SCI://TECH Engineering Design Competition – 2018 Senior High Table of Contents

“Catnado 5: F5” Version 1.00 - Updated 12/12/2017

Tentative Schedule.................................................................................................................................................................. 2 Story ........................................................................................................................................................................................ 2 Game Design ........................................................................................................................................................................... 3 Starting Section ................................................................................................................................................................... 4 Yard Section ........................................................................................................................................................................ 4 Inclined Roof Section .......................................................................................................................................................... 4 Upper Roof Section ............................................................................................................................................................. 4 Additional Storms................................................................................................................................................................ 5 Driver & Spotter Movement Areas ..................................................................................................................................... 5 Course ................................................................................................................................................................................. 6 Score Summary ....................................................................................................................................................................... 6 Competition Structure ............................................................................................................................................................ 7 Part 1 - Seeding Round ........................................................................................................................................................ 7 Part 2 – Competition Round................................................................................................................................................ 8 Competition Rules ................................................................................................................................................................... 9 ROV Check-In and Qualification .......................................................................................................................................... 9 Disqualification.................................................................................................................................................................... 9 Team Specifics ..................................................................................................................................................................... 9 Motors............................................................................................................................................................................... 10 Power ................................................................................................................................................................................ 10 Other Items ....................................................................................................................................................................... 10 Course Specifics .................................................................................................................................................................... 11 Sensors .............................................................................................................................................................................. 11 Tree Limbs ......................................................................................................................................................................... 11 Cats.................................................................................................................................................................................... 11 Dogs................................................................................................................................................................................... 11 Roofing Material ............................................................................................................................................................... 11 Campus Communication ....................................................................................................................................................... 11 Team Registration ................................................................................................................................................................. 12 Clarifications ......................................................................................................................................................................... 12 Awards .................................................................................................................................................................................. 12 Resources for Electronics ...................................................................................................................................................... 12 Appendix A – Course Schematic ........................................................................................................................................... 13 Appendix B – Common Questions ........................................................................................................................................ 15 Appendix C – Course Photos & Links ...................................................................................................... separate document Appendix D – Resources ……………………………………………………………………………………………………………………. separate document Important Notes • The maximum dimensions of the robot are 18”x18”x18”

EDC 2018 – Senior High 2

Tentative Schedule Monday

December 13, 2017

Problem announced

Friday

December 13, 2017

Web site up; Registration and Q&A begins

Friday

January 12, 2018

4:00 pm

Deadline for all Engineering Design Competition entries

Saturday

February 10, 2018

8:00 am – 9:00 am 8:30 am – 12:30 pm 1:30 pm – 3:30 pm 3:30 pm

Team Check-in (LSC – Montgomery) Seeding Round Competition Rounds Awards Ceremony

Story We thought the catnados were going to subside this year… we were wrong. While temperatures have stabilized and the catnados are no longer accompanied by snow and ice, the wind speeds are expected to be among the highest ever recorded; possibly reaching F5 levels of over 260 mph! We need you, the Consumer Robot Inventors (CRI), to design and create a robot to clean up during a catnado. Once again, the catnados are expected to contain cats, dogs, and tree branches. All need to be safely taken off the roof and into specific areas. After further analysis by Dr. Charles Pepper, it was discovered that the sensors that were used two years ago had design flaws that caused incorrect data to be returned. A newer, more accurate sensor has been created and, for proper data analysis, multiple sensors need to be placed on rooftops. Wind will be a concern this year and might pose problems during the cleanup. This will be especially problematic for the sensors; they were designed for wind speeds up to F4, but not F5 levels. They might get blown off the roof if placed during the stronger portions of the storm. Good luck!

EDC 2018 – Senior High 3

Game Design The objective of the competition is to score as many points as possible in the time limit provided. There are multiple ways that robots can earn points. The majority is from moving pieces from the one section to the other. The final score for each robot will be calculated based on the location of all pieces at the end of the match. If you score something and it moves out of scoring position you must move it back in order for it to be counted in your final score. In addition, each piece must be 50% or more inside the scoring area and must not be touching the robot in order for it to be counted in your final score. Each robot’s track is made up of four sections (detailed in Figure #01) • • • •

Starting section Yard section Inclined Roof section Upper Roof section Starting Section

Driver Starting Location

Inclined Roof Section

Upper Roof Section

Spotter Starting Location

Yard Section

Figure #01 – An individual robot’s track Note: All diagrams & figures in this section are not to scale. See Appendix A for detailed schematics with dimensions. The upper roof section is located 8” off the ground. The inclined roof section is 4’ long and goes from the ground to the upper roof section. The outside borders of the starting section and yard section will have a boundary. The robot must stay within one of the four sections. However, the robot can extend over the boundaries as long as they do not interfere with any other teams’ track. The areas to the sides of the course are considered your neighbor’s yard. Note: If any piece falls into your neighbor’s yard your robot cannot pick that piece back up. It becomes out of play.

