Trajectory¶

class acoular.trajectory.Trajectory¶

Bases: HasStrictTraits

Represents a trajectory as a continuous curve derived from sampled points.

The Trajectory class computes a smooth, continuous path through a set of discrete points in space and time using spline interpolation. It also supports evaluating the trajectory and its derivatives at arbitrary time instants.

It can be used to:

define the traveling path of a moving sound source, e.g. for microphone array data simulation (see MovingPointSource)
move a source grid along a certain path to create a fixed focus (see BeamformerTimeTraj and BeamformerCleantTraj)

Exemplary use can also be seen in the rotating point source example.

See also

MovingPointSource: Model a point source moving along a trajectory.
MovingPointSourceDipole: Model a point source dipole moving along a trajectory.
MovingLineSource: Model a line source moving along a trajectory.
BeamformerCleantTraj: Beamformer implementing the CLEAN method [21] in time domain for moving sources with known trajectory.
BeamformerTimeTraj: Basic time domain beamformer with time signal output for a grid moving along a trajectory.
scipy.interpolate.splprep(): Underlying spline generation function.
scipy.interpolate.splev(): Used for evaluating the spline.

Notes

Spline interpolation provides a smooth trajectory that passes through all sampled points. The interpolation order is adjusted automatically based on the number of points.
The trajectory can be used in simulations where a source’s motion must be modeled continuously.

Examples

Create a trajectory and evaluate positions and velocities:

>>> from acoular import Trajectory
>>> points = {0.0: (0.0, 0.0, 0.0), 1.0: (1.0, 0.0, 0.0), 2.0: (2.0, 1.0, 0.0)}
>>> tr = Trajectory(points=points)
>>>
>>> tr.location(1.5)  # Position at t=1.5
[array(1.5), array(0.375), array(0.)]
>>>
>>> for pos in tr.traj(0.0, 2.0, 0.5):  # Positions every 0.5 seconds
...     print(pos)
(np.float64(0.0), np.float64(0.0), np.float64(0.0))
(np.float64(0.5), np.float64(-0.125), np.float64(0.0))
(np.float64(1.0), np.float64(0.0), np.float64(0.0))
(np.float64(1.5), np.float64(0.375), np.float64(0.0))

points = Dict( …¶: Dictionary mapping time instants (keys, as floats) to sampled (x, y, z) positions (values, as tuples of floats) along the trajectory.

interval = Property()¶: Automatically determined tuple (t_min, t_max) representing the start and end times of the trajectory, based on the keys in points.

tck = Property()¶: Internal representation of the spline, generated using scipy.interpolate.splprep().

digest = Property(depends_on=['points[]'])¶: A unique identifier for the trajectory, based on its points. (read-only)

location(t, der=0)¶

Compute the trajectory’s position or derivatives at specified times.

Parameters:

tfloat or array of floats

Time instant(s) at which to compute the position(s) or derivative(s).

derint, optional

Order of the derivative to compute:

0 for positions (default),
1 for velocities,
2 for accelerations, etc.

Returns:

numpy.ndarray: (x, y, z) arrays representing the trajectory’s position (or derivative) at the given time(s). The shape matches that of t.

Examples

>>> import acoular as ac
>>>
>>> points = {0.0: (0.0, 0.0, 0.0), 1.0: (1.0, 2.0, 0.0), 2.0: (2.0, 4.0, 0.0)}
>>> tr = ac.Trajectory(points=points)
>>> tr.location(1.0)  # Position at t=1.0
[array(1.), array(2.), array(0.)]
>>> tr.location([0.5, 1.5], der=1)  # Velocity at t=0.5 and t=1.5
[array([1., 1.]), array([2., 2.]), array([0., 0.])]

traj(t_start, t_end=None, delta_t=None, der=0)¶

Interate through trajectory positions or derivatives at specified intervals.

Parameters:

t_startfloat

Start time for the trajectory. Default is earliest key in points.

t_endfloat, optional

End time of the trajectory. Default is the latest key in points.

delta_tfloat, optional

Time interval between consecutive points to yield. Default is the value of t_start.

derint, optional

Order of the derivative to compute:

0 for positions (default),
1 for velocities,
2 for accelerations, etc.

Yields:

tuple of floats: (x, y, z) positions or derivatives at the specified time intervals.

Notes

The function precomputes all interpolated locations for efficiency and yields them sequentially.

Examples

Create a trajectory and iterate through the positions in the interval:

>>> import acoular as ac
>>>
>>> points = {0.0: (0.0, 0.0, 0.0), 1.0: (1.0, 0.0, 0.0), 2.0: (2.0, 1.0, 0.0)}
>>> tr = ac.Trajectory(points=points)
>>> for pos in tr.traj(0.0, 2.0, 0.5):
...     print(pos)
(np.float64(0.0), np.float64(0.0), np.float64(0.0))
(np.float64(0.5), np.float64(-0.125), np.float64(0.0))
(np.float64(1.0), np.float64(0.0), np.float64(0.0))
(np.float64(1.5), np.float64(0.375), np.float64(0.0))

Acoular 25.03 documentation

Trajectory

Trajectory¶