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Re: Porsche and racechrono

Posted: Sat Jul 20, 2019 2:57 pm
by tedaf
KenJ wrote:
Thu Jul 18, 2019 5:51 pm
This is submitted respectfully... I know things have opened up with some AXs these past seasons, so, it's really best not to show the speedometer on your videos..... especially this last one. We won't have Alameda much longer, but let's not give them reason to curtail things early.

Have fun,

Totally fair point, and I wondered about this myself. I can update the overlay to not include speed in the videos I post.

Re: Porsche and racechrono

Posted: Mon Jul 22, 2019 6:48 pm
by DerekB
i had fun playing with the app this weekend and learned a bit. so far i am happy with the results just using the GPS. i did just get the the MX+ OBDLink today and that should help with accurate throttle input and speed data but the acceleration data from the GPS is great by itself.

you do need to create a new course with the GPS in hand. your phone GPS is not good enough to create the course and have it work accurately. last week when i got the course from Himanshu but was using my phone with no external GPS it did not recognize the finish some times. the app does not automatically create zones for split times so you have to create those during the course walk and 5 splits works out great on my iPad. the zones are nice to have because you can quickly see the green or red sectors in the main screen and it uses the zones to give you your theoretical best time.

i was able to sync the video from my generic action cam and i think it works well. the overlays are not as useful as using the analysis screen so i made a screen capture video of the analysis using speed delta, time delta and longitudinal acceleration. the app continues to have a problem graphing the time delta but it does show the value on the bottom of the screen. the video came out a bit choppy but it is still useful to compare my two fastest runs. i am using my first generation iPad air and i assume a newer model would fix the issue.

Himanshu has said that he doesn't want to share data/video publicly preferring to use email. i do think that is the best way to go for Alameda, i don't think there is an issue posting speed data at marina but if it is a problem i can take the video down, make it private and only share it using the email chain we have.

Re: Porsche and racechrono

Posted: Mon Jul 22, 2019 9:49 pm
by mikey
Don't worry about it. This is a private forum anyway so feel free to post.

Re: Porsche and racechrono

Posted: Sat Jul 27, 2019 10:01 pm
by hpatel
Thanks Derek for getting the communication started and thanks Mike for having this forum available for us to post.

My fastest lap at the last LPR event can be viewed at -!AvpsCl-IH8Bth8VvjszaYtQWWEz-5Q.

Note, the lag described by Teddy for throttle response in previous videos is gone in this video. That is because I replaced the Throttle Position sensor with Accelerator Position sensor in Edit Overlay menu. For everyone's sake, I use Kiwi 3 for OBDII data, but do recommend getting MX+ for the new buyers. Derek, it would be great to see if throttle response data is collected by the high speed channel with MX+.

One more piece of information. Accelerometer in iPhone is quite sensitive. It should work as well as the sensor Teddy and I have within our GPS unit. Make sure to secure your phone while driving to get good G-force data.

Re: Porsche and racechrono

Posted: Sat Jul 27, 2019 11:43 pm
by DerekB
i got the email and was able to import into racechrono with no problem. we had quite different lines in the first half of the course but similar after that. i will have to do a deep dive into accelerometer data to see where i can improve. you definitely got a good start and the tighter line paid off. great job :)

the accelerator data does look much better than the throttle but still not quite right. it never goes above %92 or bellow %15? i look forward to using the MX+ that i got and you recommended to compare our throttle input but the accelerometer data looks good and i can learn a lot from that. i was worried about the Dual GPS not having a built in accelerometer but doing research it turns out that racechrono does not use the one built in to the Vbox or the iPhone.
"The lateral and linear acceleration is calculated from GPS only. You can also enable the real accelerometer from expert settings but that is not calibrated nor rotated."
the data i got from the Dual unit looks just as good as what you are getting from the Vbox. i am curious to see if using expert mode and calibrating it would get you better results. it would probably be able to record both and you could compare the two?

i'm not sure how useful the software would be if we are not using the same map. going forward, i think we should start a new email for each event and post the map there. Teddy said he wouldn't be at the next event and Himanshu is usually busy setting up the trailer. i will try to walk the course ASAP but working the gate could slow me down. i'm sure we will figure it out but i think email would work better than meeting up and doing Air drop.

