Mods for robotic VX

[Art]

Art,
No, 33/12.50-16's will not fit without a lift AND fender trimming. I think you should be safe running 31's without problems. Its been a while since I ran tires that small, so you might want to refer to a couple of the many tire size articles on the site. The subject has come up fairly often.
Andy

Here's my current thoughts on tires, I like the Parnelli Jones because of the "E" load rating (thicker sidewalls to protect against rocks). Use STAUN internal bead locks at 48 lbs and run the tires at 25 lbs pressure. Use
TXT PRO tire sealant to plug punctures.

http://dirtgriptires.com/default.htm

Stock Number: PJ-06R
Size/LR: 31X10.50R16/E
Cross Section: 10.300
Tread Width: 8.800
OD: 31.500
Rim Wid Range: 7 to 9
Max Infl: 80 PSI
Weight: 58.5 lbs
Max Load: 2910
Tread Depth: 21/32"

Tire sealant: TXT Pro
http://www.sparty.com/techinfo.html

Bead locks (at 48 lbs):
Rim 16" x 7 to 8": SBL1678
http://www.eco4wd.com/products/Hardw...unProducts.htm

Tire pressure: 25 lbs

Comments welcome!

[Maugan_VX]

As it relates to mods for a automated VX, I'd definitely put selectable lockers in both differentials. They can really get you out of a jam if the need arises. You just have to come up with the programming and hardware on how to activate them.

[Swordy]

I think after you try the tires you'll find that 25 lbs is still pretty stiff. I would suggest trying them at 25 and at 15 and notice the difference in traction and handling on rough dirt roads.
If you are using those internal beadlocks you could actually run at 0 psi if for some reason you chose to. As for the tire sealant, I'm not sure about that brand, but some brands will cause aluminum oxide to form inside the rims making them brittle. I'd also find out from staun if tire goop will hurt the internal locks.

just thoughts

By the way, is this thing gonna be able to shift in and out of 4 Lo? or will you just leave it in 4 Lo? With a top speed of 40 it wouldn't be out of the question.
Most importantly,, when you run this puppy across the desert, let me know. I'd reallly like to watch.
Andy

[Art]

We have no plans to use 4 LO at this time, our plan is to let TOD do it's thing. We might decide to use 4 LO after testing.

Good points on the compatibility of the tire sealant and bead locks, I've sent an enquiry to both companies.

Good point on tire pressure, we need to test this.

Regarding when we will test this in the desert, that depends on whether we are selected as one of the 40 teams that go to the qualifying event in September.
We are currently testing in private ranches in Central Texas. Provided all goes well and we advance to the next round, we will be doing longer test runs in canyons in west Texas during the summer months and in California in September; the race is October 8.

[Maugan_VX]

I'd honestly rip out the TOD and put it in 4LO the whole time if you're only going to be going 40mph tops. TOD is just something else to go wrong, and if you get stuck, TOD will just be a bit late to get you unstuck.

Now what TOD MIGHT be useful for is hooking up to your computer to detect wheel spin, and if so, turning on a locker.

[Art]

We have access to the wheel speed information thru the on-board diagnostics port, let me think about this. Educate me on the lockers vs 4LO, I thought 4LO locked the differentials, is the locker you are thinking of different?

[Maugan_VX]

4 LO will only put the VX in full 50/50 power transfer mode between front and back full time. It will also change the gearing in the transfer case. (the Low part of LO)

When you have open differentials on a vehicle and one wheel loses traction for some reason, no power will be transferred to the other wheel on the axle, therefore giving you no power to the wheel with traction. A locker will "lock in" that differential so theres torque going to both wheels regardless of the position of the other wheel. This is very beneficial while offroad but does not allow the car to maneuver very well when traction is good like on pavement. Thats why its important to have a selectable locker (ARB) so you can turn it off when you don't need it.

[Art]

Maugan_VX: Thanks for the education!

I found this post that indicates the following part numbers fit the VX, does anyone disagree:

Front is part # ARB RD94
Rear is part # ARB RD44

Is this a reliable supplier:

http://www.ok4wd.com/product.asp?id=20

Thanks!

[Triathlete]

You might also try 4Wheel Parts . They sell the front/rear as a kit and throw in the compressor for free.

[GoIsuzu]

I'd go with laptops. TuffBooks for starters are designed for harsh operating environments and are probably tops when it comes to resisting damage caused by excessive vibration/impacts. From there I'd mount the laptops on anti-shock plates. A good home-made solution is to place a metal plate on top of a sealed bag of motor oil. The oil in the bag dampens vibration. The metal plate on top will sway/wave rather than vibrate.

I use an older Dell laptop as the "brains" of the DashPC/sound system in my Mits 3000GT and the suspension on it is pretty tight. Haven't had a problem with the computer so far.

So again, I'd definitely go with some laptops for your on-boards.

[Art]

A good home-made solution is to place a metal plate on top of a sealed bag of motor oil. The oil in the bag dampens vibration. The metal plate on top will sway/wave rather than vibrate.

We have chosen our computer systems, but not our shock isolation strategy. Thank you for your suggestion for shock plates. We will give that a try!

[Swordy]

Unless you are using an Ai type system, I think I'd skip the front locker. The steering is soo much different when the front is locked. It won't just go where you point it. Plus it may or may not imediately disengage when turned off. It sure would help get out of being stuck though. The solid state hard drives would be sweet too, but those are some pretty pricey little drives. Last time I checked a decent size one was like 4 to 5 grand. I guess it would cure about 95% of your vibration concerns though.

And yes, those are the correct ARB part numbers.

[Maugan_VX]

swordy: the lockers could be engaged while there is wheel spin present. I'd think they'd be smart enough to program the thing to get itself unstuck first, THEN get back on course.

I dunno, I'm pretty uneducated about the whole competition. It just seems logical for me to get out of a rough spot before concentrating on where I want to go. Of course the trick is to never get in the rough spots.... where do you start. I need more beer.

[megadan]

I don't want to sound like a downer, but your choice of vehicle for the DGC is largely irrelevant. It's not an off-road vehicle problem - it's a computer vision and mapping problem. I know, I was a software engineer on one of the original teams and spoke AT LENGTH to the DARPA people during the kick-off meeting at the Peterson Museum here in LA. We built a vehicle with dynamics that would pop the front windshield out of a VX at speed, so I am quite familiar with the development tree. And out weak point was software, not the "airframe."

80% of the 2nd gen teams out there thing they can solve this comp with a super off-road machine. What you need is some super software engineers in the areas of digital vision, path planning, fast control systems, etc. As a basic litmus test, if you can pretty much ignore GPS positioning in your Kalman filter, then you have a shot at getting into the course. (If you don't know what a Kalman is, then don't start cutting up your VX!)

Email me if you want, dan.danknick@gmail.com

Dan

PS: If you're just doing this for fun and don't have any serious intent of doing well, then ignore all of this and enjoy the ride!

[Maugan_VX]

How is a digital camera supposed to tell the difference between good traction and no traction?

I understand that it can identify obstacles, but sometimes you need all 4 wheels delivering power at once.

And if they wanted the ultimate offroad vehicle, I don't think they would have picked a VX.