try 0.9=1.9-1

[cnpcshangbo]

• s^1.9 discretization and check bode plot;
• redo the tests with disturbances (door);
• check bode plot for iopid discretization.

[cnpcshangbo]

IRID can't work with s^1.9. Therefore I tried Xue's block.
Check step response:
Simulink model:

Check door disturbance.

[cnpcshangbo]

Simulation 1 Clear
02:35 PM Elapsed: 0.56 sec
An error occurred while running the simulation and the simulation was terminated
Caused by:
Derivative of state '1' in block 'verify_Xue_block/discrete FOPD Xue/Integrator' at time 1.615 is not finite. The simulation will be stopped. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)
Component:Simulink | Category:Block error

[cnpcshangbo]

Try change solver to ode14x
Simulation 1 Clear
02:37 PM Elapsed: 1 sec
An error occurred while running the simulation and the simulation was terminated
Caused by:
Derivative of state '1' in block 'verify_Xue_block/discrete FOPD Xue/Integrator' at time 1.1983333333333333 is not finite. The simulation will be stopped. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)
Component:Simulink | Category:Block error

[cnpcshangbo]

try variable-step
Simulation 1 Clear
02:42 PM Elapsed: 1 sec
An error occurred while running the simulation and the simulation was terminated
Caused by:
Derivative of state '1' in block 'verify_Xue_block/discrete FOPD Xue/Integrator' at time 1.6196895363062527 is not finite. The simulation will be stopped. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)
Component:Simulink | Category:Block error

[cnpcshangbo]

To do:
Check Bode plot z vs s for irid s^1.9.
Check Bode z vs s for iopid slow.
Check Bode plot for Oustaloup.