requirements flow down · web viewby testing two generators that harvest the energy from rotational...

Colorado Space Grant Consortium

GATEWAY TO SPACE FALL 2010

DESIGN DOCUMENT

Lightning Rod

Written by: Christopher Bennett, Matthew Dickinson, Jesse Ellison, Matthew Holmes,

Trevor Luke, Sushia Rahimizadeh, Alex Shelanski

November 2nd, 2010Revision C

Julie Price, 11/09/10,

You go into great detail about your experiment, which is very interesting, but don’t lose sight of the other subsystems in your balloonsat. Also, have more data analysis plots

Revision Log

Revision Description DateA/B Conceptual and Preliminary Design Review 10/5/10C Critical Design Review 11/2/10

Gateway to Space ASEN 2500 Fall 2010

Table of Contents

1.0 Mission Overview...............................................................................................................42.0 Requirements Flow Down..................................................................................................53.0 Design.................................................................................................................................64.0 Management.....................................................................................................................135.0 Budget...............................................................................................................................156.0 Test Plan and Results........................................................................................................167.0 Expected Results...............................................................................................................188.0 Launch and Recovery.......................................................................................................18

Team Lightning Rod of 19 October 4th, 2010


1.0 Mission Overview

1.1 Statement The mission of Team Lightning Rod is to send Zeus, a cubic balloon satellite built from foam core and equipped with two electromagnetic generators, to an altitude of thirty kilometers and harness the vibrational and rotational energy experienced during its ascent and descent. A microcontroller shall measure the amount of energy the electromagnetic generators produce. By analyzing the data collected, team Lightning Rod shall determine if future spacecraft will be able to utilize energy generated by vibrational and rotational motion as additional alternative energy sources.

1.2 Goal and Background

The goal of this mission is to determine if vibrational and rotational energy can be harnessed as supplemental energy sources for future spacecraft. If this mission is successful, future spacecraft will be able to utilize these additional sources of energy, thereby providing their projects with increased security and protection from complications due to power failure. One of the most common reasons for balloon satellite failure is power loss (C Koehler, 2010, personal communication, September.) Most satellites rely on stored battery power and solar energy to power their systems. Batteries are not ideal because they do not last infinitely and can only be recharged when solar panels receive direct sunlight. When batteries are subjected to cold temperatures, they lose their charge. Solar panels limit the spacecraft because they must be large enough to provide energy. Also, solar panels are fragile and break easily when the satellite encounters debris or atmospheric turbulence. Solar panels are particularly vulnerable when the rectangular body of the solar panel extends out from the satellite and is narrowly attached to the structure. Because satellites are limited in their ability to power systems, energy supply is the satellites most important system. If power fails, all other systems fail. Thus, additional sources of power are greatly needed. The energy harnessed from vibrations and rotations is not expected to be enough to fully power all satellite systems. Nonetheless, it would prolong the life of a satellite and prevent mission failure.

The idea of generating power from vibrations was researched by students at the University of Southampton in England. The students developed a micro scale vibrational generator that was capable of powering wireless sensors. Although the design was only experimented on an air compressor, they stated in a journal that was submitted to the Journal of Micromechanics and Microengineering that they believe similar and suitable vibrations could be found in airplanes as well. In a book called Energy Harvesting Technologies by Shashank Priya and D. J. Inman, it was also discussed that there is an observed increase in power generation as generators increase in size. Considering that the generator developed by team Lighting Rod shall be subjected to an environment comparable to airplanes and that its design is larger than the design developed at the University of Southampton, and thus more efficient, team Lightning Rod anticipates that the vibrational generator they develop will produce more power.

By testing two generators that harvest the energy from rotational and vibrational motion, team Lightning Rod shall analyze the efficiency of the designs and determine if either design could be



Why does scaling it up make it more efficient?


How so?


In this section do you have a hypothesis as far as which mode will capture more energy and/or what magnitude of energy will be captured (V, mV, etc.)?


