PID Kontrol?

[z]

Benchmark sonuclari belli değilmi?

Siralama

Opamp, ASIC, FPGA, DSP, ve digerleri

[picusta]

Peki ARM'mi DSP'mi ? fiyat/performans?

Bence ADuC'un ARM7'si gayet güzel bir seçenek, içindeki hizli 12bit ADC ve DAC,3 faz PWM, islem gücü, genel olarak dsPIC'lerden daha iyi diyebilirmiyiz?

[Analyzer]

Selam,

Benim plc'lerde kullandığım, PID testi için çok basit bir sistemim var. Bir kutu içerisinde bir adet 220V/100W lamba, bir J type termokupl ve lambayı kontrol eden 5-10A bir SSR. Benchmark yapmak için böyle bir düzenek oluşturulup; farklı tipte ortamlarda (Op-amp, fpga, dspic, arm vs..) test edilebilir. Formül ve anlatımdan öte; mcu ile PID kontrol yapmak isteyenlere somut bir başlangıç noktası oluşturulabilir.

Analyzer

[Analyzer]

Selam,

Bu arada Fatek'in el kitabını karıştırırken bir not buldum :

Digitized PID expression is as follows:
Mn = [Kc×En]+ Σ0n[Kc×Ti×Ts×En]−[Kc×Td×(PVn−PVn-1)/Ts]

Where,
Mn: Output at time "n".
Kc: Gain (Range: 1～9999；Pb=100(%) / Kc)
Ti: Integral tuning constant (Range:0～9999, equivalent to 0.00～99.99 Repeat/Minute)
Td: Derivative tuning constant (Range:0～9999, equivalent to 0.00～99.99 Minute)
PVn : Process variable at time "n"
PVn_1: Process variable when loop was last solved
En: Error at time "n" ; E= SP – PVn
Ts: Solution interval for PID calculation (Valid value are 10, 20, 40, 80,160, 320; the unit is in 0.1Sec)

PID Parameter Adjustment Guide
�� As the gain (Kc) adjustment getting larger, the larger the proportional contribution to the output. This can
obtain a sensitive and rapid control reaction. However, when the gain is too large, it may cause oscillation.
Do the best to adjust "Kc" larger (but not to the extent of making oscillation), which could increase the
process reaction and reduce the steady state error.
�� Integral item may be used to eliminate the steady state error. The larger the number (Ti, integral tuning
constant), the larger the integral contribution to the output. When there is steady state error, adjust the "Ti"
larger to decrease the error.
When the "Ti" = 0, the integral item makes no contribution to the output.
For exam. , if the reset time is 6 minutes, Ti=100/6=17；if the integral time is 5 minutes, Ti=100/5=20.
�� Derivative item may be used to make the process smoother and not too over shoot. The larger the number
(Td, derivative tuning constant), the larger the derivative contribution to the output. When there is too over
shoot, adjust the "Td" larger to decrease the amount of over shoot.
When the "Td" = 0, the derivative item makes no contribution to the output.
For exa, if the rate time is 1 minute, then the Td = 100; if the differential time is 2 minute, then the Td = 200.
�� Properly adjust the PID parameters can obtain an excellent result for temperature control.
�� The default solution interval for PID calculation is 4 seconds (Ts=40)
�� The default of gain value (Kc) is 110, where Pb=1000/110×0.1%≒0.91%; the system full range is 1638°, it
means 1638×0.91≒14.8°to enter proportional band control.
�� The default of integral tuning constant is 17, it means the reset time is 6 minutes (Ti=100/6=17).
�� The default of derivative tuning constant is 50, it means the rate time is 0.5 minutes (Td=50).
�� When changing the PID solution interval, it may tune the parameters Kc, Ti, Td again.


Analyzer