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Published byRey Freer Modified over 10 years ago
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Feedback Speed Control Embedded Systems Interfacing
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Overview Background Task 1 MATLAB ® Step Response Root Locus Task 2 Scaled Coefficients Task 3 Proportional-Integral Speed Control Task 4 Step Response for: Critically Damped Over Damped Under Damped
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PWM/Motor Speed Labs ADC +5 VDC PWM +12 VDC +5 VDC PIC24FJ128 TD62003AP LM2907 V(speed)
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Open-Loop Load-Speed Characteristics Speed Load
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Block Diagram Internal To feedback.c PIC24FJ128 Darlington Driver, Motor and Freq-to-Volt
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PID Controller Time-Domain Laplace-Domain of PI Controller PID
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Stability Control Ratio Critically Damped
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Control Algorithm
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Task 1 – Step Response Analysis Within MATLAB ® Define A and B Define transfer Function Use step()
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Task 2 – PID Gains Condition K1 = 1024 kK2 = b K1 Under Damped Critical Damped Over Damped Unstable
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Task 3 Within main( ) Initialization RD0 Timer 3 ADC Interrupts and Timer 3 Interrupt PWM ADC PMP then LCD LCD text on screen
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Task 3 Within main( ) Endless Loop Wait for for semaphore == 1 Clear semaphore Calculate new output value using difference equation Write to PWM Update out(k+1), in(k+1), and in(k+2) Display Speed
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Task 3 Within Timer 3 ISR Clear Interrupt flag Start sampling
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Task 3 Within ADC ISR Get new speed reading and clear DONE Set semaphore Check for one-hundred passes (100 x 50ms = 5 s) If 100 passes then Toggle RD0 Calculate new reference = Step*D0 + Offset Reset pass count Else Increment pass count Clear ADC interrupt flag
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Task 3 Download to project folder feedback.c peripherals.a (library archive) peripherals.h Create project and add all three files Add linker script Create heap
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Open-Loop Load-Speed Characteristics Speed Load Closed Loop Open Loop
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Task 4 Use Internal Reference Use MPLAB’s Data Monitor and Control Interface to Adjust K1 and K2 Capture Image on MSO and repeat for Critically Damped Over Damped Under Damped
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Data Monitor and Control Interface
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DMCI Configuration Right Click
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DMCI Use Press Save after Dynamic Data Control is configured Press Halt Adjust Sliders Use Mouse Up arrow and Down arrow Press Start
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