We propose an underwater visible light communication (VLC) system for use in drones. The transmitter modulates a message using phase-shift keying (PSK) and emits the signal as LED fast-blinking light. The receiver cap...
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ISBN:
(数字)9781728198026
ISBN:
(纸本)9781728198033
We propose an underwater visible light communication (VLC) system for use in drones. The transmitter modulates a message using phase-shift keying (PSK) and emits the signal as LED fast-blinking light. The receiver captures this pattern with a CMOS image sensor using a rolling-shutter effect, and demodulates PSK. In existing VLC systems, rolling-shutter effect is used to transmit baseband signals; this system transmits a passband signal tolerant of low-frequency optical interference noise. System performance was evaluated in test-tank experiments. Findings suggested that the VLC system with PSK outperformed that using on-off keying when noise frequency did not exceed carrier frequency.
Reinforcement learning is a learning paradigm in which a control is learned automatically based on rewards through trial and error based on rewards. When reinforcement learning is employed for robot control, the actio...
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ISBN:
(数字)9781728185262
ISBN:
(纸本)9781728185279
Reinforcement learning is a learning paradigm in which a control is learned automatically based on rewards through trial and error based on rewards. When reinforcement learning is employed for robot control, the action that is output by reinforcement learning and the input of the actuator are often the same. A robot's actuator has a time constant of a first-order delay element between input and output. Delays result in the deterioration of the reinforcement learning performance because the environments that contain them lack the Markov property. Although there have been studies of such environments, they are problematic in that performance deteriorates when the time constant of a first-order time-delay element greater than the control cycle. The principal contribution of this paper is to propose a compensator for reinforcement learning that is more effective than conventional methods for environments with a time constant of a first-order time-delay element greater than the control cycle. The purpose of the compensator is to minimize the difference between actions in delayed environments and those not in delayed environments. Experiments reveal that the compensator increases rewards within wider ranges than conventional methods.
Decreasing birth rates and an aging population in society often cause labor shortages in the manufacturing industry, making the development of methods to improve productivity based on limited human resources imperativ...
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ISBN:
(数字)9781728185262
ISBN:
(纸本)9781728185279
Decreasing birth rates and an aging population in society often cause labor shortages in the manufacturing industry, making the development of methods to improve productivity based on limited human resources imperative. One way to achieve this is by enhancing product quality via the reduction of product losses and the consequent need for reassembly due to human error. Human error during assembly can arise from specific actions via the arms and fingers. We assumed that these errors can be captured based on the information on human skeletal models. The purpose of this study is to propose and develop a system that acquires information about assembly procedures by using human skeletal models, including the fingers of workers, and notifies them of skipped procedures and errors in part types. Further, we confirm the basic capability of the proposed system via experiments based on simulated assembly work. The proposed system monitors workers' motion based on color and depth images captured by a single RGB-D camera. In addition, we developed a function to detect the process and to point out errors with audible and visual feedbacks when errors were made by workers in assembly processes. In the experiment using simulated assembly work, the proposed system exhibited an accuracy rate of 98.3% with respect to acquisition of assembly processes. In the case of an error in an assembly process, the system was able to point out the error correctly and provide feedback to the worker before he had finished picking up the wrong part. In conclusion, we confirmed that the developed system exhibited the basic capability to acquire work procedures and efficiently point out errors in real time.
作者：
Isobe, AHikita, MAsai, KCentral Research Laboratory
Hitachi Ltd. Kokubunji Japan 185 (Member) graduated from the Department of Physics
Tohoku University in 1986 and completed an M.S. course in 1988. In that year he joined Hitachi Ltd. Presently he is with Hitachi Central Research Laboratory. He has been engaged in research on surface acoustic wave devices. (Member) completed the doctoral program of the Department of Electronic Engineering
Hokkaido University in 1977 and remained as a research student. In 1978 he joined Hitachi Ltd. Presently he is a Senior Researcher at Hitachi Central Research Laboratory. He holds a Doctor of Engineering degree. He has been engaged in research on the electromagnetic field analysis boundary value problem of the surface acoustic wave interaction of the acoustic wave and optics high-performance SAW filter high-frequency circuit for satellite communication and mobile communication. In 1981 he received an Academic Promotion Award from I.E.I.C.E. In 1990 he received an IEEE MTT Microwave Prize Award. In 1991 he received a Kanto District Invention Award (from the Invention Society) and in 1993 a Commendation for Research Accomplishment from the Director of Science and Technology Agency. He is a senior member of IEEE. (Member) graduated from the Department of Mechanical Engineering
Matsuyama Technical High School in 1984 and joined Hitachi Central Research Laboratory. In 1988 he graduated from the Department of Electronic Engineering Hitachi Keihin Technical School. Since then he has been engaged in research and development of the process technology of magnetic bubble memory and surface acoustic wave devices. Presently he is with the Communication Systems Department.
As a piezoelectric substrate for surface acoustic wave devices, the LST cut quartz has good temperature characteristics and low propagation loss. However, as the thickness of the metal electrodes on the substrate surf...
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As a piezoelectric substrate for surface acoustic wave devices, the LST cut quartz has good temperature characteristics and low propagation loss. However, as the thickness of the metal electrodes on the substrate surface is increased, propagation loss also increases. Further, the electromechanical coupling coefficient is small. In this paper, a cut angle of the quartz substrate is sought that has excellent temperature stability, low propagation loss, and a large electromechanical coupling coefficient in the present of metal electrode films. For the rotated Y-cut substrate in the neighborhood of the LST cut, the propagating surface acoustic wave (SAW) merle changes from the leaky surface wave to the Love wave-type surface acoustic wave for which. no propagation loss occurs in theory while the electromechanical coupling coefficient increased to 0.5 percent at the maximum if gold is used for the electrodes and the propagation direction of the SAW is shifted from the X axis. This is shown by simulation. By experiment, it is shown that the second-order temperature coefficient is on the same order as that of the ST-cut quartz substrate.
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