p15571- suntracker
TRANSCRIPT
P15571- SUNTRACKERHarrison Sprague Jason Yeh Kaung Myat Thu Jacob Halstead
Craig Bishop Patrick Chiu Tyler Nicholson
Agenda● Project Overview● Key Customer Needs and Derived Eng. Requirements ● Final Design Concept● Product Development Process● Results: Major Issues and Findings● Current State of Project● Objective Project Evaluation
Project Overview
● Design and implement a complete system for a satellite receiver dish to automatically track the Sun for the purpose of gathering RF data.
● Customer: Martin Pepe with the Astronomy Section of the Rochester Academy of Science.
Key Customer Needs and Engineering MetricsCustomer
Requirement Engineering Requirement Final Design Performance Met/unmet
Satellite Focuses on Sun’s Position
Azimuth range: 70 - 220 degrees from NorthAltitude range: 15- 72 degrees from horizon
Azimuth range: 7 - 353 degrees from NorthAltitude range: 10- 74 degrees from horizon Met
Software Interface
Compatible with RadioEyes and Windows 7 Compatible with RadioEyes, future applications that use ASCOM, and Windows 7
Met
Water Proof Construction
IP54 and IP67 ratings IP54 and IP67 ratings on all motors, connectors, enclosures, etc. Met
Preset/Home Positions
Software Interface supports programmed positions
Custom positions can be set through RadioEyes and RadioEyes Tasks Met
Key Customer Needs and Engineering MetricsCustomer
RequirementEngineering Requirement Final Design Performance Met/
unmet
Positional Accuracy ± 2° Program controlled (default 0.5° accuracy) Motors capable of 0.01° accuracy (non-tracking). Met
Limit Azimuth Prevent over-rotation Limit switches with diodes prevent over-rotation. Met
Limit Altitude Prevent over-extension/retraction
Internal and external limit switches prevent over-extension/retraction. Met
System Resists Backlash <1° backlash ~0° backlash from worm-type gearing Met
LA provides sufficient force >300 lbf The LA is rated for 400 lbf max; and original calculations overestimated C.O.G. location. Met
Slewing Drive provides sufficient torques
>150 ft lb rotation>1000 ft lb overturning>200 lb axial load
>1000 ft lb rotation~2000 ft lb overturning>2000lb axial load
Met
Key Customer Needs and Engineering Metrics
(1) - Customer will purchase backup power supply that the team has recommended and this task will be accomplished.
(2) - Testing on effect of motor noise on the receiver has been performed in the lab without using shielded cable during MSD 1. The test has no indication of noise present in the collected data.
Customer Requirement
Engineering Requirement Final Design Performance Met/
unmet
Protect DAQ Runs on backup power for 2 minutes
Cannot be tested; backup power supply has not been ordered. Unmet(1)
Collect Data Movement of dish does not affect collected data
Cannot be tested; new antenna is not installed yet. Unmet (2)
Budget of $500 Bill of Materials cannot exceed customer budget
Received approval for increased budget of total $1900 Partial
Allow Optional Manual Control
Allow user to change RA/Dec/Alt/Az
Software User Interface is provided but joystick is never attempted. Partial
Final Design (Installed in Ionia)
Slewing Drive
Original 7’ Satellite Dish
Linear Actuator
U-Bracket
Skirt covering:Pipe flangeadapter platelimit switches
LA Mounting Arms
Slewing drive Motor
Antenna
LA Limit Switch
Results: Major Issues and FindingsProblem Description Solution
Shear pin strength (1)
Original Shear pins only support 230 lb in double shear.
Rework components to accommodate next shear pin size.
Shear pin strength (2)
Larger shear pin breaks at 1000 lbf (calculated break at 440 lb, rated for 600 lbf)
External limit switch implemented to stop full retraction. Pin now serves
as “catastrophic loading” protection.
Pipe SizingPipe was measured to be 3” in diameter on 3
separate trips. Upon installation the pipe is 2.9”.Shims have been added and the
pipe-flange will be pinned to the post to prevent rotation.
Results: Major Issues and FindingsProblem Description Solution
Communication Flow/Congestion
Control
Software communication protocol has minimal flow/congestion control resulting in long
processing delay
Limited report speed of fast communication.
Reference Limit Switch Reset
Reference Limit Switch Signal cannot be reset by Arduino after capturing the event of limit
switch being pressed.
Unknown
Position ErrorsNoise in signal lines from slewing drive affected
positional feedback (fixed)Noise filter designed with D flip-flop
improve all hall signal lines.
Current State of Project● Completed:
○ Rigid, weatherproof mechanical system○ Control drivers for calibration and operation○ Communication with Radio-Eyes for tracking○ Utilizes ASCOM protocol○ <0.5° motor precision
● Unmet Functionality○ Safe position for high wind speed○ Systematic shutdown during power outage
● Unmet extra functionality○ ASCOM interface functionality
■ Sidereal Tracking, move axis, pulse guide, sync○ Manual control with joystick (“Nice-to-have” feature)
Objective Project Evaluations● Design Strength
○ Degree of rotation is ample, allowing customer to track other objects.○ The system can withstand the heavy load (overturning moment).○ Waterproof connectors, sealant and rust-preventative paint improve
environmental protection. ○ Increased motor precision is achieved by filtering hall signals and by
using shielded cables. ○ Limit switches and diodes prevent damage to the dish and wires. ○ User interface for manual and auto-calibration allows the user to make
changes conveniently and prevent human-error without the need to modify the code in several places.
Objective Project Evaluations● Future Work / Design Weakness
Software○ ASCOM
■ Sidereal Tracking/ Move Axis/ Pulse Guide / Sync functionality○ Congestion/Flow control for communication protocol○ Systematic shutdown and housekeeping○ TeamViewer
Electrical○ Wiring harness design for Usability (I/O Box for current-limiting diodes)○ Position feedbacks for daily auto-calibration○ A single custom board for all electrical designs (Plug-in shield for
Arduino)
Objective Project Evaluations● Future Work / Design Weakness (cont’d)
Electrical○ Pick a different microcontroller with more interrupts○ Manual Joystick Control○ Add or access to local weather station ○ Backup Power Supply○ Self-Diagnostic Test Plan/Program
Mechanical○ Replace Shear Pins with one larger pin○ The hardware required for installation should be standardized○ The pipe flange should be a closer fit and not require shims