MagneticSystem Using Discretize Low Pass Filter Student : Chin yi.Kuo

O u t l i n e MagneticSystem Hardware Introduction Flow diagram Discretize Low Pass Filter Low Pass Filter for cutoff frequency Compare with/without LPF results Polynomial Curve Fitting Magnetic Levitation 1-6mm Figures

H a r d w a r e Power Amplifier Electromagnetic coil ADC DAC Position Sensor Power Supply

Voltage conversion equation with position F l o w d i a g r a m ADC Using Discretize LPF Voltage conversion equation with position DAC Power Amplifier Using Discretize LPF Electro Magnetic coil PID Controller

L o w P a s s F i l t e r ISSUE： MagneticSystem unstable A to D , Noise disturbance PID-controller , D control → oscillation Solution： Add Low pass filter to program       Represent the low-pass filter as：     # Familiar transfer function of LPF. # K =ω (rad/s) = 2 π f

Discretize L o w P a s s F i l t e r Bilinear Transform： Using in digital signal processing and discrete-time control theory to transform continuous-time system representations to discrete- time vice versa. Discrete-time approximation            

Using equation in program T(s)→T(z)：           (前一次輸入+目前輸入-前一次輸出)   Using equation in program

Low Pass Filter for cutoff frequency No Low Pass Filter of reading Voltage Filter frequency ：1000Hz

Filter frequency ：500Hz Filter frequency ：100Hz

Filter frequency ：70Hz Filter frequency ：10Hz

Input Without Low Pass Filter

Output Without Low Pass Filter

Without Low Pass Filter

Using LPF to program After ADC & Before DAC

Polynomial curve fitting Position correspond to voltage DATA

First degree 5th degree

Curve fitting coefficients(A、B 、C 、D 、E 、F)  

1-6mm Magnetic Levitation Airgap_1mm Airgap_2mm Airgap_3mm Airgap_5mm Airgap_6mm Airgap_4mm

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