highlighting the implementation constraints that remain when moving from standard capabilities to COTS device behaviour. Full article

The increase in small satellites demands the integration of commercial components to reduce costs and development time. However, the lack of standardized system-level methodologies to mitigate radiation-induced degradation limits their adoption. Although majority-carrier technologies such as MOSFET transistors dominate space power electronics, modern commercial off-the-shelf BJT transistors present a robust and cost-effective alternative. This paper evaluates the viability of the new-generation commercial off-the-shelf BJT transistors in space radiation environments by analyzing their response to total ionizing dose (measured at the circuit level) and single-event effects (inferred from component-level data). A fault-tolerant design methodology is proposed based on the strict definition of the safe operating area: the collector-emitter voltage is limited to safe values to mitigate single-event burnout, and an overdrive margin, specifically a 5× worst-case factor, is applied to compensate for the parametric degradation of the current gain. These strategies are empirically validated through two circuits: a voltage clamp and a proportional base driver operating in the 5 W to 40 W range. Experimental tests on the voltage clamp demonstrate stable operation up to one hundred kilorads, exceeding the 50 krad mission requirement by 100%. This indirectly supports the proportional base driver through shared mitigation principles, which rely on base current over-dimensioning to compensate for TID degradation. In conclusion, by applying appropriate derating rules, commercial off-the-shelf BJT transistors constitute a viable and robust alternative for small satellite power systems, mitigating the need for expensive radiation-hardened components. Full article

The Automatic Identification System (AIS) is a maritime radio system that regularly broadcasts vessel data, such as the vessel’s identification, position, course and speed. For modulation, the AIS standard defines Gaussian minimum shift keying (GMSK) as an easy to implement modulation scheme with constant envelope, meaning that a GMSK complex baseband signal carries information solely in its phase. AIS does not use any forward error correction (FEC) mechanism. In this paper we propose to extend GMSK with amplitude modulation, leading to multi-amplitude Gaussian minimum shift keying (MA-GMSK). The additional modulation of the amplitude increases the spectral efficiency so that additional information, i.e., additional bits can be transmitted. We use the increased spectral efficiency to implement FEC, where we transmit the redundancy bits of a systematic channel code via the additional amplitude modulation in the proposed MA-GMSK scheme. With this approach, the proposed MA-GMSK signal can be processed by off-the-shelf AIS receivers, thus demonstrating empirical standard compatibility with the tested receivers. Based on simulations and experimental results, we propose a suitable MA-GMSK modulation parameter setting and evaluate the packet error rate (PER) performance accordingly. To verify standard compatibility, we examine the performance of commercially available AIS receivers fed with MA-GMSK signals. Using the proposed modulation and coding scheme, an advanced MA-GMSK receiver including FEC provides performance improvements up to 3 dB in the required signal-to-noise ratio (SNR) compared to state-of-the art AIS using uncoded GMSK. Full article

Small satellites provide cost-effective platforms for environmental monitoring. Open-source commercial off-the-shelf (COTS) hyperspectral payloads, such as those launched with HYPSO-1 and -2, have a ground sampling distance (GSD) of 100 m. However, detecting smaller features, such as water quality in lakes, requires a GSD below 10 m and a high signal-to-noise ratio. Terrestrial COTS Schmidt–Cassegrain telescopes lack launch-load stiffness and in-orbit refocus capability. This study presents a deployable modified COTS (MCOTS) Schmidt–Cassegrain telescope that uses the original optical COTS components, a 3D-printed high-performance polymer (HPP) structure, and a dual-lead-screw deployment and focusing mechanism. The telescope has a stowed length of 280 mm and deploys to an additional 110 mm, making integration into a 16U platform with a payload length of 290 mm feasible. The modified structure is evaluated using shock and sine-sweep vibration testing, with collimation and focus verified before and after testing. Collimation remained concentric within measurement uncertainty. Complementary random-vibration finite-element simulations predicted a $3\sigma$ von Mises stress of 26.5 MPa, yielding a safety factor of 2.8. The results demonstrate a feasible pathway for adapting COTS telescopes toward space-grade COTS (SCOTS) payloads, bridging the gap between rapid production, cost efficiency, and performance for small Earth observation missions. Full article

