control.InterconnectedSystem

class control.InterconnectedSystem(syslist, connections=[], inplist=[], outlist=[], params={}, warn_duplicate=None, **kwargs)

Bases: InputOutputSystem

Interconnection of a set of input/output systems.

This class is used to implement a system that is an interconnection of input/output systems. The sys consists of a collection of subsystems whose inputs and outputs are connected via a connection map. The overall system inputs and outputs are subsets of the subsystem inputs and outputs.

See interconnect() for a list of parameters.

Methods

check_unused_signals

Check for unused subsystem inputs and outputs

copy

Make a copy of an input/output system

dynamics

Compute the dynamics of a differential or difference equation.

feedback

Feedback interconnection between two input/output systems

find_input

Find the index for an input given its name (None if not found)

find_output

Find the index for an output given its name (None if not found)

find_state

Find the index for a state given its name (None if not found)

isctime

Check to see if a system is a continuous-time system

isdtime

Check to see if a system is a discrete-time system

issiso

Check to see if a system is single input, single output

linearize

Linearize an input/output system at a given state and input.

output

Compute the output of the system

set_connect_map

Set the connection map for an interconnected I/O system.

set_input_map

Set the input map for an interconnected I/O system.

set_inputs

Set the number/names of the system inputs.

set_output_map

Set the output map for an interconnected I/O system.

set_outputs

Set the number/names of the system outputs.

set_states

Set the number/names of the system states.

unused_signals

Find unused subsystem inputs and outputs

__add__(sys2)

Add two input/output systems (parallel interconnection)

__mul__(sys1)

Multiply two input/output systems (series interconnection)

__neg__()

Negate an input/output systems (rescale)

__radd__(sys2)

Parallel addition of input/output system to a compatible object.

__rmul__(sys2)

Pre-multiply an input/output systems by a scalar/matrix

__rsub__(sys2)

Parallel subtraction of I/O system to a compatible object.

__sub__(sys2)

Subtract two input/output systems (parallel interconnection)

check_unused_signals(ignore_inputs=None, ignore_outputs=None)

Check for unused subsystem inputs and outputs

If any unused inputs or outputs are found, emit a warning.

Parameters
  • ignore_inputs (list of input-spec) –

    Subsystem inputs known to be unused. input-spec can be any of:

    ’sig’, ‘sys.sig’, (isys, isig), (‘sys’, isig)

    If the ‘sig’ form is used, all subsystem inputs with that name are considered ignored.

  • ignore_outputs (list of output-spec) –

    Subsystem outputs known to be unused. output-spec can be any of:

    ’sig’, ‘sys.sig’, (isys, isig), (‘sys’, isig)

    If the ‘sig’ form is used, all subsystem outputs with that name are considered ignored.

copy(name=None, use_prefix_suffix=True)

Make a copy of an input/output system

A copy of the system is made, with a new name. The name keyword can be used to specify a specific name for the system. If no name is given and use_prefix_suffix is True, the name is constructed by prepending config.defaults[‘iosys.duplicate_system_name_prefix’] and appending config.defaults[‘iosys.duplicate_system_name_suffix’]. Otherwise, a generic system name of the form sys[<id>] is used, where <id> is based on an internal counter.

dynamics(t, x, u)

Compute the dynamics of a differential or difference equation.

Given time t, input u and state x, returns the value of the right hand side of the dynamical system. If the system is continuous, returns the time derivative

dx/dt = f(t, x, u)

where f is the system’s (possibly nonlinear) dynamics function. If the system is discrete-time, returns the next value of x:

x[t+dt] = f(t, x[t], u[t])

Where t is a scalar.

The inputs x and u must be of the correct length.

Parameters
  • t (float) – the time at which to evaluate

  • x (array_like) – current state

  • u (array_like) – input

Returns

dx/dt or x[t+dt]

Return type

ndarray

feedback(other=1, sign=-1, params={})

Feedback interconnection between two input/output systems

Parameters
  • sys1 (InputOutputSystem) – The primary process.

  • sys2 (InputOutputSystem) – The feedback process (often a feedback controller).

