Unit of Velocity from a Random Walk measured by an accelerometer

AI Thread Summary
The discussion centers on a Kalman filter measurement equation involving "-g + v," where g is acceleration in m/s² and v is a velocity random walk expressed in m/s/sqrt(hr). Participants highlight that the units of g and v are incompatible, indicating a potential error in the equation's derivation. There is a suggestion to reconsider the inclusion of the random walk in the measurement equation instead of the state propagation equation. The need for proper unit transformation to ensure accurate calculations is emphasized. Clarifying these unit discrepancies is essential for the correct application of the Kalman filter.
hoddy
Messages
4
Reaction score
0
TL;DR Summary
Hi, I am working on a kalman filter where my measurement equation involves "-g + v" , where g is in m/s^2 and v is velocity random walk given in m/s/sqrt(hr). Feels like a stupid question, but how can I transform the unit of velocity random walk so I can do the calculation correctly?
Hi, I am working on a kalman filter where my measurement equation involves "-g + v" , where g is in m/s^2 and v is velocity random walk given in m/s/sqrt(hr). Feels like a stupid question, but how can I transform the unit of velocity random walk so I can do the calculation correctly?
 
Engineering news on Phys.org
hoddy said:
Summary: Hi, I am working on a kalman filter where my measurement equation involves "-g + v" , where g is in m/s^2 and v is velocity random walk given in m/s/sqrt(hr). Feels like a stupid question, but how can I transform the unit of velocity random walk so I can do the calculation correctly?

Hi, I am working on a kalman filter where my measurement equation involves "-g + v" , where g is in m/s^2 and v is velocity random walk given in m/s/sqrt(hr). Feels like a stupid question, but how can I transform the unit of velocity random walk so I can do the calculation correctly?
It looks to me as though you are trying to add quantities with incommensurate units. ##g## has units of acceleration, and ##v## has units that are neither velocity or acceleration. That suggests that there is an error somewhere in the derivation of the ##-g+v## term. Maybe you have assumed that some variable has a value of ##1##, and forgotten to carry along its units.
 
  • Like
Likes scottdave
Also, I wonder why you are including your random walk process in the measurement equation rather than in the state propagation equation?
 
I have Mass A being pulled vertically. I have Mass B on an incline that is pulling Mass A. There is a 2:1 pulley between them. The math I'm using is: FA = MA / 2 = ? t-force MB * SIN(of the incline degree) = ? If MB is greater then FA, it pulls FA up as MB moves down the incline. BUT... If I reverse the 2:1 pulley. Then the math changes to... FA = MA * 2 = ? t-force MB * SIN(of the incline degree) = ? If FA is greater then MB, it pulls MB up the incline as FA moves down. It's confusing...
Hi. I noticed that all electronic devices in my household that also tell time eventually lag behind, except the ones that get synchronized by radio signal or internet. Most of them are battery-powered, except my alarm clock (which runs slow as well). Why does none of them run too fast? Deliberate design (why)? Wrong temperature for quartz crystal? Decreasing battery voltage? Or just a coincidence?
Back
Top