The increasing number of UAVs performing commercial and amateur flights necessitates the introduction of safe design principles for airborne platform architectures and UAV control algorithms. This article presents an approach to designing such solutions. UAVConfigurator is software designed for simulating the dynamics of a Commercial Off-The-Shelf (COTS) Fighter UAV airframe, developed in the MATLAB/Simulink environment. This application simplifies the design and testing of control software for unmanned systems, and is intended for use by UAV designers, researchers, and students. It serves as a Software-In-the-Loop (SIL) simulator, allowing users to build and test new algorithms in simulated environments before transitioning to real UAVs. The software accurately models UAV dynamics, as confirmed by flight tests, owing to its integration with advanced aerodynamic computations. It includes models of essential UAV components and enables users to simulate sensor failures. Additionally, it features an ISA atmosphere model. The aerodynamics model developed for the airframe enables users to conduct Hardware-In-the-Loop (HIL) simulations without requiring independent calculations of force and moment values, making it a unique tool in UAV simulation. Users also have the flexibility to modify the models of each component, including verifying system performance after using new onboard devices. The presented model allows users to design their own algorithms, coded on the Flight Computer or Mission Computer, to execute missions according to their own ideas. Full article

In-flight icing poses a major risk to the flight safety and operational availability in aviation and particularly to small electric aircraft. One suitable ice protection system (IPS) concept is the electrothermal IPS; however, it often suffers from high power consumption if not properly optimized. Ducted fans are a promising propulsion technology for urban air mobility applications, but effective IPSs for ducted fan propellers have been rare thus far. This work thus presents a framework for the development of an energy-efficient electrothermal IPS for application in an off-the-shelf ducted fan propeller. Three-dimensional ice accretion simulations of the ducted fan’s assembly were performed under centrifugal loads using the commercial icing simulation code ANSYS^® FENSAP-ICE-TURBO^™ and the most critical areas for ice accretion on the ducted fan were identified. On the basis of the ice accretion simulations, the expected performance change of the ducted fan due to ice accretion on the rotor blades was evaluated. The placement and activation of the heating elements on the rotor blades were investigated and optimized using a one-dimensional electrothermal de-icing solver. Full article

The production of one-piece composite hollow profiles with undercuts presents significant challenges to conventional mold concepts. Mandrels made of thermoplastic shape-memory polymers could facilitate demolding and reduce tooling costs. To design molds in a commercial environment, it is critical to determine their behavior using off-the-shelf Finite Element Analysis (FEA) software Ansys 2024R1. This study presents a shape-memory test procedure for coupon test specimens under tensile load. Furthermore, the test is used to validate a simulation using a generalized Maxwell model, a linear viscoelastic material model implemented in off-the-shelf commercial FEA software Ansys 2024R1. The material investigated is amorphous PET. The simulation shows good results in comparison with the thermo-mechanical shape-memory test. The results are then transferred to blow-molded bottle-shaped mandrels, e.g., for the manufacturing of Type V pressure vessels. Test results are compared with the simulation results and deviations are discussed. In conclusion, the straightforward “from material to solution” approach presented allows us to model and simulate the shape-memory behavior of linear viscoelastic polymers with off-the-shelf commercial FEA software. Full article

Neuromuscular electrical stimulation (NMES) is integral to studying muscle function in healthy and dystrophic mice. Certain commercial electrodes and laboratory stimulators used for NMES in mice are no longer in production. We developed and/or tested low-cost, open-source alternatives to discontinued commercial standards. We performed two studies—a comparison of electrodes and a comparison of stimulators. In the electrode study, in vivo NMES was applied to the left hindlimb ankle dorsiflexors in healthy C57BL/6J and dysferlin-null BLAJ mice using three electrode types: a previously available commercial electrode, a custom 3D-Printed electrode, and a custom Pen electrode assembled from off-the-shelf components. Twitch and tetanic torque were measured and compared using two-way repeated-measures ANOVA. Twitch torque differed by electrode type (p = 0.031), with lower values observed for the Pen electrode compared with the 3D-Printed electrode (e.g., 573 ± 72 vs. 666 ± 70 mN.mm in C57BL/6J mice), whereas tetanic torque did not differ significantly between electrode types (p = 0.060). In the stimulator study, twitch and tetanic contractions were elicited using the open-source StimJim stimulator and compared with contractions elicited by the discontinued Grass S48 stimulator. Twitch torque was lower with the StimJim (588 ± 107 mN.mm) compared with the Grass S48 (698 ± 116 mN.mm; p < 0.001), whereas tetanic torque values were not statistically different (p = 0.055). These findings indicate that open-source electrodes and stimulators can produce similar maximal tetanic torque under the tested conditions, although differences in twitch torque and stimulation parameters should be considered. These results reflect a methodological validation of accessible tools rather than a formal equivalence analysis. Full article

