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I have evaluated the Accelerometer offset occurring due to placement of Accelerometer away from the centre of rotation of body. In the below evaluation I am trying to calculate Accelerometer's reading away from the centre of rotation of the body. It is made sure that the Accelerometer is placed rigidly inside the vehicle.

This calculation is done because I need to calculate pure translational accelerations recorded by the vehicle, however when the Accelerometer is not placed at centre of rotation of body it will measure rotational + translational accelerations of the body.

Kindly look at my evaluation and let me know is my evaluation correct. Also I have a few questions which I have posted in the end of my evaluation which I have added as an Image file

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  1. Is the formula correct? And also, is there anything wrong with the implementation of the above formula to find acceleration at center of rotation of the body.
  2. If we replace units of angular velocity and angular acceleration from rad/sec and rad/s2 to degree/sec and degree/s2 the output values for a_x,a_y a_z change, Is this normal or do we have to use only one kind of unit in this formula? i.e., Either rad/sec or deg/sec
  3. If it is made possible that the body rotates on it's own axis(i.e., No translational velocity in the body) the accelerometer would read pure rotational accelerations of the body. In this case if we use the above formula the accelerometer readings should be 0 ? right as in the center of rotation of body we should get 0 value if the body is in pure rotational motion? Will this condition be satisfied with this formula?

Updates

  1. Rotation specification of device & Accelerometer specification includes Forward motion as motion in x axis, z axis is upwards, and y axis is corresponding to x axis. The three axis of rotation are coincident with the linear acceleration axis. Positive rotation is a counter-clockwise rotation about an axis

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  1. According to John Alexiou, Equation 3 is not correctly represented and has missing terms, Kindly review and update if necessary.

Note

  1. This post is comprised of numerical calculations to depict the use of formula; However, the question is posted only to verify the formula, i.e, is the formula correct for calculation of acceleration value at centre of gravity of the vehicle or any extra parameters may be added to it to correct the formula.

References

  1. Calculating acceleration offset by Center of Gravity (C.G.)

  2. https://www.nxp.com/company/blog/accelerometer-placement-where-and-why:BL-ACCELEROMETER-PLACEMENT

  3. https://www.basicairdata.eu/knowledge-center/compensation/inertial-measurement-unit-placement/

Akash Sagar
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  • Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. – Community Jan 13 '23 at 12:54
  • equation 2 is correct, but equation 3 is missing the rotational acceleration terms $\alpha_i$ (what is commonly referred to as Eulerian acceleration). – John Alexiou Jan 13 '23 at 14:15
  • Hi John, Thanks for your response, however as you mentioned that equation 3 is missing rotational acceleration terms, kindly let me know what equivalent equation for this situation will be. As I am seeing that there is Angular acceleration term αx, αy, αz in the equation 3. Kindly let me know if I am missing something. – Akash Sagar Jan 16 '23 at 06:45

0 Answers0