Paul's Individual Words

            Taking ME250 has given me plenty of moments to experience and learn many things, both good and bad. Relating to design and manufacturing, I expected the design process would be a tiring and a tedious one, which it was, but I never expected such complexity to be involved, such as the Pugh charts. I do agree the chart and the other introduced methods aided students in designing and planning the robot. Getting my first hands on experience with the different machines in the shop was very beneficial and exciting as well. 

            Being completely honest with no exaggeration, this teamwork was incredibly surprising simply because it is one of the best group experiences ever. Never before I had everybody so well behaved and cooperative with each other. Every past group I have been a part of always had a member with an issue about a random problem, but the synergy in this team was simply awesome. I suppose there were a couple of moments when time could have been spent more efficiently but the prior discussed meetings and teamwork always got our assignments and manufacturing finished ahead of time, at worst on time. Everybody in this team put in the, effort, nobody ever wasted time to the point where he was clearly seen as a slacker, and fighting never occurred.

            This course is definitely an important part for an undergraduate engineer to grow and learn. With that said, the course introduced the majority of what the students needed to know. However there was also an unusual amount of knowledge not needed in my opinion, or at least taught at an awkward time. The way it was organized, a midterm appeared around manufacturing time which was to test a vast amount of numerous tiny facts and material relating to things the students was to work with. I am not saying this is completely useless so it should be removed from the course, but seeing it take a chunk of time and not have as much value as I thought bothered me. That precious time could have been used to double check and trouble the machine.

            Consequently this team’s strategy and design had a simple plan with a simple solution. However, more time would have allowed this team to test the motors earlier and the tower during labs should have a guided box or area to indicate where it will actually be during the competition. The gearbox and motors not being in synced bothered this team’s machine during its performance which could have been fixed with more testing time. Moreover the strategy to move around the tower to score balls from the ledges was supposed to open on all sides, but limited to no pathways around the back. There appeared to be no room for the machine to travel through there. With the way the arm was designed to work on one side, our machine was going to be at a huge disadvantage depending on which side it would have got to start on. The tower position on the arena misled a lot of teams.

            I found it interesting that the past semester’s videos of the competition showed students that very few teams went for the tower ledge and wave field balls. As a result most teams thought there were going to be unique and have an advantage in the competition by going for those. To everybody’s surprise this was not the case and some matches even had two teams with extremely similar machines and strategies, such as ours.

            Nevertheless this course is definitely one of the more exciting ones instead of the usual conceptual and test taking classes. The working experience and competition is something unique other classes cannot provide. Personally though, I would wish the Stamps auditorium would not be used for lectures. Although the size could be useful, the setting for the class in the morning is too dark and similar to a kind of theater, making it tiring and difficult to concentrate during lectures. Having another room or diving into smaller sections would be an improvement in my opinion and would definitely help gaining more focus. I truly hope the future x50 and x95 courses will be just as beneficial, interesting, and worthwhile.

Matt's Final Thoughts

I learned quite a bit about design this semester, specifically the complexity of the design process.  It took alot of work to plan even a simple machine like ours, but I was impressed at my team mates' solidworks abilities, as well as our ability to work together.  A cohesive and friendly team was wonderful to work with, and I can see how important it is to having a successful project.  Although the design process was longer than I expected, the product was well planned and performed like we predicted it would.  Although we could have inspected the table more (the room to move in certain sections, the height of the hinge compared to the ball casters) in order to optimize our design.  

Manufacturing was time consuming, but I found that taking your time and not being rushed is very beneficial.  Our team's steady-paced precision allowed for us to stick to a plan about our manufacturing, and avoid the drama of getting replacement parts and completely re-machining parts.  Working on the mill, lathe, and bandsaw was pretty fun, and it was interesting to see how to machine different components.  Our team stuck to our manufacturing plan closely for several of our major components, but having a physical model is different than a solidworks one, and changes were made.  While the basic structure remained the same, several unused holes tell of previous ideas that were discarded.  This general concept showed me how important prototyping is in the development of a product, as a physical model is always better than a conceptual one.

Our members put in different amounts of work throughout the semester, but all had a willingness to help, and there were no ‘slackers’.  We had great communication through email, texting, and calling; and no one was squeamish about contacting other group members, which allowed for us to always be on the same page.  While there were some absences from team meetings, this is expected, as everyone is busy, but we were able to find compatible times to meet.  Planning what we will do in a meeting prior to getting there allowed for us to be very efficient. 

My performance could have been improved by maintaining concentration throughout our meetings: I felt that after being at a meeting for a while, I would become distracted and lose focus easily, although I was fairly productive during the beginning of the meeting.  Also, I feel as if I was much more efficient with machining than designing, as I did not take a liking to solidworks and was constantly stuck on how to create parts in the program.  I suppose I was not patient enough to truly learn it well during the labs, I would instead focus on getting the lab assignment done.  Now that I have had the experience of designing the robot, I see that it is something that I need to learn better, I am just glad my team mates were very proficient in it.