EDC 2018 – Senior High 4

Starting Section The starting section will be split in half. The right side from the driver’s perspective is where the robot will start. The robot must fit completely inside the starting section at the start of the match. The base of the section will be Astroturf. There will be line separating the starting and yard section drawn on the Astroturf as well as a line in the middle of the starting section.

Yard Section The yard section will be empty at the start of the match except for sensors. The base of the yard section will be Astroturf. Sensors There will be 15 sensors placed in a specific location in the yard section located in front of the robot’s starting location. (Sensors are plastic hollow golf balls; see Course Specifics) Each sensor moved to the upper roof section is worth 20 points.

Inclined Roof Section The inclined roof and upper roof sections will be covered in shingles. Be careful when driving so you don’t fall off the roof! If you do fall off you will have to stop your match. However, any pieces that you had previously scored will still count. There is a slight bump between the yard and inclined roof sections. While it will be as small as possible, please note that transition will not be smooth. The following pieces will be randomly placed throughout the inclined and upper roof section at the start of the match. Pieces may be touching one another or placed slightly on top of one another. Tree Limbs There will be 3 tree limbs scattered throughout the inclined and upper roof sections. Each tree limb moved back to robot’s starting area in the starting section is worth 15 points. If a tree limb falls into your neighbor’s yard, you will be penalized 15 points for each branch. Cats There will be 4 cats randomly placed throughout the inclined and upper roof sections. Each cat moved to the left side of starting section is worth 7 points. Dogs There will be 4 dogs randomly placed throughout the inclined and upper roof sections. Each dog moved to yard is worth 5 points.

Upper Roof Section Some of the tree limbs, cats, and dogs will be placed in this section.

EDC 2018 – Senior High 5

Additional Storms At both the 1-minute and 2-minute mark of a match, additional pieces will be randomly placed into the inclined roof section. These pieces will be dumped onto the track by the judge. The pieces will be dumped no matter the location of your robot. Depending on its location some pieces may end up on your robot. If any piece falls off into the neighbor’s yard, your yard, or upper roof section due to the storm, the judge will place the piece back on the inclined roof. All pieces from the storm can be scored like pieces that start on the track. 1-Minute Storm The following pieces will be placed randomly on the inclined and upper roof sections at the 1-minute mark: • •

4 dogs 1 tree limb

Active Catnado (Wind Storm) From the 1-minute to the 2-minute mark there will be a wind storm coming from the center of the upper roof section going down the track. It will be strong enough to blow down the sensors if not blocked by something. It should not be strong enough move the cats, dogs, and tree limbs. If a sensor is blown off the track it will not be replaced. 2-Minute Storm The following pieces will be placed randomly on the inclined and upper roof sections at the 2-minute mark: • •

4 cats 1 tree limb

At this point the wind storm will stop.

Driver & Spotter Movement Areas Both the driver & spotter do not have to remain exactly in their starting spots. However, both the driver and spotter must not enter the track or interfere with their robot (either by touching or moving the robot using the tether). If they do the team will receive zero points for that round. The driver can move around to any point behind the scoring section. The spotter can choose to move up and down the length of the track section. See Figure #03 below for the driver and spotter movement areas.

EDC 2018 – Senior High 6

Driver Movement Area Spotter Movement Area Figure #03 – Driver and Spotter Movement Areas Note: These areas will not be marked out during the competition.

Course Each course is made up of three tracks joined together. Three robots run on each course at a time.

Figure #04 – A complete course with 3 tracks together Robots cannot interfere with other robot’s tracks.

