Quote:
Originally Posted by Ginger_Extract
Have you actually tracked the car with the car as it is?
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Yes I have. Before I post some data though, this is how I collect the data:
The AIM Solo DL is a GPS-based lap timer and data logging system. It provides actual lap times and predicted lap times based on 10 Hz GPS data and internal accelerometers. In addition it can be connected to the vehicle OBDII port or directly to the CAN bus to log additional vehicle data.
http://www.aim-sportline.com/eng/pro...solo/index.htm
Real-time lap times, and in particular predictive lap times provide immediate feedback as to how well you are driving a track. The logged data provides even more information for analysis after a run or after an event. Once you are capable of driving consistent, repeatable laps at a track, the AIM Solo DL or other similar devices will make you a better driver. That is my sales pitch.
I had a Racepak G2X in my previous track car so I have some experience with GPS data loggers, but the Solo DL is substantially simpler, more powerful and has better analysis software. Most compelling was its ability to tap into the large number of chassis sensors built into our cars.
INSTALLATION
A minimal installation needs only a place to mount the device as it has an internal battery with a reasonable life. I got my DL with a Ram windshield mound, which is very sturdy. With no connections to the car at all, the DL will log the following data:
GPS Speed (km/h or mph)
Lateral Acceleration (g - from accelerometer in DL)
Longitudinal Acceleration (g - from accelerometer in DL)
Vertical Acceleration (g - from accelerometer in DL)
GPS Lateral Acceleration (g - calculated from GPS positions)
GPS Longitudinal Acceleration (g - calculated from GPS positions)
GPS Yaw Rate Gyro (deg/sec - calculated from GPS positions)
GPS Number of Satellites
GPS Positional Accuracy
GPS Path Slope (deg - calculated slope of path)
GPS Path Heading (deg - calculated track heading)
GPS Altitude (ft above sea level calculated)
Internal Battery Voltage (AIM Internal Battery)
AIM’s analysis software can download the data to produce track maps, segment times, lap analyses, etc. It is not my intent to sell you on the usefulness of GPS data logging and lap analysis. Others do that quite well.
M-World has a simple tutorial that is worth a look:
http://www.m-world.us/aimsupport/Dat...20-%202013.pdf
Racelogic has a more detailed look at data logging and analysis using a VBOX, but the principles are the same:
http://www.racelogic.co.uk/_download...it-driving.pdf
My intent is actually to review the details of installing a Solo DL in the 135i. I have seen some posts regarding the device in the 1M, but at a detailed level there are vehicle differences, and my own experience was not straight-forward.
The AIM manuals and analysis software are available for free on line. I strongly suggest their aim-sportline.com website. For some reason they (don’t) maintain another one that is hopeless by comparison. The manuals are not great. Their email and phone technical support is good, although they were completely wrong on a BMW-specific question.
http://www.aim-sportline.com/eng/download/index.htm
Richard at M-World was a great resource in getting my unit fully functional as he has experience with various BMW installations.
The device can be connected to the vehicle CAN bus via the OBDII port, or it can be connected directly to the CAN bus at the ECU. I bought my device locally, figuring that the OBDII connection was simplest, only to find that all taps to the CAN bus are not created equal and the data that I thought I would get, I couldn’t get.
Connected to the OBDII port, the following additional data parameters can be logged:
Calculated Gear (current gear based on speed and rpm)
OBDII Engine Coolant Temperature (°C or °F)
OBDII Fuel Level (%)
OBDII Intake Air Temperature (°C or °F)
OBDII MAF (I get no data on this channel)
OBDII Manifold Absolute Pressure (mbar, bar, or psi)
OBDII PPS (% - appears to track TPS)
OBDII RPM
OBDII Speed (actual not derated speed)
OBDII Throttle Position Sensor (%)
External Battery Voltage (Vehicle Battery)
Prior to logging anything, the DL needs to be configured with a logging protocol. To log data from the OBDII port the protocol has to be set as follows:
ECU Manufacturer = OBDII
ECU Model = CAN
This list of data is hardly compelling, and not why I bought the device. Logging engine data with an AccessPort yields far more.