Good job, very clear


used to generate energy for future spacecraft. Research can be found on similar instruments that were developed for the purpose of non-aerospace applications, which shall serve as the basis for the initial developments for the rotational generator. Students at the Imperial College in London also developed an energy harvester for powering wireless sensors using the rotations of the harvester's environment to create a dynamic magnetic field. As they stated in a paper titled Wireless Sensor Node Using a Rotational Energy Harvester with Adaptive Power Conversion, they sought a compliment to vibrational energy harvesting technology in order to maximize the potential of a given mechanical system's ability to gather energy. Their design consists of a mass atop a rotational disk that is offset from the center. Team Lightning Rod chose to arrange their magnets uniformly on the outer edges of the disc for the purpose of maintaining higher rotational speeds.

2.0 Requirements Flow Down

The requirements flow down is designed to portray how the requirements relate to the objectives and the goal. The goal is derived from the mission statement. The level 0 requirements are the mission objectives. The mission objectives are derived exactly from the goal and mission requirements presented by Space Grant. Each objective has several requirements underneath it that explain how it will accomplish the objective. The requirements are considered level 1 requirements on the flow chart. In the chart, the name of the objective or requirement is in the left column, the middle column has the specific objective or requirement, and the far right column shows where that specific goal or requirement is referenced.

The goal of team Lightning Rod is to send a balloon satellite equipped with two electromagnetic generators to an altitude of thirty kilometers to determine if the kinetic energy from vibrational and rotational motion can be harnessed as supplemental energy source for future spacecraft.

Objective Mission Objectives Level 0 ReferenceO1 Fly a satellite to 30 km Goal (G)O2 Keep the internal temperature of the satellite above -10 degrees Celsius Goal (G)O3 Keep the overall weight of the satellite below 1080 g Goal (G)O4 Fly a Cannon Camera and the HOBO datalogger on the satellite Goal (G)O5 Capture and store vibrational energy using the vibrating electromagnetic generator Goal (G)O6 Capture and store rotational energy using the rotating electromagnetic generator Goal (G)O7 Compare the results of the rotational generator and the vibrational generator to see

which one is most effectiveGoal (G)

Requirements Objective 1 Requirements Level 1 ReferenceO1.R1 Satellite Zeus shall be attached to a helium weather balloon that shall carry it up to

30 km.O1

O1.R2 Satellite Zeus shall be attached to the balloon on a piece of rope that shall run directly through the center of the satellite.

O1

O1.R3 Satellite Zeus shall be kept stable on the rope by using washers and clips. O1

Requirements Objective 2 Requirements Level 1 ReferenceO2.R1 Satellite Zeus shall be kept above -10 degrees by using an electric heater that shall

be created by Team Lightning Rod and shall be powered using 9V batteries.O2

O2.R2 Satellite Zeus shall have ½ inch foam insulation to keep the Satellite above -10 degrees Celsius

O2



O2.R3 Satellite Zeus shall also have no holes to contain the heat in the satellite. O2Requirements Objective 3 Requirements Level 1 ReferenceO3.R1 Satellite Zeus shall be less than 850 grams by keeping a very meticulous budget

that keeps track of the weight of every piece of equipment that shall be on the satellite.

O3

Requirements Objective 4 Requirements Level 1 ReferenceO4.R1 Satellite Zeus shall fly the Cannon camera to capture photos of near space. O4O4.R2 The camera on Satellite Zeus shall be programmed ahead of time so that it shall

work independently of all other electronics during the flight.O4

O4.R3 The HOBO datalogger shall be a standalone item in the satellite that shall record the internal temperature, external temperature, and relative pressure as measured by the sensors.

O4

O4.R4 The HOBO datalogger information shall then be used to determine the satellites position at certain times during the ascent and descent of the satellite.