Score Summary Points can be scored in the following 4 ways: • • • • •

Each cat returned to the left side of the starting section is worth 7 points Each dog returned to the yard section is worth 5 points. Each branch returned to the right side of the starting section is worth 15 points Each branch dropped into a neighbor’s yard is worth -15 points Each sensor placed in the upper roof section is worth 20 points

EDC 2018 – Senior High 7

Competition Structure The competition takes place over one day. Every team will compete during seeding and the top twelve teams will advance to the competition rounds. The current scores will be displayed during the competition in the theater.

Part 1 - Seeding Round During seeding each team can compete as often as they want (as time allows). The top 4 scores for each team will be totaled and will determine the rankings for competition round. The top twelve teams advance. Note: A team can still advance if they complete less than 4 times if their total points are still in the top twelve. Teams can choose to run at any point during the seeding round, which takes place from 8:30 am – 12:30 pm with a break from 12:30 pm – 1:30pm. The seeding ends at 12:30pm. If a team has not run all of their 4 rounds by then they will not be allowed to do anymore rounds. However, all teams must check in before 9:00am or be disqualified from the competition. Teams will line up when they are ready to do a round. Two courses will be setup during this time so that a maximum of 6 teams can run at the same time. If only 3 teams are in line they will all run on the same course. If there are 4 teams, each course will have 2 compete. Each round will last 3 minutes. You can choose to run all 4 of your rounds back to back. After your round is over you can get at the end of the line. If there are less than 6 teams in line you can run immediately in the next round. In the event of a tie at the end of the seeding round the following rules will be used: 1) 2) 3) 4)

The team with the highest point total for one round is ranked higher The team with the highest removed score is ranked higher The team that ran more times is ranked higher A coin flip performed by a judge. All decisions of judges are final.

Teams will have one minute to setup for their round. While there will be some leniency during seeding, teams should try to keep to the one-minute setup time as it will be strictly enforced during the competition round. During this round each team will also have to meet with the judges to discuss their design and notebooks. A team without a notebook will not be allowed to advance.

EDC 2018 – Senior High 8

Part 2 – Competition Round During the competition round the time limit will remain at 3 minutes per round. All advancing teams will play 4 times and the 6 teams with the highest total combined score will advance to the semi-finals. Each team will compete 4 more times and the 3 teams with the highest combined score (not including the score from the first round) will advance to the finals. In the event of a tie during the first round or the semi-finals the following rules will be used: 1) The team with the highest point total for one round is ranked higher 2) A coin flip performed by a judge. All decisions of judges are final. In the finals each of the 3 teams will play 3 times. At the end of this set the team with the highest total number of points (in the finals) wins. In the event of a tie at the end of the finals, another game of 2 minutes (shorter than the previous) will be played with all the tying teams. This game will be repeated until there is no tie. During the competition round teams only have 60 seconds to setup their robots once the match is announced. This will be strictly enforced. However, since teams will be running back-to-back games during the semi-finals and finals there will be a slight delay (between 30 and 90 seconds) between the announcement of rounds to give teams additional time to setup. Note: There will be a 10 – 15 minute break between the first round and the semi-finals and another between the semifinals and finals to let teams recharge their batteries.

EDC 2018 – Senior High 9

Competition Rules ROV Check-In and Qualification ROV check-in and qualification are required for ALL teams competing. •

•

• • •

Teacher sponsors must bring 2 copies of completed and signed Entry and Parent Permission Form to Check-In! These forms will be available elsewhere on the EfTA web site. Teams will not be allowed to check in without these forms. Judges will: (1) check each team’s ROV for compliance to all rules; (2) verify the vehicle’s capability of controlled movement, (3) go over the Cost Analysis Form and receipts, and (4) review the team’s Engineering Journal(s) and question team members about their vehicle’s design, construction, and testing; Teams will need to discuss why they selected the gears used within journals. Teams judged at least satisfactory in these four areas will be qualified for the competition. Teams will submit only one (1) journal for the judge review. All teams must be through check-in by 10:00 am. Any team not checked in during the school allotted time would not be allowed to compete.

