On February 15 we attended the Longfellow Science Night. We attended this event the previous year and were invited back. We brought our robot and the lander to use to make the kids engaged and interested. Once we were all the set up, the kids began pouring in to drive the robot. We made everyone take turns and use the robot. The kids had to pick up two gold minerals and then score them into the lander. Although we were afraid that the kids would break the robot, we had confident in our robust design. As the kids had fun driving the robot, we spoke with the parents about First and how it inspires us to pursue careers in the STEM field. Several parents asked how their child could become involved in First. We informed them that they could try either find an existing First Lego League team or create one.
On February 14, we went to Longfellow elementary school in hopes of attending their science night. After unfortunately finding out that we came a day early, we were a little bummed out. But as we walked around we noticed that the kids that stayed for their after school program were all intrigued by our robot. We asked the after school counselors if we could show the robot off to the kids and allow them to drive it. They enthusiastically accepted and gathered the kids for a surprises presentation. We gave a presentation on what First Tech Challenge is and how it improves our interest in the STEM field. After answering a few questions, we allowed the kids to drive our robot so they could engage and develop a more profound interest in robotics considering that our robot is practically one big, fun toy.
Once all the kids were gone, we spoke with the counselors about robotics and how they would like to start a summer program concentrating on the STEM field. We gladly offered our guidance for the summer and recommended that they buy LEGO robotics kits considering their simplicity and how it might set the school up to create an FLL team.
Today we decided to start the process of adding lights to our robot. We felt that the lights would add both aesthetic effect as well as aid our drivers during tele-op. To boost the effect of the LED’s on our robot, we cut a 1/16 sheet of poly carbonate with one of the protective sheets still on. This sheet is used on top of the bot. The sheet has two features with one being how it refracts the light from the LED’s making the colors more visible in bright lights and the other being how if a mineral fell onto our bot it would slide off rather than being stuck on top. One feature the lights will have are that when there are two minerals in our sorter, a pressure pad in a position where only the second mineral could touch will detect that. The lights will change color when this happens, notifying our driver that we have collected two and that he can now proceed to score them. The second feature the lights will have is that over time the lights will change color to show how close we are to endgame.
Today we had a conference call with one of our alumni, Fletcher Porter. Fletcher previously took a class on PID controllers and was happy to spread his knowledge on them. We contacted Fletcher in hopes that he would help us solve our overshooting issue on the arm. Our main issue with the arm is that it keeps traveling past its target position. This issue causes much grief during competition because it makes our driver miscalculate and sometimes even lose the minerals in the sorter.
Fletcher started off by explaining what PID controllers are. PID stands for Proportional, Integral, Derivative. These are tools the controller uses to compile past (using the integral), present (using the current position proportional to the target), and future (using linear approximation) data to move the arm as precisely as we can. Using a PID controller will negate this issue we have with the arm and improve our performance.
Today was our second design review. We invited back JPL engineer Mr. Feldmen and Mr. Zarcara from Caltech to judge our robot and our implementation of the designs we spoke about at our last review.
We explained our use of the coin sorter we had shown them at our previous review, and how we were never able to build a linkage that could complete the task of scoring in the lander. Once we finished catching them up on our design, we began to explain the problems we were experiencing and what we could do to solve them.
The first thing we wanted to address was the issue we had with the harvester and how it would sometimes make the minerals fall right out of the robot rather than depositing them into the sorter. We explained that we had suspicions that the sorter could be at too little of an angle and was simply causing the mineral to hit the first mineral and bounce out. After debating about it, we decided to test the robot and observe what would happen. We found that several times, the mineral would shoot out of the harvester very quickly as a result of too much power by the zip ties. We came to the conclusion that the simplest solution would be to simply make the top layer of zip ties shorter, reducing the amount of surface area hitting the mineral on the way out.
Minerals stuck under robot:
Another problem we brought up was the issue of getting minerals stuck under the robot. We showed them a demonstration of this and the scenario that causes this problem. After observing the problem, we found that there was no easy solution to the problem, just ways as to how we could prevent it from happening. We found that by going over the crater very slowly in the beginning of a match, we would be able to slowly descent upon the minerals and push them away from the edge of the crater. This helps us because the edge of the crater is the number 1 spot where we would get minerals stuck under the robot.
Trouble going over crater:
Another issue we had encountered with the current version of our robot was an occasional difficulty clearing the crater. After driving and observing the issue, we found that the problem was a result of bad alignment with the crater. In other words, whenever we would try to go over the crater at an angle, the robot would have trouble going over it. This was thanks to the front of the robot that had particularly low clearance. Mr. Feldmen and Mr. Zarcara both agreed that the easiest solution to this would be to simply cut the part of the robot that was too low. After doing so, we found that we had much more mobility going over the crater and were able to clear it more efficiently. We decided to update our CAD model immediately so our next cut would have the adjusted panels.
Ultimately, we found the solutions to our problems and also received constructive criticism from professionals in the engineering field.
After having our second table top review, we continued to identify and address the several mechanical issues that were slowing down our TeleOp cycle time. The two mechanisms that we found were having the most issues were the harvester and the arm that raises our sorter.
Today we found that the robot was spilling the second harvested mineral over the first, causing us to only carry one at a time. At first, we believed that our sorter was not at the proper angle to allow both minerals to sit inside it. After a few tweaks to our robot in which cut off a few pieces of the Plexiglas that was blocking the entrance of the minerals, we found that it was, in fact, the harvester that was causing the issues. After close review, we found that the third layer of our harvester was too stiff and exerting too much force, reducing the accuracy and predictability of where the second mineral would land. We solved this by simply cutting the top layer of zip ties to a shorter size.
Another issue we came across was that our scoring arm was overshooting, causing our driver to severely miscalculate and occasionally crash into the lander with the arm, spilling the minerals within the sorter. We were not able to find the origin of the problem but expect to address it in our next meeting.
Today we went over what we have accomplished so far in regards to the awards. We came up with a thesis statement for each award category and several speaking points for each.
- JPL and IRobot visits
- Mr. Feldmen from JPL spoke with us about a design process
- Mr. Feldmen and Ray Ray came in and reviewed our design
- Alumni help from Brian
- Lightgear laser cut some parts
- Plymouth demo
- Helped local teams with programming
- Helped clifton with hook
- Monrovia Days demo
- Arroyo Science Night demo
- Tensor flow
- Controls for dumper attitude
- Sonar for walls
- External camera
- JPL Design process
- Fusion 360
- Laser cut prorotuping
- Tabletop review
- Innovative components
- Wood frame-light/cheap/easy
- Compliant Wheels-Crater
- One way latch hook-allows simple drive train, no servos, simple use
- Coin sorter-fewer servos, simple, fast depositing, score from multiple positions
Today we came in and assembled the new panels for the robot. After several hours, we finally had the new robot fully assembled. We wired up the robot but did not have enough time to program it and get it to work. We came across a problem that consisted of the motor blocking the arm from being able to raise thanks to very little room between the axle with the arm and the axle being run by the motor. Fortunately, we solved the arm problem by flipping it onto the other side of the panel. This design of the robot and will have changes for improvements in future meets.
Today we went to Clifton Middle School to use their laser cutter to cut out the new panels for our updated robot. We used many ideas that came from tests, prototypes, and much more from our design process. The biggest changes to our robot are the third layer of zip-ties added to our harvester and a hole for another axle on the right-most panel so that we could add a larger gear to increase the gear ratio for our arm scoring mechanism.
Today we reflected on Meet 1 and established our goals for Meet 2. We decided that we should go to our local middle school Clifton, to cut out new panels for our robot using their laser cutter on Thursday.