EPS Sensors & Hand Tracking/Gesture Recognition IT-S0C Lab. Chonnam National Univeristy

Contents System Summary EPIC Sensor: Circuits & Principles Source Code Analysis Using Labview NUI-Based Data Preprocessing NUI-Based Gesture Recognition Algorithm

Chapter 1 System Summary

System Summary Human body outside charge ↑ ⇒ outsde voltage ↑ (Dielectric area) Sensor probe area EPIC sensor Input : Dielectric permittivity bet. human and sensor Electrostatic Field : permittivity of dielectric material deposited on EPS sensor Electric field surrounding EPIC sensors

Chapter 2 EPIC Sensor: Circuits & Principle

EPIC Sensor: Circuit Analysis (1/2) Electric Potential Integrated Circuit EPIC sensor: data detection principle ■ Detect surrounding E-field variation ■ Non-directional & metal-shut off Contact mode : bio-electric signal (ECG, EMG, EOG, etc.) measurement Non-contact mode : Measure variation in surrounding E-field Single-ended mode : measure electric potential Differential mode : measure difference bet. two sensors - Main detected signal : power line noise ■ Variation in static-electric charge Once objects with different dielectric constants) enter E-field, static-electric charges change ■ Disturbance in E-field Utilize the principle that disturbance in E-filed occurs due to the movement of human body whose role is like big container with polarity EPIC sensor input stage Bootstrapping : Corner frequency control(input resistance) Guarding : Gain control(input impedence) Basic block circuit diagram of EPIC sensor Contact mode & Non-contact mode

Input stage of a EPIC sensor EPIC Sensor: Circuit Analysis (2/2) Input stage of a EPIC sensor    

Simulation for verification       Simulation 2.  

Simulation for verificaton Non Inverting OP-AMP Kirichhoff’s current Law on node x Vx (virtual short voltage) = Vi(input voltage). - Virtual short: Input node voltage feedback AMP equals to voltage of inverting node voltage Non-inverting OP-AMP

Simulation for Verification Input bias current Current for OP-AMP operation Feed back loop gain becomes to be different from open loop gain, but it generate Offset In order to solve “offset” problem, resistance, Rin, is connected to outside of OP-AMP Input stage of EPIC sensor

Simulation for Verification Simulation Result(1/2) Frequency : 1000Hz C_ext : 250pF, C_in : 15pF, Rin : 20GΩ, Av = 50(PS25401) Cext = 250pF, Freq = 1000 Hz RG1/RG2 = 52, RG1 = 0.01~100GΩ Cext = 250pF, Freq = 0~100kHz RG1/RG2 = 52, RG1 = 1GΩ

이론 검증을 위한 시뮬레이션 시뮬레이션 결과(2/2) 주파수 : 1000Hz C_ext : 250pF, C_in : 15pF, Rin : 20GΩ, Av = 10(PS25405) Cext = 250pF, Freq = 1000 Hz RG1/RG2 = 9.6, RG1 = 0.01~100GΩ Cext = 250pF, Freq = 0~100kHz RG1/RG2 = 9.6, RG1 = 1GΩ

EPIC Detection Principle & Analysis (1/2) Change in static electric charges   Simulation result Sensor Electrode Real output from EPIC Electrometer Amplifier Skin Air   Condition : PC, CIB grounding & surrounding E-field 0.1713V/m

EPIC Sensor Detection Principle & Analysis(2/2) Disturbance in E-field   PS25201 EPIC voltage due to movement of a target PS25201 EPIC voltage standard deviation according to distance of a moving target Condition : PC, CIB grounding & surrounding E-field 0.1713V/m

Chapter 3 Source Code Analysis using Labview and C++ Compatibility Method

Computer based measurement system (DAQ hardware equipped Source code anlaysis using Labview tool(1/2) DAQ (Data Acquisition) Process DAQ hardware : Measure and generate electric signals In general, 10 AD conversion per period is desirable For example, set sampling rate to more 100KS/s if 10KHz is measured AI : Analog signal measurement AO : Analog signal generation DI : Digital signal measurement DO : Digital signal generation CI : Pulse edge no. measurement CO : Pulse signal generation Computer based measurement system (DAQ hardware equipped

Source Code Analysis Using Labview tool(2/2) DAQ (Data Acquisition) Process Measure continuous signal measurement using hardware timing Channel generation Analog input > voltage Timing setting Sample mode > continuous sample Data reading analog > Multiplexed channels > multiplexed samples > 1D Wfm(waveform) Generate the channel Setting the timing Start Read the data Stop Clear the data Error handle

C++ 호환 방법 C++ tool 을 이용한 프로그래밍을 위한 준비 사항 드라이버 설정 펌웨어 업데이트 해더 파일과 라이브러리 파일 설정 “NIDAQmxBase.h”, “NIDAQmxBase.lib” DAQ 과정에 따른 DAQmxErrChk API 함수 사용 DAQmxBaseCreateTask / DAQmxBaseCreateAIVoltageChan / DAQmxBaseCfgSampClkTiming / DAQmxBaseCfgInputBuffer / DAQmxBaseStartTask / DAQmxBaseReadAnalogF64 / DAQmxBaseGetExtendedErrorInfo / DAQmxBaseStopTask

Chapter 4 NUI Based Data Preprocessing

IIR Low Pass Filter Source Codes IIR LPF 2st 계수 설정

Data Preprocessing Process(1/2) 정전기 잡음 목표물의 움직임으로 발생된 신호 [ extracted signals in case that static electricity occurs] [ Variation in frequency domain according to movement] [ signal variation caused by static electricity]

Data Preprocessing Process(2/2) [Data preprocessing result in case of a fixed target] [ Data preprocessing result in case of a moved target]

Chapter 5 NUI Based Gesture Recognition Algorithm

[Flow diagram of the proposed DTW ] NUI Gesture Recognition Based DTW Algorithm IIR Low-pass filter 10Hz 2st order(AC) Non-Contact Electrometer Sensor Data Analog voltage(AC) Generation of Electrostatic charge? True True Calibration enabled ? Data preprocessing False Substitution to previous data buffers False Extracting maximum Value of data buffers Digital voltage(DC) Timer1 enable Extracting differential signals Store of voltage Calibration processing Kalman filter False Timer1 = 3sec? False Velocity > Th_vel ? True Extracting VNH and Th_vel True Timer2 enable Calibration enable Store of voltage False Timer2 = 1sec? True Training data Data normalization DTW Runtime recognizer Classification Argmin(class) Event [Flow diagram of the proposed DTW ]

구현된 Warping 구간의 전역 상수 제한 범위 NUI Gesture Recognition Based DTW Algorithm DTW(Dynamic Time Warping) algorithm Algorithm measuring similarity between two data in terms of time change Comparing simultaneously by searching optimal non-linear mapping function 구현된 Warping 구간의 전역 상수 제한 범위

Warping Path Type

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