Why Design Tool?

93年 10月 21日

EPS Course - 2

• Simple Problems ----------------------- Close form solution

• Complex Problems --------------------- Computer Software

• Overly Complex Problems ------------ ?????

Accuracy is Critical

to

Spacecraft Design

Why Design Software ?

EPS Course - 3

Software Skill

UnderstandInput Data

GenerateResults

ModelingTechniques

Generate AccurateResults

Output

User’sManual

Input

BackgroundTheories

Test DataCorrelation

EPS Course - 4

Commonly Used Software for Spacecraft Design

SPACECRAFT

Mission Analysis

ADCS

ElectricalPower

ThermalControl

StructureAnalysis

FlightSoftware

STK: Orbit dynamics simulation including orbit trajectory, ground trace,

and visibility access, etc.

NASTRAN: Finite element code for static and dynamic analysis.

PATRAN: Preprocessor for finite element code.

TRASYS: Calculate internal and external radiation conductor.

SINDA: Construct thermal network model which include the TRANSYS

output radiation conductor to calculate temperature distribution.

MATLAB: Synthesize control law, perform dynamic modeling for

spacecraft, actuators, sensors, and perform linear stability

analysis for the control system.

STK: Every possible and worst case orbit beta angle.

OrCAD V9.0: Electrical Power Circuit modeling and analysis

PK51-8051: Integrated Development Environment, including Editor,

Assembler, Compiler, linker, Debugger, HEX converter,

target monitor, and real-time kernel.

Orbit Power Analysis & STK Tool

朱崇惠92年 10月 21日

EPS Course - 6

Power Analysis Principle

• Power Generation

– Photovoltaic type: Solar Array Operation duty cycle

Sun/eclipse time -> OrbitBeta angle -> OrbitSun angle -> Orbit, Attitude, Articulation

Obscurity -> Form, Attitude, Orbit

• Power Consumption

– Satellite Load Operation duty cycle Sun/eclipse time -> Orbit

– Energy storage replenish Peak power demand Sun/eclipse time -> Orbit

EPS Course - 7

STK’s function for power analysis

Time

Input

Orbit epoch

Build-in tool

Map

Orbit Propagator

Attitude Sun/Moon ephemeris

Geometry calculationSatellite

Facility

Sensor

Output

Orbit Parameters

Geometry Parameters

Time

Visualization

Position

EPS Course - 8

ROCSAT2 Orbit Example

EPS Course - 9

Generate a sun-synchronous orbit

EPS Course - 10

Sun/Eclipse Time Interval

Satellite-ROCSAT2: Eclipse Times

  

Start Time (UTCG) Stop Time (UTCG) Duration (sec) Current Condition Total Duration (sec)----------------------- ----------------------- -------------- ----------------- --------------------22 Jun 2004 12:50:51.65 22 Jun 2004 12:51:02.83 11.182 Penumbra 1922.81622 Jun 2004 12:51:02.83 22 Jun 2004 13:22:43.44 1900.603 Umbra 1922.81622 Jun 2004 13:22:43.44 22 Jun 2004 13:22:54.47 11.031 Penumbra 1922.81622 Jun 2004 14:33:46.49 22 Jun 2004 14:33:57.67 11.182 Penumbra 1922.76822 Jun 2004 14:33:57.67 22 Jun 2004 15:05:38.23 1900.554 Umbra 1922.76822 Jun 2004 15:05:38.23 22 Jun 2004 15:05:49.26 11.032 Penumbra 1922.76822 Jun 2004 16:16:41.33 22 Jun 2004 16:16:52.51 11.183 Penumbra 1922.72022 Jun 2004 16:16:52.51 22 Jun 2004 16:48:33.02 1900.505 Umbra 1922.72022 Jun 2004 16:48:33.02 22 Jun 2004 16:48:44.05 11.032 Penumbra 1922.72022 Jun 2004 17:59:36.17 22 Jun 2004 17:59:47.35 11.184 Penumbra 1922.67222 Jun 2004 17:59:47.35 22 Jun 2004 18:31:27.81 1900.456 Umbra 1922.67222 Jun 2004 18:31:27.81 22 Jun 2004 18:31:38.84 11.033 Penumbra 1922.67222 Jun 2004 19:42:31.01 22 Jun 2004 19:42:42.19 11.184 Penumbra 1922.62422 Jun 2004 19:42:42.19 22 Jun 2004 20:14:22.60 1900.406 Umbra 1922.62422 Jun 2004 20:14:22.60 22 Jun 2004 20:14:33.63 11.033 Penumbra 1922.62422 Jun 2004 21:25:25.85 22 Jun 2004 21:25:37.03 11.185 Penumbra 1922.57522 Jun 2004 21:25:37.03 22 Jun 2004 21:57:17.39 1900.357 Umbra 1922.57522 Jun 2004 21:57:17.39 22 Jun 2004 21:57:28.42 11.034 Penumbra 1922.57522 Jun 2004 23:08:20.69 22 Jun 2004 23:08:31.87 11.185 Penumbra 1922.52622 Jun 2004 23:08:31.87 22 Jun 2004 23:40:12.18 1900.307 Umbra 1922.52622 Jun 2004 23:40:12.18 22 Jun 2004 23:40:23.22 11.034 Penumbra 1922.52623 Jun 2004 00:51:15.53 23 Jun 2004 00:51:26.72 11.186 Penumbra 1922.47723 Jun 2004 00:51:26.72 23 Jun 2004 01:23:06.97 1900.256 Umbra 1922.47723 Jun 2004 01:23:06.97 23 Jun 2004 01:23:18.01 11.035 Penumbra 1922.47723 Jun 2004 02:34:10.37 23 Jun 2004 02:34:21.56 11.186 Penumbra 1922.42823 Jun 2004 02:34:21.56 23 Jun 2004 03:06:01.77 1900.206 Umbra 1922.428

EPS Course - 11

Orbit Beta Angle

EPS Course - 12

Solar Array Articulation

• Solar Array Articulation

orbit plane v.s. the sun

the position of a spacecraft in one orbit

• Solar Array v.s. Spacecraft

– Pointing of spacecraft body

– Fixed mounted solar array

– Solar array with one-axis rotation

– Solar array with two-axes rotation

EPS Course - 13

RS2 Sun Vector

EPS Course - 14

Sun Angle

• Case 1: Lowest angle • Case 2: Summer solstice

• Case 3: Winter solstice • Case 4: Highest angle

EPS Course - 15

ROCSAT3 Orbit Example

EPS Course - 16

Orbit Beta Angle

EPS Course - 17

ROCSAT-3 Solar Array’s Pointing

EPS Course - 18

ROCSAT1 Orbit Example

EPS Course - 19

Orbit Beta Angle

EPS Course - 20

Summary (1)

• STK is a tool useful for orbit related analysis

– Preliminary estimate

– Preliminary design

– Quick access

– Visualized tool to acquire impression

• Correct setup for orbit configuration is important

– Orbit parameter

– Spacecraft attitude

– Solar panel orientation

• With sun ephemeris, STK can provide a predict the availability of energy resources.

EPS Course - 21

Summary (2)

• Spacecraft attitude and solar panel articulation need to be modeled

– Development of attitude simulation tool

– Development of solar panel movement simulation tool

– Model of solar panel

• STK data can be used as input/out for a separate modeling

– Input/output data type

– Input/output data format