wecopttool.pto.PTO

A power take-off (PTO) object to be used in conjunction with a wecopttool.WEC object.

__init__(ndof, kinematics, controller=None, impedance=None, loss=None, names=None)[source]

Create a PTO object.

The wecopttool.pto.PTO class describes the kinematics, control logic, impedance and/or non-linear power loss of a power take-off system. The forces/moments applied by a wecopttool.pto.PTO object can be applied to a wecopttool.WEC object through the wecopttool.WEC.f_add property. The power produced by a wecopttool.pto.PTO object can be used for the obj_fun of pseudo-spectral optimization problem when calling wecopttool.WEC.solve().

Parameters:

ndof (int) – Number of degrees of freedom.
kinematics (StateFunction | ndarray) – Transforms state from WEC to PTO frame. May be a matrix (for linear kinematics) or function (for nonlinear kinematics).
controller (StateFunction | None) – Function with signature def fun(pto, wec, x_wec, x_opt, waves, nsubsteps): or matrix with shape (PTO DOFs, WEC DOFs) that converts from the WEC DOFs to the PTO DOFs.
impedance (ndarray | None) – Matrix representing the PTO impedance.
loss (Callable[[float | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | bool | int | complex | str | bytes | _NestedSequence[bool | int | float | complex | str | bytes], float | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | bool | int | complex | str | bytes | _NestedSequence[bool | int | float | complex | str | bytes]], float | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | bool | int | complex | str | bytes | _NestedSequence[bool | int | float | complex | str | bytes]] | None) – Function that maps flow and effort variables to a non-linear power loss. The output is the dissipated power (loss) in Watts. This should be a positive value.
names (list[str] | None) – PTO names.

Return type:

None

Attributes

`PTO.force`	PTO force in PTO coordinates.
`PTO.impedance`	Impedance matrix.
`PTO.kinematics`	Kinematics function.
`PTO.loss`	Nonlinear power loss function with outputs in Watts.
`PTO.names`	DOF Names.
`PTO.ndof`	Number of degrees of freedom.
`PTO.transfer_mat`	Transfer matrix.

Methods

`acceleration`	Calculate the PTO acceleration time-series.
`average_power`	Calculate the average power in each PTO DOF for a given system state.
`energy`	Calculate the energy in each PTO DOF for a given system state.
`force_on_wec`	Calculate the PTO force on WEC.
`mechanical_average_power`	Calculate average mechanical power in each PTO DOF for a given system state.
`mechanical_energy`	Calculate the mechanical energy in each PTO DOF for a given system state.
`mechanical_power`	Calculate the mechanical power time-series in each PTO DOF for a given system state.
`position`	Calculate the PTO position time-series.
`post_process`	Transform the results from optimization solution to a form that the user can work with directly.
`power`	Calculate the power time-series in each PTO DOF for a given system state.
`power_variables`	Calculate the power variables (flow q and effort e) time-series in each PTO DOF for a given system state.
`transduced_effort`	Calculate the transduced flow variable time-series in each PTO DOF for a given system state.
`transduced_flow`	Calculate the transduced flow variable time-series in each PTO DOF for a given system state.
`velocity`	Calculate the PTO velocity time-series.