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Learning how to build Lotus Seven replicas...together!
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PostPosted: May 18, 2017, 5:07 pm 
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Mid-Engined Maniac

Joined: April 23, 2006, 8:26 pm
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Locost builder "Junior" has the Racelogic box and really liked it as I recall. I agree with the others though, it's probably best to see ways to work around the issue entirely.

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PostPosted: May 19, 2017, 1:12 am 
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Pretty sure the majority of current ESC systems are purely reactive. Meaning the vehicle is only reading where you want to go (steering angle sensor), where the car is pointed (Yaw), and how fast it is going there (lateral accell sensor, WSS). I'd bet if you got one that was reactive only, it would operate just as well on a 1500lb car (once the brake sizes were balanced). The bigger potential headache would be ensure that your car didn't cause any non-ESC DTCs that will cause the ETC to disable.

If you want a proactive ESC you'd best learn how to program and build Arduino boards or similar and have a lot of time for R&D.

Cheers.

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PostPosted: May 19, 2017, 5:53 am 
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Location: ontario
C10CoryM wrote:
Pretty sure the majority of current ESC systems are purely reactive. Meaning the vehicle is only reading where you want to go (steering angle sensor), where the car is pointed (Yaw), and how fast it is going there (lateral accell sensor, WSS). I'd bet if you got one that was reactive only, it would operate just as well on a 1500lb car (once the brake sizes were balanced). The bigger potential headache would be ensure that your car didn't cause any non-ESC DTCs that will cause the ETC to disable.

If you want a proactive ESC you'd best learn how to program and build Arduino boards or similar and have a lot of time for R&D.

Cheers.


Hi Cory,
You seem to know a good deal more about ESC than I do. I am not clear what you mean by reactive vs proactive. So far what I had understood was that all systems are reactive. ABS, TC, steering angle -Yaw. Sensors detect a differential between the car heading and its actual position. ESC corrects the situation by applying selected brakes on one side (which a driver cannot do) and reducing throttle. Can you educate me. :)


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PostPosted: May 21, 2017, 1:03 am 
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Joined: November 11, 2013, 4:47 am
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Location: No. Nevada
:ack: Sorry I clicked this one!
Isn't the whole point of 7 type vehicles that the DRIVER is to be in FULL control, not some Gov. edict device?
Any Gov. stooge even contemplating the sort of mandates under discussion should be immediately recalled, then tarred and feathered before being run out of town on a rail! :evil:
Sometimes the only proper response is an old-fashioned one.

For the expense involved in the relevant hardware and software you could probably just buy-off a couple of politicians (Campaign donations :wink: ) and prevent passage of such nanny-state feculence.

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PostPosted: May 21, 2017, 1:14 am 
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RichardSIA wrote:
:ack: Sorry I clicked this one!
Isn't the whole point of 7 type vehicles that the DRIVER is to be in FULL control, not some Gov. edict device?
Any Gov. stooge even contemplating the sort of mandates under discussion should be immediately recalled, then tarred and feathered before being run out of town on a rail! :evil:
Sometimes the only proper response is an old-fashioned one.

For the expense involved in the relevant hardware and software you could probably just buy-off a couple of politicians (Campaign donations :wink: ) and prevent passage of such nanny-state feculence.

I like the way you think.
Kristian

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PostPosted: May 21, 2017, 8:55 pm 
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phil wrote:
Hi Cory,
You seem to know a good deal more about ESC than I do. I am not clear what you mean by reactive vs proactive. So far what I had understood was that all systems are reactive. ABS, TC, steering angle -Yaw. Sensors detect a differential between the car heading and its actual position. ESC corrects the situation by applying selected brakes on one side (which a driver cannot do) and reducing throttle. Can you educate me. :)


Not that familiar with the programming of ESC as companies keep all their programming pretty secretive. All I mean by reactive is that most systems (from what little information I can get) just react to the sensors to apply the brakes etc, then only release/reduce the brakes as the sensors show the lateral speed dropping. They don't see X amount of lateral acceleration, then calculate that it will take Y amount of braking to correct it due to the mass and speed of the car. There are definitely some that seem to do this, or they may be simply sampling/reacting at speeds ridiculously higher than other cars.

https://www.youtube.com/watch?v=SywqgH7 ... u.be&t=43s

I would be very curious to see how their ESC works (besides very well).

