Racelogic VBOX 3iSL, Руководство пользователя

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VBOX 3iSL User Guide
Page 33 of 49
01/12/2011
IMU Integration
IMU integration should not be enabled for measurement of Braking distances
The main purpose of integrated navigation systems is to take advantage of the complementary attributes of two or more navigation systems (GPS and Inertial
motion unit) to achieve far better performance than through the use of either system on its own.
GPS derives data through two separate methods, Doppler (speed, vertical speed and heading) and Triangulation (latitude longitude and height). The Triangulation
calculated position data is bounded by an error (CEP value), which depends on the quality of the GPS receiver and its environment. GPS measurements are stable
but rely on weak signals, which are subject to signal blockage and interference from the surrounding environment, resulting in poor performance. The quality of the
Doppler derived channels are also affected in a similar way by the same influential factors.
Inertial sensor measurements on the other hand are continuously available but suffer from long-term drift due to the accumulation of integration errors of the
accelerometer and gyro measurements. As a result the IMU der
ived position error increases without bounds. IMU‟s of a higher accuracy are available but tend to be
large, bulky and expensive.
These complementary properties of IMU and GPS data make them ideal candidates for integration and can accurately compensate for GPS dropouts or noise.
The VBOX 3iSL has the capability of integrating the GPS data with inertial data from the IMU02/IMU03 Inertial Measurement Unit allowing accurate smoothing of the
following parameters:

Latitude

Longitude

Velocity

Heading

Height

Vertical Velocity
To use the data from a connected IMU to perform integrated Kalman filtering the VBOX 3iSL first needs to be set up using VBox Tools.
The screen shots here show the new IMU integrated Speed in blue and the non-integrated raw speed in red.
In these screen shots you can see how the IMU integrated Speed has continued to be produced perfectly through noisy and full dropout conditions