Brad's Reflection

ME250 has been an exceptionally demanding class.  In several ways this was a function of our Team’s ‘bot design (see “Most complicated Design” award), and I understand we brought this on ourselves.

However, the requirements of scheduling shop time, completing milestones, completing labs with homework, blogging, keeping track of all the course communication avenues and data, making videos, scheduling teamwork, going to lectures and labs across campus…this class needs to be worth 2 more credits, should come with a free smart-phone including a ME250-dedicated application, and also several get-out-of-work-free passes for other classes, activities, and jobs.  

Time management has been critical, and I think as a team we were reasonably successful in this realm.  Our ‘bot has been recognized as complex, but as a testament to our time-management we still completed everything on (and even occasionally ahead of) time.  A big thanks goes out to everyone on the Team for not procrastinating…we would never have made it out alive if we hadn’t been on our game every day.  

I greatly enjoyed the design process related material.   Developing creative thought methods is very important.  Ideas on how to capitalize on (and compensate for!) being a very-right brained individual were greatly appreciated.  I crave opportunities to work with a team of dedicated individuals in an environment focused on generating creative solutions to a diverse set of problems, so the presented alternative methods for idea generation and process flow were very interesting.  System-level engineering is a rewarding and natural mode of operation for me; I’m wondering if I should just move back to Providence and transfer to RISD (a joke, although RISD girls are certainly a fascinating bunch). 

Speaking to my tendency to think at a systems level, I would have appreciated more tutelage on the specifics of machine design.  I don’t feel I learned enough about the use of the presented components/systems.  This being a 250-level course I’m guessing (and hoping) there might be a greater focus on such topics in later ME courses, and also projects focusing on specific components.  I also acknowledge that I am a non-traditional student with a background in and deep passion for technology, and my motivations, knowledge base, and desired learning depth are not likely the same as a traditional sophomore. 

As time progressed and I saw the complexity growing I was repeatedly reminded of this chart Professor Hart presented to us:

While we certainly should have been more conscious and avoidant of it I think the ‘bot complexity was a result of the Team’s desire to live up to our team name, and this is a positive thing.  It speaks volumes about our personal expectations and the trust we placed on each other.  Looking back, all I would have done differently is approach system design with a much higher focus on weight optimization.

I’m very glad to have been introduced to 3D CAD, it’s a skill I’ve been missing and wanting to develop for many years.  I wish there were more tutorial sessions on more complex functions available in Solid Works, but I guess that’s what the software’s included help files are for…  The lectures on engineering drawings and tolerance specification were very helpful and the related slides will serve as excellent references in my future projects. 

The production-related portion of this class was huge, and rewarding.  For me it served as a creative outlet, and a much appreciated environment for learning techniques for upping my efficiency and build quality.  I’ve been professionally exploring (and also playing around with) fabrication and assembly techniques for several years and really want to keep expanding my knowledge and skill base in this field.  Learning CAD has been an important step in this!  I really hope I get the opportunity to develop CAM skills in the future.

Overall ME250 has helped me recognize and explore my strengths and weaknesses.  Such an opportunity has not been present at levels this intense and diverse in any other course curriculum. 

Stay On Top,

Brad

Bill of Materials

Bill of Materials

The Final Team Posting

 We've completed our machine and tested her in battle against our peers. The following are some pictures of our completed systems.  A big thanks goes out to the ME250 staff (especially GSIs) for all their advice and votes of confidence, and Bob and John for their knowledge and help in the shop.   




The mobile collection unit in foreground and the slot jammer resting in the back.

The last thing pong and squash balls see before collection!

The sliding hopper door utilizes a rack and pinion gearing system, with a guard over the motor and gearing.

Our undeployed slot jamming device (resting on it side).  You can see the rubber-tipped swingarm which allows us to score slot balls, and the spring-loaded launcher for the main jammer.  Also the aluminum pads which allow the mobile bot to park on top of the system counteracting produced during deployment can be see on the outer housing.

 

This is the slot jammer dfeployed position.  It forces the slot open while a gap in the plastic allows for the scoring of multiple pong balls by the swingarm component.

  

Another shot of the deployed jammer.



A table-top view of the deployed jammer.  Jamming the flipper and scoring pong balls is a 100% repeatable operation
(what whaaaattttt).



A closer look at the ball collection system.

