c4dynamics.sensors.navigation.gps.measure

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c4dynamics.sensors.navigation.gps.measure#

gps.measure(x_true)[source]#

Measure inertial position.

The method extracts the first three elements of x_true and adds the GPS bias and a zero-mean Gaussian noise sample to each coordinate.

Parameters:

x_true (array_like) – True position vector [x, y, z] [m].

Returns:

numpy.ndarray – Measured inertial position [x, y, z], [m].

Errors Model

A single independent noise sample is generated for each position coordinate. The returned measurement is therefore:

\[z = x_{true}[0:3] + bias + std \cdot N(0, I)\]

The bias is constant for the GPS instance, while the noise is regenerated at every call.

Examples

>>> import c4dynamics as c4d
>>> import numpy as np
>>> np.random.seed(42)
>>> gps_sensor = c4d.sensors.gps(noise_std=0, bias=[1, -2, 0.5])
>>> x = np.zeros(12)
>>> x[0:3] = [10, 20, 30]
>>> gps_sensor.measure(x) 
array([11.  18.  30.5])
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