Reflection - Amanda

What did I learn in ME 250? Here it is, broken down by category.

DESIGN AND MANUFACTURING:

Basically everything I learned, I learned in this class. Before ME 250 I made pretty much made nothing, not counting 6^th grade shop class and a silly Engin 100 project. I guess I knew some of the design process, as made sense when we went over it in lecture, but the lectures gave names to steps in the process that before were fuzzy. I found all the info on mechanical components to be fairly interesting, as I didn’t know much about them before. It was nice to get a feel for each component in our kit before actually working with them and know what each component can do. I learned a lot about using the machines in the shop, too, as I had never really used them before.

TEAMWORK:

This class reinforced the things I have already learned about teamwork. If everyone is pulling their weight and getting along, things go very smoothly. If someone doesn’t, it increases everyone’s workload and annoyance exponentially. Also, things often take longer to accomplish when everyone tries to work together on everything. It’s often more efficient for group members to work independently and then come together for discussion. Playing to team members’ strengths is important, too. For example, a few of my team members had a lot of experience from robotics in high school, which made them the best people to start off our manufacturing and teach the rest of us how to do it. That being said, even if a team member doesn’t have experience, there were still valuable ways for them to contribute.

TIME MANAGEMENT:

My time management was decent in this class. One my teams’ reasons for designing our machine the way we did was so that we could finish manufacturing early and have plenty of time to test it. This didn’t really happen. Although the manufacturing wasn’t too complicated, we were still manufacturing things up until the week of the competition. This was partly due to adjustments that had to be made, but I think if we had started manufacturing earlier we could have made even more adjustments and figured out ways to make our machine better. For assignments that we had to turn in, we were often working on them the night before. Although this is not particularly outstanding time management, we still accomplished the things we needed too without too much last minute stress.

HOW THE COURSE CAN BE IMPROVED:

Just as the students could have managed their time better, I believe the instructors could have managed their time better by getting information out earlier. It would have been nice to have a complete version of the rules that wasn’t going to change at all at the very beginning of the class. I understand that this was a completely new way of doing the class, and I appreciate all the work that went into planning the competition, but I think it would have made things easier on us if we were better informed, earlier. Also, I think the kits could have been improved with less variety of materials, but more quantity.

IMPROVING MY PERFORMANCE:

I think I could have improved my performance by going to office hours for the lecture homework assignments. Those killed me a little bit. Also, as previously mentioned, time management could have been a better when working towards the milestones.

Machine Description

Our machine is very simple to understand. It consists of two essential modules: Tape Dispenser and String Arm. These two modules work together to slide a tape measure under the balls, lift them up, and form an incline to move the balls to the opposing slot. The details of the machine are described below.

Tape Dispenser Module:
This module consists of an aluminum framework, wooden box with wheels, tape measure, and motor assembly. This module is dedicated to holding the tape measure and extending or retracting the tape.

Aluminum Framework - This part is simply two sheets of aluminum plate spaced apart from each other with four aluminum posts. There are slots cut into the plate. The purpose of this part is to suspend the Wooden Box above the arena, mount the Motor Assembly, and provided a stable and secure platform for operation. This part also houses the control box.

Wooden Box - This part is constructed of four wood panels. Two wheels are pushed against each other inside the box with a set of springs. This part holds the Tape Measure in place between the wheels and allows the Motor Assembly to interface with the wheels.

Tape Measure - The tape measure itself. The end of the tape measure is cut off and curved so that it will move down the arena slot smoothly and follow along the walls.

Motor Assembly - The motor assembly is a Tamiya gearbox with a plastic gear. It's responsible for spinning the wheels of the Wooden Box, therefore causing the tape measure to extend or retract. It is mounted to the Aluminum Framework.


String Arm Module:
The module consists of a base plate, slot arm, motor assembly, and string spool. This module is responsible for pulling on the tape measure via the strings to help pull the tape through the arena slot. It also acts as a blockage to stop opponent robots from crossing over.

Base Plate - This part is a sheet of aluminum plate. It has a slot cut into it as well as L-bracket pieces mounted on the front. The Base Plate mounts all other parts of the String Arm Module and acts as a stable platform. The L-bracket pieces prevent opponent robots from moving through.

Slot Arm - This part is a welded tube made from steel plate. It is mounted to the Base Plate and extends down into the arena slot. It has has holes to allow the String to pass through. This part is designed to stop the tape measure at a certain height thus forming an incline for balls to roll into the opposing arena slot.

Motor Assembly - The motor assembly is a Tamiya gearbox with an aluminum shaft. It controls the retraction or extension of the string. It is mounted to the Base Plate.

String Spool - The string spool is Kevlar thread wound around the shaft on the Motor Assembly. The string itself is attached to the tape measure. The string runs through the Slot Arm as well.

Final Bill of Materials

Final Bill of Materials

Trade and Expense Sheets

Expense Tracking

Trade Sheet

Week of December 6th

Our machine was finally completed today. We were able to do a lot of testing as well. The machine works exactly like we designed it to. Compared to other teams, our machine might be slightly slower. The tape measure goes down, through, and up the arena slot smoothly. Sometimes it needs assistance from the string to get it going. Once it reaches the other side, the string and tape measure both pull up and form a ramp. This is where we ran into some problems.

Kevlar Thread
The Kevlar Thread was the intended material in our design. It wraps around the string spool nicely and also allows balls through easily. The biggest downfall of the Kevlar Thread is its tendency to snap. This makes the Kevlar Thread the weakest part of our machine.

Fishing Line
In all our testing with the fishing line, it never broke once. However, the Fishing Line is comparatively inflexible and has a very hard time allowing balls to move through it. This also has a disastrous effect on the string spool; it has a tendency to create a mess.

In the end, we decided to go with Kevlar Thread. To remedy the tendency for the string to break, we will apply electrical tape and plastic bits over the sharp metal edges that the thread slides upon. Doing this will dramatically improve the durability of the thread and ensure that thread breakage doesn't occur during competition. The speed of the machine isn't something we can improve upon; the tape dispenser requires a lot of torque to work properly. Sacrificing torque for speed could make our machine useless.

Team Video

Week of November 29th

We spent last week working on the next most important module, the string retraction module. This module is essentially a motor operated spool with Kevlar thread connecting to the very end of the tape measure. This module is used to pull the tape measure up from the bottom of the arena. It also helps bend the tape measure around an angle if it gets stuck.

We spent our time machining the frame to connect the two parts of the machine together. We also did welding work to create the arm that extends into the slot. The lathe was used to create a shaft capable of interfacing with the motor spindle. With all our parts machined, all that is left for next week is to assemble everything.