Search Results (17)

Accurate heading direction tracking is essential for immersive VR/AR, spatial audio rendering, and robotic navigation. Existing IMU-based methods suffer from drift and vibration artifacts, vision-based approaches require LoS and raise privacy concerns, and RF techniques often need dedicated infrastructure. We propose UDirEar, a COTS UWB device-based system that estimates user heading using solely high-level UWB information like distance and unit direction. By initializing an EKF with each user’s constant interaural distance, UDirEar compensates for the earbuds’ roto-translational motion without additional sensors. We evaluate UDirEar on a step-motor-driven dummy head against an IMU-only baseline (MAE 30.8°), examining robustness across dummy head–initiator distances, elapsed time, EKF calibration conditions, and NLoS scenarios. UDirEar achieves a mean absolute error of 3.84° and maintains stable performance under all tested conditions. Full article

Power factor correction (PFC) can be achieved by a single-ended primary inductor converter (SEPIC) operating in boundary conduction mode (BCM) with conventional constant on-time (COT) control, but it is challenging to achieve low total harmonic distortion (THD) and high-power factor (PF), particularly at high input voltage. A variable on-time (VOT) control strategy for BCM SEPIC PFC converter without input voltage feedforward and multiplier circuits is proposed to realize unity PF in this paper. By using a variable slope sawtooth generator whose slope is controlled by the duty cycle of the main switch to adjust the conduction time of the main power switch of the converter, the proposed VOT control scheme can use a simple and easy-to-implement circuit to enhance the PF and decrease the THD significantly, especially at high input voltage. The simulation model and 100W experimental prototype are built to verify the feasibility of the suggested control method. Simulation and experiment results demonstrated that the novel VOT control scheme remarkably enhances PF and decreases THD without affecting the efficiency by contrast with the conventional COT control. Full article

The Internet of Things (IoT) envisions billions of everyday objects sharing information. As new devices, applications and communication protocols are proposed for the IoT context, their evaluation, comparison, tuning and optimization become crucial and raise the need for a proper benchmark. While edge computing aims to provide network efficiency by distributed computing, this article moves towards sensor nodes in order to explore efficiency in the local processing performed by IoT devices. We present IoTST, a benchmark based on per-processor synchronized stack traces with the isolation and precise determination of the introduced overhead. It produces comparable detailed results and assists in determining the configuration that has the best processing operating point so that energy efficiency can also be considered. On benchmarking applications which involve network communication, the results can be influenced by the constant changes that occur in the state of the network. In order to circumvent such problems, different considerations or assumptions were used in the generalization experiments and the comparison to similar studies. To present IoTST usage on a real problem, we implemented it on a commercial off the-shelf (COTS) device and benchmarked a communication protocol, producing comparable results that are unaffected by the current network state. We evaluated different Transport-Layer Security (TLS) 1.3 handshake cipher suites at different frequencies and with various numbers of cores. Among other results, we could determine that the selection of a specific suite (Curve25519 and RSA) can improve the computation latency by up to four times over the worst suite candidate (P-256 and ECDSA), while both providing the same security level (128 bits). Full article

In this paper, a new control scheme for buck converters was proposed. The buck converter utilizes the dual control loop to improve transient response and has the constant switching frequency. The control scheme is mainly as follows: (a) The switch-ON time is regulated by the constant frequency mechanism. (b) The switch-OFF time is regulated by the output voltage. The spec/features of the proposed converter are listed as: (1) The buck converter has an output of 1.0–2.5 V for the input of 3.0–3.6 V. The load current ranges from 100 mA to 500 mA. (2) The actual current sensor is not required. (3) The simulation results show that the recovery time is less than 1.6 μs during load changes. (4) The variation in switching frequency is smaller than 1.05% over the output range of 1.0–2.5 V. (5) This circuit can be fabricated in future by UMC 0.18 μm 1P6M CMOS processes. This paper depicts the control scheme, theoretical analysis, and implementation. Full article

The active clamp flyback (ACF) converter is gradually becoming popular in the application field of low or medium output power range due to its advantage of soft switching and high conversion efficiency. An asymmetric half-bridge (AHB) flyback converter has been proposed in previous studies. The main advantages of the AHB flyback are the same number of components as the ACF converter and the soft switching technique. In this paper, an AHB flyback converter with constant off-time (COT) plus pulse frequency modulation (PFM) is proposed, so that the resonant time is not affected by the input voltage and load, and can achieve a wide range of zero voltage switching (ZVS) operating range. Compared to pulse width modulation (PWM), the PFM control with COT can make the system more stable. Finally, a prototype circuit with a specification input of 48 V to an output of 2.5 V/8 A is made for verification. Full article

