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Brake Sensor Overlay?

Posted: Tue Jul 11, 2017 10:08 pm
by Dubbedown
Harry at some point would it be possible to have a sensor for brake on the video overlay for those using an obd device? It'd be a cool feature to see when you apply left foot braking :)

Re: Brake Sensor Overlay?

Posted: Wed Jul 12, 2017 8:36 am
by Harry
Brake is no OBD parameter. Only custom PIDs can help provided they are known (they will be car / model specific). Not supported yet but planned for the future (i.e. Custom PIDs, brake pressure in general, brake pressure derived from negative longitudinal direction, overlay). NB: this topic is a duplicate and has been requested and discussed several times already.

- Harry

Re: Brake Sensor Overlay?

Posted: Sat Sep 16, 2017 8:46 pm
by rbpeirce
This topic may be a duplicate but it seems to be more recent than others. Researching brake pressure suggests it is way more complicated than your comments about special PIDs. I was looking at a Porsche forum and the description of what people were going through is a nightmare. It may simply be impossible for many, even most cars, and it may be impossible to get the PIDs for those that support it. On top of that, I barely know what OBD II is let alone CAN.

From the standpoint of HLT, negative Gs might be the only way to go except that is going to vary from car-to-car as well. However, it might be possible to have a weighting number (or numbers) that people can play with until they get it where they want it. The forum might provide useful guidance as to what has been found to work for others. I can't think of another way to keep it universal like everything else in the app. We already have to enter the right gear ratios and so on for accurate read-outs. What's one more number or two?

Re: Brake Sensor Overlay?

Posted: Sun Sep 17, 2017 12:13 am
by rbpeirce
I was chatting with some friends and we realized even when videos show braking it is impossible to tell how much is being applied. The red bar moves but what does it mean? Therefore, a useful start that might be relatively easy to implement is some indication that brakes probably are being applied. We know going in that how much they are being applied depends on the car, its modifications, the driver and the grade, so a precise measurement probably wouldn't help. I doubt, unless you could be extremely precise, that it would even help me looking at my driving or you looking at yours.

Re: Brake Sensor Overlay?

Posted: Sun Sep 17, 2017 8:24 pm
by Harry
OBD data (custom PIDs) usually deliver brake pressure. Like for throttle, LapTimer would need to memorize the max value ever recorded and define this as 100%. Any other pressure measured would be a fraction of this. Max negative longitudinal acceleration will be in a similar range like max lateral acceleration. So if you are way below, your cornering is better than your braking and vice versa.

- Harry