TIME K-Mirror Assembly Preliminary Detailed Design Review MSD Team - - PowerPoint PPT Presentation

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TIME K-Mirror Assembly Preliminary Detailed Design Review MSD Team - - PowerPoint PPT Presentation

Jul 15, 2023 498 likes •890 views

TIME K-Mirror Assembly Preliminary Detailed Design Review MSD Team 18572 Ian Perry, Emily Doback, Mark Peryer, Kevin Nowak, Steven Cacner, Justin Parra November 9 th , 2017 Background Kitt Peak 12m Antenna (KP12M) Located at University of

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SLIDE 1

Preliminary Detailed Design Review

TIME K-Mirror Assembly

MSD Team 18572 Ian Perry, Emily Doback, Mark Peryer, Kevin Nowak, Steven Cacner, Justin Parra November 9th, 2017

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SLIDE 2

Background

Kitt Peak 12m Antenna (KP12M)

  • Located at University of Arizona

Tomographic Ionized-carbon Mapping Experiment (TIME)

  • Measure redshifted singly ionized carbon
  • Measure molecular gas density
  • Kinetic Sunyaev-Zel’dovich (kSZ) effect
  • Collaboration with 5 other institutions

University of Arizona

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SLIDE 3

Problem Statement

“K-mirror” Assembly

  • Several mirrors connected to rotating mount
  • Servo controlled
  • Synchronizes to angle of rotation of telescope
  • Transformation through three reflections
  • Enables the use of sensor line-scanning
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SLIDE 4

Customer Requirements

Category Customer Need # Importance Description

Functionality CN1 1 Assembly rotating is repeatable and accurate CN2 1 Assembly strong enough to keep mirrors in fixed positions relative to each other CN3 2 Electrostatic Discharge Protection CN4 2 Provide status to other sub-systems CN5 1 Control that is completely synchronous Portability CN6 1 Must be able to transport across country

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SLIDE 5

Engineering Requirements

  • Rqmt. #

Importance Source Engineering Requirement (Metric) Measure Ideal Value Margin ER1 1 CN1 Fixed Angle degrees Dynamic +/- 0.15 ER2 1 CN1 Speed of rotation degrees/second 1 +/- TBD

Surface Tolerance Type Tolerance Value (deg/mm) % Throughput Error Mirror 1 Decenter X 0.25 0.0425 Mirror 1 Decenter X

  • 0.25

0.0426 Mirror 1 Decenter Y 0.25 0.0429 Mirror 1 Decenter Z 0.25 0.0427 Mirror 1 Tilt X

  • 0.25

0.17 Mirror 1 Tilt Y

  • 0.25

0.0112

(Not complete,

  • nly a few

selected values)

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SLIDE 6

System Analysis: Functional Decomposition

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SLIDE 7

Concept Development

  • Cabin Rotates about Elevation Axis

( x - axis)

  • 90 degrees of Rotation

○ Most conservative

  • K - Mirror is within cabin
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SLIDE 8

Concept Development - Cabin Interior

Flange K-mirror assembly will replace this system

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SLIDE 9

Concept Development - Flange

  • K -mirror Assembly will be

directly mounted to the flange shown

  • Material INVAR 38
  • ID = 800 mm
  • OD = 1500 mm
  • t = 18 mm
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SLIDE 10

X Z Y

M2 Rigid Structure (Dynamic, z-axis) M3 M1 Static Structure Flange Motor Center of Rotation

Concept Development - Center Centric

Legend MSD owned Customer provided MSD w/ Customer

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SLIDE 11

Center Centric Assembly - CAD Model

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SLIDE 12

Center Centric Assembly - CAD Model

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SLIDE 13

Engineering Analysis

  • Mass of rotating system

estimated using solid aluminum plates and multiplier for counterweight Material Max Displacement at 0deg [mm] Max Displacement at 90deg [mm] SW “Alloy Steel” 0.305 0.00005 Carpenter Invar 36 0.461 0.00008 Carpenter Super Invar 32-5 0.448 0.00008

