High Altitude Rocket Team
Avionics ECE Sub-Team
Project Overview
The OSU High Altitude Rocket Team requires a new avionics bay and launch control and ignition system. The avionics bay gathers flight data to store and relay back to ground control, and has some influence for the staging of the rocket. For our project, we will be modifying the previous year's avionics bay design.
We are adding a pressure sensor each rocket motor to monitor fuel reactions for both stages during flight. Our custom AV board will be processing this data, and storing it onto a micro-SD card while transmitting it back to a receiver on the ground.
The Ground Station is used to remotely trigger the ignition of the rocket. Before sending the signal to ignite the first stage, the launch button is required to have safety switches in place to avoid accidental and unsafe launches, and inform the user of continuity problems with the igniter.
The Igniter system is what receives the launch command and sends a high-current pulse to the electronic matches which ignite the first stage motor. When idle, it checks the continuity of the electronic matches and sends their status back to the Ground Station. The Ground Station and Igniter systems must communicate while they are two miles apart.
Above: The AV board prototype we designed.
Current Status
AV Board:
So far, we have finished designing and programming the AV board, and we have collected data during the static fire test during the Winter Term. However, while we have the PCB, we haven't been able to solder it while the labs were closed all Spring.
Above: A section of pressure data from the static fire test. Here you can see the initial spike is detected, and then the thrust pressure increases linearly, then dampens. Near the end, you can see the slight effect where heat increases the transducer's low pressure output.
Ground Station / Launch Control:
The Ground Station has been programmed, but has not been constructed fully, although we have solved our wireless connection range issues with the Igniter system's transceiver.
Igniter:
The Igniter has been designed but is not yet finished. So far it can connect to the Ground Station, but it is still missing relays for switching modes between continuity detection and arming the output, and for sending the high-current output to the rocket motor.
Looking Ahead / Next Steps Summary
For this project to continue with next year's team, we will continue this project into the upcoming summer. We had planned to complete everything within Spring Term, but due to the COVID-19 response, we were unable to access the tools we needed during this time. In the continuation of this project, a few tasks to consider are:
- Acquiring a better antenna for receiving pressure data at the chosen frequency (900 MHz).
- Choosing a RF module chip with higher transmission power than the XBee-PRO S3B. While this module is easy to program and has a range to meet our requirements, we could increase our data transmission range if we had a stronger output signal. We also want to use a module which could change transmission channels easily, and not interfere with, or have interference from other teams at the launch site.
- Adding more telecommunications features between the Ground Station and the Igniter. These may include remote battery checks, connection reliability/latency checks, and a launch command feedback signal.
- Reducing pressure sensor noise by using a separate, high-resolution ADC or by finding and using a reliable DC amplifier.
- Programming a periodic auto-calibration on the pressure transducer prior to the launch. The transducer's output can vary due to temperature changes.
- Making PCBs for the Igniter and Ground Station.
- Using a better micro-controller, mounted on a custom board to reduce weight.