control.ss

control.ss(A, B, C, D[, dt])

Create a state space system.

The function accepts either 1, 2, 4 or 5 parameters:

ss(sys)

Convert a linear system into space system form. Always creates a new system, even if sys is already a state space system.

ss(updfcn, outfucn)`

Create a nonlinear input/output system with update function updfcn and output function outfcn. See NonlinearIOSystem for more information.

ss(A, B, C, D)

Create a state space system from the matrices of its state and output equations:

\dot x = A \cdot x + B \cdot u y = C \cdot x + D \cdot u

ss(A, B, C, D, dt)

Create a discrete-time state space system from the matrices of its state and output equations:

x[k+1] = A \cdot x[k] + B \cdot u[k] y[k] = C \cdot x[k] + D \cdot u[ki]

The matrices can be given as array like data types or strings. Everything that the constructor of numpy.matrix accepts is permissible here too.

``ss(args, inputs=[‘u1’, …, ‘up’], outputs=[‘y1’, …, ‘yq’],

states=[‘x1’, …, ‘xn’])

Create a system with named input, output, and state signals.

Parameters

  • sys (StateSpace or TransferFunction) – A linear system.

  • A (array_like or string) – System, control, output, and feed forward matrices.

  • B (array_like or string) – System, control, output, and feed forward matrices.

  • C (array_like or string) – System, control, output, and feed forward matrices.

  • D (array_like or string) – System, control, output, and feed forward matrices.

  • dt (None, True or float, optional) – System timebase. 0 (default) indicates continuous time, True indicates discrete time with unspecified sampling time, positive number is discrete time with specified sampling time, None indicates unspecified timebase (either continuous or discrete time).

  • inputs (str, or list of str, optional) – List of strings that name the individual signals. If this parameter is not given or given as None, the signal names will be of the form s[i] (where s is one of u, y, or x). See InputOutputSystem for more information.

  • outputs (str, or list of str, optional) – List of strings that name the individual signals. If this parameter is not given or given as None, the signal names will be of the form s[i] (where s is one of u, y, or x). See InputOutputSystem for more information.

  • states (str, or list of str, optional) – List of strings that name the individual signals. If this parameter is not given or given as None, the signal names will be of the form s[i] (where s is one of u, y, or x). See InputOutputSystem for more information.

  • name (string, optional) – System name (used for specifying signals). If unspecified, a generic name <sys[id]> is generated with a unique integer id.

Returns

out – Linear input/output system.

Return type

LinearIOSystem

Raises

ValueError – If matrix sizes are not self-consistent.

See also

tf, ss2tf, tf2ss

Examples

>>> # Create a Linear I/O system object from from for matrices
>>> sys1 = ss([[1, -2], [3 -4]], [[5], [7]], [[6, 8]], [[9]])

>>> # Convert a TransferFunction to a StateSpace object.
>>> sys_tf = tf([2.], [1., 3])
>>> sys2 = ss(sys_tf)