control.InterconnectedSystem

class control.InterconnectedSystem(syslist, connections=[], inplist=[], outlist=[], inputs=None, outputs=None, states=None, params={}, dt=None, name=None, **kwargs)

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.

__init__(syslist, connections=[], inplist=[], outlist=[], inputs=None, outputs=None, states=None, params={}, dt=None, name=None, **kwargs)

Create an I/O system from a list of systems + connection info.

The InterconnectedSystem class is used to represent an input/output system that consists of an interconnection between a set of subystems. The outputs of each subsystem can be summed together to provide inputs to other subsystems. The overall system inputs and outputs can be any subset of subsystem inputs and outputs.

See interconnect() for a list of parameters.

Methods

__init__(syslist[, connections, inplist, …])	Create an I/O system from a list of systems + connection info.
copy([newname])	Make a copy of an input/output system.
dynamics(t, x, u)	Compute the dynamics of a differential or difference equation.
feedback([other, sign, params])	Feedback interconnection between two input/output systems
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)
issiso()	Check to see if a system is single input, single output
linearize(x0, u0[, t, params, eps, name, copy])	Linearize an input/output system at a given state and input.
name_or_default([name])
output(t, x, u)	Compute the output of the system
set_connect_map(connect_map)	Set the connection map for an interconnected I/O system.
set_input_map(input_map)	Set the input map for an interconnected I/O system.
set_inputs(inputs[, prefix])	Set the number/names of the system inputs.
set_output_map(output_map)	Set the output map for an interconnected I/O system.
set_outputs(outputs[, prefix])	Set the number/names of the system outputs.
set_states(states[, prefix])	Set the number/names of the system states.

Attributes

idCounter

copy(newname=None)

Make a copy of an input/output system.

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)

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.

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].