Segment#

class pyCGM2.Model.model.Segment(label: str, index: int, sideEnum: SegmentSide, calibration_markers: List[str] | None = [], tracking_markers: List[str] | None = [])#

Represents a rigid body segment in a biomechanical model.

A Segment is a fundamental component in biomechanical modeling, representing a part of the body like a limb or a section of the spine. It holds information about the segment’s markers, technical and anatomical referentials, body segment parameters (BSP), and other relevant biomechanical data.

Parameters:

label (str) – Label of the segment.
index (int) – Unique index of the segment.
sideEnum (enums.SegmentSide) – Side of the body this segment belongs to.
calibration_markers (List[str], optional) – Labels of calibration markers associated with this segment. Defaults to [].
tracking_markers (List[str], optional) – Labels of tracking markers associated with this segment. Defaults to [].

__init__(label: str, index: int, sideEnum: SegmentSide, calibration_markers: List[str] | None = [], tracking_markers: List[str] | None = [])#: Initializes a new instance of the Segment class

Methods

`__init__`(label, index, sideEnum[, ...])	Initializes a new instance of the Segment class
`addCalibrationMarkerLabel`(labels)	Add one or multiple calibration markers to the segment.
`addExternalDeviceWrench`(btkWrench)	Add an external device wrench to the segment.
`addMarkerLabel`(label)	Add a marker label to the segment.
`addTechnicalReferential`(label)	Add a technical referential to the segment.
`addTrackingMarkerLabel`(labels)	Add one or multiple tracking markers to the segment.
`downSampleExternalDeviceWrenchs`(appf)	Downsample external device wrenches associated with the segment.
`getAngularAcceleration`(sampleFrequency)	Calculate the angular acceleration of the segment.
`getAngularVelocity`(sampleFrequency[, method])	Calculate the angular velocity of the segment.
`getComAcceleration`(pointFrequency[, method])	Calculate the global linear acceleration of the center of mass of the segment.
`getComTrajectory`([exportBtkPoint, btkAcq])	Get the trajectory of the center of mass of the segment.
`getComVelocity`(pointFrequency[, method])	Calculate the linear velocity of the center of mass of the segment.
`getExistFrames`()	Returns the list of frame numbers where the segment exists.
`getReferential`(label)	Get a technical referential from the segment.
`isExternalDeviceWrenchsConnected`()	Check if any external device wrenches are connected to the segment.
`removeTrackingMarker`(labels)	Remove one or multiple tracking markers from the segment.
`resetMarkerLabels`()	Reset the marker labels for the segment.
`setComPosition`(array3)	Set the local position of the center of mass of the segment.
`setExistFrames`(lstdata)	Sets the frame numbers where the segment exists in the biomechanical model.
`setInertiaTensor`(array33)	Set the inertia tensor of the segment.
`setLength`(value)	Set the length of the segment.
`setMass`(value)	Set the mass of the segment.
`setRog`(value)	Set the radius of gyration of the segment.
`zeroingExternalDevice`()	Zeroing (reset) the external device wrenches associated with the segment.
`zeroingProximalWrench`()	Zeroing (reset) the proximal wrench associated with the segment.

addCalibrationMarkerLabel(labels: str | List[str])#

Add one or multiple calibration markers to the segment.

Parameters:: labels (Union[str, List[str]]) – Label or list of labels of the calibration markers to be added.

addExternalDeviceWrench(btkWrench: btkWrench)#

Add an external device wrench to the segment.

Parameters:: btkWrench (btk.btkWrench) – A BTK wrench instance to be added.

addMarkerLabel(label: str)#

Add a marker label to the segment.

Parameters:: label (str) – Label of the marker to be added.

addTechnicalReferential(label: str)#

Add a technical referential to the segment.

Parameters:: label (str) – The label of the technical referential to be added.

addTrackingMarkerLabel(labels: str | List[str])#

Add one or multiple tracking markers to the segment.

Parameters:: labels (Union[str, List[str]]) – Label or list of labels of the tracking markers to be added.

downSampleExternalDeviceWrenchs(appf: int)#

Downsample external device wrenches associated with the segment.

