Dodge Durango drive-by-wire

[Moparnut]

Hey guys...I've been browsing the forums for a while but just registered. Anyway, I'm disabled and trying to modify my '99 Durango so that I can drive it. I want a 2-axis joystick for steering and independent throttle/brake. The systems on the market don't fit my desire to have a high performance vehicle. After I am able to drive (AND have the money to do so ) I plan to have a turbo'd 440 small block installed.

For steering I'd like only 1/3 lock till I hit a momentary switch for full travel. The joystick trigger needs to be fully proportional for throttle. I figure pushing the stick forward for brakes. Gotta be able to do a burnout, right?

Ideas?

[dertsap]

i'm sure some of the RC forums would be able to help you with great ideas ,sounds like your going to have yourself quite the machine to play with ,
good luck dude !

[NEATman]

Moparnut-
Take a look at these vehicle actuators:
http://www.thehoffmangroup.com/Autol...ducts_LA.lasso
You could probbably adapt one of these for the brakes, as they did something like this on Mythbusters, although that was full radio control.
http://dsc.discovery.com/fansites/my...thbusters.html

Ideally, this actuator could be mounted under the hood, and could only pull on the brake pedal arm, and this would allow anyone else to drive the car, and it would appear stock.

The throttle should be simpler, perhaps even a large RC servo motor would do the trick. Alternately, you could try to find a late model drive by wire throttle actuator like one from a new corvette. Mount that under the hood to pull the cable, then remove the pedal potentiometer or encoder, and mount it where you like.

Sounds like fun!

NEATman

[vacpress]

i think you need to be very worried about safety issues! this sounds like the sort of thing which is not allowed on the streets.. i am not sure how well 2 joysticks can replace the more tactile normal driving experience. (insert arguments here about figher jets and other joystick maneuvered transportation)

consider using commercial and specifically designed products for such a project, it would be a real shame to have some RC servo hooked to the throttle of an enormous car being piloted by a disabled person to get stuck or geek out and otherwise hurt the driver or anyone else nearby.

still, best of luck!

[Geof]

There are a couple of organizations that may be able to help you if they have members in your area. One is RESNA, the acronym stands for Rehab Engineering Society of North America but I think the organization now has a different name. You will find information at www.resna.org I think. The other organization is called TETRA but I don't think that has any meaning other than the organization was founded by a chap who is quadriplegic and the name is a bit of a play on words. Both these organizations call on volunteers to dream up things for someone with a disability or to convert your ideas into reality. RESNA is involved with university departments across the country and is involved in clinical evaluation of lots of ideas and products; it is a professional organization for rehab engineers. TETRA is more of an amateur volunteer organization but the amateur only refers to the fact the people involved are unpaid; I think a large proportion of the TETRA volunteers are retired professional engineers keeping their life interesting.

[Moparnut]

Having no mechanical linkage does concern me but, as mentioned, I know it works for fighter jets and heavy equipment. My dad's 1998.5 24 valve Cummins Ram is throttle-by-wire with no trouble in 300,000 miles. I admit the idea was a bit scary at first though it proved reliable. Joystick controls are sold as "medical equipment" but would not be legal unless you have a need for it. I'm more worried about not being killed than meeting the minimum gov't regulations...redundancy will definately be a priority.

Having said that, the normal controls will remain intact. The C5 'Vette throttle sounds like a good idea...does it communicate with the various other computer modules? If I just need the potentiometer and throttle servo it would make life simpler. For steering I'll need a motor strong enough to work if I lost the serpentine belt or power steering pump. I would have a capacitor as well as a dedicated backup battery.

It would be nice to just order giant Futaba servos from Towerhobbies..

[NC Cams]

Drive by wire is NOT the same as R/C although they both rely on servo's to turn electronic signals into mechanical motion.

A basic primer on creating a servo can be found by doing a web search for an NE544 servo IC. Once you find this, you can see how to turn a DC motor into a servo motor with feedback.

A couple of 555's can be configured to create an analog driver for the NE544 that does NOT involve radio control.
There are a number of "pulse width" stretching circuits that can be used to create a "driver" for the NE544 based servo amp using 555's.

At one time, this was an easy to get/find IC. But with the advent of digital circuitry, it has turned into a harder to find "legacy" IC. Took me about an hour to find a source via the internet but that was a while ago.

You can create a drive by wire prototype system that works like a champ on the bench. Bolting it into a car is a WHOLE ANOTHER ISSUE. When I worked at an OEM, they thought they had the drive by wire thing down pat. BUT all of a sudden, the servo feedback pot didn't feedback for some dumb reason and the thing went open loop.

RESULT: they had to redesign the whole thing to add redundancy that they didn't plan on. You have NO idea what that glitch did to the whole program and to the sleep patterns of the product liability people. It is NOT an easy thing to do nor an easy thing to redundantly develop.

Right now, you might merely be disabled. An out of control servo can maime, kill you or somebody else, especially if it is NOT trying to control a Durango gone wild.

CAVEATE EMPTOR!!!!!!

[Moparnut]

Maybe servo assist would be better. Steering is my biggest problem...I could handle normal throttle/brake if I had a thumb throttle and brake lever.

Borzoi joystick car

[Geof]

If you do a Google search for adapted joystick driving controls or similar terms you will find companies that are involved in this type of thing such as this one; http://www.ahnafield.com/

[keebler303]

from the offroad world there are street legal hydraulic assist steering systems which would let you steer with a pinky if setup correctly.

Matt

[NEATman]

I had not intended for the car to accually be RC controlled, I was just stating that that type of mechanics could be used. I have not looked closely enough at the drive by wire servo module on a corvette, it may well be tied into the computer, as it controls tire spin.

Building on keebler303's comment, it may be easier to raise the pressure in the power steering pump by changing the pressure relief spring (increasing the strength). Many hot rodders do the opposite and weaken the spring lowering the pressure, as the steering is too easy on a light hotrod. There are some aftermarket companies that sell lower force springs for this type of application.

NEATman

[Moparnut]

I sent an e-mail to PSC Motorsports about hydraulic assist using a handle bar rather than a joystick. The joystick idea would allow left handed operation and freeing up my right hand to shift gears, though.