Wireless Triggering Research Articles

Wireless liquid-alloy-based induction heating for soft devices by alternating magnetic field: From characterization to application

Soft heating has attracted remarkable attention due to its extraordinary potential in the emerging multifunctional thermal applications, e.g. heating clothing, thermal therapy and therapy support products. However, current soft heating devices are mostly realized by wired configurations, which will constrain the overall flexibility and increase wiring complexity, especially for discrete multipoint circuits. Here, we propose a wireless liquid alloy induction heating method through a high-frequency alternating magnetic field (AMF), and can achieve rapid wireless heating for fully intrinsically soft devices. Then, we characterized the heating performance under different sizes and their quantitative relations. Further, we found a new phenomenon that liquid alloy continuously shrinks into a ball shape in AMF by mutual repulsion force based on the skin effect. Finally, we demonstrated a wireless trigger detection circuit for AMF and a fully soft wireless electric hot water bag with comparable performance to commercials. This work provides a convenient and rapid wireless heating technology option for fully soft devices and is potential for wireless functional devices and thermal therapy.

A novel wearable device to deliver unconstrained, unpredictable slip perturbations during gait

BackgroundTask-specific perturbation training is a widely studied means of fall prevention, utilizing techniques that induce slips or slip-like perturbations during gait. Though effective, these methods only simulate narrow ranges within the larger space of possible slipping conditions encountered in daily life. Here we describe and test a novel, wearable apparatus designed to address these limitations and simulate a diverse range of slipping disturbances.MethodsThe device consists of wireless triggering and detachable outsole components that provide adequate friction with the floor when secured to the wearer’s foot, but suddenly create a low-friction surface underfoot upon release. “Benchtop” tests were carried out to quantify device triggering characteristics (i.e. cutting temperature, release delay) and the resulting friction reduction. The device was also tested on six healthy young adults (3 female, age 23 ± 2.4 years), who walked with and without the device to observe how gait kinematics and spatiotemporal parameters were influenced, then performed 12 walking trials ending with a slip delivered by the device. Each participant also completed a survey to obtain opinions on device safety, device comfort, slip realism, and slip difficulty. A linear mixed effects analysis was employed to compare subject spatiotemporal parameters with and without the apparatus, as well as correlation coefficients and root mean square errors (RMSE) to assess the impact of the device on lower limb gait kinematics. Slip onset phases, distances, directions, velocities, and recovery step locations were also calculated.ResultsThis device rapidly diminishes available friction from static coefficients of 0.48 to 0.07, albeit after a substantial delay (0.482 ± 0.181 s) between signal reception and outsole release. Strong correlations (R > 0.93) and small RMSE between gait kinematics with and without the device indicate minimal effects on natural gait patterns, however some spatiotemporal parameters were significantly impacted. A diverse range of slip perturbations and recovery steps were successfully elicited by the device.ConclusionsOur results highlight the efficacy and utility of a wearable slipping device to deliver diverse slip conditions. Such an apparatus enables the study of unconstrained slips administered across the gait cycle, as well as during different locomotor behaviors like turning, negotiating slopes, and level changes.

Design of an Interactive Spatial Augmented Reality System for Stage Performance Based on UWB Positioning and Wireless Triggering Technology

In this research, the authors designed an interactive spatial augmented reality system for stage performance based on the technologies of UWB positioning and Bluetooth® triggering. The position of the actor is obtained through the antenna tag carried by the actor and the signal base station placed on the stage. Special effects can be triggered through the Bluetooth® module according to the actor, and rendered at the relevant location on the screen, which has higher concealment. The system has a higher degree of freedom in practical applications, which can present an interactive spatial augmented reality effect, and therefore provide new possibilities for the application of spatial augmented reality in the stage performance.

Compact, battery powered, wireless digitizers for in situ data acquisitions in the sino-united spherical tokamak.

