Incorrect Acceleration Vector Length

Citizen07 · Jul 3, 2018

Sum of separate acceleration axes doesn't equal the value of gravity vector length, example code:
Code:
  M.gx = obj:getSensorX()
  M.gy = obj:getSensorY()
  M.gz = obj:getSensorZnonInertial()
  Vector = math.sqrt(M.gx*M.gx + M.gy*M.gy + M.gz*M.gz)
I think the problem is that gravity vector projection is not included in gx and gy sensor values.

Issue is most pronounced when vehicle is stationary on a steep incline (last part of image 8-11 second):

Accelerations:

See attached .txt file for logged data

Is there a solution to receive acceleration data with values which correspond to measured in a real car with accelerometer (with a gravity vector projected to all axes)?

estama · Jul 3, 2018

Very nice analysis . Your conclusions are also correct.

The sensor data for X and Y do not include the gravity vector (so that accelerations on X and Y are not affected by gravity).

I'll add a function to get the raw sensor data (including gravity) in the next update (which comes in a few days: 13 July 2018).

Edit:

You can get the non inertial forces with current version by using the following code:

local refNodes = v.data.refNodes[0]
local mass = v.data.nodes[refNodes.ref].nodeWeight
sensorX = obj:getNodeForceNonInertial(refNodes.ref, refNodes.left) / mass
sensorY = obj:getNodeForceNonInertial(refNodes.ref, refNodes.back) / mass
sensorZ = obj:getNodeForceNonInertial(refNodes.ref, refNodes.up) / mass

Diamondback · Jul 3, 2018

What exactly are you trying to do btw?

RobertGracie · Jul 3, 2018

I would guess it's SOMETHING to do with how the car reacts in game compared to real life....but I am not exactly sure

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Incorrect Acceleration Vector Length

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Incorrect Acceleration Vector Length

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estama
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RobertGracie
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