When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I'm a new AiM Solo user. I know it measures lateral and longitudinal acceleration but does it actually use an internal accelerometer to do this? When I view the results in the Race Studio Analysis software, it calls the results "GPS_LatAcc" and "GPS_LonAcc". If it really has an accelerometer, what does GPS have to do with it?
Mathematically speaking, acceleration can be calculated as the second derivative of position, so you can, in principle, get acceleration without an accelerometer if you track position over time, as you would with GPS. Is that what's really going on here?
The Solo uses data from the GPS and the Solo DL has the accelerometers turned on.
So the Solo (not the DL) is not actually using accelerometers? That would make the DL more accurate for measuring acceleration because it would be a direct measurement rather than indirect via GPS. GPS always has some errors. But then what does the accelerometer calibration function do for the non-DL Solo?
Speaking about the MXL2 only, I would say that 95% of the time both accelerometer graphs overlay each other very closely. I personally like the gps graph most of the time because it smooths out a little better at the expense of .05 resolution or so. Maybe 5% of the time the accelerometer jumps 1 or 2 10th G's if you get a little anomaly in the corner pavement, but it always quickly blends back with the gps calculated. I believe part of my accelerometer problem is due to not being able to filter out all of the vibration so I get a bit of a small saw tooth pattern on the graph line.
Bill Parenteau
So the Solo (not the DL) is not actually using accelerometers? That would make the DL more accurate for measuring acceleration because it would be a direct measurement rather than indirect via GPS. GPS always has some errors. But then what does the accelerometer calibration function do for the non-DL Solo?
As Bill said, the GPS and actual accellerometer data match up very well. The GPS data looks like filtered accell. data.
I know some will argue, but for most people, the GPS data is more than accurate enough. It will pick up any braking issues, work well in G-Sum calculations, and provides excellent location data.
The accelerometers in the non-DL Solo were enabled in early units and disabled by a firmware update. You can re-enable them by opening "Device Configuration" in Race Studio 2, selecting "Solo DL", then clicking "Receive", setting the sampling frequency of the three ACC_n sensors (e.g. 20 Hz), then clicking "Transmit". For the data to be useful you need to calibrate the sensors once the unit is installed in the car (via Race Studio, unfortunately, there's no way to do it from the unit's menus). Ideally, you should to mount the unit axis-aligned with the car but it's not essential.
I have to disagree with GPS Acc being close to the actual trace from an accelerometer. GPS only refreshed 10 times a second. In a very hard braking zone, a lot changes in 1/10 of a second. I would recommend trying to trick the SOLO into using the built in accelerometers as MJG stated. Here is a plot of actual accelerometer vs GPS generated for Longitudinal G in a heavy braking zone. It would be pretty tough to make any meaningful decisions off the GPS trace IMHO.
Your example is different than I typically see between sensor and GPS based lateral G's. I grabbed a recent NJMP test I have and show the results below. This is more typical of what I see.
For deep analysis I agree that a sensor actually measuring the acceleration is best but I believe that for most uses the GPS based (calculated) acceleration values work very well.
A couple of notes... I push our users to place their GPS sensors where they have the best view of the sky (on sedans, up on the roof is best) and it is in data like this that the best GPS positional accuracy pays off. Also, the mounting of the hardware can also affect the accelerometers in cars with a lot of vibration/harmonics. Try to use the rubber mounts that are sent with the AiM display/dashes and with the EVO4's use a rubber pad between the car and the logger.
That is interesting. I have never seen it that close to the accelerometer. My setup is a GPS 05 on the roof, Pista dash with external accelerometer mounted at CG of car. Accuracy was good at 1.14 M
Jerry - Mine is mostly like Rogers but it does occasionally strays a bit, but usually is back on GPS target quickly. One difference being I drive more of a momentum type car (SRF3), where as you have more power and better brakes. I'm not sure if that makes a difference.
Bill Parenteau
Here is one with the GPS at 10 Hz and accelerometers at 50 Hz. This is what I typically see for matching. This is from an MXL2 with the GPS antenna on the front cowl in front of the windshield.
Here is one with the GPS at 10 Hz and accelerometers at 50 Hz.
Man, that 50 Hz sensor trace is noisy! Is that dash hard mounted?
__________________ -Peter Krause www.peterkrause.net www.gofasternow.com
"Combining the Art and Science of Driving Fast!"
Specializing in Professional, Private Driver Performance Evaluation and Optimization
Consultation Available Remotely and at VIRginia International Raceway
08-10-2015, 04:04 PM
Does the AiM Solo really have an accelerometer?
