U NIVERSITY OF M ASSACHUSETTS, A MHERST Department of Electrical and Computer Engineering

UUNIVERSITY OF NIVERSITY OF MMASSACHUSETTSASSACHUSETTS, A, AMHERST • MHERST • Department of Electrical and Computer Engineering Department of Electrical and Computer Engineering


Agenda

• Background & Motivation

• Deliverables

• Principle of Operation

• System Block Diagram

• Design Alternatives

• Proposed MDR Specifications

• Summary


Background

• ~60 Amateur rocket hobbyists from 15 countries• 27 foot tall rocket• Max velocity ~mach 5.2 (3440 mph)• Max altitude >100km (100km = “space”)• Powered with sucrose fuel (sugar)• Low budget volunteer program

Our design project

• A sensor control system, providing data to flight control system• Resilient to power problems• Providing data even in the event of sensing element failure


Motivation


Deliverables– Gerber plot files– Schematic– Documented source code– Hardware prototypes (not flight qualified)

User manual– Program the flight plan– Edit config file– Installation verification

Acceptability Tests

- Test broad temperature range - Simulate bad sensor readings - Power disturbance


Principle of Operation

• Power Buffering• Premature to design this component now• Specifications based on operating times after power failure

• Sensors may have different power profiles• Final output requires long duration of power supply

• Computational Persistence• Approximation Algorithm• Validity Checking Algorithm• Persistent Output

• Inputs to algorithms:• Multiple sensors• Pre-programmed flight plan• Flight history


• Computational Persistence– Approximation Algorithm

• Algorithm design– Laws of Physics– Flight history– Flight plan

• Output– Expected sensor values– Crude uncertainty measure


• Computational Persistence– Crosschecking Algorithm

• Algorithm design– Multiple sensor values– Compare data from sensors of same type– Compare data from sensors of other types– Compare data to Expected Value from approximator

• Output– Single most probable data for each sensor type– Crude uncertainty measure


• Computational Persistence– Persistent Output

• Design– Arbitrates data from Approximator and Crosschecker– Power buffered to sustain output for length of flight

• Output– Single set of data for each sensor type– Data is provided to flight computer– Data is also stored in Flight History

» History stores uncertainty values with data



Design Alternatives


For MDR:

- Purchased and Tested Sensors

- Simulate and Verify approx Algorithm (Proof of Concept)

- Estimated Resources (Power, Mass, Volume, Memory etc)

- Purchased Microprocessors

- Power Buffer design idea and possibly simulate


Summary

Documents

U NIVERSITY OF M ASSACHUSETTS, A MHERST Department of Electrical and Computer Engineering