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Capstone Project Proposal Introduction

Who is the Portland State Aerospace Society (PSAS)?

• PSAS is a student chapter of the Aerospace and Electrical Systems Society (AESS) which is a technical society of The Institute of Electrical and Electronics Engineers (IEEE). It was founded in 1997, PSAS has designed, built and launched five rockets or launch vehicles (LV) into the lower atmosphere. Three of those flights were LV0, LV1a, and LV1b. LV2 was flown twice, once with airframe only (not considered a "complete" LV), and the second time with avionics. As far as the group knows they are the most advanced amateur rocketry group in the world and the first AESS student chapter (Portland State University, Portland, OR) in the United States.

What is the purpose and objectives of PSAS?

• Pioneering active guidance and open source software and hardware aerospace systems. Coupled with those objectives is a "moral" of PSAS which is furthering the use of open source software and hardware. PSAS almost excusively use open source tools. Also if generous financial resources reveal themselves, a goal of PSAS is to lanuch a "nanosatlellite" into Earth orbit.

What are PSAS's future plans?

• With respect to the exploration of active guidance, PSAS plans to build and launch their fourth launch vehicle, LV2b, within the next few years. LV2b will be a research platform for actively guided rockets. LV2b will use an avionics system which will gather, process, record and transmit data from several sensors similar to previous vehicles. These sensors include: a GPS module, gyroscopes, accelerometers, pressure sensors and temperature sensors. The rocket will record all telemetry and internal data it receives onto an on board flash memory card as well as transmit the data via a 2.4GHz downlink. It will also broadcast a live video image over amateur TV broadcast. The block diagram of LV2b consists of nodes which include:

• MASTER NODE: Flight Computer (FC)

  • The "brain" of the LV. Its main function is to use data from the other nodes to control flight sequencing and dectect apogee (peak of flight) and engage stage separation.
  • Controls the communication between the nodes and ground.
  • Records all data (raw) it receives from the nodes and ground to an onboard flash memory card.
• Amateur TV (ATV)
  • This node uses a amateur TV broadcast to relay real-time video and audio of the LV's complete flight from liftoff to recovery using the LV's onboard video camera.
• Inertial Measurement Unit (IMU)
  • This node has sensors for gathering linear and angular acceleration data.
  • There are temperature and pressure sensors as well as propriceptive sensors (sensors monitoring variables within the LV) to monitor voltage levels and stage separation.
• Magnotometer
• Global Positioning System/Satellite (GPS)
  • This node uses the GPS protocol to track the LV's position during launch and recovery and will also be used for active guidance.
• Recovery Node
  • This node has the igniters/pyros which will separate the rocket stages (body and nose cone) at apogee and deploy the parachutes.

Where does the Capstone team fit into PSAS's plans?

• The Capstone team consisting of Glenn LeBrasseur, Sarah Bailey, Jacob Davidson will be in charge of designing the common electronics that run all of the avionics nodes, all of which will be designed with open source tools. Called the node front end, these electronics include:

• 32-bit microcontroller

• Switching power supply
• Communciation bus interface
  • The two candidates for the communications bus between the all of the nodes are the Controller Area Network (CAN) and Universal Serial Bus (USB). After the decision is made regarding the bus protocol, we will be choosing a node microcontroller with the appropriate CAN and/or USB interface and other needed features. Given that CAN protocol was used for the previous LV1 and LV2 rockets this decision could potentially result in a fundamental design platform change.

What are the deliverables required of the Capstone team?

The Capstone team would ideally produce all of the following:

• Design of node front end which includes:
  • Choice of a 32-bit microcontroller
  • Design of switching power supply
  • Design of communication bus interface
  • Schematic capture and PCB layout of node front end design
  • Design notes
• Node prototype which includes:
  • Commercially built 2 layer PCB
  • Populated and tested components
• A white paper on the front end