Power series racing
|Power Series Racer|
The goal of this project is to:
1- Make an awesome racer!
2- Promote cool projects and teamwork within the space
3- Use as many areas of the hive as possible! (Welding, 3d printing woodworking, laser cutting, electronics/soldering, Mill, CNC, ECT.)
4- Did I say make an awesome racer? I mean seriously, burnouts in the parking lot! (depending on the tire budget)
- Contributor 1
If you're a part of this, please edit and add your name so that you're part of the team!
Approve initial budget
Begin concept creation
3- Settle on a concept and order electronic components to design frame around
4- Search for and purchase cost effective batteries
5- Begin CAD design
6- Design out drivetrain goals
7- Finish CAD frame design and manufacture frame assembly
8- Finish CAD drivetrain design and manufacture drivetrain
9- Wire up electronics/drivetrain and begin testing
10- Mount seat and run first driving tests
11- Finish CAD exterior design and begin manufacture
12- Compile pieces and begin shakedown testing
- [Power Series Rules] Seriously, read the rules
- [Budget Spreadsheet] If we buy something, put it on the spreadsheet!
- [Files go to this drive!] Cad, design, sketches, resources, etc
- [MIT's ChibiMikuvan] And this. It's a complete talk about the build up, racing, issues, failures, successes, and results of the racing, VERY WELL DONE
- [MIT's Current limiting Solution]
- [Charles Guan's "How to get hybrid Batteries"]
- [Battery Value Calculator]
- [A great start guide to chargers and batteries ]
- Batteries (18-24v NiMH batteries @ ~25Ah, ideally from an old hybrid pack)
- ESC (2x amperage required to achieve 1440W)
- Motor (sized to provide 1440W @ selected voltage)
- CAD design (solidworks)
- Steel Tube (frame)
- Tires (must be capable of withstanding abuse)
- Drivetrain (gear reduction to allow maximum acceleration without limiting top speed)
- Creative Exterior to achieve "I AIN'T EVEN MAD" status
- Safety Gear (Helmet, gloves, wrist guards, elbow pads, etc)
- Proper mechanical brakes (15ft stopping distance!)
- Battery Charger
- Throttle linkages
- Steering Design
August 10, 2014.
We met again both Saturday and informally today and a concept for the design has begun to take root! Here's a picture of the ideation board. These are the concepts so far, but by far the mine craft pig is taking the lead.
Who wouldn't want to ride a pig?
In addition Jim ordered a bunch of various bits and pieces that will come in handy once we get into electrical wiring. The main components ordered were the motor and ESC as well as the battery charger. The components should come in in about 3 days and we'll hopefully get to start doing CAD models of actual hardware. Not to mention spinning it up for the lols ;).
August 13, 2014.
Wednesday was a great first official class! We seem to have gotten most of the core items we'll need to start actually putting a kart together! We took MIT's lead and got the same 9" angle grinder they used for chibimikuvan. I mean it's ~$30... it's hard to get it that cheap at harborfreight...
Approximate speed design, IE how fast do we go if we get X motor and Y Size wheels?
Solution: 570Kv motor (rpm per volt) @ 24v with 8" tires
First find the circumference of the tires: 8*3.14= 25.12" Find the rpm of the motor: 580kV * 24v = 13,920rpm How many inches per minute?: 13,920rpm * 25.12" = 349,670 in/min convert to mph: 349,670in/min * 60min/hr * 1/12 ft/in * 1/5280 mi/ft = 331 mph
We'll assume motor under load only makes 3/4ths of that (as a fudge factor) or 248.25mph
Assuming we want to go 25mph max, 248.25mph/25mph = 10/1 gear ratio.
We'll start there and see how it actually performs, fortunately gears/sprockets shouldn't be too hard to change.
Will and Dan worked on Solidworks, the goal for tonight was to make the minecraft pig that we'll be using for the body of our racer. I'd say they did pretty well :) Now that parts have arrived, we'll start doing real hardware so we can make an actual assembly!
Ellie and Franklin put together some code to run my old battlebot shuffle drive train. The code took in a potentiometer signal (producing an analog voltage signal from 0-5v) and outputs a servo signal to control the hobbyking speed controller which is very similar to our actual design. We may use dynamic current limiting like the MIT team, but we'll have to see how the power wheels system actually performs first.
Unfortunately I didn't get pictures because we were running out of time, but you'll see them again before long!
So all in all, it was a very productive first class and hopefully it'll continue this way! I'm also going to change the class structure to Tuesday night being exposition and planning for Wednesday, while Wednesday will be more instructional and I'll assign and help out with the assigned work. This way everyone will have until Tuesday to finish their projects so we can show off progress in the meeting.
As a forward, this week should be a more intense focus on batteries and precautions we'll have to take on our equipment to prevent battery damage.
November 1, 2014.
Updates Updates Updates
Well, first off, we missed the October deadline for the PPPRS racing...
But it's for a good cause. We just picked a date that was much too ambitious for both learning and racing and it's been WAY less stressful to work on the project. (surprisingly enough we all have lives... if only we could fix that... ;) )
That being said, progress has been steady and the team has been doing very well on picking up CAD!
So, the summary of what's been up so far is the following:
Bought a used 2007 Ford Hybrid Escape battery for $350
Ripped it apart
And then stacked all 50 sticks, starting the long long process of charging and testing each cell. They performed really well! we got a good deal! The value is ~5100 (V*mAh)/USD And yes, that's a made up unit I did to try and compare batteries ;)
Then, we had Kirk, a new member who welds regularly at his job, teach us to run weld beads. First learnings from trying to run this class? we should do two classes or a 6hr session. 3hrs isn't enough to be thorough... but I think we could competently lay beads if we ran a few on a test piece first. We'll definitely have a lot of practice soon! As for the rest of it... We'll have to try and write up a wiki page about it.
Now, we've made a few missteps in the last month. We tried to make a universal joint driveshaft linkage for a 9" angle grinder head. On paper it works really well, Without the motor running... it seems to work... and that's the end of the success on that :/. It seems that the shaft needs to be double supported. The bevel gears inside the head grind against each other and produce somewhere on the order of 100+ dB of noise... yeah... Either it was reassembled incorrectly (possible), or the shaft needs to be supported to provide correct supporting of the correct gear mesh. (likely). It's only one bearing supporting the current configuration which makes a lot of sense. Oh well, so much for a modular drive train. Instead we'll try the drivetrain will and I mocked up with a two stage chain reduction. It should also be cheaper than the angle grinder setup!
That's it for October, November should be filled with making parts that move! Yay!