All this being said, as much as I appreciate the technology of the ESC, T/C, and ABS....... I still prefer to drive/race without it.

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PostPosted: May 22, 2017, 10:32 am 
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C10CoryM wrote:
phil wrote:
Hi Cory,
You seem to know a good deal more about ESC than I do. I am not clear what you mean by reactive vs proactive. So far what I had understood was that all systems are reactive. ABS, TC, steering angle -Yaw. Sensors detect a differential between the car heading and its actual position. ESC corrects the situation by applying selected brakes on one side (which a driver cannot do) and reducing throttle. Can you educate me. :)


Not that familiar with the programming of ESC as companies keep all their programming pretty secretive. All I mean by reactive is that most systems (from what little information I can get) just react to the sensors to apply the brakes etc, then only release/reduce the brakes as the sensors show the lateral speed dropping. They don't see X amount of lateral acceleration, then calculate that it will take Y amount of braking to correct it due to the mass and speed of the car. There are definitely some that seem to do this, or they may be simply sampling/reacting at speeds ridiculously higher than other cars.

https://www.youtube.com/watch?v=SywqgH7 ... u.be&t=43s

I would be very curious to see how their ESC works (besides very well).


Thanks again for your thoughts. You are right. I believe that the long account I read about a locost builder plugging this technology on his build had to do with traction control and maybe ABS both being essentially reactive. My understanding of all this is that 21 st century ESC involves steering position sensors and yaw motion sensors and the data are managed by a central program. The end resulting output however is still delivered the old fashion way: individual wheel brakes and torque control (throttle or ignition) .

I too believe that this level of technology is overkill for I kind of machines and that it would also make them more vulnerable to failure.

I do hope that this thread will not worry our Canadian colleagues too much. Chances are that model kits will never be concerned by changing ESC federal /provincial regulations. On the Piston Head forum someone pointed that the whole subject discussion ignored the fact that the Feds are aiming at "manufactured cars" we...are not manufactured car builders but hobby individual builders. This distinction has always been made by law makers. :cheers:


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PostPosted: May 29, 2017, 2:24 pm 
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Phil:
I too live in Ontario and was slapped with the concept of putting stability control in my now finished 7. Its not possible and in looking I started asking several kit car builders Ive met what they are doing.

According to them the need for stability control is only for car manufacturers. We, as a one off builder are not car manufacturers and do not need to comply.

It makes sense to me and thats the path IM going to take when I apply for my vin.


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PostPosted: May 30, 2017, 4:39 am 
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Location: ontario
alkidd wrote:
Phil:
I too live in Ontario and was slapped with the concept of putting stability control in my now finished 7. Its not possible and in looking I started asking several kit car builders Ive met what they are doing.

According to them the need for stability control is only for car manufacturers. We, as a one off builder are not car manufacturers and do not need to comply.

It makes sense to me and thats the path IM going to take when I apply for my vin.


Thanks for chiming in. Yes this is what I understand from what I have read. Kit and home builds will stay below the legislative radar.

However I would like to know (as many others) how your licensing went. Please post something when you have got your licence plates. Your other point (that ESC on locosts is not «possible»). I am not sure. I would say «difficult» yes. «low cost» NO, «counter productive (because folks would turn the device off at the first opportunity)» yes. IMO nothing is impossible in this day and age and it is a matter of years if not months for the market (Bosch or others) to offer programmable components aimed at retrofitters.

Where are you in Ontario. What do you build? :cheers:


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PostPosted: June 5, 2017, 12:27 am 
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hey guys, thanks for the info. i'm at the very early stages of building one of these in ontario and wanted to wrap my head around registration process first before i get to far into it. agreed with above though about arduino (or some other processor, probably TI launchpad for the processing power). all you are missing is the math that determines which wheel to apply brake to and for how long to get desired response (error null to zero) and this can be found by google search. anyway, sounds like ESC isn't going to be too much of an issue.

i'm trying to find where exactly on Ontario gov web pages where all this is detailed on how to get registration? a few years ago i asked at local DMV and they just handed me a quick form basically said you paid for all parts, paid taxes, got safety from canadian tire, you good. sounds like this has changed.. trying to find this on gov web site now, not so easy! any tips?

