444
13 Metrology Technology of Lunar Lander
lander again. Then the coordinates of A, B, C and D were converted to the coordinate
system of simulated the lunar lander, and the normal equation and vector angle were
calculated. By analysis of experiment data, the maximum error was 0.017°, which
satisfied the measurement requirement.
13.4.2 Laser Scanning for Interface Ring Based on General
USMN Adjustment
1. Requirements
The interface ring between the lunar lander and the launch vehicle supported the
total weight of the lunar lander, so its structural strength played an important role in
maintaining the accuracy of the lunar lander. In order to improve reliability of the
lunar lander, during the system assembly, it was necessary to measure the shape of
the bottom flange of interface ring in the reference coordinate system of the lunar
lander so as to verify whether the structure could meet the requirement.
2. Technical Design and Principle
A great many point cloud data is necessary for shape measurement. The point
measurement methods based on theodolite intersection or laser tracking could
not meet the requirement. Therefore, the laser 3-D scanning method was applied.
However, the laser 3-D scanning system could not directly measure the reference
coordinate system of the lunar lander. The reference prism coordinate system should
be measured by theodolite at first. How to integrate measurement data of two different
measurement systems was a challenge. Therefore, the general USMN adjustment
method was applied.
The general USMN technology is applied to solve the problem of unified spatial
metrology network adjustment for various spherical coordinate measuring systems,
in order to implement the spatial positioning and orientation of various measuring
instruments, and provide the unified position and orientation reference for the spatial
coordinate measurement of various instruments.
Laser radar scanning technology was applied in measurement of interface ring
of the lunar lander. The laser radar system is shown in Fig. 13.8. The laser radar
combined the FM laser ranging technology with the positioning mechanism of the
precision mirror [7], whose principle is shown in Fig. 13.9.
A laser interferometry system was applied to measure the distance R between
the infrared laser spot center and the origin of laser radar measurement coordinate
system. The positioning mechanism could accurately measure the angle between the
laser beam and the coordinate axis of the laser radar coordinate system, including
the pitching angle E I and the yaw angle A Z . The 3-D coordinates of the measured
point were calculated by the distance and encoder angle information. The equation
is as follows [8]:
13 Metrology Technology of Lunar Lander
lander again. Then the coordinates of A, B, C and D were converted to the coordinate
system of simulated the lunar lander, and the normal equation and vector angle were
calculated. By analysis of experiment data, the maximum error was 0.017°, which
satisfied the measurement requirement.
13.4.2 Laser Scanning for Interface Ring Based on General
USMN Adjustment
1. Requirements
The interface ring between the lunar lander and the launch vehicle supported the
total weight of the lunar lander, so its structural strength played an important role in
maintaining the accuracy of the lunar lander. In order to improve reliability of the
lunar lander, during the system assembly, it was necessary to measure the shape of
the bottom flange of interface ring in the reference coordinate system of the lunar
lander so as to verify whether the structure could meet the requirement.
2. Technical Design and Principle
A great many point cloud data is necessary for shape measurement. The point
measurement methods based on theodolite intersection or laser tracking could
not meet the requirement. Therefore, the laser 3-D scanning method was applied.
However, the laser 3-D scanning system could not directly measure the reference
coordinate system of the lunar lander. The reference prism coordinate system should
be measured by theodolite at first. How to integrate measurement data of two different
measurement systems was a challenge. Therefore, the general USMN adjustment
method was applied.
The general USMN technology is applied to solve the problem of unified spatial
metrology network adjustment for various spherical coordinate measuring systems,
in order to implement the spatial positioning and orientation of various measuring
instruments, and provide the unified position and orientation reference for the spatial
coordinate measurement of various instruments.
Laser radar scanning technology was applied in measurement of interface ring
of the lunar lander. The laser radar system is shown in Fig. 13.8. The laser radar
combined the FM laser ranging technology with the positioning mechanism of the
precision mirror [7], whose principle is shown in Fig. 13.9.
A laser interferometry system was applied to measure the distance R between
the infrared laser spot center and the origin of laser radar measurement coordinate
system. The positioning mechanism could accurately measure the angle between the
laser beam and the coordinate axis of the laser radar coordinate system, including
the pitching angle E I and the yaw angle A Z . The 3-D coordinates of the measured
point were calculated by the distance and encoder angle information. The equation
is as follows [8]: