Speed signal pulse rate?

BillyDoc

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Does anyone know that the characteristics of the SP PULSE signal line on the option plug are? I would particularly like to know the pulse rate as a function of speed.

The reason I'm interested is that I've been reading the various threads on cruise control installations and finally checked out the MCcruise website . . . and went into shock over the price. And that's apparently a vacuum controlled unit, just like the Audiovox. So, I was wondering how difficult it would be to put together an "open source" project to design our own. Just as a first look at the problem, it looks like an all digital phase locked loop would work nicely for a speed control, with output to a stepping motor and slip clutch for the actual control unit. All of which would probably cost less than a hundred dollars, with the biggest expense being the four button switch to control the system. Surplus stepper motors are very cheap.

Related to this, are there any other electronic geeks out there who might be interested in such a project?

Bill
 
The signal is designed to feed the European OEM GPS option. You might want to poke around the UK Deauville forum and see what info you can find their... Or any documents on the OEM GPS off the Honda sites in Europe. Another thought is to find out who makes that GPS for Honda and see if they have any tech documents on it... The Euro ST1300 uses the same setup, or so I have read, so you might try the ST Owners forum as well....
 
Thanks Wayne, I followed your leads and at least found out that the speed signal originates at the transmission, or at least aft of it. Or so some posts said. Which means I can put the bike on the center stand and measure the pulse rate myself. That would have been awkward if the signal originated at the front wheel. I hope it's a nice high frequency because that would give very good control.

Bill
 
When Mike installed my Rostra, he measured the pulse rate at that location on the left side of the bike close to the shift rod. The 53,000 number sounds about right, IIRC.

The Rostra from Murph was more expensive than the Audiovox CCS-100, but about 1/4 of the cost of the MC Cruise system.

I will compare my DIP switch settings with some others I've seen one of these days, but it's likely I'll just ride with it like it is until sometime during the winter of '13.

As I've told BobAgain, it works better than the CC in my wife's Altima...above about 51 mph. Below that, with the exception of 30mph, it surges and bucks. The fastest I've had it set has been 82 and it was very smooth at that speed.
 
Thanks everyone!

BobAgain, I went to the Greatdanez link you provided (much thanks!) and picked up his value of 52,212 pulses per mile, which is close enough for design purposes. If we pursue this we will be using these pulses in a negative feedback control loop in any case, so the exact value isn't that important. Using Greatdanez's value, I calculate that at sixty mph the pulse frequency would be 870.2 Hz, which is a very nice value to use for a cruise control. It's low enough so almost any electronics, including hand wired, would work nicely, including small "utility" computers such as the Arduino ($24.45 on Amazon). Once the speed pulse stream is in a computer, plus input from the brakes, clutch, and the four control switches, then output to a stepper motor is a piece of cake and just about any control function you want can be implemented in software.

The real issue, as Tattoo Paul points out, is the throttle connection.

On our NTs the throttle is controlled with two cables, so that one of the cables is in tension either opening or closing the throttle. The throttle itself has a return spring. This means that a lot of force can be applied to the throttle to either open or close it.

We could, for example, design a system that disconnects the throttle hand grip when the CC is actuated, and that would have the advantage of leaving that grip to hang on to with the right hand, but would also pose a serious safety issue. Alternatively, the system could be designed so that the throttle hand grip remains active at all times, that is, rotates under power from a stepper motor via a solenoid operated clutch that can be forced (overpowered and slipped) by exerting force on the throttle hand grip. That approach has the advantage of allowing the operator to override whatever the CC is doing in an emergency. The stepper motor linkage can also easily be designed so that it can only act against the existing throttle spring, that is, the equivalent of the bead chain approach where the bead chain goes slack if the throttle is operated to accelerate. The disadvantage to this approach is that the hand grip cannot be held strongly, but must be allowed to slip so the cruise control can work.

I'm favoring the second approach at the moment, but am sure interested in your comments! This could be implemented as a module that would be placed anywhere convenient and have the existing throttle cables connected, plus a second set of cables to the throttle hand grip. That way we don't need to make connections at the throttle body at all.

Am I on the right track here? Suggestions?

