I've noticed that subsystems can produce outputs = 0 on every other call to a system's output function. The final result of the simulation is correct; however if you are doing something like processing quaternions in the output function, a quaternion of all zeros is invalid and an error results (without some hacky handling of that situation).
In the code below, line 1 printouts alternate between 0 and 1 rather than printing 1 at each call.
import numpy as np
import control as ct
def output_sys_outputs(t, x, u, params):
print(u) # alternates between zero and 1
return u
output_sys = ct.nlsys(updfcn=None, outfcn=output_sys_outputs, inputs=1, outputs=1, name="output_sys")
def input_sys_outputs(t, x, u, params):
return 1
input_sys = ct.nlsys(updfcn=None, outfcn=input_sys_outputs, outputs=1, inputs=0, name="input_sys")
# outputs just 1's
input_sim = ct.input_output_response(input_sys, T=np.linspace(0, 1, 100))
system = ct.interconnect(
(input_sys, output_sys),
connections=[
['output_sys.u', 'input_sys.y']
],
inplist=[],
outlist=['output_sys.y']
)
timeseries = ct.input_output_response(system, T=np.linspace(0, 1, 100))
y = timeseries.outputs
print(y) # prints all 1's
I've noticed that subsystems can produce outputs = 0 on every other call to a system's output function. The final result of the simulation is correct; however if you are doing something like processing quaternions in the output function, a quaternion of all zeros is invalid and an error results (without some hacky handling of that situation).
In the code below, line 1 printouts alternate between 0 and 1 rather than printing 1 at each call.