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SLIDE 14

Engineering Analysis - Arm Revision

Material Max Displacement at 0deg [mm] Max Displacement at 90deg [mm] SW “Alloy Steel” 0.0368 0.0051

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SLIDE 15

K-Mirror Control System Architecture

Control System Motor Telescope Monitoring/Status

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SLIDE 16

Overall Telescope System Architecture

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SLIDE 17

Data Communication

  • Ethernet
  • Fiber

○ Can easily interface with the Raspberry Pi

  • TCP/IP socket protocol

○ Unknown data packet structure as of now ○ Local Area Connection (LAN) ■ Low latency

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SLIDE 18

Data Communication - Fiber

  • Fiber:

○ Use GPIO pins through interface board to convert to fiber

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SLIDE 19

Raspberry Pi

  • GPIO pins for motor control board connection
  • Python to interface with GPIO pins

○ Fairly trivial

  • Ethernet port for TCP/IP connections

○ Simple client/server python POC completed

  • HDMI and 2 USB ports for display, keyboard, and mouse
  • Runs operating system off SD card

○ Currently Raspbian but can be changed for application specific needs

  • Powered from micro-USB
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SLIDE 20

Stepper Motors

  • High torque at low angular velocity
  • Good angular repeatability
  • Most common full step resolution: 1.8

degrees

  • Control board allows for greater

flexibility

○ Half-stepping, microstepping, or gear box are options Stepper Motor Torque Curve

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SLIDE 21

Motor Controller

  • RS232 interface

○ 115kbaud

  • Ethernet interface

○ TCP/IP ○ 100 Base-T

  • Encoder input

○ control feedback

  • Capable of microstepping for increased

angular resolution

Galil DMC-3x01x single-axis motor controller

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SLIDE 22

Closing the Loop

  • Galil solutions:

○ End-point correction ○ Closed-loop microstepping

  • Many other commercial solutions
  • Rotary Encoders

○ Optical vs. Magnetic ○ Highest resolution: 0.009° per pulse

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SLIDE 23

Questions?

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SLIDE 24
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SLIDE 25

CAD - Backup

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SLIDE 26

CAD - Backup

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SLIDE 27

CAD - Backup

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SLIDE 28

Concept Development - Center Centric - Other Ideas

X Z Y

Load Bearing Support Arm (Help Deflections) Off set Motor and remove compressive load

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SLIDE 29

Concept Development - Comparison

What wasn’t included: Cost For both designs cost will be driven by the choice of materials as well as the geometry necessary to minimize the deflections. However, the Flange Centric Design will most likely require a much larger thrust bearing. Variability in design Center Centric Design leaves areas that can be used for extra support structures. The motor could also be offset to minimize the compressive loading on the motor.

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SLIDE 30

Telescope

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SLIDE 31

How to Design for Deflections: How we expect system to deflect:

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SLIDE 32

Full Deflection Numbers

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SLIDE 33

Tolerance Calculations

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SLIDE 34

Concept Development - Flange Centric

M2 M1 M3 Flange Motor Center of Rotation Rigid Structure (Dynamic, z-axis)

x Y Z

M2 M3 M1 Legend MSD owned Customer provided MSD w/ Customer

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SLIDE 35

Concept Development - Comparison

Center Centric Criteria Flange Centric

+

Weight

  • +

System Deflection

  • Modularity

+ +

Design Time

  • +

Complexity

  • +

Denotes design is better for selected criteria

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SLIDE 36

Control System Comparison

Criteria Raspberry Pi Arduino FPGA

Ease of Programming

+ +

  • Does not require host

computer to program

+

  • Modular clock source

+

  • Computation speed
  • +

Cost

+ +

  • +

Denotes design is better for selected criteria

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SLIDE 37

Proposal Risk

Risk Likeliness (0-10) Severity (0-10) Score Ideas to limit risk Over Rotation of K - mirror 3 8 24 Create physical interference to keep the array from rotating any further. Connection between Static Structure and Flange fails 2 8 16 Add more than one connection to the Flange, if

  • ne fails the other can support until noticed by
  • perator.

Mirrors fall outside of tolerance 5 4 20 Design to allow minor adjustments using screw/shimming techniques.