Potential isolation and long cable drive are very important in acquiring certain signals from tokamak diagnostics. Compact, battery powered, wireless digitizers for in situ data acquisition have been developed and routinely used in the sino-united spherical tokamak to solve the problems of isolation and long cables. The wireless digitizers utilize the integrated analog to digital converters and the static random access memory of microcontrollers but transfer data wirelessly. They consist of simple and concise circuits but have considerable performances of 12-16 bit in resolution and 500-1000 kS/s in sample rate. Wireless triggering and energy saving are two major challenges of the wireless digitizers. Wireless transceivers in the data link layer are used as trigger and can reduce the trigger jitters to be smaller than 1 μs. In order to reduce the energy consumption, the wireless digitizers are waken only when the tokamak is about to discharge. After discharges, they turn to a periodic checking mode with current consumption smaller than 200 μA. Because of low duty cycle, the wireless digitizers have a battery life of up to four weeks. In general, the wireless digitizers have better performance than normal isolation amplifiers and can greatly simplify the cable connections. They are very suitable for the data acquisition of dangerous and/or susceptible analog signals in tokamaks.

A novel approach in the measurement of high frequency disturbances from very large electrical systems

This paper demonstrates the feasibility of an interactive distributed measurement system having the capability of wireless triggering and time synchronisation for the purpose of detection, measurement and location of disturbances from very large electrical systems. System design, laboratory testing and preliminary site trials are discussed. Examples of how the system might be used are included. The first example relates to railway track circuit monitoring; the 2nd example relates to multi ended PD monitoring for insulated power cables; third example relates to radiometric partial discharge monitoring in substations and the last example relates to power quality monitoring and phasor measurements.

Precise Wireless Triggering System for Anemometers with Long-Baseline Acoustic Probes

A wireless triggering system for acoustic anemometers using an acoustic probe with a long baseline is investigated. Acoustic probes for measuring micrometeorologic parameters, such as temperature and wind velocity, are used as noncontact and nondestructive methods. The acoustic probe with a long baseline was previously proposed by the authors and investigated to form a sensing grid system for micrometeorologic measurement. The authors have also partially investigated a wireless sensing grid using a wireless local-area network (LAN). However, because of the synchronization problem between sensor nodes, the trigger line has been left wired. In this paper, the problem of synchronization is solved by investigating a wireless triggering system using frequency modulated (FM) radio waves. The primitive triggering system of FM radio waves has some instability on time synchronization depending on such the communication environment as signal-to-noise ratio (SNR). To overcome the influence of the instability, a cross-correlation method is adopted to the triggering system. As a result, the time synchronization errors of the trigger system were reduced by up to one tenth. In addition, not only the instability problem but also other larger errors are compensated by the proposed system in an experimental wind velocity measurement.

Development of a Global Positioning System–Based Vehicle Tracking System for the Minnesota Road Research Facility

One of the more important tasks in operating a pavement research test track is tracking the location of individual vehicles during load response testing. The location of a vehicle's tires profoundly affects values obtained from embedded pavement load response sensors. To improve the efficiency of load response testing both in the field and during analysis, a Global Positioning System-based vehicle tracking system (VTS) was developed and tested at the Minnesota Road Research Facility (MnROAD). The VTS demonstrated its capability of tracking vehicle motion with an accuracy of ± 1 in. (2.5 cm) at speeds up to 45 mph (70 km/h). These results matched or exceeded the accuracy obtained with a high-definition video camera previously used for tracking vehicle position at MnROAD. Additional field trials were conducted in greater Minnesota to determine the operational area of the VTS. Overall, the VTS received real-time kinematic signal correction in nearly 80% of the tested areas. The capabilities of the VTS spawned the development of the wireless triggering system. Through wireless triggering of data acquisition, the load test process can be greatly simplified. Although preliminary testing confirmed it as proof of concept, hardware issues dictate that additional development is necessary.

Development of an extremely compact impedance-based wireless sensing device

This paper describes the development of the next generation of an extremely compact,wireless impedance sensor node for use in structural health monitoring (SHM) andpiezoelectric active-sensor self-diagnostics. The sensor node uses a recently developed,low-cost integrated circuit that can measure and record the electrical impedance of apiezoelectric transducer. The sensor node also integrates several components, including amicrocontroller for local computing, telemetry for wirelessly transmitting data, multiplexersfor managing up to seven piezoelectric transducers per node, energy harvesting and storagemediums, and a wireless triggering circuit into one package to truly realize acomprehensive, self-contained wireless active-sensor node for various SHM applications. Itis estimated that the developed sensor node requires less than 60 mW of total power formeasurement, computation, and transmission. In addition, the sensor node isequipped with active-sensor self-diagnostic capabilities that can monitor the conditionof piezoelectric transducers used in SHM applications. The performance of thisminiaturized device is compared to our previous results and its broader capabilities aredemonstrated.