Disqualification Judges will disqualify teams for the following reasons: a) Any team whose vehicle is not in compliance with the rules b) Failure to provide a cost analysis and/or exceeding the maximum allowable cost c) Any team that, in the judges’ view, does not demonstrate adequate knowledge of the vehicle’s design and construction; including not being able to explain gear selection d) Any vehicle that does not move e) Any team that receives or has received, in their view, inappropriate outside assistance before or during the competition f) Deliberate damage of the track or course g) Deliberate damage of the control wiring h) Deliberate interference with a neighboring team in the judges’ view i) The robot must fit within a box that is 18x18x18 inches. The vehicle must be within these dimensions at the start of each race, but may extend beyond these dimensions after the match has started. Must control any retractable or extension devices from the main portion of the vehicle. These extensions must fit within box. j) No one may touch any vehicle after a round begins. • There is one exception to this rule. As long as the robot is still in the starting area the driver may touch the robot after the round has begun. However, the team will incur a 30 second penalty starting from when the driver finishes with the robot.

Team Specifics • • • •

Only 2 students per team will be allowed on stage during the competition (driver & spotter only) o The spotter may not use a second controller to help control the robot May consist of up to three people. A single individual may not belong to more that one team. May be made up of people from different schools unless not permitted by the school/sponsor. Teams from any EfTA-member school/district may enter. Must have a teacher sponsor. Teacher from school must be present for student to compete.

EDC 2018 – Senior High 10 •

• •

• • • •

Must be the persons solely responsible for the design, construction, and maintenance of their vehicle before and during the competition. In the view of the Judges, any team receiving inappropriate outside assistance before and/or during the competition will be disqualified. The Judges may issue a warning. A disqualification decision during competition may not be appealed. May seek funding sources to help offset the costs. If a sponsor is acquired, the team should consider displaying the logo of the sponsor on their vehicle. Must not exceed $150 in total cost toward the vehicle’s construction. At check-in, each team must provide a Cost Analysis Form for their vehicle signed by their teacher sponsor for all purchased and donated materials. Purchased items will be detailed on the official cost analysis form. All receipts must be attached to this form. Any donated materials must be given a fair value and included in the $150 cost limit. The motors used for translation are considered in the $150 cost limit. Any component attached to the vehicle, such as the battery, power supply and/or controller must be considered as part of the cost. o Note: The battery charger is not included in the $150 cost. Must have two team members present at all times during all aspects of the competition. Vehicle will start competition at designated area. Pulling on cords cannot move vehicle. Vehicles cannot use propeller or continuous rotational motion for movement.

Motors •

• • •

Must not modify the electric motors internally. The only exception that certain motors have "add-ons" or "stages" that are sold by the motor manufacturer and are designed to change the gear ratio of that specific motor (i.e. Banebot motors). Be prepared to prove you have a legitimate add-on and discuss with the judges the technical aspects. May use servos as long as no modifications are made and remain in original state. Servos will be allowed for movement other than translation. Continuous rotation servos are allowed for non-translation. May use any motor, any geared motor, any transmission, any gears and any kits (with exception). Kits cannot contain complete subsystems. They cannot be a full robot, a full arm system, a full lift system, a full drive system, etc. Kits are not meant to allow you to buy a solution, rather they are meant to be another tool in your tool chest--a source of additional components. Judges are going to be very strict on the abuse of using kits. If you have any question about using a certain kit, contact the competition administrators. You should value used motors at the cost to buy it new. The appropriate gearing calculations (power, speed) should be included in the journal.

Power During the competition, each team must provide its own controller and power supply. This year, the only power supply that will allowed for a robot is one (1) 7.2 volt NiCd battery pack with a maximum rating of 2000 mAh. Batteries may not be changed during a match.

Other Items • • • •

Must not be radio controlled Must not utilize any flammable substances, open flames and/or explosive substances of any kind it its design and/or operation Must not utilize any hazardous chemicals of any kind in its design and/or operation Must not utilize any fluids (including liquids or compressed gas)

EDC 2018 – Senior High 11 • • • • •

Must not place any adhesive material on the playing surface for enhanced friction capabilities or for any other reason Must not use sharp implements such as razor blades, knives, etc. in its design and/or operation Must not be a pre-manufactured vehicle, pre-engineered kit or be the components from a pre-existing kit All components of the vehicle must remain attached and intact during the competition Must not have any removable components that are tethered by a wire or string longer than 3" Team members must stay in the controlling area between rounds. This area will be marked. Teams will leave this area 4 rounds prior to their race and go to the stage area. Only Sponsors will be allowed in the pit area and on the stage competitive area

To work in the pit area, the sponsor must be with the student. Students who are working on vehicles will be the only people in the pit area. No parents/spectators in this area.

