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GPS controlled speedos


areamike

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Anyone ever seen this?

http://www.nauticlaugic.com/nl2-gps.html

Here's the packages:

http://www.nauticlaugic.com/nl2%20packages.html

It's a GPS adapter for your current speedos. It appears that it simply plugs into your existing speedo and runs it off a gps instead of running the speedos off the pitots or paddlewheel. Seems like a good idea. I'm wondering what the differences are in the gps adapters offered with each package.

The video is pretty funny when you see how their are driving the boat.

http://www.nauticlaugic.com/MBGPS.wmv

EDIT: I see now. The difference in the GPS versions is the refresh rate for one. The garmin has a refresh rate ever 200ms. while the others have a refresh rate every one second.

See here:

http://www.nauticlaugic.com/gps%20receivers.html

Edited by areamike
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I know Garmin is who provides the GPS software for the perfect pass stargazer so I would say the Garmin would be the way to go. A refresh rate of 1 second compared to 200ms is a huge difference I wouldn't even consider buying anything but the Garmin.

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I know Garmin is who provides the GPS software for the perfect pass stargazer so I would say the Garmin would be the way to go. A refresh rate of 1 second compared to 200ms is a huge difference I wouldn't even consider buying anything but the Garmin.

Yeah, after watching the video, there is a huge difference between once every second and once every 200ms. I'm thinking about getting one of these things since my pitots get clogged with debris all the time.

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I'm using this, it rocks compared to all the problems I had with the stock set up.

I tested both gps units, and I agree, there is a speed difference. I'm trying to get into surfing, and I'm really glad I went with the garmin unit, as I think it would have been hard to really track the lower speeds using the globalsat unit.

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martinarcher

That's cool. I've been sick of my pitot speedos so I started a little project of my own. I'm a controls and automation engineer by day so it's about time I use my profession for the boat!

So far I've bought a little controller, GPS receiver that pumps out standard NEMA GPS strings, and an LCD display. I wrote some software to interface to the LCD display as well as retrieve useful information from the GPS such as Speed, Heading, Lat/Long, GMT, and number of Satellites locked onto.

I cut a peice of carbon fiber plate to hold the LCD in an old speedo housing I had in the basement. I had the guy in the graphics department at work give it a little Malibu love. Thumbup.gif It's at our electronics supplier right nor being fully potted to make it fully waterproof. Should be ready for the first "field test" when I get back form Australia in two weeks.

I've also worked on getting an input form a potentiometer to control a throttle servo. Eventually I want to convert the Skier to throttle by wore using a linear pot on the throttle control and a servo on the carb.

To close the loop I am planning in writing software to control the speed. I want to add buttons to set or cancel cruise control and also bump the current cruise speed up or down by 0.1 mph increments. It will be my poor man's Perfect Pass. Biggrin.gif

Let me know what you think!

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martinarcher

Cool! I love custom tweaks that look stock. I think you should build two... I'll buy the other one.

I could do that! How about a trade for a wedge? Thumbup.gif

Edited by martinarcher
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I've also worked on getting an input form a potentiometer to control a throttle servo. Eventually I want to convert the Skier to throttle by wore using a linear pot on the throttle control and a servo on the carb.

To close the loop I am planning in writing software to control the speed. I want to add buttons to set or cancel cruise control and also bump the current cruise speed up or down by 0.1 mph increments. It will be my poor man's Perfect Pass. Biggrin.gif

Impressive job on the speedo display for sure. As for your poor man's Perfect Pass, I think you might want to give that one some more thought. Think Toyota and the recent histeria of runaway cars. Not to say they do or don't (did or didn't) have a problem, but the concern of failure of a DBW system is great, and the consequences of a failed system even greater. My day job for a number of years was engineering DBW systems - you'd be amazed at the amount of potential failures that have to be protected for in the design - both HW and SW complexity. Honestly, this is not something you should play around with as a hobby.

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Jerry has a good point. (personally, I hate any DBW, or brake by wire, or any of these things)

But, I think if Martin made his system so that it can be over ridden manually just like PP is now, he's probably safe. If the boat goes careening out of control, just grab the throttle and hold her back.

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martinarcher

Yeah safety is a concern for sure, but there will be an "e-stop" button to return the throttle to neutral. Also, there is always the key and the throttle control as well. Even if the throttle would totally fail which is unlikely, but always a possibility, returning the throttle to neutral will disengage the tranny and stop the boat. You'd rather see the driver hit the key as it's a bit easier on the motor, but either would safely stop the boat.

There are a few possible failures I've gone over (I'm sure there's more that I haven't covered yet, but I'm not near done yet)....

