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In recent years, wireless positioning and tracking devices based on semiconductor micro electro-mechanical system (MEMS) sensors have successfully integrated into the consumer electronics market. Information from the sensors is processed by an attitude estimation program. Many of these algorithms were developed primarily for aeronautical applications. The parameters affecting the accuracy and stability of the system vary with the intended application. The performance of these algorithms occasionally destabilize during human motion tracking activities, which does not satisfy the reliability and high accuracy demand in biomedical application. A previous study accessed the feasibility of using semiconductor based inertial measurement units (IMUs) for human motion tracking. IMU hardware has been redesigned and an attitude estimation algorithm using sequential Monte Carlo (SMC) methods, or particle filter, for quaternions was developed. The method presented in this paper uses von Mises-Fisher and a nonuniform simulation to provide density estimation of the rotation group SO(3). Synthetic signal simulation, robotics applications, and human applications have been investigated.

Abstract:Piezoelectric vibration based energy harvesting systems have been widely utilized and researched as powering modules for various types of sensor systems due to their ease of integration and relatively high energy density compared to RF, thermal, and electrostatic based energy harvesting systems. In this paper, a low-power CMOS full-bridge rectifier is presented as a potential solution for an efficient energy harvesting system for piezoelectric transducers. The energy harvesting circuit consists of two n-channel MOSFETs (NMOS) and two p-channel MOSFETs (PMOS) devices implementing a full-bridge rectifier coupled with a switch control circuit based on a PMOS device driven by a comparator. With a load of 45 kΩ, the output rectifier voltage and the input piezoelectric transducer voltage are 694 mV and 703 mV, respectably, while the V OUT versus V IN conversion ratio is 98.7% with a PCE of 52.2%. The energy harvesting circuit has been designed using 130 nm standard CMOS process.

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