Course Specifics Links to related parts and photographs are included in Appendix C.

Sensors The decorations are hollow plastic practice golf balls.

Tree Limbs The tree limbs will be constructed out of dowel rods. The main part of the limb will be a 10” long piece with a 3/4" diameter. There will be 3 smaller limbs sticking off of the main part that are 3” long with a 1/4" diameter. One side will have 1 limb and the other will have 2. They will be angled upwards at a 45-degree angle. See Appendix A for a drawing.

Cats The cats are stuffed animals. They are about 6” long.

Dogs The dogs are stuffed animals. They are about 6” long.

Roofing Material The inclined roof and upper roof section will be covered in shingles. They are made out of asphalt fiberglass and as 36 x 12” long.

Campus Communication Each campus whose students and teachers will be involved in the competition must designate a campus EDC representative who serves on the SCI://TECH 2018 EDC Committee. This committee meets periodically to provide input to the Competition Committee regarding the general parameters of the competition and other areas of running a successful competition. Each school will need to provide support/supervision to cover the pit area and student controlled area during the competition.

EDC 2018 – Senior High 12 Information from the Competition Committee will be communicated to all team teacher sponsors by e-mail and other means as necessary. It will be placed in the Robotics Folder within FIRST CLASS for reference. The campus EDC representative is responsible for the flow of information from his/her team(s) to the Competition Committee.

Team Registration Each teacher who will be sponsoring students must download the Entry and Parent Permission Form and give one to each student on each team. Non-CISD teams should modify the permission part of the form before use. Once the forms are signed and returned, sponsors may register EACH student.

The final deadline for teams to be entered in the competition is 4:00pm on January 12, 2018. Clarifications •

• •

Clarification and other questions for the Competition Committee must be e-mailed through the EDC website by the sponsoring teacher. Clarifications will be answered by the Competition Committee and e-mailed back to teachers. Clarifications will also be posted for all teams unless the question asked is viewed as related strictly to the team asking it. Clarifications sent from non-registered email addresses will not be addressed by the committee. Teams are responsible for keeping copies of their transmissions.

Awards Cash awards will be given to the top 3 teams from the competition. In addition, the judges will make awards for the following. Tentative awards are: • • • • •

Outstanding Engineering Project – journal, drawings, presentation to judges Unique Engineering Design – innovative, creative, unusual approaches to accomplishing the mission Best Team Spirit – working together during the competition Top Gun Award – top score in a single round Founders Award

Resources for Electronics • •

Pitsco www.pitsco.com All Electronics www.allelectronics.com

Additional resources are available in Appendix D.

EDC 2018 – Senior High 13

Appendix A – Course Schematic

EDC 2018 – Senior High 14

EDC 2018 – Senior High 15

Appendix B – Common Questions Below is a list of some common questions. If you have any other questions please review the Clarifications section for contact procedures. Q: Can a robot carry more than one thing at a time? A: Robots can carry as many branches, cats, and sensors simultaneously as they can.

Q: Can you explain how someone who runs only 3 times can beat someone who runs 5 times during the seeding round? A: Suppose team #1 runs 5 times and scores 5, 5, 10, 10, and 15 points. Their total score is 40, since a 5 point round was removed from their total. Team #2 runs 3 times and scores 15, 15, and 20 points. Their total score is 50, since no points were removed. Team #2 is ranked higher overall than team #1.

Q: What happens if a piece ends up on my robot after a storm? A: Only pieces that end up in a section other than the inclined roof will be moved. Any piece that ends up on a robot will remain there.

Appendix C – Course Photos & Links Tree Limbs

The tree limbs will be constructed out of dowel rods. The main part of the limb will be a 10” long piece with a 3/4" diameter. There will be 3 smaller limbs sticking off of the main part that are 3” long with a 1/4" diameter. One side will have 1 limb and the other will have 2. They will be angled at 45 degrees. See Appendix A for a drawing.