In this paper the design, modelling, and performance assessment of a miniaturised dual-purpose optical instrument for small satellites are presented. The instrument can function as a star tracker and as a space-debris detection camera. The system integrates commercial off-the-shelf components, i.e., a CMOS sensor, a processing unit and lens assembly, together with a custom three-vane optical baffle optimised for stray-light suppression. A complete numerical evaluation was conducted through optical ray-tracing, lumped-parameter thermal modelling, and structural finite-element analysis to validate the instrument prior to hardware testing. Optical simulations confirmed effective stray-light suppression and acceptable Point Source Transmission behaviour, enabling signal-to-noise ratio performance suitable for star and debris detection up to ∼5.8 mag. The resulting instrument, with a mass of approximately 172 g and dimensions of 105 mm × 52 mm × 52 mm, demonstrates a compact, low-cost, and multifunctional solution for small-sized platforms. Future work includes environmental testing and on-orbit demonstration to prepare the system for flight qualification. Full article

Hypernasality is a common characteristic of several speech disorders and can significantly affect perceived speech intelligibility and quality. Nasometry quantifies nasalance by calculating the proportion of acoustic energy emitted from the nasal cavity relative to the combined nasal and oral acoustic output during speech production and is commonly used in clinical assessment and research. However, commercially available nasometers are costly and limited in portability, restricting their use in resource-limited or remote settings. The primary purpose of this study was to design and build a low-cost, open-source mobile nasometer prototype (“mNasometer”) by leveraging advances in 3D printing, off-the-shelf electronic components, and a custom open-source mobile application. A secondary aim was to compare the electroacoustic and subjective performance of mNasometer with that of a gold-standard commercial nasometer. Electroacoustic analyses focused on comparing long-term averaged spectra and the oral/nasal acoustic isolation between the gold-standard commercial nasometer and the proposed mNasometer, which incorporates a 3D-printed nasal separation plate. In addition, nasalance scores were collected from ten healthy young adult participants using both systems during structured speech production tasks (i.e., reading standard passages or nasal sentences). Agreement between devices was evaluated using correlational analyses and comparative statistical procedures. Long-term averaged spectra exhibited similar profiles between the commercial nasometer and the mNasometer across different test stimuli, indicating comparable capture of stimulus energy distributions. Although the mNasometer demonstrated reduced oral–nasal acoustic isolation relative to the commercial system, objective nasalance scores followed similar overall trends between devices, with statistically significant stimulus-dependent differences observed. Frame-wise correlational analyses revealed significant correlations between nasalance measures obtained from the commercial nasometer and the mNasometer across most of the speech production tasks, suggesting that the reduced isolation did not critically compromise measurement correspondence. In summary, the low-cost, open-source mNasometer prototype provides nasalance measurements that show promising agreement with those of a gold-standard commercial device. Its reduced cost and increased portability suggest potential for expanded research and field-based applications in the objective assessment of nasalance. Full article

The Research and Observation in Medium Earth Orbit (ROMEO) mission, developed at the University of Stuttgart‘s Institute of Space Systems, seeks to demonstrate a cost-effective exploitation of the medium Earth orbit (MEO) for sustainable access to space. It uses a green propulsion system with water as propellant to reach up to 2500 km altitude starting from a 450 km sun-synchronous orbit (SSO). This paper presents the design and intended use of the ROMEO satellite as well as its two in-house developed camera systems, the public relations (PR) and the near-infrared (NIR) camera system. The PR camera system features two silicon sensors with a Bayer color pattern in a compact, lightweight package and in a cold redundant setup to reduce the impact of radiation-related degradation. Their wide field of view (128 × 96°) allows imaging of the complete visible Earth in the mission‘s final orbit and supports calibration of the Earthshine telescope, which is the primary payload. The NIR camera system uses a commercial InGaAs sensor with a high quantum efficiency up to 1700 nm, coupled to a 100 mm focal length optics assembly that yields a ground sampling distance of 45 m in the initial orbit. Its scientific objectives include monitoring gas flares and wildfires, which are relevant to climate change research, and demonstrating an exoplanet transit detection—an unprecedented capability for a small satellite using a commercial off-the-shelf InGaAs sensor in the NIR spectrum. This paper demonstrates that ROMEO’s compact, low-mass camera systems meet mission constraints while enabling a broad spectrum of scientific and outreach activities. Full article