This paper proposes a novel control scheme for the buck converter without an inductor current sensor. The architecture of the proposed buck converter is simple and suitable for integration and mass production. It employs an output-voltage-measurement method to determine the switch ON time; therefore, the current sensor is not required. The design specification targets the application with a standard battery power source to generate the low voltages for low-power MCU or ASIC. The load current range aims for several hundred milliamps. The proposed control scheme is analyzed and simulated by SIMPLIS. The control scheme, theoretical analysis, circuit realization, contributions, advantages, and simulation results are presented in this paper. Furthermore, the circuit can be fabricated by a 0.35 μm CMOS process. Full article

This paper presents a novel buck converter with dual-loop control technology, which does not need to detect the inductor current directly. The structure of the control loops is easy to implement, one loop controls the output voltage, and the other controls the switching frequency. With the dual loops control mechanism, the output voltage and switching frequency can be accurately controlled only by measuring the output and input voltage, without sensing the inductor current. The buck converter can generate an output voltage of 1.0–2.5 V when the input voltage and load current are 3.0–3.6 V and 100–500 mA, respectively. The design was verified by SIMPLIS. The simulation results show that the switching frequency variation is less than 1% at the output voltage of 1.0–2.5 V. The recovery time is less than 1.5 μs during the load change. The circuit can be fabricated by using the TSMC 0.35μm 2P4M CMOS processes. The control scheme, theoretical analysis and circuit implementation are presented in this paper. Full article

Usually, towed hydrophone arrays are instrumented with a set of compasses. Data from these sensors are utilized while beamforming the acoustic signal for target bearing estimation. However, elements of the hydrophone array mounted in the neighborhood of a compass can affect the Earth’s magnetic field detection. The effects depend upon the materials and magnetic environment present in the vicinity of the platform hosting the compass. If the disturbances are constant in time, they can be compensated for by means of a magnetic calibration procedure. This process is commonly known as soft and hard iron compensation. In this paper, a solution is presented for carrying out the magnetic calibration of a COTS (Commercial Off the Shelf) digital compass without sensor motion. This approach is particularly suited in applications where a physical rotation of the platform that hosts the sensor is unfeasible. In our case, the platform consists in an assembled and operational towed hydrophone array. A standard calibration process relies on physical rotation of the platform and thus on the use of the geomagnetic field as a reference during the compensation. As a variation on this approach, we generate an artificial reference magnetic field to simulate the impractical physical rotation. We obtain this by using a tri-axial Helmholtz coil, which enables programmability of the reference magnetic field and assures the required field uniformity. In our work, the simulated geomagnetic field is characterized in terms of its uncertainty. The analysis indicates that our method and experimental set-up represent a suitably accurate approach for the soft and hard iron compensation of the compasses equipped in the hydrophone array under test. Full article

Fast load transient response and high light-load efficiency are two key features of the constant on-time (COT) control technique that has been widely used in numerous applications, such as for voltage regulators and point-of-load converters. However, when load step-down occurs during an on-time interval, the COT controller cannot respond until the COT interval expires. This delay causes an additional output voltage overshoot, resulting in unloading transient performance limitation. To eliminate the delay and improve the unloading transient response of the COT controller, a load step-down detection circuit is proposed based on capacitor current COT (CC-COT) control. In the detection circuit, the load step-down is monitored by comparing the measured capacitor current with the preset threshold voltage. Once the load step-down is monitored, the on-time is promptly truncated and the switch is turned off. With the proposed detection circuit, the CC-COT-controlled buck converter can monitor the load step-down without any delay and obtain less output voltage overshoot when the load step-down occurs during the on-time interval. PSIM circuit simulations are employed to demonstrate the feasibility of the detection circuit. Full article

This paper presents a buck converter with a novel constant frequency controlled technique, which employs the proposed frequency detector and adaptive on-time control (AOT) logic to lock the switching frequency. The control scheme, design concept, and circuit realization are presented. In contrast to a complex phase lock loop (PLL), the proposed scheme is easy to implement. With this novel technique, a buck converter is designed to produce an output voltage of 1.0–2.5 V at the input voltage of 3.0–3.6 V and the maximum load current of 500 mA. The proposed scheme was verified using SIMPLIS and MathCAD. The simulation results show that the switching frequency variation is less than 1% at an output voltage of 1.0–2.5 V. Furthermore, the recovery time is less than 2 μs for a step-up and step-down load transient. The circuit will be fabricated using UMC 0.18 μm 1P6M CMOS processes. The control scheme, design concept and circuit realization are presented in this paper. Full article

This study presents a new virtual inductor current circuit to reduce circuit complexity, which is not necessary to sense inductance current directly. The buck converter was designed to produce an output voltage of 1.0–2.5 V for a 3.0–3.6 V input voltage. The load current range was from 100 mA to 500 mA. It was simulated and verified by SIMPLIS and MathCAD. The simulation results of this buck converter show that the voltage error is within 1%, and the recovery time is smaller than 2 ms for step-up and step-down load transients. Additionally, it achieves less than 26 mV overshoot at full-load step transient response. The circuit topology would be able to fabricate using TSMC 0.35 mm 2P4M CMOS technology. The control mechanism, implementation, and design procedure are presented in this paper. Full article

