[python-control-developers] [python-control/python-control] d267fa: initial release of I/O systems module (#301)

[Richard M. <no...@gi...>]

  Branch: refs/heads/master
  Home:   https://github.com/python-control/python-control
  Commit: d267fa27bd8c9910a979acd237ede2aa5ce35b13
      https://github.com/python-control/python-control/commit/d267fa27bd8c9910a979acd237ede2aa5ce35b13
  Author: Richard Murray <mu...@cd...>
  Date:   2019-06-08 (Sat, 08 Jun 2019)

  Changed paths:
    M control/__init__.py
    M control/bdalg.py
    A control/iosys.py
    M control/lti.py
    M control/statesp.py
    A control/tests/iosys_test.py
    M control/timeresp.py
    M doc/classes.rst
    M doc/control.rst
    M doc/conventions.rst
    A examples/cruise-control.py
    A examples/steering-gainsched.py

  Log Message:
  -----------
  initial release of I/O systems module (#301)

This PR introduces a new module for representing (nonlinear) input/output systems and support for simulation, linearization, and composition. The following features are supported:

* Input/output systems can be created using the LinearIOSystem and NonlinearIOSystem classes, and I/O systems can be simulated in continuous and discrete time using the input_output_response() function, which is equivalent to the forced_response() function for LTI system.

* Input/output systems can be composed using the existing series, parallel, and feedback functions, as well as using the * and + operators. In addition, the InterconnectedSystem class can be used to interconnect a collection of I/O subsystems, with functionality similar to the connect function in MATLAB.

* Input/output systems and input/output signals can be named and Interconnections between I/O systems can be specified using system and signal names.

* Input/output systems can be linearized about an equilibrium point using the linearize() function, which returns a LinearIOSystem object. The LinearIOSystem is derived from the StateSpace class, allowing all operations on linear systems to be applied to the linearized system. The find_eqpt() function can be used to find an equilibrium point for an input/output system.

Documentation and examples are included to illustrate the use of the iosys module.