Attitude Determination of a Powered Launch Vehicle Stage with Conventional Satellite Sensors
One of the main objectives of the first of the Stretched Rohini Satellite series SROSS-1, planned to be put into a 400 km near circular orbit by ASLV, is to assess the performance of the last stage of the launch vehicle. The inertial measurement unit (IMU) which provides the attitude information from lift-off will be separated from the last stage at the end of AS3 long coast. Hence, no further information of attitude of the fourth stage boost phase will be available through the IMU. In ASLV-SROSS-1 mission, it is proposed to determine and study the behaviour of the attitude of the composite (last stage of ASLV and SROSS) using horizon sensors, magnetometer and sun sensor, put together called the ALPHA package, housed on the satellite. Additionally, a single accelerometer along the longitudinal axis of the composite is also proposed to meet the objective. The methodology proposed here is a point-to-point coupled trajectory reconstruction using the sensor and velocity encoder data. Typical data of sensors and velocity encoder have to be generated so that a real life situation can be evolved for testing the near real time software required for attitude determination of the last stage powered flight. The behaviour of the composite during the AS4 boost phase with dynamic imbalance and thrust misalignment is a complex phenomenon which warrants a detailed simulation exercise.
KeywordsInertial Measurement Unit Body Frame Attitude Determination Velocity Encoder Translational Equation
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