Launch Control Settings

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johnfelstead
Posts: 21
Joined: Wed Jan 29, 2014 12:23 am

Launch Control Settings

Post by johnfelstead »

I have just been watching the Syvecs Help video (which are all very helpful) for launch control setup and something doesn't make sense based on how my launch was setup.

My setup uses the following:

launch ramp mode = hold timer
stage parameters = not used, just uses main tables for control
exit speed = 1.6kph
the speed reference is the gearbox speed sensor

Now based on the help video, Ryan says this is too low and should be set high enough to not switch off launch control until a speed you want it to be switched off is attained. So in my case i would think the shift point to 2nd would be a good option to aim for, say 84kmh

The way it was explained to me previously was the hold timer starts once the exit speed is reached, so the exit speed is the start point for the hold timer to start counting, and not the speed launch control switches off.

The question is, who is right? Is launched switched off at exit speed or is the hold timer triggered at exit speed and launch then works until the hold timer has finished its count up to the max value?

What starts the hold timer counting up if its not exit speed?

Slowie
Posts: 105
Joined: Thu Jan 17, 2013 7:30 am

Re: Launch Control Settings

Post by Slowie »

Based on my understanding of the online help item and Syvecs Manual, if Ramp Mode is Hold Timer then the vehicle exit speed triggers the start of the hold timer.
Last edited by Slowie on Tue Jan 22, 2019 4:10 pm, edited 1 time in total.

johnfelstead
Posts: 21
Joined: Wed Jan 29, 2014 12:23 am

Re: Launch Control Settings

Post by johnfelstead »

That's how i understand it and how the help tab is SCal explains it, so Ryans help video is wrong, or he is explaining a function that is triggered by something else not covered in the video.

Reading previous topics on launch, they all say the timer starts on the speed being exceeded.

Prior to the speed being exceeded, the engine is limited by the values set at launch.

pavlo
Zen Performance
Posts: 406
Joined: Mon Aug 04, 2008 9:18 am

Re: Launch Control Settings

Post by pavlo »

Hi John,

It's good to see you're taking in an interest in your setup again!

The reason your activation speed is set so low is to try and overcome the delay the occurs due to the speed converter fitted on your car. When we initially set it up at Combe in 2014 that was causing a problem with prompt activation of the launch hold timer, in the end I reduced the number of speed pulses used to calculate the vehicle speed to just 1, as it was already being averaged by your converter. Before we did that the first speed update was taking 0.55seconds to reach the launch strategy after you had already set off.

The launch exit speed is the trigger that takes out of "stationary launch mode" (my term) and starts the hold timer going. While you're within the launch hold phase, the launch limiter is applied using the "Launch Control/Base Engine Speed" map which is RPM vs hold timer(s). The launch hold timer has a max value set in "Launch Control/Launch Hold Time" and once the hold timer reaches this value you are out of the hold phase, and into the exit phase. The launnch exit phase lasts as long as the time set in "Launch Control/Launch Exit Time" which is currently 0 on your car, but can be used to set launch specific boost target limitation and/or nitrous duty adjustment.

You can see all this happen in the screenshot of your log below
johnf-lc1.png
johnf-lc1.png (51.25 KiB) Viewed 4076 times
Since 2014 Syvecs firmware has improved massively in this regard, and I've improved what I do with it too. With your car we still have the problem of it being 4wd and spinning all 4 wheels, so the launch hold time is the way to go (with Syvecs). I would recommend you look at updating the firmware to add the Stage and Launch individual phases, and I would also work on using more retard and less cut. You're cut tables already do this to an extent but with more tuning it can be improved.

Looking at some more of your original logs, we could speed up the vehicle speed logging to test, but on launch it pops up immediately to about 20km/h so you could raise the 1.6km/h exit thresholds to a more normal 10km/h. This means that if you creep in staging while launch is active (unlikely on in a sprint/hc event) you don't trigger the launch hold timer.