1. Servo failure (not much you can do if the servo doesn't respond on any system I will try to find a SIL rated servo for my application to up reliability and lower to risk of failure)

2. Potentiometer failure on throttle sensor. (the software will have a sanity check value in it, if an unrealistic value is received, return throttle to zero)

3. Controller failure (servo failsafe returns throttle to zero)

4. Power loss on servo (throttle return spring returns throttle to zero)

5. GPS loss (return throttle to zero)

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Sorry I don't have time for a longer response right now...

But a couple thoughts:

1. Any safety system that relies on driver intervention as the last ditch effort to bring the vehicle (boat) under control is not a safety system. Research startle effect on drivers and what it can do to their ability to respond rationally. You may be fine, but what about others that might be driving while pulling you?

2. Regarding potentiometer failures - what are you going to do to determine rationality? Are you going to put in redundant sensors so you can compare the two? Will you use opposite slope sensors to make sure that those sensors are not somehow shorted together?

3. You seem to assume that sensor or controller failures are limited to open circuit faults. Have you considered pin to pin (wire to wire) shorts, including shorts to voltage? What about failure of the reference voltage in your controller that feeds the sensors? Maybe the gain circuit fails in a way that supplies more voltage than normal, causing your sensor output to increase too?

There is little doubt you can put together a system and go for a ride. But doing so in a completely safe manner is a whole-nother-ballgame.

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martinarcher

Sorry I don't have time for a longer response right now...

But a couple thoughts:

1. Any safety system that relies on driver intervention as the last ditch effort to bring the vehicle (boat) under control is not a safety system. Research startle effect on drivers and what it can do to their ability to respond rationally. You may be fine, but what about others that might be driving while pulling you?

I would think 90-100% of boat drivers behind the wheel would pull the throttle to neutral in order to stop a runaway boat as their first response. I also think a boat is a bit lower risk for tis project than a car as you are not limited to a lane with close proximity obstacles and WOT on a ski boat is still a safe speed unlike a car/truck.

2. Regarding potentiometer failures - what are you going to do to determine rationality? Are you going to put in redundant sensors so you can compare the two? Will you use opposite slope sensors to make sure that those sensors are not somehow shorted together?

I was planning on using dual linear pots. I'm not too worries about opposite slope sensors as I think dual sensors and wiring are plenty of redundancy on the throttle input.

3. You seem to assume that sensor or controller failures are limited to open circuit faults. Have you considered pin to pin (wire to wire) shorts, including shorts to voltage? What about failure of the reference voltage in your controller that feeds the sensors? Maybe the gain circuit fails in a way that supplies more voltage than normal, causing your sensor output to increase too?

I did think about that. They are very good points. I thought about a RPM sensor input to monitor the loop. That way you can check if the sensor inputs are providing a normal/resonable engine response. If the throttle pots are reading anywhere a neutral value, the RPM's should be low. I also thought about an encoder on the throttle body of the engine. Either would be a reasonable way to monitor the loop. A vacuum operated vehicle cruise control does neither of these checks that I know of.

There is little doubt you can put together a system and go for a ride. But doing so in a completely safe manner is a whole-nother-ballgame.

No matter what I or anyone else designs, safety risks will never be completely mitigated. Is there a chance that even you vehicle FBW system can fail? Sure, Toyota is a great example of a system that certainly would have gone through safety reviews, but still failed. I am going to do my best to mitigate all the risks I can, but in the end using the system will be accepting a certain level of risk. Hopping in the truck and towing the boat to the lake involves risk as well, but it's a risk we are all willing to take.

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Martin,

Nice work, your project looks very cool. I would agree on failure mode issues, certainly a major concern mainly when someone is pulling you as the skier. Their response to an issue will certainly surprise you, Jerry is certainly well versed in human response algorithms. An option for the red button stop switch would be the Accuski button, it works quite well and is as intuitive as pulling back on the throttle. You might look at the Accuski system for layout and configuration as a guide. You might also check out comments on the Zero Off (ZO) speed control system as it provides a very firm throttle response pull for the slalom skier.

First question, what type of pitot's do you have? The venturi style units that come on line in the late '90's are very good and significantly better than the pressure style units. That is a very inexpensive fix. To be quite honest, I have actually found that a pair of Airguides coupled with the venturi pitot's are as good as anything out there. We ski on a short set up course and the airguides are to speed as quick as anything else, including a hand held GPS unit. The tachometer still seems to be the easiest quick method to check speed. Interestingly, I have observed that the newer boats tend to have inaccurate speedo calibrations and simply rely on the speed control for accuracy.

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martinarcher

Martin,

Nice work, your project looks very cool. I would agree on failure mode issues, certainly a major concern mainly when someone is pulling you as the skier. Their response to an issue will certainly surprise you, Jerry is certainly well versed in human response algorithms. An option for the red button stop switch would be the Accuski button, it works quite well and is as intuitive as pulling back on the throttle. You might look at the Accuski system for layout and configuration as a guide. You might also check out comments on the Zero Off (ZO) speed control system as it provides a very firm throttle response pull for the slalom skier.

