In this paper, a sensor based on polyvinylidene fluoride (PVDF) piezoelectric thin film was designed and fabricated to detect wrist motion signals. A series of dynamic experiments have been carried out, including the contrast experiments of different materials and force-charge signal characterization. The experimental results show that when the excitation signal exceeds 15 Hz, the sensitivity of the sensor is always stable at 3.10 pC/N. The signal acquisition experiment of the wrist motion has been carried out by using this sensor. The experiment results show that, with the advantages of small size, good flexibility, and high sensitivity, this wrist PVDF sensor can be used to detect the wrist motion signals with weak amplitude, low frequency, strong interference, and randomness.
Finger motion recognition is one of the key technologies of human-computer interaction based on gestures. In this paper, we propose a method of recognizing finger motions by using a wearable wrist device (WWD). This method not only avoids the problem that the user's hands are limited by wearing motion detection sensors, but also avoids the problem that vision-sensorbased gesture recognition technology is difficult to use in a mobile environment. Moreover, this method, which uses polyvinylidene fluoride (PVDF) sensors as the detection units of WWD, has the advantages of being noninvasive, comfortable, and convenient. In this work, we first studied the distribution and optimization of the PVDF sensor array, and used this array to complete the acquisition of wrist motion signals. Then, we used short-term energy to solve the problems of the real-time detection of motion signals' endpoints and the extraction of motion signal fragments. Then, we encoded these fragments into 64-digit eigenvectors for finger motion recognition. In the experiment, we transmitted the eigenvectors as input values into a four-layer back propagation (BP) network to recognize three essential finger motions for mouse control. The experimental results show that the recognition effect of this method is satisfactory and the recognition accuracy is up to 96.7%.
A novel scheme that can simultaneously measure the Doppler frequency shift (DFS) and angle of arrival (AOA) of microwave signals based on a single photonic system is proposed. At the signal receiving unit (SRU), two echo signals and the reference signal are modulated by a Sagnac loop structure and sent to the central station (CS) for processing. At the CS, two low-frequency electrical signals are generated after polarization control and photoelectric conversion. The DFS without direction ambiguity and wide AOA measurement can be real-time acquired by monitoring the frequency and power of the two low-frequency electrical signals. In the simulation, an unambiguous DFS measurement with errors of ±3 × 10−3 Hz and a −90° to 90° AOA measurement range with errors of less than ±0.5° are successfully realized simultaneously. It is compact and cost-effective, as well as has enhanced system stability and improved robustness for modern electronic warfare systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.