This repository outlines the flight software developed by Team Sammard for the CanSat Competition 2018, an annual aerospace student design-build-launch competition organized by The American Astronautical Society (AAS), NASA Goddard and U.S. Naval Research Laboratory among others.
The problem statement for the year was as follows-
To stimulate a space probe entering a planetary atmosphere
containing electronics, egg and a detachable heat shield.
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The probe shall carry a single large hen's egg simulating a delicate sensitive scientific instrument, which must survive the atmospheric re-entry and the entire flight.
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The aero-braking heat shield shall protect the probe until deployment.
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The aero-braking heat shield shall be released at 300 meters and the probe shall deploy a parachute.
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The aero-braking heat shield shall be released at 300 meters and the probe shall deploy a parachute.
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All structures shall survive 15Gs of launch acceleration and 30Gs of shock.
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During descent, the probe shall transmit all telemetry collecting air pressure, external temperature, GPS position and tilt sensor for stability verification during descent.
Fig 1 : System Concept of Operations
The probe on which the flight software is designed to be implemented is shown below. The design and development of the other various subsystems will not be discussed here as it is beyond the scope of this repository.
Fig 2 : 3D Render of the probe
The flight software was written for an Atmel ATmega328p on a nano breakout board. The basic architecture of the electronics interfaced with the microcontroller is shown below.
Fig 3 : Electronics Overview
The the flight software was designed to read the real-time data from the GPS, IMU, air & temperature sensor, power bus voltage sensor and output the parsed data into the Serial Bus which is transmitted to the Ground Control Station (GCS) via a Xbee S2C module at a fixed rate of 1Hz. Additionally, it also uses the gathered sensor subsystem data to determine various states of the mission, thereby deploying passive control surfaces for self-orientation during descent, ejecting the heat shield and deploying a parachute for safe landing. The state diagram is showcased below :
Fig 4 : State Diagram
The Probe state is updated based on the altitude change and saved in a state variable which is stored in the EEPROM of the micro-controller and updated every second. In the event of a processor reset due to sudden shock to the probe, the system will recover the last known state from the EEPROM memory.
The team bagged the 1st position in all of Asia-Pacific and the 18th position worldwide in its maiden effort. Pictures from the launch site can be found here, at the cansat competition's official website.