TIME K-Mirror Assembly Detailed Design Review MSD Team 18572 Ian - - PowerPoint PPT Presentation
TIME K-Mirror Assembly Detailed Design Review MSD Team 18572 Ian Perry, Emily Doback, Mark Peryer, Kevin Nowak, Steven Cacner, Justin Parra December 5 th , 2017 Background Kitt Peak 12m Antenna (KP12M) Located at University of Arizona
MSD Team 18572 Ian Perry, Emily Doback, Mark Peryer, Kevin Nowak, Steven Cacner, Justin Parra December 5th, 2017
Kitt Peak 12m Antenna (KP12M)
Tomographic Ionized-carbon Mapping Experiment (TIME)
University of Arizona
“K-mirror” Assembly
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
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
(Not complete,
selected values)
anywhere in the sky
Axis ( x - axis)
90 degrees about z-axis
Flange K-mirror Mounting Points Cabin Rotates 90 degrees about elevation axis
X Z Y
M2 Rigid Structure (Dynamic, z-axis) M3 M1 Static Structure Flange Motor Center of Rotation
Legend MSD owned Customer provided MSD w/ Customer
Mounting points to flange Drive system Mates to rotating assembly
1) Confirming location of M1, M2, M3 2) Add key structural elements (Struts, Gussets, etc.) 3) Iterative process of designing for mirror and mounts 4) Iterative process of designing to optimize drive system 5) Optimize based on FEA and deflection calculations
Deflection of Arms - Solid Block [micron] Material Case 1 Case 2 Case3 SW “Alloy Steel” 129.4 11.2 5.35
Material Max Displacement at 0deg [mm] Max Displacement at 90deg [mm] SW “Alloy Steel” 0.0368 0.0051
Material Max Displacement at 0deg [mm] Max Displacement at 90deg [mm] SW “Alloy Steel” 0.072 0.0051
Control System Motor Telescope Monitoring/Status
○ Fairly trivial
○ Simple client/server python POC completed
○ Currently Raspbian but can be changed for application specific needs
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
Mirror mounts x3 (details TBD) Mates to drive system
X Z Y
Load Bearing Support Arm (Help Deflections) Off set Motor and remove compressive load
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.
How to Design for Deflections: How we expect system to deflect:
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
Center Centric Criteria Flange Centric
+
Weight
System Deflection
+ +
Design Time
Complexity
Denotes design is better for selected criteria
Criteria Raspberry Pi Arduino FPGA
Ease of Programming
computer to program
Cost
Denotes design is better for selected criteria
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
Mirrors fall outside of tolerance 5 4 20 Design to allow minor adjustments using screw/shimming techniques.
degrees
flexibility
○ Half-stepping, microstepping, or gear box are options Stepper Motor Torque Curve
○ 115kbaud
○ TCP/IP ○ 100 Base-T
○ control feedback
angular resolution
Galil DMC-3x01x single-axis motor controller
○ End-point correction ○ Closed-loop microstepping
○ Optical vs. Magnetic ○ Highest resolution: 0.009° per pulse
○ Can easily interface with the Raspberry Pi
○ Unknown data packet structure as of now ○ Local Area Connection (LAN) ■ Low latency
○ Use GPIO pins through interface board to convert to fiber