I think the class could be improved by having a longer portion for strategy development, and publicizing other team’s strategies in order to get a feel for which ones are being used most commonly.  I feel that our strategy was used by many and thus was not as effective.  If we would have been exposed to all of the groups’ initial strategies and then had time to rethink it, we would have had a more complete experience in analyzing which strategy would work the best.

Final Documentation

Our machine and team were depending on a very simple strategy needing only a simple design. The main components of our robot were the arm, funnel, and tube. Assuming that few teams were to attempt to score from the tower ledges, this team believed it had an advantage by planning to quickly score a single tower ledge ball at which the machine would continuously defend from then on. The arm would knock the ball off the tower ledge, which the funnel would guide towards an attached tube to secure the capture ball. The strategy was to be very simple and concise, giving the team plenty of time to defend.

The final design for the robot was quite similar to the CAD model in most respects. We used a mill to machine the base and brackets to length and to drill the holes in them. We used the mill for those parts because they connected the wheels, and any misalignment would have caused the robot to not drive correctly. The Arm did not need to be quite as precise, so the arm was cut to length with the band saw and filed, and the holes were drilled with a drill press and tapped by hand. The axles were cut roughly to length with the bandsaw and then finished on the lathe. The skirt was cut on the water-jet and then bent into shape using the break. We assembled the axle assembly by drilling a hole through the gear and axle and installing a spring-pin to fasten them together, and then the wheel was pressed onto the axle with the arbor press. We also added sandpaper to the wheels to increase the friction between the wheels and table. Our original design for the arm release was to use a torsional spring to force the upper arm back into place; this system was replaced by two extension springs inside the arm. We assembled most of the components with clearance holes and bolts, and only used screws where there was insufficient room for a nut. The chute was made from the 2 inch outer diameter corrugated tubing, and the funnel on top was constructed from rubber sheet. The Tube and funnel were attached together with tape and epoxy, and the tube was held in place with zipties, which allowed it to be adjusted slightly to remain just within the size constraint.

We had to change parts of the robot design when we manufactured it. In the CAD model we used two 1.5” gears for each wheel. In the robot, due to the placement of bolts, we had to use a 2” gear on the axle and a 1” pinion gear on the motor. This caused a different motor placement than the original design, so we had to drill a few new holes for it. The arm is also modified from the original CAD design. Our idea of using the 180 degree torsion spring was not working because we weren’t able to attach it on the arm very well. Instead we used two 3” extension springs that connected the two horizontal push rods in the arm. This worked very well for releasing the arm into the upright position. After we installed the skirt, it turns out to be very low to the ground and the front corners were getting stuck on the field. We decided to cut off the front corners on the skirt to give us better clearance.

Final Documentation Appendix

ROBOT GIRAFFE'S BOM
Item Description	Price	Quantity	Subtotal	Use	Supplier	Part #
black corrugated flexible tubing, 2" O.D. x 1-3/4" I.D.	$0.22	1	$0.22	tubing	McMaster	53145K33
Aluminum plate, 1/4" thick	$13.82	1	$13.82	baseplate	Alro	Quote
Aluminum rod, 1/4" diameter	$2.31	1	$2.31	axle	Alro	Quote
Aluminum Square Tube Stock - 1"x1", 1/8" Wall	$10.10	1	$10.10	square bracket + top arm	Alro	Quote
Aluminum Square Tube Stock - 3/4"x3/4", 1/8" Wall	$3.12	1	$3.12	caster block	Alro	Quote
Steel threaded rod, 1/4"-20	$4.06	1	$4.06	pins	McMaster	94210A125, divide
Bright Brass Surface-Mount Hinge with Holes Nonremovable Pin, 3/4" Open Width	$0.81	1	$0.81	arm hinge	McMaster	1603A3
Flanged brass bushing - 1/4" ID, 3/8" OD	$0.43	4	$1.72	bushing	McMaster	2938T1
48 D.P.,72 Teeth, 20° Pressure Angle, Acetal/No insert spur gear	$1.35	2	$2.70	gear	ADP-SI	A 1M 2-Y48072
48 D.P.,96 Teeth, 20° Pressure Angle, Acetal/No insert spur gear	$1.43	2	$2.86	gear	SDP-SI	A 1M 2-Y48096
3" Extension springs	$1.22	2	$2.44	arm spring	McMaster	9271K182
Polypropylene wheels, 3" diameter, 1/4" bore	$1.43	2	$2.86	wheels	McMaster	2781T72
1" ball caster	$4.00	2	$8.00	ball casters	McMaster	6460K31
Felt	$0.99	1	$0.99				Purchased
Tamiya 72005 6-Speed Gearbox Kit (includes motor)	$13.25	2	$26.50	motor	Pololu	74
2" 1/4-20 bolts	$0.35	2	$0.70	Bolts	Jack's Hardware	(none)	Purchased
Buna-N sheet, 1/16" thick	$0.19	2	$0.38	funnel	McMaster	9023K324
Stock fasteners (screws, washers, bolts, nuts)	$0.00	as needed	$0.00	screws & bolts	McMaster	as needed
TOTAL COST			$83.59
*NOTE: traded 1/8" Delrin plate for 1" ball caster + 2 gears + 2 48 D.P.,96 Teeth, 20° Pressure Angle, Acetal/No insert spur gear*
*NOTE: traded Tamiya 70168 Double Gearbox Kit for 2nd Tamiya 72005 6-Speed Gearbox Kit*