If you want to see where this ends up, using almost no cut, see here: https://youtu.be/9xAQqn_Bgrw?t=173

TimH
JT Innovations
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Joined: Wed Sep 01, 2010 2:51 pm

Re: Launch Control Settings

Post by TimH »

Is it perhaps worth adding GPS to get an accurate vehicle speed measure?

pavlo
Zen Performance
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Joined: Mon Aug 04, 2008 9:18 am

Re: Launch Control Settings

Post by pavlo »

Not really Tim. In this case we are just using the vehicle speed as a stationary/moving status flag. If the GPS speed were 100% reliably then we could perhaps start to do some better things with it, as it becomes a "5th wheel" speed which can can peg RPM against. If you switch from a timer to an speed based LC setup, this means you can target an amount of slip (in effect) and when there is less grip it will naturally take longer to reach the peak RPM.

The Syvecs GPS unit has been good on Damien's legacy, but I know that Pat was looking at tweaks to the maths it used, so maybe there improvements to be had. But I've yet to see a GPS that was 100% reliable in tree cover, besides cliffs etc, but if GPS was skillfully combined with accelerometer and gyro data a reliable speed reading could be obtained (I'm not sure how much of that Pat's unit does).

The latest firmware has many useful updates, especially the "Stage" phase which means you can use a one set of cut/retard maps to regulate engine speed and build boost while stationary, and then a different set to limit wheelspin and smooth power delivery from stationary.

RICE RACING
Posts: 214
Joined: Mon Feb 24, 2014 1:08 am

Re: Launch Control Settings

Post by RICE RACING »

As a side note to above,
My Racelogic VB3i + IMU is the only system I have seen yet that is 'reliable' and of any use it tree cover, power poles, or poor satellite lock environments). Only issue is it costs more than some peoples whole cars :)

I remember when a few years ago LR were telling me about the 50Hz GPS/IMU and I told them to come speak to me when they got it working ;) the current 50Hz unit works ok but it has distinct issues where there are real environments to deal with, let alone sat number changes that confuse it.

You can buy a speedbox from RL but its like ~$23kAud last time I priced it up (IMU04 = $5600 and 100Hz slip speed sensor was $17000).
Anyway I have the same and it works flawlessly, we always test in real world and have been using GPS (Race Logic) since the first original VB3 was released, now with the IMU integration (took 2+ years to sort out) its a tool you can use everywhere, it does take a couple of minutes stationary for the items to sync up despite a 'hot start' but once she is happy its amazing in how it functions.
http://www.riceracing.com.au
Real turbo road cars fast > reliable > durable
Water Injection Specialist

pavlo
Zen Performance
Posts: 406
Joined: Mon Aug 04, 2008 9:18 am

Re: Launch Control Settings

Post by pavlo »

^^^^^^^^^^^
What he said

TimH
JT Innovations
Posts: 627
Joined: Wed Sep 01, 2010 2:51 pm

Re: Launch Control Settings

Post by TimH »

FWIW...

When Syvecs did their GPS they used the same chip that I'd used on the mini expansion unit a few years earlier...and it's different to the Life Racing 50Hz design.

I only have limited feedback (compared to Racelogic!) but not had any reported issues of the GPS dropping out. Yet :lol:

johnfelstead
Posts: 21
Joined: Wed Jan 29, 2014 12:23 am

Re: Launch Control Settings

Post by johnfelstead »

Hi Paul (and Tim)

Thanks for the update. I'm always trying to learn with the syvecs setup and the video i watched didn't make any sense on that one point.

I've updated my firmware a while ago, been running 1.84 for some time, but not done anything much with the launch since i finished competing in 2014.

The main reason for the query was to do with the TA car i am driving for the owner at a few events this year in TA and in some sprints, i did a sprint in it at Snetterton end of last year and had to set up launch as it was never done before, being a purely TA used car. Grip was so bad (freezing and trofeo tyres) it was a waste of time, but i'd like to get that working properly this year. There are no speed converter lag issues on this one thankfully.

My own car is still going strong, has 120K miles on it now and still the same engine build as when you mapped it, but no plans to compete in it anymore. It's been ultra reliable and considering it was used as a daily driver and won a sprint series outright, you cant do better than that.

I'd love to have you involved in the TA car mapping, its something we could improve a lot IMHO. I've tidied up a lot of the map as it was very messy in terms of what each CAL did and have setup the sequential shift gearbox we installed recently, but havent done any performance tuning as that needs a proper mapper.

Interesting info on the Racelogic kit, i'm doing some work for Julian at the moment.

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