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FireHopper
01-13-2009, 11:51 PM
replacing my car's cruise controll, with a updated one with more features, based on a propeller :)


lcd screen for inputing speed and displaying car computer information. (speed/rpm?)

elm 327 interface for getting speed/rpm or use the harness that goes to the built in cruise controll..

read brakes/clutch as the factory one does, allow you to enter a speed via a keypad. factory cruise controll only controlls speed from 35 mph - 99.

mine might go as low as 5mph-10mph depending.

not sure what else I could enhance it with.
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Searider
01-14-2009, 12:54 AM
My biggest complaint about my cruise control is that it has no tollerence for going up a hill. In other words, when I am in manual mode, I will allow the car to slow down somewhat when going up a hill to prevent the care from downshifting. I will also speed up slightly when going down hill. The cruise control does not allow this. It will try to keep the targeted speed going up and down hills with a lot of un-needed shifting and also fuel wasting. you could use a sensor to detect the angle of the hill and then allow a slight decrease in speed when going up-hill.

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Searider
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SRLM
01-14-2009, 12:58 AM
Distance sensor in front that slows you down temporarily (if you come up behind a slower car).

mpark
01-14-2009, 01:35 AM
Hook it up to a radar detector :)

Jay Kickliter
01-14-2009, 02:13 AM
I hope you have a beater and a long closed road to test it out. Seriously, this sounds like a bad idea. Definitely don't use floating point. Would suck to accidentally divide by <1.

Post Edited (Jay Kickliter) : 1/13/2009 7:20:40 PM GMT

Erik Friesen
01-14-2009, 02:44 AM
I have done a very similar thing with a 86 honda and the bs2. I have a few pointers that are important in my opinion.

The biggest problem could be getting a clean signal from the VSS. I would recommend the schematic below. It should work with most VSS sensors.

The next issue is safety. On the honda there are two power wires that come the the original box. One comes from the brake pedal. When the brakes are pushed the power is turned off one wire. This power feeds a PNP transistor that controlls the pull solenoid. The significance is that the solenoid will automatically close whenever the brake pedal is pushed. However you implement it I think it would be a good idea to implement solendoid releases in hardware, not software only.

You also will need to average out the VSS unless it is quite clean. I think it will be quite a bit of trouble to make this work at the slow speeds you want.

Make sure and use clamping diodes on the solenoid drivers so that everything doesn't continually reset.

Having spent hours trying to create a surge free program, and seeing how the audiovox aftermarket cruise is right on the money,(perfect) I would like to find out the algorithm that controls that cruise.

I did something like this. I continually took speed measurements. I then extrapolated the estimated speed in x amount of time. The program then used the estimated speed to control the solenoids.

Maybe someone on this forum has programmed something like this who knows?

Ken Peterson
01-14-2009, 02:59 AM
I think there are one or two PID controller objects out there. Since cruise control is really a closed-loop process control, a PID controller might be appropriate.

I agree with Erik and Jay. Be sure your brake light signal can override the system without fail.

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SRLM
01-14-2009, 06:50 AM
You may want to test it out in a drag racer. That way, you have your parachute to stop you should something go wrong :)

FireHopper
01-14-2009, 10:52 AM
and acutally my car is manual, so I'd need 2 switches. one for break or one for clutch. :)

BradC
01-14-2009, 07:45 PM
FireHopper said...
and acutally my car is manual, so I'd need 2 switches. one for break or one for clutch. :)


I had a friend who installed a cruise control in his manual car and he thought he could get away without a switch on the clutch. It was an old second hand cruise unit with no minimum speed, and *he* never had a problem as approaching traffic lights he would brake and this would disengage the unit. Unfortunately his wife drove the car one day and accidentally engaged the resume function while sitting at the lights with the clutch in. It was the sort of mistake you can only actually make once.

Can you say "Holy block Batman!"

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Cardinal Fang! Fetch the comfy chair.

FireHopper
01-15-2009, 05:26 AM
ouch

mikediv
01-16-2009, 09:12 AM
FireHopper (http://forums.parallax.com/member.php?u=42126),, thats interesting I have never seen a cruise control in a manual car, what happens when you come to a big hill or big downhill?? is there some indicator to tell you to shift? I would be interested in the theroy of operation if you dont mind. I just can't see how to get around the manual shift part

BradC
01-16-2009, 10:06 AM
mikediv said...
FireHopper (http://forums.parallax.com/member.php?u=42126),, thats interesting I have never seen a cruise control in a manual car, what happens when you come to a big hill or big downhill?? is there some indicator to tell you to shift? I would be interested in the theroy of operation if you dont mind. I just can't see how to get around the manual shift part


My old mans new car has a cruise control in it. It's a 6 speed manual. It simply tries to do the best it can with limits to stop it trying too hard. You are expected to use your bonce and if the car is slowing down and can't make it up the hill you just change down, drive it up the hill and re-engage the cruise when you hit the top. Generally the engine braking is not strong enough to regulate your speed down the hill and you need to brake manually also (we get pinged here for going more than 10% over the limit so it's worth being very careful on hills)

We just accelerate up to the limit, pop it in 5th or 6th and set the cruise control. I love it personally and it's probably saved my license several times recently.

You could add indicators to say change up/down, but you may as well give the driver a lobotomy while you are at it. You need _something_ to keep you awake! ;)

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Cardinal Fang! Fetch the comfy chair.

FireHopper
01-16-2009, 10:49 AM
yeah I was thinking of putting a keep awake switch in. you have to hit a switch every 30 seconds or something or it'll disengage and sound a loud alarm.

pems
01-16-2009, 11:51 AM
FireHopper said...
yeah I was thinking of putting a keep awake switch in. you have to hit a switch every 30 seconds or something or it'll disengage and sound a loud alarm.


