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

Original Dish Status

Original 7’ Satellite Dish

Linear Actuator

Declination Bracket

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

Product Development Process

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