ME250 Final Reflection - Andy Dun

As the course comes to an exciting and somewhat disappointing end (8^th seed, losing in round 2) last Thursday, I can’t help but to think that there were things that we could have done to improve our performance.

Reflection on The Robot

First of all, we underestimated how unpredictable the electric motors and control boxes were. We had the motors set up and ready early on in the semester, but we never thought to test their performance and controllability. The control box turns out to be unpredictable sometimes, which was one factor that lost us the game. It would have been nice to practice with the motors early on to get a better idea of how it performs. If we knew the fact that the control was not sensitive before hand, we may have chosen a strategy that required less precise driving.

Secondly, we did not study the field as well as we should have. We didn’t realize our robot was unable to go behind the tower. On the day of the competition, we also realized that we had a harder time getting balls on the left side of the field.

Lastly, I wish that we had more time to come up with a strategy. I think our strategy was a great one and it make a lot of sense with the way the competition is set up, but the fact that so many teams had the similar idea was a disadvantage we underestimated.

Reflections on Design and Manufacturing

Over the course of the semester, I learned a more formal process of design, instead of trial-and-error like we did in high school robotics. However, I feel that I learned much more about manufacturing. It was great to have the hands on opportunity to make parts using the mill and the lathe. This gave me a better idea of what is a realistic design, and what is a design that’s easier to manufacture. This experience also gave me a good foundation for working on engineering student project teams.

Reflections on Teamwork and Time Management

Comparing to many teams I’ve talked to, I believe that my team worked very well together. I was rarely stressed out or frustrated about the team project. Our team leader Garrett did a great job taking care of many little things that the team overlooked throughout the semester. The whole team also communicated very well using texting and emails. I don’t think everyone put in exactly the same amount of work and time on the project, but that is always the case with teamwork, and nobody on our team put in a subpar effort. I think this is also the reason that we have been ahead of almost every deadline. MS6 was the only one we had to work past our scheduled meeting hours.

How The Course Can Be Improved

I liked the course overall mainly because of the hands-on part and the competition. But there are a few things that I think can improve. For one, the lecture had seemed to be quite a burton. I was not motivated to absorb the information. For one, it was nine in the morning; also, much of the information wasn’t covered on the exam/homework or affects our grade directly. To improve the performance our robots, it would be helpful to form groups on the first or second week, so we have more time to work out a better strategy. The game itself can use a major improvement. I did not like the fact that there is only one way to score. This limited the creativity very much. There simply should’ve be one strategy that ends the game (i.e. sitting on the opponent’s goal). I also didn’t like the wave-field. It was way more difficult to get the balls from than the tower, while the reward is almost the same. The difficulty to reward ratio is not balanced in many parts of the game. I’m glad at least the rubber balls are not sitting on the ground anymore (like last semester). I think this lopsided difficulty to reward ratio is what undermined creativity and made many robots look the same. Especially after every team did the Pugh-chart, the tower was obviously the easy solution with lots of points. 

Garrett's Individual Reflection

I learned a considerable amount about the design process in this class, from the design steps to clarifying intuitive design concepts and how easy it is to overlook aspects of a device during the design phase. I had worked on design projects before this class, but I had never covered the steps of design as throughly as in ME 250. I thought that the strategy-concept-module-component method was a good way to outline a design process, and I had intuitively practiced a similar process before. I had also intuitively removed unnecessary parts of a design in accordance with Occam's principal, but I had never formally thought about the technique, as with St. Venant's principle. I also learned the necessity of considering all parts of a machine before beginning construction. While designing the robot, I overlooked a few attachment details while making the Solidworks model, notably, the location of the motor holes and the attachment of the tube. When placing holes for the motor, I briefly looked at a picture on the website, and thought that I knew the position for the holes. Instead, I should have aligned the parts and checked that the measurements were correct – which they were not. This resulted in the team having to re-drill the motor holes several times to avoid interfering with the wheels, skirt, and gears. I also forgot to include a way to attach the tube to the arm of the robot because I could not think of a method initially.

