automation - My PID Controller in Java is not operating correctly -

i looking implementation of pid controller in java , found one:

https://code.google.com/p/frcteam443/source/browse/trunk/2010_post_season/geisebot/src/freelancelibj/pidcontroller.java?r=17

so, understand using way:

package lol.feedback;  public class dsfdsf {      public static void main(string[] args) throws interruptedexception {         final pidcontroller pidcontroller = new pidcontroller(1, 1, 1);         pidcontroller.setinputrange(0, 200); // input limits         pidcontroller.setoutputrange(50, 100); // output limits         pidcontroller.setsetpoint(120); // target value (pid should minimize error between input , value)         pidcontroller.enable();         double input = 0;         double output = 0;         while (true) {             input = output + 30;             pidcontroller.getinput(input);             output = pidcontroller.performpid();             system.out.println("input: " + input + " | output: " + output + " | error: " + pidcontroller.geterror());              thread.sleep(1000);         }     }  } 

but never stabilizes. doesn't behave pid @ all... output get:

input: 30.0 | output: 100.0 | error: 90.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 input: 80.0 | output: 100.0 | error: 40.0 input: 130.0 | output: 50.0 | error: -10.0 

can me tell me missing?

thank you!

firstly, try set of pid parameters - example final pidcontroller pidcontroller = new pidcontroller(10, 1, 0.5); first parameter responsible gain of closed-loop system. second responsible eliminate fixed error on output. third responsible dynamic of control.

second thing - possible real signal output out of limit, takes minimum/maximum value.

thirdly, why add 30 output , assign input?