Cats Each field will eventually have a dozen stuffed animal cats from Oriental Trading. They will be Plush Halloween Black Cats; part number: IN-25/3988 http://www.orientaltrading.com/plush-halloween-black-cats-a2-25_3988.fltr?prodCatId=550218

Dogs Each field will eventually have a dozen stuffed animal dogs from Oriental Trading. They will be Plush Realistic Dogs; part number: IN-6/1310 http://www.orientaltrading.com/plush-realistic-dogs-a2-6_1310.fltr

Sensors (Plastic Golf Balls) The sensors are plastic, hollow practice golf balls. https://www.amazon.com/gp/product/B01NBEU2DI

Roofing Material The inclined roof and upper roof sections will be covered in shingles. We will be using Owens Corning 25-Year Supreme Onyx Black AR 3-Tab Shingles. It is item # 14612 and model # PM01. http://www.lowes.com/pd_14612-278-PM01_4294745065__?productId=3013746

Yard to Roof Transition The transition from the yard section to the roof is not smooth. See this photo from a previous year:

Note: This photo is from a previous year and contains pieces (pine cones) that are not in this year’s game.

Appendix D – Resources Table of Contents Articles & References .............................................................................................................................................................. 1 Some Recommended Motors ................................................................................................................................................. 2 Sellers .................................................................................................................................................................................. 2 Design Tips .............................................................................................................................................................................. 2 Design Tips for Motors ........................................................................................................................................................ 3 Voltage ............................................................................................................................................................................ 3 Motor Speed ................................................................................................................................................................... 3 Force................................................................................................................................................................................ 3 Electrical Power............................................................................................................................................................... 4 Conclusion ............................................................................................................................................................................... 5 References .............................................................................................................................................................................. 5

Articles & References American Wire Gauge  http://en.wikipedia.org/wiki/American_wire_gauge  http://www.rbeelectronics.com/wtable.htm Vehicle Speed / RPM / Wheel Diameter Finder (Calculator)  http://www.lynxmotion.com/images/html/wheelspd.htm Understanding Torque  http://www.baldormotors.com/cowern/motorterms7.html DC Drive Fundamentals  http://www.baldormotors.com/cowern/motorterms23.html Other Motor Related  The Cowern Papers - http://www.baldormotors.com/cowern/contents.html Understanding and Using DC Motor Specifications  http://www.gearseds.com/files/Lesson3_Mathematical%20Models%20of%20Motors.pdf Understanding DC Motor Characteristics  http://lancet.mit.edu/motors/motors3.html  http://lancet.mit.edu/motors/ (main) Torque Conversion and Equivalents (including calculator)  http://www.engineersedge.com/torque_conversion.htm A Simple DC Motor  http://mit.edu/cmse/educational/motor_lp_kristy.pdf Servo Controller circuit  http://www.seattlerobotics.org/encoder/200210/servoex/ServoExcerciser.htm

Appendix D – Resources 2

Some Recommended Motors These are just recommendations, especially for beginners. Your design may be completely different and use different components. There are just ranges to help you search for motors. Your design will dictate the actual values you need. For your drive system, here are some choices:       



http://www.allelectronics.com/cgi-bin/item/DCM-285/400400/MINI-GEARHEAD_MOTOR,_166:1_RATIO_.html (47 RPM @7.5VDC, $17.75) http://www.allelectronics.com/cgi-bin/item/DCM-282/400400/70_RPM_GEARHEAD_MOTOR,_USED_.html (70 RPM @6VDC, $12.00) http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=1&storeId=10001&catalogId=10001&productId=155854&pa=155854PS (87 RPM @ 3-12VDC, $23.49) http://www.robotstore.com/store/product.asp?pid=1027&catid=1565 (70 RPM @ 5 VDC, $6.45) http://www.robotstore.com/store/product.asp?pid=1026&catid=1565 (66 RPM @ 5 VDC, $6.45) http://www.banebots.com/pc/MS-16XXX-050/MS-16118-050 (127 RPM @ 4.5-8VDC, $14.80) Arm/Forklift/Steer/Extender (15 RPM) http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=1&storeId=10001&catalogId=10001&productId=153437&pa=153437PS (15 RPM @ 3-12 VDC, $18.95 each) http://www.banebots.com/pc/MS-16XXX-050/MS-16574-050 (26 RPM @ 4.5-8VDC, $14.80)

Sellers           

http://www.robotstore.com/ http://www.jameco.com/ http://www.mouser.com/ http://www.digikey.com/ http://www.allelectronics.com/ http://www.mcmaster.com/ http://www.lynxmotion.com/ http://www.banebots.com/ http://www.tamiyausa.com/product/category.php?main-id=50 http://www.tamiyausa.com/product/category.php?sub-id=40000 http://www.tamiyausa.com/product/category.php?sub-id=38000

IMPORTANT: Remember (especially with the Tamiya products), you cannot use full robot kits. You can use gearboxes, battery boxes, universal arm set, universal plate set, tires, tire set, ladder-chain & sprocket set, track & wheel set, pulley set, etc. You CANNOT use kits that assemble in a full vehicle or robot.

