Model base class

pynamics.models.base

This module contains the model base class, which forms the template for every plant model supported by this package.

Classes:

Name	Description
BaseModel	Model base class.

BaseModel(initial_state, input_dim, output_dim, input_labels=None, output_labels=None)

Bases: ABC

This is the parent class for every plant model supported by pynamics. While custom models are supported, they must all inherit from this class.

Parameters:

Name	Type	Description	Default
initial_state	ndarray	The system's initial state. Should be an array shaped (n, 1), where n is the number of state variables.	required
input_dim	int	Number of system inputs.	required
output_dim	int	Number of system outputs.	required
input_labels	list[str] | None	List of input labels. If None is passed, the inputs will be given generic names.	None
output_labels	list[str] | None	List of output labels. If None is passed, the outputs will be given generic names.	None

Attributes:

Name	Type	Description
x	ndarray	The system's state vector.
input_dim	int	Number of system inputs.
output_dim	int	Number of system outputs.
state_dim	int	Number of states in the state vector.
input_labels	list[str]	List of input labels.
output_labels	list[str]	List of output labels.

Methods:

Name	Description
get_state	Get the current state vector.
get_output	Compute the system's output from the current state.
get_input	Get the current inputs.
set_input	Pass new inputs to the system.
update_state	Assign new values to the system's state vector.
eval	Compute the system's state derivative.

Warning

This is an abstract base class. It should not be used directly.

Source code in pynamics/models/base.py

def __init__(self, 
             initial_state: np.ndarray, 
             input_dim: int, 
             output_dim: int,
             input_labels: list[str] | None=None, 
             output_labels: list[str] | None=None) -> None:

    """
    Class constructor.
    """

    super().__init__();
    self.x = initial_state;
    self._dim_checks(input_dim, output_dim);
    self.input_dim = input_dim;
    self.output_dim = output_dim;
    self.state_dim = self.x.shape[0];
    self.input_labels = self._labels_check(input_labels, self.input_dim, "u");
    self.output_labels = self._labels_check(output_labels, self.output_dim, "y");

    return;

eval() abstractmethod

Compute the system's state derivative.

Abstract method. Implementation details may vary with the model.

Source code in pynamics/models/base.py

@abstractmethod
def eval(self) -> np.ndarray:
    """
    Compute the system's state derivative.

    Abstract method. Implementation details may vary with the model.
    """

    pass

get_input() abstractmethod

Access the system's input.

Abstract method. Implementation details may vary with the model.

Source code in pynamics/models/base.py

@abstractmethod
def get_input(self) -> np.ndarray:
    """
    Access the system's input.

    Abstract method. Implementation details may vary with the model.
    """

    pass

get_output() abstractmethod

Compute the system's output from the current state vector.

Abstract method. Implementation details may vary with the model.

Source code in pynamics/models/base.py

@abstractmethod
def get_output(self) -> np.ndarray:
    """
    Compute the system's output from the current state vector.

    Abstract method. Implementation details may vary with the model.
    """

    pass

get_state() abstractmethod

Access the system's state.

Abstract method. Implementation details may vary with the model.

Source code in pynamics/models/base.py

@abstractmethod
def get_state(self) -> np.ndarray:
    """
    Access the system's state.

    Abstract method. Implementation details may vary with the model.
    """

    pass

set_input(u) abstractmethod

Pass a new set of inputs (references, control actions, etc.) to the system.

Abstract method. Implementation details may vary with the model.

Source code in pynamics/models/base.py

@abstractmethod
def set_input(self, u: np.ndarray | float) -> None:
    """
    Pass a new set of inputs (references, control actions, etc.) to the system.

    Abstract method. Implementation details may vary with the model.
    """

    pass

update_state() abstractmethod

Assign new values to the system's state vector.

Abstract method. Implementation details may vary with the model.

Source code in pynamics/models/base.py

@abstractmethod
def update_state(self) -> None:
    """
    Assign new values to the system's state vector.

    Abstract method. Implementation details may vary with the model.
    """

    pass