O4

Requirements Objective 5 Requirements Level 1 ReferenceO5.R1 The electromagnetic generator shall have magnets that vibrate across a copper coil

as the satellite vibrates, thus producing an electric current.O5

O5.R2 The created energy shall then be held in a capacitor. O5O5.R3 The amount of energy in the capacitor shall be constantly measured and recorded

by the data storage device on the microcontroller.O5

Requirements Objective 6 Requirements Level 1 ReferenceO6.R1 The electromagnetic generator shall have magnets that rotate across copper coils

as the satellite rotates around the flight string, thus producing an electric current.O6

O6.R2 The generator energy shall be held in a capacitor. O6O6.R3 The amount of energy in the capacitor shall be constantly measured and recorded

by the data storage device on the microcontroller.O6

Requirements Objective 7 Requirements Level 1 ReferenceO7.R1 After Satellite Zeus is retrieved, the data from the two generators shall be uploaded

onto a computer for analysis.O7

O7.R2 The data results shall be documented as a function of time and also in reference to the information retrieved by the HOBO datalogger so that the best results at the relative moments of the flight shall be known.

O7

3.0 Design

3.1 Concept

Utilizing principles defined by modern electromagnetic theory, two generators on-board Zeus shall produce electricity derived from the mechanical oscillations of eight neodymium magnets near a fixed copper coil per generator. The vibrations shall move the magnets, inducing a magnetic flux across the copper coil, as described by Faraday's Law. The magnetic flux across the copper coil drives a current. The force on the charges from the magnetic field shall oppose the change in magnetic flux and drive the current in the coil, according to Lenz's law.

Satellite Zeus features two electromagnetic generators. One harnesses energy from vibrational motion, the other captures energy from rotational motion. Each is connected to a separate



Make sure you’re keeping your requirements the same (above it says 1050 g)


electrical load that is monitored by a microcontroller. The load seen by the generators is in the form of a capacitor bank. The bank has a limited capacity, and shall be monitored and emptied when it is halfway filled. Each time the bank is emptied the micro-controller shall register the dump. This data shall be used to calculate the total energy created. There are four components that were considered in the model design of the vibrational generator: a magnetic field, a coil, a vibrating mechanism, and an electric circuit (or load). A coil made of copper is fixed to the frame of the spacecraft and is inside a set of randomly oscillating magnets. There are two sets of magnets, two square neodymium magnets of alternating polarity for each set, each placed near one side of the copper coil. The vibrating mechanism, in the form of spring metal, supports the bidirectional movement of the magnets, which together creates a magnetic flux when experiencing acceleration from force. The ends of the coil are connected to a circuit capable of accumulating the energy generated, as well as manipulating the current as desired to support the objectives of the experiment. The rotational generator was designed considering the same electric laws, but has a different method of creating the moving magnetic flux. There are two copper coils fixed to the body of the satellite. Sitting above the coils is a free spinning disk with eight equally spaced neodymium magnets. The disk rotates freely about an aluminum pole over the copper coils, creating the moving flux that then drives a current in the coils. The coils are connected in parallel and then to an electrical load identical to that used by the vibrational generator.

For the duration of the flight, energy shall be harvested from the local environment via the generators and stored into a custom designed capacitor bank. Diodes regulate the direction of a dynamic current flow produced by the generator. A full-wave rectifier was implemented in order to ensure a single output polarity, as well as a direct current instead of an alternating current. A full-wave bridge rectifier was used instead of a half-wave rectifier because it is more efficient. The rectifier was designed with 4 diodes arranged in a “diode bridge” configuration that feeds the load. The load is a single capacitor bank for each generator. A capacitor bank was constructed by connecting ten tantalum capacitors is parallel. This construction technique is known as multi miniature capacitor bank, or MMC bank. A MMC bank was chosen partly because of the robustness of tantalum capacitor. Due to the fact that the MMC shall be subject to low pressure and extreme temperature, it was built to withstand a large amount of abuse. The other factor that determined the construction technique was the low capacitance of tantalums for their cost. Many small capacitors in parallel are much more cost effective when compared to a single high capacitance tantalum capacitor. To solve the issue of the generators possibly over charging the MMC and damaging it, the voltage shall be constantly monitored. When the MMC bank is half-filled, the bank shall be shorted and the energy stored shall be dumped. When this occurs, the microcontroller shall make note within the data timeline. A relay will be used to short out the MMC and dump the energy.

