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README.txt
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README.txt
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------------------------
mainTSI_tudatversion.cpp
------------------------
THE PROGRAM
To propagate the state of a spacecraft expressed
in the Unified State Model (USM) with the use of
Taylor Series Integration (TSI), do the following:
1. Open mainTSI_tudatversion.cpp
2. Provide relevant inputs on the following lines:
(You can also find these inputs by using CTRL+F for "INPUT")
All inputs are in SI units, unless mentioned otherwise
77: The output folder
83: The gravitational parameter of your main body
90: The specific impulse of the motor of your spacacraft
94-101: The initial Keplerian state of your spacecraft
103: The initial mass of the spacecraft
111: The folder in which the thrust profile is specified
127: The method used to interpolate the thrust profile (see list of options)
135: The order of the TSI
138: The integration start time
139: The integration end time
144-150: The absolute error tolerances on each of the seven USM7 elements
153: Safety factor for the step-size, (used in combination with tolerances to enhance TSI accuracy
156: Initial integration step-size
159: Minimum integration step-size
162: Maximum integration step-size
165: Factor to interpolate between integration steps to refine the output
320: Name of output file
3. Build application_mainTSI_tudatversion
4. Run application_mainTSI_tudatversion
5. The output is stored in a .txt file in the specified folder and file.
See the README.txt file in the default output folder to interprete the output.
THE ASSUMPTIONS
In the default setup, the following assumptions are made:
1. The spacecraft is subject to a central gravitational field.
2. Besides the gravitational force and the thrust force, no other forces act on the spacecraft.
3. The fourth and higher order derivatives of the thrust accelerations in the velocity frame are zero. (See pages 16, 51*)
4. The fourth and higher order derivatives of the thrust accelerations in the RTN frame are zero. (See pages 17, 56*)
THE VALIDATION
As explained in the Conclusion* the developed TSI-USM integrator was found to be
sufficiently** accurate for cases in which the thrust force is constant.
*https://repository.tudelft.nl/islandora/object/uuid:2567c152-ab56-4323-bcfa-b076343664f9/datastream/OBJ/download
**A sufficient accuracy is defined as an absolute accuracy in position and velocity
of below 1 km and 1 m/s respectively for interplanetary low-thrust trajectories (semi-major axis > 1 AU) after an integration
period of 10 years.
--------------------------
mainRKusm_tudatversion.cpp
--------------------------
THE PROGRAM
To propagate the state of a spacecraft expressed
in the Unified State Model (USM) with the use of
the Runge-Kutta 8(7) integrator with 13 stages (RK8(7)13M),
do the following:
1. Open mainRKusm_tudatversion.cpp
2. Provide relevant inputs on the following lines:
(You can also find these inputs by using CTRL+F for "INPUT")
All inputs are in SI units, unless mentioned otherwise
116x: The gravitational parameter of your main body
120: The specific impulse of the motor of your spacacraft
125: The integration start time
126: The integration end time
127: Initial integration step-size
128: Minimum integration step-size
129: Maximum integration step-size
131: The absolute and relative error tolerance limits
140: The folder in which the thrust profile is specified
145-153: The initial Keplerian state of your spacecraft
155: The initial mass of the spacecraft
289: Name of output file containing the spacecraft state history
290: Output folder for the spacecraft state history
298: Name of output file containing the thrust acceleration history
299: Output folder for the thrust acceleration history
3. Build application_mainRKusm_tudatversion
4. Run application_mainRKusm_tudatversion
5. The output is stored in a .txt file in the specified folder and file.
See the README.txt file in the default output folder to interprete the output.
THE ASSUMPTIONS
In the default setup, the following assumptions are made:
1. The spacecraft is subject to a central gravitational field.
2. Besides the gravitational force and the thrust force, no other forces act on the spacecraft.
THE VALIDATION
The RK-USM integrator displays a sufficiently* accurate propagation for specific thrust cases (e.g. constant tangential thrust), but it requires
further testing of different cases to guarantee its validation.
*A sufficient accuracy is defined as an absolute accuracy in position and velocity
of below 1 km and 1 m/s respectively for interplanetary low-thrust trajectories (semi-major axis > 1 AU) after an integration
period of 10 years.