While Im On Top did not progress to the final round of the SlotBotII competition, the system recieved the "Most Complicated Design" award.  While we understand this is a mixed statement, this recognition vindicates the hours of hard, excellence-dedicated work put forth by our four-man crew! 

Bill of Materials

https://spreadsheets.google.com/ccc?key=0AqVvy0w8--M7dExyaElxZjRZR3VCVTAyeng0OW5hVkE&hl=en

Arthur's Reflection

After reading the feedback presented by last semesters slot teams, I knew that this class would require a significant amount of time and dedication. That being said I was still somewhat caught off guard even though the long hours spend working on our machine were probably more due to our design then the layout of the competition. As we progressed through the semester there were feelings of excitement mixed with dread, but in the end I felt that the experience as a whole was worthwhile and rewarding.

In the design and manufacturing phase, I enjoyed the classes on CAD. I had been meaning to learn how to use CAD software for a while now, and the CAD process as a whole was very helpful for designing and visualizing the vehicle. A downside of using CAD was how it made the design process almost to easy, once the vehicle was started in CAD the complexity of the design sort of got out of hand. I believe that our team already had a general understanding of the existence of all the mechanisms covered in the lectures, but the lectures were still useful in the way that they refreshed our memory of all the mechanisms that we could incorporate into our design.

With regards to manufacturing, I believe that everything went relatively smoothly. Our team knew that we had quite a few parts to complete, and we had things planed out way in advance. Problems did still arise such as slight alignment issues with the table, and failure in some of our bought components, but because we had given excess time in our schedule we were able to finish on time. The only thing I was disappointed with was our ability to run practice tests on the table and fine tune things in the end. With only two tables and four remotes with 28 teams though, I’m sure many teams were experiencing the same issue.

Overall, I was very pleased with the strong teamwork in our group. Every time we had a group meeting everyone would show up to the best of their ability. Rather then assign set roles, group members would step up and take on certain tasks. The rest of the group would then discus and critique the result so that we would have a solid finished project.

If I were to redesign the machine, I would make numerous changes. Our design was focused around the fact that we would gather up all the balls on the top of the table. In hindsight this is an incredibly unrealistic feat to accomplish in 90 seconds. Overall, the strength of the machine’s components were significantly stronger then they needed to be. This lead to a heavy vehicle with a slow rate of translation as the double gearbox was unable to over come this. Despite the disappointing performance by the double gearbox, I was happy with the performance of the flipper and the hopper release. The machine easily gathered up all three types of balls if only we could get the vehicle to them.

With regards to the competition, there were a few things that I thought could be improved upon. Most of the teams could have performed significantly better if they had a week of testing to make slight modifications to their machines. In addition I believe that the overall time of the competition rounds should be lengthened. When I first envisioned the game, I thought that most of the balls would be collected. Except for Team Boss which had a very effective and well built design, no other teams came close to bringing in large amounts of balls.

Video Introduction

Here is our introduction video for the competition!

This will be the last thing enemy bots will see before they fall in competition....

Final Week Until Competition

The last week of school is on the horizon and with that our completed assembly. Thecompletion of our project was to a great relief as hours and weekends were spent to complete this for the slot b0t competition. We did however come across many bumps within this past week. One of them had to do with the drop bar. As we tested it on the tables found in the machine shop, we noticed that the tables were not designed equally. In particular, the slots of the tables were not the same. one was measured to be 2.33 inches wide, while the other was found to be around 2.4 inches. The reason forthis major difference was blamed on the warping of the plexiglass. Due to this warp, the slot was smaller than it was previously designed. This big difference affected how the slot jammeroperated in the slots. With a smaller space, it was difficult to install the slot jammer within the 2.33" wide slot. However, our slot jammer operated easily within the 2.4" wide slot. After talking to the instructors and GSIs, we were told to modify our design to fit the natural variation seen in any design. Therefore we came to the solution to cut the entire slot jammer in half and weld it together in order to make the widthsmaller.

Another problem that we came across had to do with our track wheels. With the enormous amount of torque that our double gearbox produced, the shaft filed down the inside of the wheels and were unable to grip onto the shaft. We came to a solution that involved clamps, in order to deform the plastic onto the shaft.

Even with all of these set backs, the assembly fit together, and we were able to have a completed assembly. A net was constructed to contain balls within the hopper as the flipper motor was observed to be powerful enough to flip the balls over the hopper.