...or redirect the high voltage from an ignition coil to the driver's seat http://forums.parallax.com/images/smilies/freaked.gif

Ken Peterson
01-16-2009, 12:44 PM
I used to own a Saturn with a 6-speed and cruise. It's really only good for relatively flat terrain. I can't imagine using cruise in the mountains anyway.

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·"I have always wished that my computer would be as easy to use as my telephone.· My wish has come true.· I no longer know how to use my telephone."

- Bjarne Stroustrup

RinksCustoms
01-18-2009, 05:52 AM
Ken Peterson said...
I used to own a Saturn with a 6-speed and cruise. It's really only good for relatively flat terrain. I can't imagine using cruise in the mountains anyway.


Torque is king! '94 Firebird Formula (5.7L) LT1 / 6-speed. 1800RPM @ 80MPH in 6th, most hills don't even phase the cruise on mine.

--A parachute is only effective at 70+ MPH.....

I will be implementing this very idea very soon on my friends tow truck using a tach signal and a giant scale hobby servo (sailboat continuous type), and once i get the PTO throttle unit to work good ,i'll integrate it into my ProFI Fuel injection system (Prop based)

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mikediv
01-18-2009, 06:00 AM
Brad-C·· thanks the reason I ask, I have a new 09 Chevy truck its a Diesel automatic if your in cruise control my vette same thing
and touch the gas pedal or brake it kicks out of auto cruise control, so is it a "real" cruise control in a manual shift car
using my example big hill if you just keep letting the auto cruise run will the car just keep slowing down until it starts bogging or will it disengage itself. same thing if going down hill and you start to speed up a lot what will it do? Thanks man I am just curious and trying to picture how· or what it does.
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BradC
01-18-2009, 07:30 AM
mikediv said...
Brad-C thanks the reason I ask, I have a new 09 Chevy truck its a Diesel automatic if your in cruise control my vette same thing
and touch the gas pedal or brake it kicks out of auto cruise control, so is it a "real" cruise control in a manual shift car

using my example big hill if you just keep letting the auto cruise run will the car just keep slowing down until it starts bogging or will it disengage itself.

In this case I just change down and put the boot in manually. It disengages when I hit the clutch in any case. This unit auto-disengages at about 35kph also, so if I ignored it long enough and the gearbox had not dropped out the bottom of the car from all the chugging a diesel does at 35kph in 6th gear, it'd just drop out.


mikediv said...
same thing if going down hill and you start to speed up a lot what will it do? Thanks man I am just curious and trying to picture how or what it does.


The cruise just pulls back the power as much as it can. Its up to the driver to notice the speed increase and hit the brakes to slow it down.

Luckily Perth is pretty flat, so its not an issue that comes up often. I'm with Ken though. I reckon cruise control on mountain roads is just asking for trouble.

It's a drivers aid, not an autopilot :)

I always remember the urban legend about the US Winnebago driver who goes out for his first shakedown run, engages the cruise control and then goes back to make a sandwich thinking it'll drive for him.

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Cardinal Fang! Fetch the comfy chair.

TJHJ
01-18-2009, 12:51 PM
Recently I drove the new BMW 335xi, it has one of the most intuitive cruise controls I have ever seen, as well as some neat features.

Features that I thought was cool,
Active distance control, slows down when you are behind a car, then when it moves speeds back up again.
Uses the brakes to control downhill decent speed, but if the gas is pressed allows coasting.
Has a very nice display that shows the number the current speed it is set at. Located between the two main gauges. Its part of a MFD, but when you touch CC it shows the setting.
Places a mark, on the outer bezel of the speedo, showing the current set point for speed.

The controls are what I though was best. Its a 4 way stick, with a resistance point, I am not sure what type of switches are in it, but it is capable of sensing if you press it to the resistance point, or past it.

So here is how it works, Tap it forward it comes on at your current speed, Back is resume, up or down movement kills it. Pretty standard.

but where it gets cool is, once its on,
Push it forward to the resistance point but not past it, it increases the set speed by 1mph, push it all the way through the resistance point it increases the set speed by 5mph.
The same changes if you pull it back, but it reduces the speed by 1 or 5.
What I liked was if you want to go a bit faster just tap the stick, no messing with holding it down till it accelerates, then stopping at the new set point ect, it just goes to the speed it is set to.

Note, they also did this on the blinkers, a push to the resistance point gives 3 or 5 blinks, through it stays on until you turn.

Also I didnt find the bottom limit, but I did tell it to accelerate to 95mph from about 40, it didnt complain at all, accelerated up and stayed at 95, as long as I could bear the idea of the following ticket.

Just some thoughts, maybe go take one for a test drive, an excuse to drive the new twin turbo BMW cant be a bad thing.

TJ


EDIT : Dont forget that when it goes wrong, the car still can be turned off.... in that moment of OHHHHHH S**********. Do I yank the whole controller out, kick it to neutral and watch it peg the limiter till it hurts its self.....



BradC said...

It's a drivers aid, not an autopilot :)


Now there is an idea that could use the prop to its potential, car autopilot......

Post Edited (TJHJ) : 1/18/2009 6:00:42 AM GMT

SRLM
01-18-2009, 01:17 PM
The Toyota RAV-4 has the increment feature. It's the only cruise control that I've ever driven, so I didn't know its a unique feature. Same thing there though: push the lever up, you increment by 1 mph, pull it down, decrement.