RockSat-C 2012 PDR Minnesota Sound Wreckers Comprehensive Design Review University of Minnesota Alexander Richman Jacob Schultz Justine Topel Will Thorson 11/30/11 1

RockSat-C 2012 PDR Mission Overview Justine Topel 2

RockSat-C 2012 PDR Mission Overview Our mission is to design a system that actively removes noise in a test chamber during a rocket launch We require at least some reduction in intensity of noise in the test chamber compared to the control chamber as well as the safe operation of the entire payload. 3

RockSat-C 2012 PDR Mission Overview cont. We expect to show that this technique is a viable solution to noise sensitive testing onboard rockets. This would benefit any sound sensitive experiment onboard a rocket including any testing in which live subjects are used and it is desired to lower their stress levels. 4

RockSat-C 2012 PDR Theory and Concepts The theory of active noise cancellation is that when one sound wave meets another wave which is an inverse of itself the two waves cancel out and overall noise is reduced While no research has been done onboard rockets to our knowledge, active noise cancellation has successfully been used in many other aplications. 5

RockSat-C 2012 PDR Concept of Operations Data collection will begin upon the signal line going hot. We expect to see limited noise reduction during initial burns and maximum reduction after the completion of both burns and through reentry. 6

RockSat-C 2012 PDR Example ConOps t ≈ 15 min Splash Down -All systems on -Data collection running t = 0 min Apogee t ≈ 2.8 min Altitude: ≈115 km End of Orion Burn t ≈ 0.6 min Altitude: 52 km Altitude t ≈ 5.5 min Chute Deploys

RockSat-C 2012 PDR Expected Results 8 We expect to be successful in reducing the overall power of the wavelength spectra between about 50 Hz and 20kHz This means a reduction in amplitude at most of the frequencies within this range. –We are going to use a middle range speaker, and thus will maybe see more response from 1kHz to 10kHz

RockSat-C 2012 PDR System Overview Jacob Schultz 9

RockSat-C 2012 PDR Subsystem Design – Physical Model 10 Power Supply Data Logger ANC System

RockSat-C 2012 PDR Design in Canister 11

RockSat-C 2012 PDR Standoffs 12 Two pieces attached to upper and lower plates by sunk head Allan screws 1in diameter (.75 in through the middle plate) The pieces will screw into each other just above the mid plate Made of aluminum

RockSat-C 2012 PDR Canisters 13 Made of aluminum Capable of holding 1 atm of pressure for a short time in case of pressure loss to ensure continuation of the experiment Cap will insert into canister and have a rubber o-ring to hold atmosphere Wire holes will be sealed with epoxy or rubber cement

RockSat-C 2012 PDR Bottom Plate 14 Made of Makrolon This is to provide extra insulation for electronics to ensure no stray current runs into the canister Strong enough to withstand forces and weight of electronics

RockSat-C 2012 PDR Integrity calculations 15 Calculated the compressive stress at launch on the standoffs to ensure they would not buckle under the large G loads. Calculated the hoop stress for the canisters under 1atm internal pressure For both cases the payload passed initial testing with large safety factors

RockSat-C 2012 PDR Critical Interfaces 16 Interface NameBrief DescriptionPotential Solution ANC/STR The electrical power system and boards will need to mount to the canister plate to fix them rigidly to the launch vehicle. The connection should be sufficient to survive 50Gs in the thrust axis and 10 Gs in the lateral axes. We will screw the power supply and electronics for the ANC system directly into the Makrolon plate. DL/STR The data logger will need to mount to the canister plate rigidly. The connection should be sufficient to survive 50Gs in the thrust axis and 10 Gs in the lateral axes. In the same fashion as the ANC system the data logger will mount directly to the plate. CHM/STR The chambers must affix rigidly to the mid plate so that they survive 50Gs in the thrust axis and 10 Gs in the lateral axis. The base of the chambers will be welded to the mid plate ensuring a strong rigid connection. SPK/CHM The speakers must be placed inside the chambers so that they stay affixed and do not move in flight. Possible solutions include making a bracket that attaches to the base of the cylinder or some other kind of mount. MIC/CHM The microphones must attach to the top of the chamber so that they do not move during flight. Either they could be hung off of wire or a mount could be quickly designed to attach the microphones to the top of the chamber.

RockSat-C 2012 PDR System Level Block Diagram 17 DSP System speaker microphone Data Logger microphone Power Supply Wallops activation signal

RockSat-C 2012 PDR Requirement Verification 18 Requirement Verification Method Description The ANC system should cancel noise in a cylindrical chamber TestMock up chamber with a speaker and microphone will be made and tested for noise reduction. The power supply should have enough power to drive the speaker AnalysisThe speaker’s power requirements will be researched and the amount of power we can supply will be calculated. All components must fit within the canisterInspectionVisual inspection of the SolidWorks drawing will fulfill this requirement

RockSat-C 2012 PDR RockSat-C 2012 User’s Guide Compliance 19 Our estimated structure weight not including canister is 9.4 lbs. This does not account for the electronics but leaves a large margin for them to Our predicted CG is.05 in above the geometric center. This does not account for the electrical components.

