Inertial sensors are used for human motion capture in a wide range of applications. Some kinds of human motion can be tracked by inertial sensors incorporated in smartphones or smartwatches. However, the latter can scarcely be used if misclassification of user activities is highly undesirable. In this case electronics and embedded software engineers should design, implement and verify their own human motion capture embedded systems, and oftentimes they have to do so from scratch. One of the issues the engineers should face is selection of suitable components, primarily accelerometers, gyroscopes and magnetometers, after thorough examination of commercially available items. Among technical characteristics of inertial sensors their sample frequency determines whether the sensor will be able to capture a specific motion kind or not. We propose a novel algorithm that allows the researcher or embedded software engineer to calculate the minimal sample frequency sufficient for tracking a prescribed motion scenario without significant signal losses. The algorithm utilizes the Poisson equation for motion of a triaxial rigid body, the Shoemake's algorithm for interpolating quaternions on the unit hypersphere, and the frequency analysis of a discrete-time signal. One can use the proposed algorithm as an argument for acceptance or rejection of a gyroscope when selecting hardware components for a human motion tracking system.
The book is devoted to the development of radiation-resistant Hall magnetic field sensors and instrumentations for harsh radiation conditions in nuclear fusion reactors and charge particle accelerators. Designed for scientists in the field of sensorics, radio physics, nuclear energy, as well as for lecturers, graduate and Ph.D. students.
The subject of research is the process of forming signals in magnetic tracking systems including those used for spatial position calculation within the concepts of Industry 4.0 and Industrial Internet of Things. Such systems are based on calculating the spatial position of objects upon measurements of reference magnetic fields in low-frequency electromagnetic radiation spectrum. The goal is to develop and verify a signal model for spatial position calculating in magnetic tracking systems. The signal model is developed upon experimentally obtained dependencies of the informative signals on the distances and angles between sensor and actuator coils. Objectives: analysis of signals in magnetic tracking systems, development of tools for experimental study, mathematical interpretation of the research results along with development of the signal model, verification and use of the developed model. General scientific methods were used, including experiment, measurement, analysis, synthesis, probabilistic and statistical methods. We have obtained the following results: The structure of a signal chain of the programmable magnetic tracking systems and its implementation on the basis of PSoC of 5LP Family by Cypress Semiconductor has been disclosed. Experimental results obtained at different distances and angles between the actuator and sensor coils have been presented. For spatial positions calculation signal models that describe distribution of magnetic fields and signals of sensor coils are used. We have analyzed typical inaccuracies and ways of their minimization. For verification of the introduced signal model we propose to use the mean square deviation of normalized signals. Conclusions. A signal model for the mutual position of actuators and sensors in magnetic tracking systems has been developed. The model describes functional dependencies whose main parameters are the distances and angles between coils. Further development of the presented results implies the proposed signal model to be used when solving problems of developing and specifying algorithms of spatial position calculation, system debugging and rapid analysis, optimization of calibration procedures.
Główne wyniki opracowania RETwix zostały przedstawione w artykule. RETwix jest uniwersalnym sprzętem i oprogramowaniem do badań laboratoryjnych, które można wykorzystać do badania zarówno komponentów elektronicznych, jak i dowolnych procesów elektrycznych, termicznych, chemicznych lub biochemicznych. W tym celu zostały wykorzystane czujniki, aktuatory i przetworniki sygnału Analog Front-End. RETwix zawiera dwa urządzenia CV-LAB (Capacitance & Voltage LABoratory) oraz UA-LAB (Universal Analog LABoratory). Zostały opisane osobliwości budowy oraz przykłady zastosowania RETwix.
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