First question, what type of pitot's do you have? The venturi style units that come on line in the late '90's are very good and significantly better than the pressure style units. That is a very inexpensive fix. To be quite honest, I have actually found that a pair of Airguides coupled with the venturi pitot's are as good as anything out there. We ski on a short set up course and the airguides are to speed as quick as anything else, including a hand held GPS unit. The tachometer still seems to be the easiest quick method to check speed. Interestingly, I have observed that the newer boats tend to have inaccurate speedo calibrations and simply rely on the speed control for accuracy.

Thanks guys. I will look at the Accuski and the Zero Off systems for ideas. I really appreciate the advice and concern from both you guys. I'm glad there has been feedback about the safety aspect of the system as it is too easy to look over something simple that could be avoided.

Jerry, are you into control systems as well at work? Sounds like you know your stuff! I appreciate you sharing your expertise! Thumbup.gif

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martinarcher

Martin,

Nice work, your project looks very cool. I would agree on failure mode issues, certainly a major concern mainly when someone is pulling you as the skier. Their response to an issue will certainly surprise you, Jerry is certainly well versed in human response algorithms. An option for the red button stop switch would be the Accuski button, it works quite well and is as intuitive as pulling back on the throttle. You might look at the Accuski system for layout and configuration as a guide. You might also check out comments on the Zero Off (ZO) speed control system as it provides a very firm throttle response pull for the slalom skier.

First question, what type of pitot's do you have? The venturi style units that come on line in the late '90's are very good and significantly better than the pressure style units. That is a very inexpensive fix. To be quite honest, I have actually found that a pair of Airguides coupled with the venturi pitot's are as good as anything out there. We ski on a short set up course and the airguides are to speed as quick as anything else, including a hand held GPS unit. The tachometer still seems to be the easiest quick method to check speed. Interestingly, I have observed that the newer boats tend to have inaccurate speedo calibrations and simply rely on the speed control for accuracy.

I believe mine are airguide pitots, but I'm not entirely sure. Here's pics of them. They constantly are off (not in agreement) and they often are plugged. The bad part if when pulling a boarder when the boat is heavily weighed down RPM sucks pretty bad as an indication of speed. You need to be slightly on and off the throttle constantly with a small boat with lots of weight to keep a nice smooth speed. Our drivers our pretty good at it, but a control system will be better and much easier for the driver to keep his mind on other thing like the water ahead and other boats.

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Jerry, are you into control systems as well at work?Thumbup.gif

Yeah, I've been in powertrain controls since about '93. I actually used to do the heavy lifting, now I'm just the pointy haired boss (dilbert reference). I did a lot of the controls for the first DBW system in the Vette in '97. Your project is an interesting one, no doubt. I gave you my perspective, but I'm not going to ride that angle any harder - you seem to be more capable than the average Joe, and you're a big boy, so have at it. Just be careful ;).

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Martin,

Those are the older units, the non venturi style. The "trash" can and does block the inlet port to these causing them to quit reading (a lot of the time!). The venturi style allows the "trash" to flow right through, most of the time and the actual reading port is located 90 degrees to the venturi. I strongly suggest a pair of the newer ones, you will be very pleased with the results. They also stay in calibration much better, you don't have to keep choosing which speedo to read. They are pretty much a direct replacement. SkiDim has them p/n 1804 tournament pitot asm.

PS: great looking banner on the transom on a great looking boat.

Edited by Woodski
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martinarcher

Yeah, I've been in powertrain controls since about '93. I actually used to do the heavy lifting, now I'm just the pointy haired boss (dilbert reference). I did a lot of the controls for the first DBW system in the Vette in '97. Your project is an interesting one, no doubt. I gave you my perspective, but I'm not going to ride that angle any harder - you seem to be more capable than the average Joe, and you're a big boy, so have at it. Just be careful ;).

Thanks Jerry. I appreciate the advice you have given. Feel free to add more if you think of anything.

I will be careful. I think I am actually going to add a red E-Stop to my auxiliary switch panel that will drop the 12V power to my ignition coil for a bit of added safety. It might not look at home on a ski boat, but I think it is worth it!

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martinarcher

Martin,

Those are the older units, the non venturi style. The "trash" can and does block the inlet port to these causing them to quit reading (a lot of the time!). The venturi style allows the "trash" to flow right through, most of the time and the actual reading port is located 90 degrees to the venturi. I strongly suggest a pair of the newer ones, you will be very pleased with the results. They also stay in calibration much better, you don't have to keep choosing which speedo to read. They are pretty much a direct replacement. SkiDim has them p/n 1804 tournament pitot asm.

PS: great looking banner on the transom on a great looking boat.

Thanks man! I'll look into the venturi style units! Good to know I had a known bad unit as they certainly are bad. Crazy.gif

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