Cruise Control (with MPG sensitive logic)

[getnpsi]

I just pulled the trigger on the CCS-100. Should get it next week. A question about driving operation: when you step on the throttle to pass someone or speed up a lot, as when vacuum goes to almost zero on acceleration does the system react funny? In other words does the system work the same as if it was on the VSS or do you have to reset and restart/resume it?

[MetroMPG]

When mine was working, it didn't care if you over-rode it with the throttle. The set point stays. (But I never went to 0 vacuum.)

[getnpsi]

I don't like how "when mine was working" sounds! Is this a poorly made product, or did you have a hand in why it's not working?

[oldpecan]

hope posting this link isn't redundant or misplaced:

(seems like early versions of this concept might have allowed the truck to go 150 MPH downhill!)

Predictive Cruise Control unveiled for trucks

similar to what MD2000 (on p. 8 of this thread) learned about Toyota's future GPS-informed cruise control

[2005_rs]

Originally Posted by brucey

That is some really neat stuff with the cruise control. Although the idea of simply hooking up a bicycle gear shifter to the throttle body seems simpler (KISS), this is definately better to impliment in all cars.

It occurred to me that a combination of both ideas might work.

The existing cruise control could be used to hold the throttle position by building a pulse generator to feed the signal input. The cruise would recieve an unchanging signal, and would therefore hold the throttle steady. No cables or wires through the firewall.

[rjacob]

Originally Posted by 2005_rs

It occurred to me that a combination of both ideas might work.

The existing cruise control could be used to hold the throttle position by building a pulse generator to feed the signal input. The cruise would recieve an unchanging signal, and would therefore hold the throttle steady. No cables or wires through the firewall.

I have been thinking the same thing. Have a pulse generator fooling the cruise control into thinking you are going at a steady speed. There could also be a switch that would control the inputs, one setting would feed the steady pulse, the other would feed the speed sensor output. This way it would work as either a cruise control, or a throttle lock.
One thing that I would be concerned about the steady pulse feed, would be if you hit the cruise button to bumb up the speed. It would try to go faster, but since the pulse would never increase, it might keep adding throttle until the pedal was floored.

[Xringer]

Same thing might happen when you tried to slow down a little.
I keep forgetting it's a feed-back system.

Maybe a little micro controller that looked at the TPS and used the
CC up-down lines (from the buttons) to keep the TPS at the same setting??

You could program the timing of the Up-down pulses, so they were slow
and smooth.

[rjacob]

So you could increase the pulse rate for a seconds or two, the CC would think the car sped up, it would release the throttle a little, then you could return the pulse rate back to the original rate. The CC would think the car was now going the right speed again, and hold the throttle there. And if you briefly decreased the pulse rate, it would the car slowed dwon, it would increase the throttle, then you return the pulse rate back to the original, and the CC would think the car was back at speed, and hold the throttle there.

[2005_rs]

Those are good points I hadn't thought of. I'd be tempted to disable the CC up down buttons, at least for a start to get the thing working safely.

Unfortuneately, I don't have the expertise to design this thing. It sounds simple to me, but that's easy to say when I don't know what I'm doing. Is the VSS pulse AC? Can I just hook up my digital multimeter to determine the frequency and voltage?

[rjacob]

It's been years since I have messed around with electronics. And most of what I dealt with was building analog synthesizers. Nothing digital. Not sure if these new multimeters would have features to tell you frequency, or peak voltage. I think an oscilloscope would be used, not that I have ever owned one. But you can probably find the specs online somewhere. Since they make universal cruise controls, the voltage from the speed sensor is probably standard. You might be able to find that in the specs for an aftermarket cruise control. And you might be able to find approximate pulse rates for various speeds. But for this project, you would just need a pulse rate that the unit wouldn't reject. It doesn't matter whether pulse rate represented 40mph, or 80mph. You just want the CC unit to try to maintain the artificial speed by holding the throttle steady.