I went with the Race capture setup due to the sale they are running today. http://www.autosportlabs.com/
And since this thread is the most recent, how is everyone hooking up steering angle sensors? These race capture says that an optical distance sensor will work so I ordered one to try out. Here http://www.autosportlabs.net/RaceCapturePro_Sensors and here http://www.acroname.com/robotics/inf...arp/sharp.html
other ways I have seen are "string pots" and linear distance sensors. Anyone with experience want to chime in?

 

I'm using SoloStorm on a new Nexus 7 tablet. It's getting GPS and other data from a Race Tech DL1. I've also tried pulling video from a GoPro Hero2 with a wifi backpack, but it took too long and had a variety of issues.

I'm quite used to looking at data on a PC with the DL1, SoloStorm is quite basic in comparison. That's not a bad thing, you won't be doing hardcore analysis of car performance between runs. SoloStorm is focused on driver performance, specifically time delta between your previous run and the fastest run of that day.

I had some issues that seem to be specific to our narrow runway lot, SoloStorm sets the staging, start, and finish lines as circles. It doesn't matter which way you're going, if you break the perimeter of a circle, then it logs that as a trip. Those circles are the width of our lot, so it causes false trips when you pass near the finish. I just turned off the start and finish lines and manually align the maps.

The video from the GoPro was improved late last year with the new firmware that creates a .lrv (low res video) file. This takes a lot less time to download than a 1080p file! I've had numerous errors with the GoPro though, but I think they're mostly the GoPro's fault. Sometimes the camera reboots, sometimes it doesn't start, sometimes it won't shut off. It always uses tons of battery life, I can't get through 8 runs (6-7 mins between) without having the camera and wifi backpack plugged into a USB charger.

The staging area to auto-start recording within SoloStorm has been a little flaky. It starts about 40% of the time. I gave up on it and start it manually from the tablet.

Analysis is pretty light compared to the Race Tech software, but it can give you a quick estimate of where one driver/run is losing time. It takes some training to be able to figure out why you're losing time, but a throttle trace reveals a lot. Scared/late driver = off throttle.

Note that all GPS has a 3m (10ft) random error built into it. It doesn't affect you most of the time once you're moving, but you see some funny jumps every now and then. I don't trust the traces on the maps enough to analyze line selection, but that's common to any GPS logger.

I'm a little beyond what I want to do on the start line right now. I start the DL1, SoloStorm, and one or two GoPros. That's too much, and any co-drivers struggle with all that crap. In theory, SoloStorm should be able to start logging and start the GoPro, but it hasn't been reliable enough for my liking.

If I were starting fresh, I'd grab a tablet, SoloStorm, the OBD & GPS units. The DL1 is awesome, but I tend to focus more on the driver than the car as the source of problems. Now that I have the DL1, I'm keeping it as it has some amazing potential.

JeffJ uses Harry's Lap Timer on his iPhone4 with good results, though he had the same issue with the big finish line circle that cuts off his runs early.

 

I'm using a string pot that runs down to the steering column. There's a stud way up under the dash that I mounted the string pot to. It's practically behind the gauge cluster, only visible if your head is right in the footwell. Then a hose clamp attaches the string to the steering shaft with the steering turned all the way one way.

It's ok, but there are some oscillations in the signal as the cable retracts on quick steering movements. I assume the cable starts whipping as it retracts. It's smooth for quick motions in the other direction.

You can do some neat analysis with some math to compare GPS radius with steered angle. You can predict what steering angle is needed to achieve a given radius, and if your actual steering angle doesn't match then the car is under or oversteering.

After running through all that, I realized I could just look at the video instead. LOL! I don't use the steering angle data much, I much prefer looking at video.

 

Thanks for the post! My hardware just came in this week and I haven't had a chance to set it up yet. Does solostorm take advantage of the dl1 instruments? As in is there a "widget" for steering angle, yaw, throttle position etc? Having an ap1 I can't really take advantage of obdII data due to refresh rates and I'd like to look at that on the app between runs without having to hook up a laptop.

 

SoloStorm only grabs throttle position, RPM, G-force, and GPS data from the DL1.

 

I am still setting up my rcp so I have no data to back this up but my current plan is to use throttle position sensors for steering angle and suspension movement and an EGR position sensor for brake pedal. The are super cheap and available at any auto-parts store.

The problems to overcome are:
1. Mounting.
This is true of any add on sensor short of tapping into factory ones which Ive read is a bad idea. Some aluminum angle or bar has been helpful so far in my application.
2. Actuation
The problem with making a sensor detect a linear movement when it was designed to measure a 90* movement can be overcome by attaching an arm to the sensor. A better way (due to having a true linear relation) would be to attach a cam to the sensor such as whats attached to most throttles. The size (diameter or radius) of said cam would be determined with some math to give the full range of motion that the application requires. So the bigger the cam attached to the tps the longer a linear motion it can translate. Another thing to decide is whether or not to actuate it by attaching the wire or string that will twist the cam to the steering arm or to have it wrap around the steering shaft. If wrapping around the shaft more math (which I feel is just as bad as the worst four letter words) will be needed obviously to decide the size of the sensor cam.

My current plan is to use one off an 06 kia optima (google a pic) because it has a metal tab that is relatively easy to rig a cam/arm to. The egr sensor is more straight forward in that all it needs is to be placed in a position close to the pedal that allows full movement of each, so closer to pivot point for less movement and further for more.
I'm not able to put the time into this that I might have years ago so I have no hard tech to post yet. this is more than likely child's play to most of the guys (and a waste of time if you have no problem spending $300 on a string pot etc) on here but someone might find it a useful way to rig sensors on the cheap.

 

TPSs are a viable and relatively affordable potentionmeter for travel sensors as long as you can measure however you setup the linkage.

as far as steering angle goes - I've looked at a few options and the AIM kit seems to be the best for the price - at 140 it isn't nearly as unreasonable as many sensors go - http://www.aim-sportline.com/downloa...er_102_eng.pdf

non-linear sensor tracking shouldn't be a problem - most sensors aren't 100% linear anyways - you just have to carefully measure your movement vs sensor output and adjust the sensor outputs in your logger to match your actual movement.

The other option for brake pedal rather than measuring travel (which isn't 100% due to wear and heat introduced in the system and pad knockback) is high pressure sensors - 2000 PSI sensors will let you measure actual braking pressure in the system. If you want to get really fancy you can do front and rear pressures to adjust bias as well. The generic bosch ABS pressure sensor is used in a lot of OEMs and can be junkyarded if you were really dedicated to affordable - otherwise you can find them new for around 80 bucks each.