if you take some broken down car and rebuilt it, you have to get the frame inspected. this doesn't apply to us as we start from raw, new, material... but.. in principal sounds like it SHOULD apply to home built. https://www.ontario.ca/page/safety-standards-certificate#section-7


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PostPosted: June 5, 2017, 12:39 am 
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Quote:
owever, I would venture to guess that if an ESC will be a requirement, then that's just the tip of the iceberg. Airbags, certified bumpers and a slew of current safety items will surely be part of the requirements as well.


don't think this applies to homebuilt locost. these are safety bits and safety bits and you don't need a safety certificate for homebuilt because:

You need a safety standard inspection and certificate if you are:

registering a rebuilt vehicle
transferring a used vehicle to a new owner (unless the new owner is your spouse)
registering a vehicle in Ontario that was bought in or came from another province, territory or country
changing the status of a vehicle from unfit to fit

^ none of the above apply to homebuilt from raw materials... so .. no safety standard inspection and certificate required. of course, i haven't tested this theory yet... :wink:

https://www.ontario.ca/page/safety-standards-certificate#section-2


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PostPosted: June 5, 2017, 5:43 am 
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Location: ontario
slloyd wrote:
hey guys, thanks for the info. i'm at the very early stages of building one of these in ontario and wanted to wrap my head around registration process first before i get to far into it. agreed with above though about arduino (or some other processor, probably TI launchpad for the processing power). all you are missing is the math that determines which wheel to apply brake to and for how long to get desired response (error null to zero) and this can be found by google search. anyway, sounds like ESC isn't going to be too much of an issue.

i'm trying to find where exactly on Ontario gov web pages where all this is detailed on how to get registration? a few years ago i asked at local DMV and they just handed me a quick form basically said you paid for all parts, paid taxes, got safety from canadian tire, you good. sounds like this has changed.. trying to find this on gov web site now, not so easy! any tips?

if you take some broken down car and rebuilt it, you have to get the frame inspected. this doesn't apply to us as we start from raw, new, material... but.. in principal sounds like it SHOULD apply to home built. https://www.ontario.ca/page/safety-standards-certificate#section-7


Hi, thanks for your points.
Sofar I have not heard back from the MTO . I was asking about ESC.
On Ontario registration all I have to offer is my experience in 2009. I have registered my first build (Locost seven). To register your car as a Model Kit (the term they use) you have to present proof that you used an actual kit. This can be some GF body parts. In my case: nose cone, scuttle, fenders. You have to present proof of the origin of mechanical parts. They do NOT want USA engines and transmissions. The best way is to scavenge a Canadian donor car, which I did and showed the bills. Then you have to get a mechanical fitness inspection. I went to my local Ford dealership and they were happy with my work. To get your licence you will have to show the proof of insurance. In my case I had to get my car professionally upraised before Haggerty issued my policy. I hope this helps. Good luck. Keep us posted. This group is a tremendous source of knowledge and moral support.


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PostPosted: June 5, 2017, 8:25 am 
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There are manymany SAE papers on stability control. Most of them are rubbish, unfortunately.

If Canada has something equivalent to the US Inter-Library Loan System you should be able to borrow papers at low cost or free. If not, you might see if a local university might work with you. Most US universities don't want to deal with the general public, but the registrar's office might be able to swing some kind of deal for you.

Since Canada is in the Commonwealth it might be possible to get IMechE papers, which tend to have a much higher standard of usefulness than SAE papers. And plain old web searching will find quite a bit of stuff now; many authors put their work online, and the Japanese and Korean SAE chapters put much of their stuff online as well, in English.

Most stability control systems are essentially enhanced ABS. The goals and algorithms of the ones I'm familiar with have two goals: "prevent oversteer" and "straighten the car to hit things straight on."

You're already following up the first question, on whether the rule applies to you. The second question, if "yes", is "what constitutes 'stability control' as far as the rule is concerned?" And maybe "other than taking your word for it, how could they test it?"

If there is no real definition, you could program almost anything you wanted, as long as you reduced the control authority low enough.

