Correct units for yaw, pitch and roll rates

   #1  

tnisov

Verified VCDS User
Verified
Joined
Jul 15, 2015
Messages
2
Reaction score
0
Location
Finland
VCDS Serial number
C?ID=26492
Hi!
I was investigating crash data in SRS control unit recently.
I'm wondering - why units for yaw rate, roll rate and pitch rate are in m/s2 and not in angular acceleration unit - in rad/s2 for example?

Code:
Address 3B: Sensor Elect. (J849) Labels: 4G0-907-637.clb
Part No SW: 4G0 907 637 B HW: 4G0 907 637 B
Component: SARA 6D H02 0004
Revision: -------- Serial number: EJ1BPA42039EYH0
Shop #: WSC 00000 000 00000
ASAM Dataset: EV_SARA 006014
ROD: EV_SARA_006.rod
VCID: 2D12CF807C7F32EC99-8078
2 Faults Found:
7340432 - Longitudinal Acceleration
C10B1 29 [108] - Signal Implausible
[ECU temporarily disturbed: Signal ACC_X]
Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Reset counter: 120
Mileage: 291055 km
Date: 2021.01.27
Time: 04:12:56
DCU Temperature: 12 °C
Voltage Clamp 15: 14.7 V
Voltage Clamp 30: 14.2 V
Ignition Cycle Count: 52115
Roll rate: 5.13799 m/s2
Pitch rate: 6.08956 m/s2
Yaw rate: -1.38321 m/s2
Yaw rate 2: 0.00000 m/s2
Longitudinal acceleration: -42.67595 m/s2
Lateral Acceleration: -25.73899 m/s2
Lateral acceleration 2: 0.00000 m/s2
Body acceleration: 21.69236 m/s2
7344528 - Latteral Acceleration 1
C1022 29 [108] - Signal Implausible
Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Reset counter: 120
Mileage: 291055 km
Date: 2021.01.27
Time: 04:12:56
DCU Temperature: 12 °C
Voltage Clamp 15: 14.4 V
Voltage Clamp 30: 14.1 V
Ignition Cycle Count: 52115

Roll rate: 26.96524 m/s2
Pitch rate: 1.49112 m/s2
Yaw rate: -1.91050 m/s2
Yaw rate 2: 0.00000 m/s2
Longitudinal acceleration: -49.42278 m/s2
Lateral Acceleration: -40.24062 m/s2
Lateral acceleration 2: 0.00000 m/s2
Body acceleration: 38.29579 m/s2
 
   #2  

iichel

Verified VCDS User
Verified
Joined
Aug 10, 2016
Messages
2,290
Reaction score
2,721
Location
Eindhoven, NB, NL
VCDS Serial number
C?ID=284912
you're probably right, just a translation/interpretation error.
 
   #3  

Andy

Administrator
Staff member
Joined
Jan 29, 2014
Messages
2,780
Reaction score
4,249
Location
Sector 7G
VCDS Serial number
HC424490
As requested via email, a controller channel map would be helpful since my understanding is that freeze frame data correlates to some measuring values. I tried in vain to cause the 3B module in our 2012 A6 to have any faults at all, including removing fuses that shut off 01,13,15, and 3B itself. I agree that rotational acceleration should be in units of degrees per second squared, or radians per second squared, not meters per second squared. That said, if they factory tool displays the same thing then that's wrong too. You may want to try checking this with ODIS.
 
  • Like
Reactions: Uwe
   #4  

DV52

Verified VCDS User
Verified
Joined
May 16, 2014
Messages
4,242
Reaction score
4,788
Location
Melbourne, Australia
VCDS Serial number
C?ID=194404
@tnisov: Hi.

I'm not in anyway knowledgeable about crash data in a vehicle's SRS control unit - but simply from the units "m/s2", my guess is that the underlying transducer for the measurements of yaw, roll and pitch is a micromechanical type accelerometer, rather than being a piezoelectric type gyroscope.

Again, without being knowledgeable about either device type, my understanding from a quick read is that the difference between the two is that the former type transducer can measure something called "Coriolis acceleration".

I'll leave it to you to research these very arcane topics. Mercifully, I became insane-in-the-membrane many years ago - so well beyond my current pay-scale (which ain't much)!! :)

Don
 
Last edited:
Top