AIM tech support advised, sorry that is as good as it gets. Richard at M-World advised otherwise so I followed Richard’s advice and bought a plug-and-play CAN bus harness from him. With that, I could use the following protocol to get 28 lines of vehicle data:
ECU Manufacturer = BMW
ECU Model = BMW_PT6
The M-World harness is a standard AIM CAN/RS232 harness with some very convenient crimped pin terminations that allow the ECU connection to be made without any cutting of wires. Here is the process:
1 Disconnect the battery
2 Remove the cover below the glove box to access the connectors
3 Remove the blue connector
4 Make the connection to the CAN+ and CAN- wires per the M-World instructions
5 Secure the harness
6 Route the harness to the device location
Connect the battery, ensure the DL configuration is set properly, connect the device. Then turn it and the vehicle on to confirm that it is receiving data.
Just to be clear, the BMW protocol does not work with an OBDII connection. Clearly not all CAN data is present on all branches of the CAN bus.
Incidentally, removing the side vents deserves a DIYof its own. Some of the DIYs I have seen are simply instructions on how to break things. The vent has 4 clips, the two inboard of which are only accessible through the grill. Working each of these clips in turn and pulling up on the bottom of the grill the whole thing pops out fairly easily. Brute force is not necessary. Disassembling the vent means breaking it. Putting the vent back in is extremely easy. Once you figure out how to retract the 4 clips getting the vent out isn’t to bad either.
With the BMW_PT6 protocol up and running the following additional lines of data are now available in addition to the basic GPS data:
Calculated Gear (current gear based on speed and rpm)
RPM
Accelerator Pedal Position (%)
Speed (BMW derated) (km/h or mph)
Speed (BMW actual) (km/h or mph)
Wheel Speed Front LH (km/h or mph)
Wheel Speed Front RH (km/h or mph)
Wheel Speed Rear LH (km/h or mph)
Wheel Speed Rear RH (km/h or mph)
Steering Wheel Angle (deg)
Clutch Switch (Inactive on 6MT)
Brake Switch (Inactive on 6MT)
Brake System Pressure (bar or psi)
Brake Pressure Front LH (bar or psi)
Brake Pressure Front RH (bar or psi)
Brake Pressure Rear LH (bar or psi)
Brake Pressure Rear RH (bar or psi)
Engine Coolant Temperature (°C or °F)
Engine Oil Temperature (°C or °F)
Outside Air Temperature (°C or °F
Outside Air Pressure (mbar, bar or in.Hg. - this is not MAP)
Gear (Inactive on 6MT)
Longitudinal Acceleration from ECU (m/s^2)
Lateral Acceleration from ECU (m/s^2)
Yaw Rate Gyro from ECU (deg/s - not deg as stated in software)
Distance (useless data)
Fuel State (%)
External Battery Voltage
Fuel Injector? (Inactive on 6MT)
Most data can be sampled at 10 Hz, some can be sampled at higher frequencies.
Not found in the AIM manuals is the requirement to run the Device Calibration routine from the RaceStudio software, while the device is installed in the vehicle in its normal orientation. Without doing that the DL accelerometer data will be incorrect.
Making up for the poor manuals, AIM has some useful tutorial videos that cover many subjects. They can be found at:
vimeo.com/aimsports/videos
I am interrupting the Ohlins post to cover this because the data from this device is necessary for some of the posts that will follow. For me, the single most compelling piece of chassis data is steering wheel angle, and the ability to correlate it with lateral g and speed. With this data, understeer and oversteer can be quantified. Also, individual wheel speeds and brake pressures permit the function of the e-diff and the actual benefits of a true LSD to be quantified.
Stay tuned …