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IMU381 Series User's Manual
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IMU381 Series Default Coordinate System
The IMU381 Series Inertial System default coordinate systems are shown in Figure 6. As with
many elements of the IMU381 Series, the coordinate system is configurable with either NAV-
VIEW or by sending the appropriate serial commands over the UART port. These configurable
elements are known as Advanced Settings. This section of the manual describes the default
coordinate system settings of the IMU381 Series when it leaves the factory.
Figure 5 IMU381 Default Coordinate Frame
The axes form an orthogonal SAE right-handed coordinate system. Acceleration is positive when
it is oriented towards the positive side of the coordinate axis. For example, with a IMU381 Series
product sitting on a level table, it will measure zero g along the x- and y-axes and -1 g along the
z-axis. Normal Force acceleration is directed upward, and thus will be defined as negative for the
IMU381 Series z-axis.
The angular rate sensors are aligned with these same axes. The rate sensors measure angular
rotation rate around a given axis. The rate measurements are labeled by the appropriate axis. The
direction of a positive rotation is defined by the right-hand rule. With the thumb of your right
hand pointing along the axis in a positive direction, your fingers curl around in the positive
rotation direction. For example, if the IMU381 Series product is sitting on a level surface and you
rotate it clockwise on that surface, this will be a positive rotation around the z-axis. The x- and y-
axis rate sensors would measure zero angular rates, and the z-axis sensor would measure a
positive angular rate.
Doc# 7430-3881-02
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