Design Tips This year you will be allowed to use motors and gears from any source or kit to allow you to focus on solving the problem rather than spending most of your time fabricating a drive system. You CANNOT buy a preassembled robot or even subsystem. The spirit of this year's competition is to apply engineering principles combining various components and stay within a budget to achieve a goal.

Appendix D – Resources 3 On the surface it looks easy - drive, pickup an object, drive, drop an object. In fact, you will find it very challenging. You will be forced to make some hard decisions about your design and strategy while coming up with creative solutions. But you will find your life a lot easier if you will do some design work before attempting to build the robot. It's going to be extremely disappointing (and costly) if you decide to buy four $20 motors and then find out your battery pack doesn't work with them, or even worse that the motors are too slow/fast for what you need. Or you will get very frustrated to find that your robot tends to tip over when you extend your arm to pick up the object. All of these scenarios can be avoided with proper design ahead of time.

Design Tips for Motors When designing your motors there several things to consider: voltage, speed, tire size, force, power (wattage, amperage) Voltage First thing to determine is your voltage. For this competition, that's easy. Your power source is 7.2 volts. Your motor should operate at that voltage. Most motors can operate within a "range". If 7.2 volts is within that range, you can use that motor. For motors that operate at lower voltages, it's possible use them, but they will run very fast and probably burn up. You can use circuits to bring down the voltage. For instance, using an LM7805 voltage regulator chip, a circuit circuit (2) can be built to bring down the voltage from 7.2 volts to 5 volts. But will the LM7805 output enough power to drive that motor?! Motor Speed Second thing to consider is speed. How fast should your robot go? As a reference, a person walking at a medium speed goes about 30 inches per second. The slower your robot goes, the more control you will have driving and grabbing the objects. The faster your robot goes, the quicker you can get from one end of the course to the other. You must find a way to decide what speed you want your robot to travel. Third thing to consider is tire size. If you're using treads or another type of drive system, you can ignore this section. I make no recommendations here. Maybe cost is a factor. Maybe availability. One thing to consider, if you're robot is going too fast or too slow, changing the diameter of the tire you are using is one way of changing the speed the robot travels. Bigger tire=faster; smaller tire=slower. After you know your speed and tire size, you can calculate how fast your motor needs to be. This is usually given as RPM (revolutions per minute) in the motor specifications. You can do these calculations yourself, or find a good online calculator (3). Do not be shocked to find that you will not be able to find a motor that exactly matches your calculations. This is where good engineering comes in. Sometimes you're forced to compromise and find the closest match or you must change another component in your design. Force Next thing to consider is force. By force, I mean the torque (5) your motor must have. You must pick a motor that has enough torque or your motor will simply not turn. Torque is given in many different units and many calculators are available for converting between them (4). So what is torque? It's often called a "moment" or "rotational force". For beginners, you can think of torque this way: Hold a long stick at one end with your hand. Put a weight on the other end. Hold the stick straight out (parallel to the ground). Now raise the stick with letting your hand move left or right or up or down - in other words just rotate your hand so that the stick goes from horizontal to vertical. Did you feel the force as you tried to rotate the stick? That's torque. There are some interesting things to consider here. If you move the

