Browsing by Author "Chao, Paul C. -P"

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A New Adaptive Readout System For a New OLED OPD Flexible Patch PPG Sensor
(2019-01-01)
Pandey, Rajeev Kumar
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Pribadi, Eka Fitrah
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Chao, Paul C. -P
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電機資訊國際學位學程
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EECS International Institute
This study proposes a new multiwavelength OLED-OPD flexible PPG sensor with a time-interleaved, optimal high order adaptive analog filter-based readout system for the longtime continuous monitoring of PPG signal. First time, temperature modulation of the light absorption and scattering coefficient of the human skin and its compensation strategy has been explored in this study. This study intended to minimize the issue like motion artifacts and mispositioning. Analog front end of the readout circuit incorporates a transimpedance amplifier, optimal filter, programmable gain amplifier (1x to 7x), PWM-DAC based OLED intensity control, Bluetooth transceiver, MCU with inbuilt ADC and a power management unit. At the backend, digital control and pre-signal processing-algorithm are developed to improve the adaptability of the readout system against non-idealities which enable the readout system for the longtime continuous measurement of the biological sign. Digitally variable resistance is used herein to tune the central frequency of the bandpass filter which helps to minimize low heart rate issue. The sensing range of the readout circuit is 20nA to 10 mu A. With 3.3 V power supply the total power consumption of the readout system is 0.4W. Experimental result shows that the heart rate measurement error is less than 3.4bpm. In the worst case, the measured repulsive pulse transit time (RPTT) variation from PPG cycle to cycle is less than 2%.
A SIX-DOF FORCE/TORQUE SENSOR FOR COLLABORATIVE ROBOT AND ITS CALIBRATION METHOD
(2017-01-01)
Trong-Hieu Tran
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Tan-Phat Phan
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Chao, Paul C. -P
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Wang, Yu-Jen
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Wang, Chun-Chieh
This study presents a new six-DOF force/torque sensor and its calibration method for a "collaborative robot or cobot". This new calibration method applies the so-called "maximum likelihood estimation (MLE)". MLE is used to determine and identify the parameters related to applied torques/forces and resulted deformations at varied locations of the sensor structure. Formulating the relations in a vector-matrix form, such parameters are captured as the coefficients in a matrix relating torques/forces to angular/linear deformations in different directions. In addition to applying MLE, finite element (FEM) modeling and analysis are conducted to generate realistic-like empirical data for the aforementioned calibration computation based on MLE. The matrix formed by these coefficients can then predict forces and torques with good accuracy via deformations detected by strain gauges. Seen in simulation results, the worst sum of error for three forces is less than 0.04%, while that for three torques is less than 0.00005%. Very small values of sum of error demonstrate a strong correlation of the model with the results obtained from MLE, indicating high precision in sensing forces and torques without decoupling matrix. The developed sensor is highly suitable for real-time sensing of multidimensional interactive forces/torques in industrial robots.