platform for attitude control...

1

PACE Platform for Attitude Control Experiment

Jiun-Jih Miau and Jyh-Ching JuangNational Cheng Kung University

Tainan, TAIWAN

PACE website: www.iaalab.ncku.edu.tw/pace/

PACE: National Cheng Kung University, Taiwan 2

Introduction Significances of cubesat researchCubesat research in Taiwan

NSPO: YAMSAT (2001-2002)NCKU: PACE (2003- )

PACE: National Cheng Kung University, Taiwan 3

PACE FeaturesMass: Less than 2 kg Dimension: 100 x 100 x 200 mmADCS Requirement : 3-axis stabilizationPayload: MEMS temperature sensorDual on-board CPUsTCS: Passive thermal controlOperating Orbit (TBD):

Near-circular orbit 600 km , inclination 98ºTT&C: Amateur Radio Communication;

Up/Down link: 433MHz , Data Rate: 1200bpsCW: 144 MHz band

Power: Body mount solar array & Li-ion batterySatellite Life Time 2 months Launch Scheduled 2004-2005

PACE: National Cheng Kung University, Taiwan 4

Characteristics of the PACEA double cube design Three-axis stabilization for pico-satellites

Momentum biased wheel + magnetic coilSensor suite integration for attitude determination:

magnetometer, gyro, coarse sun sensorTwo CPU design

8051-based CPU: C&DH and ADCSMEMS sensor technology demonstration

Temperature sensorCoarse sun sensor

PACE: National Cheng Kung University, Taiwan 5

PACE OrbitOrbit altitude = 600 km, inclination = 97.79ºPeriod = 96.69 min, mean contact duration = 657sec

PACE: National Cheng Kung University, Taiwan 6

PACE PayloadPACE payload: MEMS sensor

Temperature sensorCoarse sun sensor

Coarse sun Coarse sun sensorsensor

TemperatureTemperaturesensorsensor

PACE: National Cheng Kung University, Taiwan 7

PACE Configuration

CW

C&DH

ADCSEPS

TT&CCoil

Magnetometer

Gyro sensor

X

Y

Z

Wheel

Battery

Antenna

PACE: National Cheng Kung University, Taiwan 8

System Diagram

C8051F020

CPU

Internal A/D

TT&C

CW

Transceiver

Tx (DIO 1 bit)

Tx (UART)

Rx (UART)

PTT (DIO 1 bit)

MEMS Temp. Sensor

Sensor

MU

X

EPS

Power Monitor

Power Controller

ADCS

ADCS

CPU

Momentum Wheel

Coil Magne- tometer

CMD (DA)

F/B (AD 12 bit)

TXRX External RAM

C&DH Kill SwitchAntenna Dep.

Gyro Coarse

SunSensor

PACE: National Cheng Kung University, Taiwan 9

EPS

DRU

Solar Cells

Batteries

12V

5V

Momentum Wheel

Magnetometer

OBCSlave OBC

ModemCW

Payload

Magnetometer

Gyro

Coils

EPSTransceiver

PACE: National Cheng Kung University, Taiwan 10

PACE Operating Mode

Boot/Reset Mode

Normal Mode

Power Monitor Mode

Boot Complete

Ground Test Mode

(Idle)Remove

Before Flight On

Bit error occurred

No Contact > N days

Power On

Low power

Charge completed

Contact ModeGround Command

Max Contact Time Exceed

Launch Mode

Safe Mode

Initial & 3-Axis Mode

Low Power

PACE: National Cheng Kung University, Taiwan 11

Momentum WheelA momentum wheel is developed for the 3-axis control of the PACE.

PACE: National Cheng Kung University, Taiwan 12

PACE ADCS

Attitude DeterminationAttitude DeterminationKalmanKalman filterfilter

GyroGyro

S/C DynamicS/C Dynamic Disturbance Disturbance TorqueTorque

Attitude Control Attitude Control SystemSystem

Coarse Sun Coarse Sun SensorSensor

ω_Body Φ, θ, Ψ

ω_estimated

Θ_estimated

Θ_measuredω_measured

MagnetometerMagnetometer

B_Body

Orbit informationOrbit information

IGRF ModelIGRF Model

PACE: National Cheng Kung University, Taiwan 13

SummaryTaiwanese Cubesats

Cubesat YAMSAT PACE

Development 2001-2002 2003-Developer NSPO NCKU

Size/Weight Single cube, 1 kg Double cube, 2 kg

Technology demonstration

system engineering

3-axis control

C&DH One CPU Two CPUs

Payload Microspectrometer MEMS temp sensor

PACE: National Cheng Kung University, Taiwan 14

Thank you