Saturday, October 8, 2011

Singapore Post

I was in Singapore again last week for the Singapore University of Technology and Design's first ever Open House.

When I went to Singapore last year, SUTD had just the two upper floors of a Chinese language school, mostly for administrative offices. Now, it has fully moved in to the interim campus, part of the ITE Dover Campus. We built up a small workshop ("the shed" or Gecko Works) at the interim interim campus, which has now been transplanted to a room at the interim campus:

It was cool to see the shop space I helped put together actually being used by future SUTD students and faculty to work on projects. I was expecting the interim campus to have a full shop, since it was formerly part of a technical institute, but it seems Gecko Works is still the primary fabrication space for SUTD. That makes our trip last year seem like a pretty good investment of time, actually.

As you can see in the above picture, Charles and I significantly increased the number of moving vehicles on campus, as usual. But in fact, some of the future SUTD students have been forming an Electric Vehicle Team of their own, using an electric bike we got from MKP Bikes last year as their first vehicle. It's been converted to a chopper bike, and now runs on a frightening amount of lithium polymer battery. You can see it towing half of the SUTD student population here:

Also featured in the video above are a fire ant-motivated top speed test of Pneu Scooter and Charles taking RazEr Revolution's name literally.

Pneu Scooter's officially-measured fire ant-induced top speed: 21mph.
Pneu Scooter actually took its very first test drive in Singapore last year. I finished building the frame and began testing on my 3ph v3.x line of controllers during my last trip. Unfortunately, the v3.0 controller had serious electrical noise issues, so I redesigned it when I got back and wound up with the v3.1, which has been ultra-reliable for almost a year now...

...and then two of them broke on this trip. I don't really know what happened since both times it was being ridden by someone other than myself. (Not that I would know what exactly caused the failure if I was riding it, but I could at least eliminate some possible causes.) My theories are:
  1. The ambient temperature in Singapore is just that much higher than it is in Boston, and the FETs failed due to thermal overload after basically racing it around all day.
  2. Since replacing the rear wheel a few weeks ago, the motor timing had shifted enough to cause commutation failure, leading to a destructive current spike.
I would weight theory #2 a bit more heavily since both controllers (the original and the spare) had the same phase fail. In any case, having burned through even my spare controller and having neglected to pack an extra IXYS module, I went back to MKP Bikes for Plan B: an off-the-shelf e-bike controller similar to the one I used in Singapore last time when my controller also failed. With that, I was able to get through the Open House. When I got back to Cambridge, I promptly changed the FETs on my controller:

Precision MOSFET removal tool.
All the gate drive was in working order, which is unusual after a FET failure. I re-timed the motor and have been riding it around with no issues, so I still have no idea what the problem was. I am going to pretend that nothing ever happened. But I did buy all the GWM100 IXYS modules remaining on the internet.

Scootering around at the Open House was not the only thing I did in Singapore for a week. Earlier, we visited a place called evHUB, which is a Singapore-based electric vehicle conversion and R&D house. They  have a somewhat hidden EV showroom/dealership with the name FSG Mobility Concepts, where I continued my trend of finding Tesla Roadsters scattered around outside the US.

In addition to the Tesla, FSG also carries the YikeBike. Rather than dedicate a paragraph of this post to describing the YikeBike, I'll just put in a video of us attempting to ride it:

I think the evHUB crew had an easier time learning how to handle Pneu Scooter than I had learning how to ride the YikeBike. Also the YikeBike is more expensive than Pneu Scooter by about the same ratio as the Tesla Roadster is to the YikeBike. So I'll stick with the kick scooters for now.

I also brought over 4pcb, my mini PCB quadrotor. It still doesn't fly spectacularly, but I wanted to bring it because I was meeting up with Ali S. to see his somewhat larger quadrotor in action...

Recursive quadrotors...
The exhibition hall actually turned out to be a perfectly reasonable place to fly a mini quadrotor and a perfectly suicidal place to test the one with 10" blades. For that reason, the mini one got a bit more air time. Here it is taking a few short hops:

It still needs work. After returning, I replaced the one weak motor and it at least hovers level now. But at some point in the near future I will replace the IMU with a different board. Not because I think it will necessarily handle the vibrations better, but because I am just sick of dealing with this one. And because Sparkfun doesn't make this one anymore.

I also got to visit most of my favorite Singaporean hobby shops and industrial centers. (I am such a bad tourist...) So overall, another successful trip to Singapore. I don't know how frequently I'll be going back, but I'm sort-of used to the climate and I seem to have a system for dealing with jet-lag. (I just sleep for the entire 25-hour set of flights.) Soon, there will be actual students and classes at SUTD, so maybe I'll go for an entire semester next year.

Because clearly this is my type of university.
For now, though, I have resolved to stop doing anything resembling a demo/expo/faire/whathaveyou for at least a few months. For one, I'm tired of answering misinformed technical questions from the slightly-more-tech-savvy-than-general public. I might just sound cranky but there's only so many times you can explain that MEMS rate sensors are not the same as flywheel gyroscopes without going crazy. Secondly, I am tired of having my vehicles turned into amusement park rides and then having to repair them after every event. And most importantly, I don't actually get any work done on new projects when I'm constantly exhibiting old ones. It's fun, but I need a break, so no more demos until at least IAP.

Now, what was I working on?...

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