Bill
 
Bill, You're a better engineer than I am...not that exceeding my engineering ability would take much! With the setup Mike used on the Rostra install on my bike, the throttle grip moves while I'm holding it. But movement is more like pressure than movement. I can see the grip move incrementally and feel it move incrementally when I transition from a downhill to an uphill gradient, but can't really tell that I'm impeding the action of the cruise control servo. I was using the grip heaters yesterday as I rode to Denver so I wsa holding the throttle more than I have. The CC held speed just as accurately as it has when I've held onto the bar end (which I do a lot of the time anyway).

Paul, one of the advantages of the NT / Rostra install with the parallel pulley arrangement Mike devised and I described above is that the NT throttle only turns 90-degrees. So there's not a lot of slack involved. I can't see any way that the CC linkage could foul the throttle linkage. We were more concerned about the CC cable jumping the pulley, but after we ended up with 1/4" overlap between the center washers and the outside washers in our 4-washer stack, and got the whole stack closer to the throttle cable, that doesn't seem as it it will be an issue either.
 
I've been looking into stepper motor controllers, and have tentatively focused on a part from Allegro, their A4989 "Dual Full-Bridge MOSFET Driver with Microstepping Translator." This would be the device that goes between the stepper motor and the computer. Interestingly, the data sheet promises current control on the stepper motor, so it may be possible to program the current used to a value low enough so the motor can be over-ridden by hand, thus eliminating the need for a slip-clutch. The microstepping function means that if a stepper is picked with, say, 1.8 degrees of rotation per step as it's natural step size, then each of those steps can be sub-divided by up to sixteen. That means a step size of only 0.1125 degrees. Assuming a throttle range of about 90 degrees, that would mean 800 steps over the range of the throttle . . . and more if we were to use gearing of some sort. I would think that 800 steps would give very fine control, but I'm not sure of that.

So here's my current guestimate of the cost of a cruise control.

Arduino computer board $25
A4989 chip $5
8 MOSFET transistors $8
board to mount electronics $15
Stepper motor $15
2 extra throttle cables $20?
Mount for stepper, etc $25?
four control switches, waterproof $40?

Total: $153 And that doesn't include the stuff I forgot . . .

It adds up fast, doesn't it? On the other hand, I think the end result would be better than the MC cruise at many times more, and it would not require vacuum. We would have complete access to the programming and could make it whatever we wanted. I'm still wrestling with whether or not to try this project. I also haven't looked at the programming required, but expect that to be fairly straightforward, and once done, it's done.

Bill
 
Look at the Rostra. It's not vacuum-activated. And it's not that much more.

But you wouldn't get the joy of putting something together and making it work. And you might be able to make something signficantly better than the Rostra.
 
That's certainly an attractive price and I like that it is electronic and not vacuum. I've looked at the various CC discussed on this forum for the NT. The Rostra is interesting but its performance characteristics below 50 would be unacceptable for me. I'd want smooth operations for speeds down to at least 30-35mph. I have used my CC at extended speeds as low as 40mph.

I also would not feel comfortable with a CC that doesn't disengage with the activation of clutch, either brake, or throttle override (when enough resistances is placed on the throttle when the CC is in operation, the CC will disengage).

Unfortunately, I've zero electronics knowledge so I'm not much help with how to do it but based on what you've written, I think you have definitely got the desired operating characteristics correct.
 
Rob, BobAgain set his DIP switches at different values than he started with and it sounds like he's got the Rostra working at those lower speeds.

After having had a CC for well over 100,000 miles, I definitely would NOT want one that wouldn't disengage if I touched either brake. I want it off right now when I do that, just like I do in a car. Not having it disengage with clutch operation doesn't really feel like a real big deal, and I'm betting that sticking a relay in the clutch switch circuit is probably not as complicated as some think it's going to be. When I use the throttle to accelerate in passing a vehicle, the CC disengages.
 
Thanks, Phil. It certainly sounds like Bob has made some fine tuning to increase the operation of the CC at slow speeds. I've only had a CC for about 80k miles on a motorcycle and have really enjoyed it and wouldn't consider a touring motorcycle without one.

But I guess its kinda like ABS for me, even though I'm relatively experienced at operating a motorcycle, I still want that safety device just in case. It certainly sounds like adding a clutch shutoff is possible based on what I've read. Thanks!
 
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