The data associated with the generator shall be continuously recorded for the duration of the flight and stored on a separate data storage device. The information that is stored onto the micro-controller shall include the data from all of the sensors accept for temperature and humidity. Team Lightning Rod shall analyze the temperature and humidity data using the HOBO’s “Boxcar” program and shall analyze the generator data using Matlab and Excel as these programs are best suited for disseminating this information. The team shall also match data from both the HOBO and Microcontroller Data Storage on a single timeline and determine any



The oscillations aren’t really random, you could say something more to the effect of semi-freely moving magnets


existing correlations. These correlations may include: energy output during ascension, energy output during burst, and energy output during the subsequent fall.

3.2 Plan

Team Lightning Rod ordered many of its necessary hardware components from the following places:

Magnets4less.com Neodymium magnets

McMaster.com Spring Steel

McGuckins Machine Screws Aluminum Tape Aluminum Tube Aluminum Flat Plate Bearing Nuts 9V Batteries

Mouser.com LDO Regulator Data Storage device Switches

Provided by ITLL Plexi-Glass 30 ga. Copper Wire

Provided by SpaceGrant Aluminum tape Anti-abrasion washers Canon Camera Foam Core Sheets Heater HOBO Hot Glue

SparkFun.com Microcontroller Accelerometers Development board

Team Lightning Rod cut the plexi-glass and formed the basic structure of the two generators. After creating the structures of the generators, the plexi-glass was attached to the machined spring steel using machine screws. The magnets then were attached on the end of the spring steel, and the copper wire was placed between the magnets. This was the vibration generator for Zeus. Similarly to the vibration generator, plexi-glass for the rotational generator was cut and magnets were fixed into their respective locations. A bearing insured that the generator was free to turn the plexi-glass housing the magnets together. The generators were then tested to make sure that the conceptual design worked. The next system that was created was be the structure of Zeus. To begin constructing the structure, Team Lightning Rod cut foam core into the 2-dimensional cube pattern. Then, the 2-dimensional cube pattern was transformed into a 3-dimensional cube. The holes for the string attachment were cut and the string attachment was added to the cube through two washers, a tube, and the paper clips. Testing of the cube’s durability then ensued with the Whip Test, Drop Test, and Kick Test. Once the structure was known to have a durable design, Team Lightning Rod assembled all electronics according to the functional block diagram. Finally, the constructed project was tested with a Cold Test and a vibration test to make sure that everything was insulated and working properly. The Team then made necessary changes, placed contact information and an American flag on Zeus, and launched it.

3.3 Diagrams and Drawings



How?


3D Isometric View

Rotational Generator



Vibrational Generator


Bearing

14 cm

Magnets

Coils not shown (they’re attached to the structure)



15.7 cm

Spring Steel

Coil

Magnets


Unfolded View


17

17


2D Unfolded with Dimensions

4.0 Management

Team Lightning Rod is be managed by Trevor Luke. Each member holds a vital role in the project and all members shall contribute to construction and finalization of the satellite Zeus and its components. Each team member is assigned a formal role and assistant duties to ensure that not only one person is working on each aspect of the satellite. Finalization of Zeus is estimated


17

17


to occur two weeks before launch. All of the roles of team members are detailed in the charts given below:

4.1 Organizational Chart

NAME TITLE ADDITIONAL RESPONSIBILITIESJESSE ELLISON ELECTRONICS HEAD DRAFTING/DESIGNMATT HOLMES BUDGET HEAD PROGRAMMING ASSISTANT/

DOCUMENTATIONMATHEW DICKINSON

STRUCTURE CO-HEAD TESTING ASSISTANT

CHRIS BENNETT STRUCTURE CO-HEAD PRESENTATION COLLABORATORTREVOR LUKE TEAM LEADER TEAM SCHEDULING/

COMMUNICATIONS/ DOCUMENTATION

ALEX LOUIS TESTING HEAD FILMSUSHIANS RAHIMIZADEH

PROGRAMMING HEAD MISSION DESIGN

ALL ALL TEAM MEMBERS WILL ASSIST IN EVERY ASPECT OF THE PROJECT.