Parameters:: appf (int) – Analog points per frame rate for downsampling.

getAngularAcceleration(sampleFrequency: float) → ndarray#

Calculate the angular acceleration of the segment.

Parameters:: sampleFrequency (float) – The sample frequency of the motion data.
Returns:: np.ndarray – An array representing the angular acceleration of the segment.

getAngularVelocity(sampleFrequency: float, method: str = 'conventional') → ndarray#

Calculate the angular velocity of the segment.

Parameters:

sampleFrequency (float) – The sample frequency of the motion data.
method (str, optional) – The method used for computing the angular velocity (‘conventional’ or ‘pig’). Defaults to ‘conventional’.

Returns:

np.ndarray – An array representing the angular velocity of the segment.

Notes:

The conventional method computes angular velocity through the matrix product $dot{R}R^t$

The pig method duplicates a bodybuilder code of the plug-in gait in which the velocity is computed from differentation between the next and previous pose

getComAcceleration(pointFrequency: float, method: str = 'spline', **options) → ndarray#

Calculate the global linear acceleration of the center of mass of the segment.

Parameters:

pointFrequency (float) – The point frequency for the calculation.
method (str, optional) – The method for calculation (‘spline’ or ‘spline fitting’). Defaults to ‘spline’.
**options – Additional options for filtering.

Returns:

np.ndarray – An array representing the center of mass linear acceleration.

getComTrajectory(exportBtkPoint: bool = False, btkAcq: btkAcquisition | None = None) → ndarray#

Get the trajectory of the center of mass of the segment.

Parameters:

exportBtkPoint (bool, optional) – If True, export as btk.point. Defaults to False.
btkAcq (Optional[btk.btkAcquisition], optional) – A btk acquisition instance if export is needed. Defaults to None.

Returns:

np.ndarray – An array representing the center of mass trajectory.

getComVelocity(pointFrequency: float, method: str = 'spline') → ndarray#

Calculate the linear velocity of the center of mass of the segment.

Parameters:

pointFrequency (float) – The point frequency for the calculation.
method (str, optional) – The method for calculation (‘spline’ or ‘spline fitting’). Defaults to ‘spline’.

Returns:

np.ndarray – An array representing the center of mass linear velocity.

getExistFrames() → List[int]#

Returns the list of frame numbers where the segment exists.

Returns:: List[int] – Frame numbers where the segment is present.

getReferential(label: str) → TechnicalReferential#

Get a technical referential from the segment.

Parameters:: label (str) – The label of the technical referential to retrieve.
Returns:: TechnicalReferential – The requested technical referential.

isExternalDeviceWrenchsConnected() → bool#

Check if any external device wrenches are connected to the segment.

Returns:: bool – True if external device wrenches are connected, False otherwise.

removeTrackingMarker(labels: str | List[str])#

Remove one or multiple tracking markers from the segment.

Parameters:: labels (Union[str, List[str]]) – Label or list of labels of the tracking markers to be removed.

resetMarkerLabels()#: Reset the marker labels for the segment.

setComPosition(array3: ndarray)#

Set the local position of the center of mass of the segment.

Parameters:: array3 (np.ndarray) – A 3-element array representing the center of mass position.

setExistFrames(lstdata: List[int])#

Sets the frame numbers where the segment exists in the biomechanical model.

Parameters:: lstdata (List[int]) – List of frame numbers where the segment is present.

setInertiaTensor(array33: ndarray)#

Set the inertia tensor of the segment.

Parameters:: array33 (np.ndarray) – A 3x3 matrix representing the inertia tensor.

setLength(value: float)#

Set the length of the segment.

Parameters:: value (float) – The length value to be set for the segment.

setMass(value: float)#

Set the mass of the segment.

Parameters:: value (float) – The length value to be set for the segment.

setRog(value: float)#

Set the radius of gyration of the segment.

Parameters:: value (float) – The radius of gyration value to be set for the segment.

zeroingExternalDevice()#: Zeroing (reset) the external device wrenches associated with the segment.

zeroingProximalWrench()#: Zeroing (reset) the proximal wrench associated with the segment.