Re: Porsche and racechrono

Posted: Tue Sep 03, 2019 8:29 pm
by DerekB
i got the MX+ OBD2 and am not impressed with the results. the throttle position is not calibrated and that is the only thing i am using it for. there is also the possibility of getting braking data but it needs programming? i am sure it would be useful on track having a heads up display for temps and a shift light but i was able to get that stuff from a cheep unit for less than $20.
i did use RaceChrono in my Miata when sharing the car with a friend and that worked great. we were able to compare runs and see who was fast where using the GPS acceleration data and speed delta. i even convinced him to purchase the app and sent him the data i collected.
the accuracy seemed to vary during the day and im not sure why. the timing slip time and RaceChrono time should stay at the same accuracy but it seemed to vary by almost half second, the RaceChrono time should be a consistent 1s more than the timing slip but it wasn't consistent. the finish was at a strange angle and that could have been the problem.
well worth the purchase so far but i would not recommend get the MX+ OBD2 reader. i will continue to use it and update if i change my mind.

Re: Porsche and racechrono

Posted: Fri Sep 06, 2019 4:20 pm
by hpatel
Hi Derek,
We are all learning about RaceChrono environment together. MX+, as you know comes recommended by users online. I have a spare Kiwi 3/4 I can bring to the next event, if you want to give that a try. I am curious about MX+ and would appreciate if I can test it as well.
I recently found this tip for users of gopro with GPS capability (Hero 5+). You can import an external video from this camera and use Gopro's GPS data to sync the video to your laps in RaceChrono - This is a handy feature for drivers with multiple cameras.

Re: Porsche and racechrono

Posted: Fri Sep 06, 2019 4:52 pm
by DerekB
Himanshu, i can definitely let you use the mx+.
i'm sure it will come in handy and i think it could be a good tool but the GPS alone will get me more than enough data to compare runs. specifically the acceleration and speed data. just using that i can see where i am braking, how long i am on the throttle and how hard i am pushing in the turns.
in the video i made above i was using longitudinal acceleration to see braking and acceleration. i also look at lateral acceleration and can see how hard i am pushing in the turns. that is quite useful when comparing myself with James driving the turbo miata. i can see that he is at least .1g more in each turn and i will try to work on that. that data could help us in the Porsche with tire pressure to see if a lower pressure gets us more grip and comparing different drivers to see if we are cornering hard enough.

thank you and Teddy for getting us started. i know it will make us all faster :)

Re: Porsche and racechrono

Posted: Wed Sep 11, 2019 1:18 pm
by DerekB
i got another chance to use the software Saturday with the corvette club and it was very useful. i did have some initial hiccups and my first two runs were not recorded.
the GPS was off by about 100 ft south from my course walk and run start? i noticed it during the course walk and couldn't get it to correct even after pressing the realign/target icon multiple times. i noticed that the position icon on the google earth view was not where i was on course for the start. it looks like it corrected by the time i got to my first sector point and the rest of the course was ok, ish. i was able to move the start point from my car using the app and made the start line wider. moving the start trap was clunky and it moves the map under the trap and not the trap on the map, if that makes sense?
the finish line was misaligned but that was an easy fix and i somehow ended up with an extra trap in the middle of the course. it took me a bit to figure all this out but it worked great after that. the accuracy was spot on and i think that had a lot to do with the start and finish being straights.

the event was a two lap enduro and the sector trap times only worked on the first lap which made the final trap time half of the total time. like 8s for the first 5 traps and then 40s for the finish one. i might see how to fix this but we don't do many enduro events so not a big problem.
i ended up about .1s faster than James and the app was a great tool to figure out how i did it. my corner speeds were slower and we took a different line in a few sectors but i gained close to 1s each time i went through the slalom. i ended up going through the slalom 10 mph faster on the first lap and 15 on the second. i rendered a video comparing our two fastest runs and you can see where i made up the time and where i can improve. the video is useful but i still need the Analysis screen to compare lines. James started the final slalom on the opposite side as me. that's why his speed is slower at the start but better at the finish.