I also learned a lot about machining. In addition to learning how to operate a mill and lathe, I learned a lot about ways to operate them correctly and efficiently. I learned that it is better to set up a mill so that one can zero off of a fixed reference point, such as the top edge of the vice, which does not move. This allows one to use the same zero for multiple parts. I also learned how long it can take to mill down a large piece of stock, making it more efficient to start with a band saw. I learned that it is far too easy to go into a machine shop without thinking through a design enough, and then making mistakes from lack of forethought. Most importantly, I learned that working in a machine shop takes several times longer to do anything in a machine shop than expected.

I learned a lot about working on a group on a fast paced project; specifically, I learned about distributing and scheduling group work. I thought that the team worked well together overall, but we could have tweaked a few aspects to work better as a group. There was usually at least one point during the group meetings when everyone would be waiting on one person to finish something before leaving or moving on, which is very inefficient. Instead, we should have done a better job of finding something else to work on to avoid wasting time. I also, as team leader, should have done a better job of assigning tasks to the other group members to ensure that everyone had the same amount of work. In regards to scheduling the project work, I thought that we did a good job. I originally expected to be finished with the project a couple of weeks early because we spent so much time in the machine shop during the first few weeks, but that time was eventually used up anyway, and we finished the robot only a few days ahead of time. The fact that projects take so much longer than expected taught me that I should definitely leave more time than expected, and to try to finish early on subsequent projects as well.

I realize that the class needs to teach us skills before we can begin designing and machining and that there is a large emphasis on the initial components of design, but I would like to be able to spend more time on the actual project work. I also did not think that the homework assignments and work for the first month were very time consuming, and I think that it would be a better idea to assign the initial work closer together and then leave more time for project work later in the class.

I think that the biggest things that brought my grade down were the early homework assignments, which I did not take seriously enough. I should have put more time and effort into the homeworks, and I should have taken the class more seriously in the beginning on the whole. I also should have communicated more with the group to make sure that everyone had the same understanding. We also should have checked each other's work to catch the errors that we will inevitably make.

Overall, I enjoyed the class, and I learned a lot about the design process. I thought that the project was challenging, but reasonable for a sophomore level class. This class has inspired me to look forward to the next design and manufacturing classes, as well as a career in design engineering.

Final Progress Report

We completed the robot last Monday, and have only had to make very minor tweaks in the past few days, leading up to the competition in a few hours. We spent most of the time testing the robot and familiarising ourselves with the responsiveness of the robot. The motors are a little difficult to balance precision and speed at times, but having both will be highly beneficial in the competition. We also need to be careful of our casters catching on the hinge in the middle of the table and the arm catching on the ledge of the tower, but both issues are trivial enough to overcome when operating the robot.

Our seeding round did not go particularly well; we knocked down two balls without catching them, but we still managed to score enough points to get the eighth seed for the competition. We also refined our tactics during the seeding round and learned how to approach the balls, which will help us significantly during the competition.

Overall, the project has been an enjoyable learning experience, and I am excited to see how the team's hard work pays off during the competition this afternoon.

Team Video! Check it out!

Progress Report Apr. 6

We completed the skirt! We cut the aluminum sheet with water jet an bent them into shape using the break in the machine shop. They fit well but we need to shave off the front corners to prevent the skirt from getting caught on the field.

We have also figured out how to make the arm unfold. We put springs inside of the arm, connecting the two horizontal bars.

Progress as of April 2nd

After considerable time and effort over the past weeks, the robot is finally beginning to take shape. There are still several components left to machine, and the system needs to be tweaked in a number of ways, but the overall lay out is now coming together. We have the chassis completed, and the arm is manufactured but not fully assambled. We still have to make the chute, skirt, and finish the wiring of the robot before it is ready for testing and the competition.

Having gotten ahead on the mill during the first week, we have mostly been able to use the drill press and band saw to make the final holes for the less critical parts. We have also used the drill press for holes that depend on other parts, so that we can use a center punch to mark the exact location where the parts need to fit together relative to eachother. We have also spent time on the lathe, making the axles for the robot and on the arbor press to assamble the wheels, gears, and axles.

The biggest problem that we have run into recently was an error on the arbor press that resulted in a bent axle which needed to be remade from scratch. We have also realized that a few of the components did not work as we had predicted in the CAD model, and we have had to alter our design accordingly. We also did not pay attention on the arm parts, and accidentally drilled in the wrong location on one component, and on the wrong side of another. These errors will not affect the effectiveness of the robot, but they will look somewhat unprofessional.