INU Command

The set-up questions listed in your configuration vary depending upon your set-up and how your have responded to previous questions.

This command configures the optional Inertial Navigation Unit (INU). The INU provides RCP8 with navigation and attitude information that is necessary for stabilizing a moving platform.

Use platform stabilization algorithms: YES

A NO response disables all INU features and inhibits all coordinate transformations between pedestal and Earth frames (the 2 frames are assumed identical.) None of the questions below are displayed.

A YES response enables the separate pedestal and Earth coordinate frames and prompts the user with the following additional questions:

Negate sign of Roll angles: NO

Negate sign of Pitch angles: NO

Negate sign of Heading angles: NO

Use these questions if you must change the sign of the attitude angles.

Roll offset from true orientation: 0.00 deg

Pitch offset from true orientation: 0.00 deg

Heading offset from true orientation: 0.00 deg

Use these questions if there are fixed offsets in the attitude angles. Typically, this occurs if the INU is not bolted directly in line with the ship's principal axes.

Lead time for velocity extrapolation: 0.050 sec

The stability of the Earth-frame velocity servo can sometimes be improved by leading the time derivatives of the attitude angles by a small amount. Typical values are between 0 and 80 ms.

Dead INU detection time: 5.0 sec

RCP8 stops performing coordinate transformations if the INU data stream is absent for more than this length of time. During the dead time, all INU angles and velocities are artificially set to 0.

Built-in INU Simulation: External

RCP8 contains an internal INU simulator that is useful during program development as well as for testing simulated moving environments.

  • The response OFF disables the simulator and suppresses the remaining questions in this section.
  • The response EXTERNAL results in simulated INU SDLC data signals generated at the INU backpanel connector. This simulated stream can be looped back into the normal INU inputs for testing.
  • The response INTERNAL runs the same INU data simulation, but internally loops it back into RCP8 and does not generate any SDLC output signals.

The simulated motion is sinuosity on each axis and includes an adjustable amplitude, a center value, and a period. The default values that are displayed are simulating rather rough conditions in presumably bad weather.

Amplitude of motion for Roll axis: 12.00 deg

Amplitude of motion for Pitch axis: 8.00 deg

Amplitude of motion for Heading axis: 80.00 deg

Sets the peak amplitude of simulated motion on each axis.

Center of motion for Roll axis: 0.00 deg

Center of motion for Pitch axis: 0.00 deg

Center of motion for Heading axis: 0.00 deg

Sets the center of simulated motion on each axis.

Period of motion for Roll axis: 15.0 sec

Period of motion for Pitch axis: 13.0 sec

Period of motion for Heading axis: 60.0 sec

Sets the period of simulated motion of each axis.

Serial INU Simulation: NO