On Thursday 29 September 2005 13:51, Hans-Georg Wunder wrote: > Time, reference,input,output > 09:10:00,0,0,0 > 09:10:01,0.6,0,-0.4999999999999999 Jump into saturation. Thats OK. > Only a P-Part, no I-Part > 09:10:02,0.6,0,-0.4999999999999999 snip! > 09:10:13,0.6,0,-0.4999999999999999 > 09:10:15,0,0,0.0999999999999999 Here the output value should > return to zero, because there is no I-Part
Maybe it should?! > > In this example, the output flips from the min saturation > to max-saturation. In a two phase controller (climb - altitude), > it impossible to control the aircraft. Are you saying that it's not possible to make cascade configurations? We've had cascade configurations since day one! > The problem is, that the change of input is store in ep_n. > Only the changes are given to the output. But in saturation > the change is not given to the output because of the windup logic > The controller gets out of sync > > Same test with delta_u_n =u_max - u_n_1 and ep_n = (ep_n * u_max > )/(delta_u_n+ u_n_1 ); > (My solution. Meanwhile I think it is not necessary to change the > edf_n-value, because the windup > logic is for the integrator part, but I am not completly convinced. snip! > > This should work in any situation. > Of course I can not deny the fact that your altering of ep_n does return the output closer to zero in one time step for the open loop case, but what about the closed loop case? Open loop PID controllers are really useless. Does this altering of ep_n improve the performance when used in closed loop controllers? I think that some of the "problems" that your tests expose can be traced back to the fact that you use an open loop configuration. I suggest that you do some tests with closed loop controllers to see if there is any performance gain. I also suggest that you fiddle around with the beta value, try setting it to zero. PS! I'm a bit disappointed by the BESTune application. I seems that the demo version is able to recognize the original input data, and when you try to change them it barks that it don't want to use anything but the _original_ input data. It does display the custom input data, but it does not seem to calculate useable values for Kp, Ti and Td. -- Roy Vegard Ovesen _______________________________________________ Flightgear-devel mailing list [email protected] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