You're likely to find a lot of papers talking about resonant frequencies of the tires and suspension members. Engineers worried about that a lot in the early days of ABS, until someone realized that different tires and worn suspension parts threw all their careful calculations into the dustbin. As-shipped vehicles generally have the cyclic limits turned way down below optimum to keep them from being too sensitive to handle wear and tire changes.

It doesn't have to be perfect; it just has to be not-actively-dangerous.


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PostPosted: June 5, 2017, 11:40 am 
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phil, what i read from that is to proceed in the normal way. donor car to be canadian made. keep receipts, show paid taxes. document yourself building it so you can prove it was you. get it safetied, get it appraised, get it insured, ask local DMV to provide a VIN. get it saftied means you built car with doing no more about safety than what is described in the "build your own sports car on a budget" book. nothing here is different than method 10 years ago. all we need now is confirmation from DMV that this is actually the case in 2017. hopefully they get back to you with your questions.


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PostPosted: June 9, 2017, 6:23 am 
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Interesting topic for me, I spent the first 13 years of my engineering career as a stability control calibrator for Bosch and GM working on projects from pickup trucks to sports cars. SO, to condense 13 years of intimate knowledge of every line of code into a forum reply that's useful is a bit challenging! I'm trying really hard not to come off as a know-it-all but on this specific topic I kind of am :lol:

1. Calibration of the system to a new vehicle is a full time 40hr/wk job that takes roughly 1.5yrs for a new vehicle. Maybe half or 3/4 of that is stuff you could skip on a hobby car and still get good performance but, still...

2. This calibration is extremely sensitive to the specific handling of the vehicle. The 'reactive' idea presented in an earlier post here is definitely correct but the magic is knowing the target yaw rate to react to. i.e. how that steering wheel input you measured *should* translate to yaw when a corner is going just fine (no noticeable over/understeer). You need a yaw target to compare too and any car in any corner is technically ALWAYS over or understeering (that's how tires work) and every car is VERY different. You have to drive thousands of situations over and over again to make that model work. (the model being: for a given speed, surface grip, bank angle of the road, steering angle, steering angle rate, brake or throttle apply - how much *should* the car yaw if everything is going well) You need that number which is constantly calculated every 5 milliseconds to know when you have too much or too little yaw in any of those situations that needs to be 'fixed' with brakes.

3. The cal is also extremely sensitive to the layout of the hydraulic system. Once it sees a yaw that is different from that model it needs to know how much fluid to pump into the brakes to get a result. This relies on a good ABS calibration which is a whole other ball of wax that has to be done first!

4. Putting a system calibrated for ANY street car (min weight for a street car equipped with ESC is maybe a 2200lb Miata??) onto a <1500lb locost with a pieced together steering system, suspension, wheel tire package, and brake system is almost certainly going to result in a system that either doesn't respond to oversteer at all or locks wheels randomly when it just *thinks* the car is oversteering because the model is wrong (the more likely scenario, IMHO).

5. To emphasize this sensitivity it might be surprising to know that almost every trim level of the same make and model car you buy has a unique ESC calibration! Even on a Miata the sport suspension car will have a separate cal from the touring suspension, the big brake car a separate cal from the small brake car, etc. The OEMs don't spend this money for fun, there are real results that are unacceptable in normal driving if you don't do it.

SO, I'm not saying not to try, I love a good experiment, but I am saying it's a HUGE crap shoot if it works or not and I can 100% guarantee that it won't work *well.* (also, insert safety warning here, randomly locked front wheels at high speed are bad and likely)

Modifying the calibration is a tempting idea but there are >1200 parameters to calibrate in hundreds of thousands of lines of code (which is why it takes an experienced pro 1.5 yrs to do it). It's just not feasible to calibrate for any reasonable cost, trust me, I've pushed on the aftermarket option for a long time and the cost is just overwhelming to even do it to a hobby car level.

Also, you have to crack the controller (don't think anyone's done this to an ESC controller yet) and learn the code first, takes maybe 3 years for a professional to learn it with all the documentation you get working at a supplier. I can't imagine making sense of a set of cracked cal tables with no documentation.

Someday maybe a supplier will do a dumbed down version with a few dozen easily understood cal tables that can work as a safety backup (I think that's possible with some engineering effort up front) but it doesn't exist right at the moment.

Hope this was helpfull.

Alex


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