Appendix D – Resources 4 weight closer, it will be easier to raise (less torque). If you make the stick longer and move the weight farther away, it will be harder to raise (more torque). Torque will be less of an issue for your drive motors because the robots usually don't weigh much, they are on a flat surface, and they usually have wheels. If you have hills to climb, have a very heavy robot, or are using a drive with a lot of friction (like a tank drive), you need to factor in torque. In this competition, if your robot has a significant weight, then you may have to consider torque when accelerating. The more torque, the faster you can accelerate. Beginners, think about the stick example above. How would it apply to accelerating a heavy weighted robot? Torque is very relevant when creating a robot arm. This topic is so extensive I cannot possibly cover it in a few sentences. But I can give you some topics to research. Wikipedia is a great resource. In this competition, you are allowed a maximum 18" base. But the most valuable object is 24" away. You will need to find a solution for reaching that object. In general, you will be lifting, rotating, turning, or extending some kind of appendage. Questions to consider: What kind of moment (torque) does your arm create on the robot; in other words will it tip your robot over? This is also related to the center of gravity. What kind of torque is required to lift an object? Most of you will discover the problem of backlash when your motor can't keep your arm in position. Some have used counterweights and even rubber bands to overcome this. BE CREATIVE!! If you want a real edge in this competition, learn about levers (6). For students who want a challenge and a super advantage, there are solutions out there that let you extend a robot arm without directly using levers (telescoping (7), scissors (8)). Also you will be making some appendage that can grab an object and release that object. How much force to hold the object? How do you keep it from falling out until you are ready to drop it? You don't want a motor/design so strong that it crushes or damages the object. But you have to hold that object even though you will bump other objects, your robot will jerk around while turning, etc. Also consider that you might actually drop the object. Will you robot be able to pick it up off the ground? For your armature appendages, you may also want to consider using servos. Servos do not suffer from the backlash problems that most DC motors do. I've found a circuit that allows me to use a potentiometer to control a servo (9). Though the circuit moves the servo in a jittery way, it is very inexpensive. There are servo controllers on the market, but they are very expensive. Make sure you get an analog one. We don't use microcontrollers in the competition, and the majority of the servo controllers are made to be controlled by computers. Mr. Scott Rippetoe has schematics for an even simpler circuit, so you may want to contact him for more details. Electrical Power The final consideration for your motor is current. In general, your 7.2 VDC battery pack will probably deliver whatever current (amps) your robot needs. But the more current you draw, the faster the battery pack will be drained. Battery packs are rated in amp-hours (Ah) (10) or sometimes milli-amp hours (mAh) which is just amp-hours divided by 1000. A typical 7.2 VDC battery pack rated at 1600 mAh, can deliver 1.6 amps over 20 hours. So ideally, 1.6 divided by 20 = .7 amps (or 700 milliamps) could be steadily delivered over a 20 hour period before the battery pack is discharged. But if you use 4 motors that draw 1 amp each, you will use 4 amps--almost 6 times the batteries' .7 amp rating. The worry isn't so much about damaging the battery, though it will substantially shorten the life of it. The real concern is that instead of the battery going dead in 20 hours (at 700 milliamps), it may go dead in a matter of minutes.

Appendix D – Resources 5 There are other considerations for the electrical part of your robot. You have to consider what size wires to use. Check out the American Wire Gauge standard (11) for more information on this. You also must consider power ratings for any electronic components like resistors, capacitors, potentiometers and switches. Power can be calculated using Watt's Law (12) as P = V x I. Power is in Watts, V is voltage in Volts, I is current in Amps. Ohm's Law (13) is V = I x R. V is voltage in Volts, I is current in Amps, and R is resistance in Ohms. For safety, consider using a fuse coming off the positive side of your battery. Fuses are life savers. If you accidentally get a short, it's much better for a 30 cent fuse to be destroyed instead of an $18 motor.

Conclusion This is by no means a comprehensive discussion on any aspect of motors. But hopefully it will serve as a guide to help you get started designing your robot. Many times I've seen students start scavenging for parts, or start buying parts without any master plan. But if you take the time and design for your motors ahead of time, you'll know exactly what parts to look for and what parts to buy.

References 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11)

http://www.radioshack.com/sm-5v-fixed-voltage-regulator-7805--pi-2062599.html, Catalog #: 276-1770, $1.59 http://www.national.com/mpf/LM/LM78M05.html http://www.lynxmotion.com/images/html/wheelspd.htm http://www.engineersedge.com/torque_conversion.htm http://en.wikipedia.org/wiki/Torque http://en.wikipedia.org/wiki/Lever http://en.wikipedia.org/wiki/Ball_screw http://scissor.lpi-inc.com/ http://www.seattlerobotics.org/encoder/200210/servoex/ServoExcerciser.htm http://www.1st-optima-batteries.com/amp_hours.asp http://en.wikipedia.org/wiki/American_wire_gauge http://www.rbeelectronics.com/wtable.htm 12) http://en.wikipedia.org/wiki/Watt%27s_law 13) http://en.wikipedia.org/wiki/Ohms_law