  • sign (scalar, optional) – The sign of feedback. sign = -1 indicates negative feedback, and sign = 1 indicates positive feedback. sign is an optional argument; it assumes a value of -1 if not specified.

Returns

out

Return type

InputOutputSystem

Raises

ValueError – if the inputs, outputs, or timebases of the systems are incompatible.

find_input(name)

Find the index for an input given its name (None if not found)

find_output(name)

Find the index for an output given its name (None if not found)

find_state(name)

Find the index for a state given its name (None if not found)

isctime(strict=False)

Check to see if a system is a continuous-time system

Parameters
  • sys (Named I/O system) – System to be checked

  • strict (bool, optional) – If strict is True, make sure that timebase is not None. Default is False.

isdtime(strict=False)

Check to see if a system is a discrete-time system

Parameters

strict (bool, optional) – If strict is True, make sure that timebase is not None. Default is False.

issiso()

Check to see if a system is single input, single output

linearize(x0, u0, t=0, params={}, eps=1e-06, name=None, copy=False, **kwargs)

Linearize an input/output system at a given state and input.

Return the linearization of an input/output system at a given state and input value as a StateSpace system. See linearize() for complete documentation.

ninputs

Number of system inputs.

noutputs

Number of system outputs.

nstates

Number of system states.

output(t, x, u)

Compute the output of the system

Given time t, input u and state x, returns the output of the system:

y = g(t, x, u)

The inputs x and u must be of the correct length.

Parameters
  • t (float) – the time at which to evaluate

  • x (array_like) – current state

  • u (array_like) – input

Returns

y

Return type

ndarray

set_connect_map(connect_map)

Set the connection map for an interconnected I/O system.

Parameters

connect_map (2D array) – Specify the matrix that will be used to multiply the vector of subsystem outputs to obtain the vector of subsystem inputs.

set_input_map(input_map)

Set the input map for an interconnected I/O system.

Parameters

input_map (2D array) – Specify the matrix that will be used to multiply the vector of system inputs to obtain the vector of subsystem inputs. These values are added to the inputs specified in the connection map.

set_inputs(inputs, prefix='u')

Set the number/names of the system inputs.

Parameters
  • inputs (int, list of str, or None) – Description of the system inputs. This can be given as an integer count or as a list of strings that name the individual signals. If an integer count is specified, the names of the signal will be of the form u[i] (where the prefix u can be changed using the optional prefix parameter).

  • prefix (string, optional) – If inputs is an integer, create the names of the states using the given prefix (default = ‘u’). The names of the input will be of the form prefix[i].

set_output_map(output_map)

Set the output map for an interconnected I/O system.

Parameters

output_map (2D array) – Specify the matrix that will be used to multiply the vector of subsystem outputs to obtain the vector of system outputs.

set_outputs(outputs, prefix='y')

Set the number/names of the system outputs.

Parameters
  • outputs (int, list of str, or None) – Description of the system outputs. This can be given as an integer count or as a list of strings that name the individual signals. If an integer count is specified, the names of the signal will be of the form u[i] (where the prefix u can be changed using the optional prefix parameter).

  • prefix (string, optional) – If outputs is an integer, create the names of the states using the given prefix (default = ‘y’). The names of the input will be of the form prefix[i].

set_states(states, prefix='x')

Set the number/names of the system states.

Parameters
  • states (int, list of str, or None) – Description of the system states. This can be given as an integer count or as a list of strings that name the individual signals. If an integer count is specified, the names of the signal will be of the form u[i] (where the prefix u can be changed using the optional prefix parameter).

  • prefix (string, optional) – If states is an integer, create the names of the states using the given prefix (default = ‘x’). The names of the input will be of the form prefix[i].

unused_signals()

Find unused subsystem inputs and outputs

Returns

  • unused_inputs (dict) – A mapping from tuple of indices (isys, isig) to string ‘{sys}.{sig}’, for all unused subsystem inputs.

  • unused_outputs (dict) – A mapping from tuple of indices (isys, isig) to string ‘{sys}.{sig}’, for all unused subsystem outputs.