Fly-buck converter is a multi-output converter with the structure of a synchronous buck converter structure on the primary side and a flyback converter structure on the secondary side, and can be utilized in various applications due to its many advantages. In terms of control, the primary side of the fly-buck converter has the same structure as a synchronous buck converter, allowing the constant-on-time (COT) control to be applied to the fly-buck converter. However, due to the inherent energy transfer principle, the primary-side output voltage regulation of COT controlled fly-buck converters may be poor, which can deteriorate the overall converter performance. Therefore, the primary output capacitor must be carefully designed to improve the voltage regulation characteristics. In this paper, a theoretical analysis of the output voltage regulation in COT controlled fly-buck converter is conducted, and based on this, a design guideline for the primary output capacitor considering the output voltage regulation is presented. The validity of the analysis and design guidelines was verified using a 5 W prototype of the COT controlled fly-buck converter for telecommunication auxiliary power supply. Full article

In recent years there has been an increased interest in ocean surveillance. The activity includes control and monitoring of illegal fisheries, manmade ocean pollution and illegal sea traffic surveillance, etc. The key problem is how to identify ships and ship-like objects accurately and in a timely manner. In this context, currently, many solutions have been proposed based on high resolution optical and radar remote sensing systems. Most often, these systems suffer from two major limitations viz., limited swath, thereby requiring multiple satellites to cover the region of interest and huge volumes of data being transmitted to ground, even though effective per-pixel information content is minimal. Another limitation is that the existing systems are either simulated on ground or built using the non-space qualified/Commercial Of-The-Shelf (COTS) components. This paper proposes an efficient on-board ship detection system/package connected with medium resolution wide swath optical camera. The methodology adopted has three major components, viz., onboard data processing for improving the radiometric fidelity, followed by a ship detection using modified Constant False Alarm Rate algorithm (CFAR) and a false alarm suppression module to mask false identifications. Finally, the package outputs only the locations of the ships, which is transmitted to the ground. The proposed system reduces the effective volume of data to be transmitted and processed on ground and also significantly cuts down the turnaround time for achieving the end objective. The system is built on radiation hardened Field Programmable Gate Array (FPGA) devices to meet the various engineering constraints such as real-time performance, limited onboard power, radiation hardness, handling of multiple custom interfaces etc. The system is tested with one of the medium resolution Multispectral Visual and Near Infra-Red (MX-VNIR) sensor having a spatial resolution of around 50 m and swath of around 500 Kms, which would be flown with one of the upcoming satellites. The systems performance is also verified on ground with Indian Remote Sensing (IRS) Satellite’s Resourcesat’s Advanced Wide Field Sensor (AWiFS) data and the results are found to be quite encouraging as well as meeting the mission objectives. Full article

To achieve a designed and fixed operating frequency for a controller with high dynamic performance and a high load capacity, a hybrid constant on-time (COT) voltage mode for a Buck circuit is proposed and discussed in this paper. The proposed hybrid strategy is a combination of the classical COT method, a dynamic reference voltage technology and a proportional–differential (PD) module. The workflow is demonstrated in brief, simulations of a Buck circuit with the proposed hybrid COT mode are conducted and comparisons with developed pulse-width modulation (PWM) technology and the hysteresis mode are made. The results show that, with the help of the proposed control scheme, impressive performance from the Buck circuit can be expected. The operating frequency can be fixed well by the hybrid technology without losses of performance and robustness in steady state and will not jump much even with the sudden change of the inputs and the load. The proposed control strategy contributes to the foundation of circuit design and optimization. Full article

Consumer electronic manufacturing (CEM) companies face a constant challenge to maintain quality standards during frequent product launches. A manufacturing test verifies product functionality and identifies manufacturing defects. Failure to complete testing can even result in product recalls. In this research, a universal automated testing system has been proposed for CEM companies to streamline their test process in reduced test cost and time. A universal hardware interface is designed for connecting commercial off-the-shelf (COTS) test equipment and unit under test (UUT). A software application, based on machine learning, is developed in LabVIEW. The test site data for around 100 test sites have been collected. The application automatically selects COTS test equipment drivers and interfaces on UUT and test measurements for test sites through a universal hardware interface. Further, it collects real-time test measurement data, performs analysis, generates reports and key performance indicators (KPIs), and provides recommendations using machine learning. It also maintains a database for historical data to improve manufacturing processes. The proposed system can be deployed standalone as well as a replacement for the test department module of enterprise resource planning (ERP) systems providing direct access to test site hardware. Finally, the system is validated through an experimental setup in a CEM company. Full article