4.3 Flow Chart

4.2 Schedule

Complete proposal and presentation and submit online Due 9/16 by 7:00 amFill out order form and order hardware 9/23 at 11:30Team meeting 10/4 at 3:00Cut out generator structures 10/4Wrap copper coils 10/4Write presentation Due 10/5 by 7:00Team meeting 10/5 at 3:00 pmTest structure 10/5 to 10/8Assemble magnets and spring steel for vibrational generator 10/5Complete construction of vibrational and rotational generators 10/8



It would be helpful to see what has been completed by crossing it out, what was late, etc.


This is unnecessary with the flow chart right after it since it contains the same information but the flow chart is more useful (it shows who reports to whom). The assistant positions should be put in the flow chart


Team meeting 10/10 at 2:00 pmTest and adjust generator design to optimize voltage 10/10Assemble and wire satellite 10/10 to 10/15Complete the wiring of satellite 10/16Team meeting 10/17 at 2:00 pmProgram satellite hardware 10/17 to 10/22Final Construction Completed 10/23Team meeting 10/24 at 2:00pmFinal Testing 10/24 to 10/29Project Finished 10/30Buffer Week 10/31 to 11/5Finish Critical Design Review 11/2Launch 11/6Write final presentation 11/30Finish Analysis and Final Report 12/4Team video due 12/4

Time Limitations:As of November 2nd, Team Lightning Rod has two days to finish the satellite Zeus. A

launch readiness presentation shall be given in class on November 2nd. The satellite is due on November 5th and shall be turned into Professor Koehler. Launch is the following morning; November 6th.5.0 Budget



If your mass budget is allowed to be over the requirement of <850 g, then it needs to be discussed


6.0 Test Plan and Results



Team Lightning Rod did a whip test by attaching a prototype of the satellite to a string, the same type as the one used on launch day, and swung it around in circles. This tested both the ability of the structure to endure the whipping motion after burst as well as the structure’s ability to maintain a good hold onto the flight rope. In order to replicate the actual scenario, Team Lightning Rod filled the balloon satellite structure with objects to duplicate the weight of the actual equipment inside. Team Lightning Rod’s structure passed this test easily as the balloon sat retained a firm hold on the flight string and there was no damage whatsoever to the structure itself.

Team Lightning Rod also did a series of drops from varying height. This test was accomplished by dropping the structure from different heights in order to find its weak points. The satellite was weighted with objects to make it weigh about the same as the final satellite. The reason for this test was mainly to ensure that the balloon sat and the data within would not get destroyed upon landing. To ensure the safety of others while performing this test, the team made sure that nobody was in the vicinity of impact when dropping the balloon satellite. As this was the last structure test to be performed on that prototype, the balloon sat was tested until there was noticeable damage. After six tests a seal broke, probably due to the fact that the rock broke loose of the tape holding it down and smashed into the corner. Team Lightning Rod still judged this test as a success because the balloon sat only has to endure only one impact upon landing. The break can be seen in the picture below.

Another test that was done by Team Lightning Rod was the flight simulation test. This test had two parts; first, the box was laid on the table with one side left open so that the team could see



Were these masses secured in the same relative places that the actual equipment will be?


that the generators were performing correctly under the expected flight conditions (spun and wobbled it). The next stage of this test was to hang the fully sealed box over the edge of the table to see if it were balanced and if it would spin and shake as the team hoped it would. This was probably the most important test done because, although Team Lightning Rod had already tested and proved that the generators would work under vibration and rotation, they had not yet determined whether or not the flight would produce such vibration and rotation. The structure passed this test because the team was able to see that both generators were enduring enough motion to produce a discernable amount of energy.