RockSat-C 2012 PDR Subsystem Design Active Noise Cancellation Subsystem Alex Richman 20

RockSat-C 2012 PDR ANC: Block Diagram 21 Experimental Chamber Dummy Chamber Control Systems Power Supply Mic Preamps Power amplifier Mic Speaker Data Logger DSP In Out

RockSat-C 2012 PDR DSP: Feedback ANC System 22 Single-Channel ANC System Block Diagram The diagram below shows the generalized block structure of the DSP feedback ANC system. One microphone is used, along with one speaker and one DSP noise cancellation system. Feedback ANC d’(n) NOISE Error Microphone e(n) y(n) Speaker

RockSat-C 2012 PDR DSP: Planned Control Algorithm 23 Filtered-X LMS Algorithm This adaptive filter attempts to minimize the squared error at any time. A model for the secondary path, the path from the loudspeaker to the error microphone (S(z)), is needed to be estimated. This includes the acoustic response of the chamber and any effects added to the signal from sampling and the various amplifiers in the path. S’(z) LMS W(z)S(z) x(n) d(n) x’(n) y(n) d’(n) + - e(n) W(z) – Adaptive Filter S(z) – Path from loudspeaker to error microphone LMS – Least Mean Squares Algorithm S’(z) + +

RockSat-C 2012 PDR ANC: Trade Studies 24 The following trade study shows the differences between the Pyle Pro PMHMS20 Omni-Directional Microphone and the Dayton Audio EMM-6 Electret Measurement Microphone. We will be using the EMM-6 for model estimation in prototyping, and the Pyle Pro for actual use due to the size of the EMM-6. Microphone EMM-6PMHMS20 Cost 89 Availability 10 Frequency Response 109 Size 09 Sensitivity 107 Average:

RockSat-C 2012 PDR ANC: Trade Studies 25 The following trade study shows the differences between the Dayton ND /2" Aluminum Cone Full-Range Driver 8 Ohm and the Tang Band W3-881SJ 3" Cast Frame Neodymium Driver. Currently, the W3- 881SJ looks to be a better choice, but we are interested in the aluminum cone of the ND90-8. Speaker ND90-8W3-881SJ Cost 109 Availability 10 Frequency Response 810 Diameter 99 Depth 710 Average:

RockSat-C 2012 PDR ANC: Trade Studies 26 This trade study shows the overview of DSP versus a prebuilt IC designed to cancel noise. We will be using the DSP solution for the increased customizability so we may fine tune our system for our particular acoustic environment. DSP vs ANC DSPANC IC Cost 510 Availability 10 Ease of Implementation 47 Risk of Complications 64 Customizability 102 Average:

RockSat-C 2012 PDR ANC: Risk Matrix 27 Consequence ANC.RSK.1 ANC.RSK.2 Possibility ANC.RSK.1: microphone fails in flight causing the amplifier to stop sending cancellation sound ANC.RSK.2: the speaker creates a positive feedback and breaks itself, causing a mission failure

RockSat-C 2012 PDR Prototyping Plan Will Thorson 28

RockSat-C 2012 PDR 29

RockSat-C 2012 PDR Prototyping Plan 30 Concern about the efficiency and ability to cancel noise in the chamber DSP Test our hypothesized noise cancellation in mock ups. Risk/ConcernAction Due to scheduling and ordering issues prototype testing has fallen behind schedule we hope to make up for this in the coming weeks as well as over break During our prototyping phase, we will be getting familiar with our DSP system as well as predicting the unknown secondary path, S(z). The vast majority of time spent prototyping will be spent writing code for the DSP system, as well as fine tuning filter parameters for our acoustic environment.

RockSat-C 2012 PDR Plan for succes 31 According to the new plan initial testing will focus on code and processes using large scale equipment and second stage prototyping will focus on implementation in the small scale onboard equipment We believe with this plan we can produce the equipment in plenty of time for the testing to begin.

RockSat-C 2012 PDR Project Management Plan Jacob Schultz 32

RockSat-C 2012 PDR Organizational Chart Our sponsor is the Minnesota Space Grant Consortium 33 Project Manager Jacob Schultz System Engineer Will Thorson Faculty Advisor Ted Higman Sponsor MSGC Faculty Advisory William Garrard Safety Engineer Justine Topel Testing Lead Alexander Richman Structure Jacob Schultz Justine Topel ANC/ Electrical Will Thorson Alexander Richman

RockSat-C 2012 PDR Schedule 34

RockSat-C 2012 PDR Next Steps 35 First we will work on physical systems prototyping and building Additionally we will make parts drawings for fabrication of the structural members After we have cleared the CDR we will place orders for the parts

RockSat-C 2012 PDR Budget 36 ItemSupplierEstimated, Specific CostNumber RequiredTotal CostNotes MicrophoneParts Express$48.263$144.78Including one back up for testing. SpeakerParts Express$26.803$80.40Including one back up for testing. DSPTI$13.352$26.70 ANC ICAustria Micro Systems$3.802$7.60Including back up chip. Data LoggerDATAQ$5991$599.00May be able to use last years data logger. Misc. ElectronicsDigi-Key$100.00N/A$100.00Various Resistors, Inductors, Caps, etc. High Fidelity Audio AmplifiersDigi-Key$19.364$77.44Including back up chips in case of soldering failures. Mic PreampsDigi-Key$5.004$20.00Back up chips included. Testing Materials???????$ Machine TimeUniversity of Minnesota$400.00N/A$400.00for chambers and structural materials Total (No Margin):$1, Total (Margin):$2,069.90

RockSat-C 2012 PDR Our Mission is to employ active noise cancellation onboard a rocket We have designed a structure to hold the experiment that will safely withstand the forces of launch We have a plan and the materials to begin system prototyping and building. Conclusion 37