15.7 Test of Engine Thrust Pulsation Effect on GNC Sensors
507
15.7 Test of Engine Thrust Pulsation Effect on GNC
Sensors
15.7.1 Test Objective
The test objective of engine thrust pulsation effect on GNC sensors was to determine
the influence of engine thrust pulsation on GNC landing navigation sensors, so as
to verify adaptability of GNC sensors such as accelerometer to the thrust pulsation
environment.
15.7.2 Test Constraints and Methodology
When the test system for engine thrust pulsation effect on GNC sensors was designed,
the following constraints should be considered.
(1) It could simulate the free boundary of the lander when the engine was firing
on orbit.
(2) It could simulate the pulsation thrust condition when the engine was firing on
orbit.
(3) It could simulate the interface and mode of pulsation thrust when the engine
was firing on orbit.
(4) It could simulate the transfer path and transfer characteristics of pulsation thrust
on the lunar lander.
(5) It could simulate the mass property of the lunar lander.
(6) The real main structure and real landing gears should be applied in the test.
(7) The flight hardware of GNC landing navigation sensors should be applied and
powered on in the test.
In order to satisfy the above constraints and simulate the mechanical impact of the
engine thrust pulsation on orbit environment on the lunar lander as realistically as
possible, the real main structure and the real landing gear should be applied to simulate the force transfer path and load transfer characteristic. A gravity compensation
system of near zero stiffness spring should be designed to simulate the free boundary
of the lunar lander. A pulsation thrust simulation method should be developed to
simulate the pulsation thrust. The pulsation thrust input was simulated through an
exciter.
When the test plan was designed, the time domain data of the pulsation loads under
all condition in the ground vacuum firing test of the engine should be statistically
analyzed at first. The time slice with the largest time domain load in nominal thrust
and throttling thrust should be selected as the input excitation of the test, and the
closed-loop control method should be applied in the test.
507
15.7 Test of Engine Thrust Pulsation Effect on GNC
Sensors
15.7.1 Test Objective
The test objective of engine thrust pulsation effect on GNC sensors was to determine
the influence of engine thrust pulsation on GNC landing navigation sensors, so as
to verify adaptability of GNC sensors such as accelerometer to the thrust pulsation
environment.
15.7.2 Test Constraints and Methodology
When the test system for engine thrust pulsation effect on GNC sensors was designed,
the following constraints should be considered.
(1) It could simulate the free boundary of the lander when the engine was firing
on orbit.
(2) It could simulate the pulsation thrust condition when the engine was firing on
orbit.
(3) It could simulate the interface and mode of pulsation thrust when the engine
was firing on orbit.
(4) It could simulate the transfer path and transfer characteristics of pulsation thrust
on the lunar lander.
(5) It could simulate the mass property of the lunar lander.
(6) The real main structure and real landing gears should be applied in the test.
(7) The flight hardware of GNC landing navigation sensors should be applied and
powered on in the test.
In order to satisfy the above constraints and simulate the mechanical impact of the
engine thrust pulsation on orbit environment on the lunar lander as realistically as
possible, the real main structure and the real landing gear should be applied to simulate the force transfer path and load transfer characteristic. A gravity compensation
system of near zero stiffness spring should be designed to simulate the free boundary
of the lunar lander. A pulsation thrust simulation method should be developed to
simulate the pulsation thrust. The pulsation thrust input was simulated through an
exciter.
When the test plan was designed, the time domain data of the pulsation loads under
all condition in the ground vacuum firing test of the engine should be statistically
analyzed at first. The time slice with the largest time domain load in nominal thrust
and throttling thrust should be selected as the input excitation of the test, and the
closed-loop control method should be applied in the test.