Team lightning rod tested the ability of its structure to withstand cold temperatures. The structure was placed inside a Styrofoam cooler with five lbs. of dry ice. The test ran two hours. During the test, the Hobo was turned on, as well as the Camera and the Micro-controller. The purpose of the test was to see if all of the electronics, stayed on, and continued to work after the two hours of exposure to extremely cold temperatures. The total flight time of the satellite will be approximately two hours, thus the electronics only need to function in a cold environment for that time period. This test was successful because all of the electronics were still working after the two hours of the cold test.Lastly, for the imaging test, the team turned on the camera to see if it would continuously take pictures. The test lasted 30 minutes and the camera worked perfectly, taking a picture every 20 seconds for the full 30 minutes that it was turned on.



Again, a plot here would be a good ida


How were you able to see this? A graph here would be great, as it would both prove/show your results and demonstrate that you are capable of extracting data from your balloonsat and analyzing it


7.0 Expected Results

Team Lightning Rod expects to have a very large amount of data to interpret results from. First, it is expected that the vibrational generator will generate at a measurable amount of energy (at least 1 mV) with each pass across the coil. The data acquired shall be matched to that of an external accelerometer, which is attached to the magnets on the vibrational generator. The energy produced shall be compared to the motion of the generator to validate how much energy is produced during the flight. Team Lightning Rod expects that the satellite shall rotate more than it shall vibrate. Thus, Team Lightning Rod predicts the rotational generator to produce slightly more energy than the vibrational generator. The generators shall fill a capacitor bank with a charge, and the micro-controller shall measure the change in energy stored each time it checks the capacitor bank. The voltages on the capacitor banks for each of the generators shall be measured by the microcontroller twenty times a second. The capacitor bank shall be shorted out when it is approximately half full in order to ensure that the microcontroller measures accurate data. The capacitor bank shall be shorted out directly after a measurement is taken by the micro-controller so that data isn’t lost during the time it takes the capacitor to short out. The data measured by the micro-controller shall be stored on an SD card. This shall enable easy access to the data. After recovery, the SD card shall be retrieved and uploaded by a computer. The data shall be analyzed using Excel and Matlab. Team Lightning Rod shall condense the data to calculate the total energy produced and the efficiency of the generators.

Team Lightning Rod expects that there shall be an increase in the energy generated when the balloon passes through the more turbulent parts of the atmosphere. It is expected that the vibrational generator will generate a peak amount of energy just after burst. The performance of the generators should be semi-impervious to environmental factors. The change in temperature could have an effect on the energy output of the generators. When the temperature is at its lowest, there could be a slight increase in temperature output due to a decrease in the resistance of the copper wire in the coils. Thus less energy is lost to heat.

8.0 Launch and Recovery

All members of Team Lightning Rod shall attend both the launch and the recovery of Zeus. Chris Bennett and Jesse Ellison shall provide vehicles and drive the team to the launch site. Once the team arrives at the launch site, Alex Shelanski shall activate the switch that turns on the satellite. The satellite shall be attached to the flight string and prepared for launch. Jesse Ellison shall carefully launch the satellite. The team shall wait patiently for the satellite to ascend and descend. All members of Team Lightning Rod shall help to retrieve the satellite. When found, Trevor Luke shall take the satellite home with him and keep it safe until the team meets to analyze the data. To analyze the data, the team shall remove the SD card and upload the text file to a computer. The file shall then be imported into Excel. The team shall analyze the data using Excel and Matlab under the direction of Sushia Rahimizadeh. The team shall compile the results to be presented in the final presentation.



This is the first mention about accelerometers since the parts list – have you tested it, have you compared its results with your energy results?

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