Читать книгу Global Navigation Satellite Systems, Inertial Navigation, and Integration - Mohinder S. Grewal - Страница 156

Refer to Appendix B for coordinate system definitions, and satellite orbit equations.

1 3.1 Which, if any, of the following coordinate systems is not rotating?Northeast–down (NED)East–north–up (ENU)Earth‐centered Earth‐fixed (ECEF)Earth‐centered inertial (ECI)Moon‐centered moon‐fixed

2 3.2 What is the minimum number of two‐axis gyroscopes (i.e. gyroscopes with two, independent, orthogonal input axes) required for inertial navigation?123Not determined.

3 3.3 What is the minimum number of gimbal axes required for gimbaled inertial navigators in fully maneuverable host vehicles? Explain your answer.1234

4 3.4 Define specific force.

5 3.5 An inertial sensor assembly (ISA) operating at a fixed location on the surface of the Earth would measureNo acceleration1 acceleration downward1 acceleration upward

6 3.6 Explain why an inertial navigation system is not a good altimeter.

7 3.7 The inertial rotation rate of the Earth is1 revolution per day15 deg/h15 arc‐seconds per secondNone of the above

8 3.8 Define CEP and CEP rate for an INS.

9 3.9 The CEP rate for a medium accuracy INS is in the order of2 m/s200 m/h2000 m/h20 km/h

10 3.10 Derive the equivalent formulas in terms of (yaw angle), (pitch angle), and (roll angle) for unit vectors 1, 1, 1 in NED coordinates and 1, 1, 1 in RPY coordinates.

11 3.11 Explain why accelerometers cannot sense gravitational accelerations.

12 3.12 Show that the matrix defined in Eq. (3.35) is orthogonal by showing that the identity matrix. (Hint: Use .)

13 3.13 Calculate the numbers of computer multiplies and adds required forgyroscope scale factor/misalignment/bias compensation (Eq. (3.4 with )accelerometer scale factor/misalignment/bias compensation (Eq. (3.4 with ) andtransformation of accelerations to navigation coordinates (Figure 3.22) using quaternion rotations (see Appendix B on quaternion algebra)If the INS performs these 100 times per second, how many operations per second will be required?