Monday, June 16, 2014

Trike Trailer Prep Continued

This week's meeting featured the highly anticipated return of some more team members to the Milkdrop, as the summer EVT crew is gradually reuniting and continuing to grow!

In preparation for the weekly meeting, the full-time UROP gang set the tone for the meeting with some long nights in the shop consisting mostly of work on the trike along with a healthy dose of messing around on Roberto's motorcycle...



Productivity from the week before carried into the meeting, with the crew up at 6am and off to work finishing up the frames for the trailer walls!  Although the painting was all done, we continued filling the Milkdrop shop with wonderful scents as we applied clear coats of polyurethane at 4 hour intervals.   

 We also finally adjusted the brake cables on the motors so that they're ready for some testing.  Joey added an intermediate wire to run the power wires to the brake motor through the base of the trailer so that we can seal around it with the silicone and still be able to disconnect all the other wires.

Extra connectors for the brake motor wires

After a long, heated debate, we finally decided that it would be best to just tip the trailer onto the back.  Everything was securely mounted and the weight balanced enough that we didn't have a problem tipping up the massive trailer, and we had an optimally convenient way to apply the silicone caulking in all the exposed openings.  This also gave us a great opportunity to clean out all the dirt that had been slowly building up under the trailer.  Erich showed his experience and mastery with the caulking gun as he meticulously sealed up all the edges along the aluminum frame.

Hanna and Joey continued plugging away on the Xbee work so that we can pull the data from the trike wirelessly on the chase car.  Although there was some trouble sorting through the drawer of old Xbees and figuring out which ones still were in working order, we got one set of Xbees transmitting the data from the batteries and almost finished getting another set to transmit the data from the cycle analyst.

Hanna and Joey mastering Xbees 

Friday, June 13, 2014

Trailer Brakes Update

We've been plugging away on the emergency brakes for the trailer for a while now, finally putting up the pics!  Eric and Rango on the Electrical Engineering team worked through all of the electronics for actuating the brakes a while ago, leaving them just to be mounted.

We stuck with the car window motors after being unable to find a solenoid or other alternative that could offer the amount of power that we needed.  Their worm gear drive makes them very powerful, as well as being unable to be backdriven, which is a helpful feature for pulling the brake cable.  One downside to using them was just that they had very irregular shapes, which made them slightly inconvenient to mount.  The position of the motors below the trailer also caused orienting them to require a lot of consideration so that there was still sufficient clearance with the ground.  We also didn't have symmetric models, meaning that we needed to have separate mounting plates for each side.   

I started mocking up some mount ideas by just laser cutting some crazy shapes out of MDF to find an optimal way of fitting them up under the trailer.  As with the suspension and everything else we've attached to the trailer in the past, I mounted it by compressing it between plates and squeezing it up against the trailer frame as opposed to drilling directly into it.

I tried to make the mounting plates fit the angle of the angle iron that attached the rim brakes.  I ended up going with a 3 plate sandwich sort of setup in which I made the back plate holding the angle iron larger, and compressing the trailer frame box tube between that and a second plate to which the motor was attached, and then squeezing the motor between that second plate and a smaller third plate.  The only problem was that because of the asymmetry, I could only fit 2 hex bolts through all 3 mounting plates on the right side as opposed to 4 on the left, but it seems like the 2 fewer bolts does not sacrifice the structural integrity of the mount.  Here's what the final waterjetted aluminum plate configurations looked like:

Left Side Brake Motor

Right Side Brake Motor

The EE team had steadily pushed forward through all of the work with controlling the motors, and you can see the plans of the custom electronics for the brakes in a November blog post.  Here is a video of Rango demonstrating the firmware.

The only major problem once the brakes were mounted was that they were drawing too much current, which was solved by just adding another DC to DC converter to power them.


Although we didn't use the brakes on our way to Providence, they were securely mounted for the duration of the trip.  The mounting held up fine, but the elements did a number on the exposed steel surfaces of the angle iron mounting plates and parts of the motor.  A much needed cleaning and spraying with the rust restore, primer, and black spray paint cleaned everything up pretty nicely, and now the black finish matches the black bar over the wheels on the trailer.

Monday, June 9, 2014

Summer Kickoff!

After a successful display at Commencement, we were ready to get back to work in the lab on the trike project.  We're hoping to finish up the last bit of work and plan out the trip to New York soon.  Saturday was our first meeting for the summer, and it looks like we're in good shape!

This summer is shaping up to be a very exciting and busy EVT season.  Jacob and I (Jarrod) are the two full full-time UROPs for the team, and a number of other members are around the area and helping out for the summer.  We have a lot of different projects going on, but the priority is still getting the trike ready for New York.  Here're some updates:


We're still plugging away on our wooden picture frame style cage to encase the trailer.  Erich modified the front panel so that if fit around the fixture we mounted to run the necessary wires from the trailer up to the trike.  Now we just need to finish priming, painting, and mounting the plastic within the panels.

We also wanted a slight curve in the top panel, so that we could avoid any potential issues with water puddling up on the top in the case of rain.  Jacob went ahead and ordered some PETG for the walls since it is flexible and could be easily heated and formed if we needed to bend it.  At 1/16" thick, the sheet is also slightly thicker than the clear pvc sheet that we were going to use, and hopefully more durable.  

I ended up just laser cutting a couple ribs that mounted directly to the top panel of the frame and give us the contour that we wanted.  Initially, the plastic sheet fits in decently, with some minor bending at the sides where we might end up bending the plastic.  Hopefully we are nearing the completion of the final waterproofing stage of the trike.


So we finally had to go back and correct the rusting problem that we were experiencing on the steel trailer brake mounts and the surrounding hardware:

The mud and salt from the wet roads on the Providence trip did a number on the exposed steel angle iron and motor mount, and had just been setting up until this point.  We finally took everything back apart, sanded down the pieces, and sprayed it with rust reformer, a couple coats of primer, and black paint to try to minimize the rusting on the New York trip.

Other Considerations:

Hanna also started looking into using Xbees so that we could wirelessly transmit the data from the Cycle Analyst to a laptop on the chase vehicle so that we can keep up with the condition of the trike throughout the duration of the trip.  We also discussed trying to get radio equipment in the helmet of the rider so that we can communicate much more easily on the road.

We also started to briefly look into planning the trip to New York.  Ideally, we want to plan it much more carefully than the Providence trip, so as to eliminate some of the unnecessary stops that we needed to make.  We also considered whether we want to make the trip multiple days, or just continuously drive the entire distance with multiple drivers rotating.  At over 20 hours, it would definitely be a long trip, but many of us felt that a trip from Boston to New York is not quite as exciting of a story if it takes us all week to get there, and we want to show that our trike is durable enough and capable of working through the sustained demand of 200+ miles in 20 hours. If we do attempt the 20 straight hours, then we do need to work out the logistics of traveling at night as well, and install lights and plan accordingly.  We've got a lot more to plan out, so we will hopefully be making these decisions soon.

Saturday, June 7, 2014


We presented some of our electric vehicles at the MIT Commencement yesterday as part of the Mechanical Engineering Showcase.  Big congrats to all of our graduating members!

It was a fun day and everyone had a really good time.  We brought down the Porsche, the Trike/Trailer combo, and Roberto's new EV Cholocycle.  Harry also brought his normal motorcycle for contrast, and Charles displayed his new Chibi-Mikuvan.  We got to present and talk about our work with a number of alumni, students, and parents who were at the event, and it was great seeing that so many people interested in our work.