The project this semester has been a practice in comunication and design alteration due to oversights and lack of communication in our first semester.
The first big problem came when we realized nobody had been working on propulsion design the entire first semester. Apparently, groups either didn't think of it or thought someone else was going to work on it. So we needed a motor that would be small enough to fit on the bogey and powerful enough to propel it up the slopes we added in to the track. I volunteered for the duty of finding the motor and working out propulsion, with the help from others in my group and the EE team.
Unfortunately, the scale we had chosen the previous semester alongside the increase in power needs for going up and down slopes made finding a motor very difficult. In the end, even the smallest motor I could find that fit our power and torque requirements was so large we had to move its location to between the two bogey sections. We ended up choosing the Crystalyte 408, a hub motor built for electric bikes, with the 4825 controller. It will need to output 0.6 HP and exert 95.5 N-m to get the podcar up the slope.
The motor and controller arrived on 20 April 2016 and I obtained epoxy and rubber tires to fit around the motor.
The next steps are to finalize the motor mount which will press the motor wheel into the ceiling of the track, and to interfact the controller with an Arduino to control the bogey.
Monday, April 25, 2016
Monday, September 14, 2015
Preliminary Sketches For Bogey Fail-safe
The second idea was simply a static arm from the side of the bogey that would catch the car should it fall off the track for any reason. I placed wheels on this arm so that the car could still be pushed along the track while it is hanging.
In both ideas, I felt the ability for the car to retain some ability to be moved along the track after failure was essential so that it may be quickly cleared from an in-use track section and brought to a station for repair without needing another vehicle to come disconnect it from below. While I don't think either is or should be the entire solution to the fail-safe problem, they and other ideas like it will help the team get closer to a reliable system.
Shortcoming In Track Design
As part of preparation for this project, I read through last year's report, focusing on the areas related to the mechanical design of the bogey, the track, and the scale model. I did note the lacking of functionality made apparent in the very first meeting, namely the lack of a fail safe, the slow switching of the bogey steering mechanism, and the need of track redesign to support the addition of elements such as wayside power pickup. As I'm sure many people have pointed out these problems in their own blogs already, I'm going to focus on something I mentioned in my last post: the track network design.
During the first meeting, I did the following sketch to explore what a potential four-way intersection would look like:
As the image shows, there are a great many problems with an intersection like this using static track segments. Two cars cannot be going in different directions along the same track, so parallel tracks would need to be used somehow. The problem then is in looking at the implementation of a traditional intersection done without expanding the tracks vertically. One track can be split into many directions, but not without cutting off tracks coming in from different directions seeking to go elsewhere.
In brainstorming a solution to the problem, my initial idea is to simply make networks out of nothing but continuous loops, with the cars traveling exclusively along the outside of these loops. However, more specific implementation and possible needed exceptions to this will need to be explored before a large, expandable system can be implemented.
During the first meeting, I did the following sketch to explore what a potential four-way intersection would look like:
In brainstorming a solution to the problem, my initial idea is to simply make networks out of nothing but continuous loops, with the cars traveling exclusively along the outside of these loops. However, more specific implementation and possible needed exceptions to this will need to be explored before a large, expandable system can be implemented.
Wednesday, September 9, 2015
Weekly Update - 2 September, 2015
During last Wednesday's meeting, we opened with short speeches to introduce ourselves, our engineering interests with regards to the project, and some of what we had read so far in the INIST library. It had unfortunately been a while since I had taken Public Speaking. While I had prepared a short speech, I feel I did not deliver it very well as stage fright set in and I spoke more rapidly than intended and skipped some of the content. It was not a great first-showing, but I believe I will do better in the future as I grow more comfortable with the Superway project group.
After everyone had delivered their minute speech, we had a quick tour of the Spartan Superway Design Center (SSDC). It was slightly redundant since I had seen much of it the week before at the first dinner meeting, but there were some new things pointed out as well.
After the short tour, we broke off to form groups, talking with other students about what different people wanted to do on the project. I went over to the full-scale group to talk about the gantry. We split off into two general groups: one to work on a suspension and the other to work on a fail safe. I tentatively joined the latter, thinking my mechanical design focus would do the most good there.
After that, the meeting was done. However, I wasn't entirely done. During the meeting, I had done some quick sketches of what intersections for the Superway network might look like and noticed some problems. When I asked Dr. Furman if the team had designs for intersections worked out, he told me that that would be my job (obviously meaning the whole team, but I took it to heart). So I did some thinking about what the full track network might look like, and made some progress. I have taken it upon myself to work out some of those logistics, since I find that kind of thing fun, and will try making a mock-up network and posting the ideas here on the blog some time in the future.
After everyone had delivered their minute speech, we had a quick tour of the Spartan Superway Design Center (SSDC). It was slightly redundant since I had seen much of it the week before at the first dinner meeting, but there were some new things pointed out as well.
After the short tour, we broke off to form groups, talking with other students about what different people wanted to do on the project. I went over to the full-scale group to talk about the gantry. We split off into two general groups: one to work on a suspension and the other to work on a fail safe. I tentatively joined the latter, thinking my mechanical design focus would do the most good there.
After that, the meeting was done. However, I wasn't entirely done. During the meeting, I had done some quick sketches of what intersections for the Superway network might look like and noticed some problems. When I asked Dr. Furman if the team had designs for intersections worked out, he told me that that would be my job (obviously meaning the whole team, but I took it to heart). So I did some thinking about what the full track network might look like, and made some progress. I have taken it upon myself to work out some of those logistics, since I find that kind of thing fun, and will try making a mock-up network and posting the ideas here on the blog some time in the future.
Introduction
A senior BSME student at SJSU, Christopher McCormick is yet untested as a professional engineer. He joined the Spartan Superway project hoping to contribute to the mechanical design of one of the most important projects presented to the senior class. He brings to the project leadership and communication skills learned as an Eagle Scout as well as everything he has learned in mechanical engineering classes at SJSU.
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