IAP Week 4 - To the streets

Street day for EVT!

We got the trike a flag!

helmets, safety vests and bike tools

roberto as the first pilot

lauren on the trike

In all, it was a pretty successful first day on the streets. Not all our instrumentation is set up so we don't have an accurate speed read out but we estimate the top speed was around 17-20mph.

IAP Week 3 - maiden crawl

Another extremely productive week at EVT.

Sprocket got machined! Here are some action shots!

the joys of cnc machining

done!

hub fits!

After the sprocket got machined we did a couple of tests with the wheel propped up.

Then it was time to get to the hallway!

woops

IAP Week 2 - Lots of building!

IAP Week 2 is over and we are on schedule to be able to make a maiden crawl by next Saturday. This week lots of milling, turning, broaching, drilling, deburring, crimping, tapping, brushing, sanding occurred and we are very proud with the results!

waterjetting the alumnium (thanks Javi!)

Broaching the key on the sprocket

sprocket has been keyed!

fitting the bulkhead connectors

looks like the parts fit! time to sand and clean them!

yay! motor fits!

eric and joey making connectors

data connector layout

getting ready to rivet the angle stock to the waterjet plate

erich lining up both pieces carefully

the riveting art of riveting

notice our temporary acrylic sprocket (steel coming soon)

ready to assemble! 

putting in the new stays

looking pretty thus far! (notice the sexy bulkhead connector)

getting the motor in place!

"fully" assembled!! shorter u-bolts and steel sprocket coming soon!

1

starboard side of the trike

rear of the trike!

everyone tweaking the mounts

a video of the motor turning! (tension needs to be adjusted)

jacob on the trike!

woohoo the brake firmware/motor control works! thanks EE team!

in order to get familiar with HSMworks on the EZ track Jacob and Roberto machined a piece of abs with same features that are going to be machined on the steel sprocket this coming week (thanks to Andrew Carlson for the help!)

IAP 2014 Week 1

IAP is a very busy time for us! Lots of design, machining and electronics going on these past couple of days as we ramp up to be able to drive the trike around the block by the end of the month!

Following are a couple of photos of the progress made by mechanical sub-teams, in another post the EE dudes will be posting their advances as well! lots of CAD advances this week, we plan to waterjet the plates this week!

sexy EVT chainguard and nice hollowed out sprocket

note how the data and the power connectors mount on the aluminum

Hollowed out sprocket under max chain load. Stresses are reasonable.

lauren busy machining

finished sprocket adaptor

sprocket adapter  mounted!

ubolts for the base done!

2nd Laser Cut Drive Assembly

Happy Holidays and happy new years to everyone!

We have fabricated a new laser-cut prototype with more details. Next up is the waterjetted final assembly.

The structural support for the motor is comprised of three plates which we
named "Base", "Shark Fin", and "Rear Fork".  As shown in the photo, we
laser-cut new plywood prototypes of all three.  The seat is supported with
aluminum angle, which might be the actual pieces that we use in the final
build.  The actual LMC-170 motor had indeed arrived and was relocated
slightly in the new Shark Fin plate, so it is now well clear of any
interference.  The Base plate still needs to be remade to solve U-bolt
alignment and clearance issues.

We have received the LMC-170 motor and intend to install it during IAP.

second laser cut prototype

Custom Electronics from the EE Team

Overview

The EE team this year is working on some custom electronics in addition to all of the COTS (commercial off the shelf) work we do on the larger electric vehicles. Our responsibility has grown to not only include the interface and safety circuitry for the large motor controller, battery pack, and system logger for the trike but also a variety of custom electronics.
We have two (new) main projects):

1. Electronic actuation of a brake system for the NY bike trailer
2. A custom BMS (battery management system) for small (bike) to medium (moped/go-cart) electric vehicles

In addition to these two tasks, its also my job to teach electronics to the EE-team; the engineering goals of the projects have to balance cost, effectiveness, and the potential to teach electronics design principles.

Our lab space was recently upgraded with a new electronics test bench (courtesy of the MIT Edgerton Center) to accommodate, in part, our new role.

Brake system

We needed a way of actuating a pair of rim brakes on the bike trailer, and while a mechanical linkage was preferred initially, mocking up the requirements for quick disconnects and cable pull routing lead us to shift to electrical actuation. The system uses a worm-driven motor to pull and release the brake cable; because this can not be back driven (a property of the work gear) the motor does not need to stall to continue apply brake force. While the ME's worked on enclosures and mounting, team produced a schematic and a board layout for this task using an Attiny85 micro-controller at the center. 

Layout for NY-bike-trailer-brakes

Battery Management System

We are working on a battery management system that is fully modular. Someone who wants to build an EV, once our system is complete, could connect several 4s2p modules together with a central controller to form a 'smart pack' capable of self balancing and charging. We are still at the system design level and currently working on a digital communications bus to communicate between all of the individual modules.

More updates are coming your way in the future.

Follow us on github

Mock-up of the Drive Train config

Busy day today at EVT!

The MechE team built an awesome mockup of the drivetrain design out of laser parts, sprockets and zip ties.

yes... our final version will have acrylic sprockets!

lauren and erich dismounting a wheel