1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Calculating a correction factor

  1. Jun 21, 2006 #1
    I am trying to calibrate this circuit, and it is hooked up to a voltmeter and also a power supply. When the circuit is horizontal, the voltmeter is supposed to read zero both in the x and y direction. Here, the x-direction is determined by tilting the circuit up and down and the y-direction is determined by tilting the circuit left and right (or something like that). Anyway, when I put the circuit on the leveled surface however, the voltmeter doesn't read zero for both x and y values. Therefore, in order for the voltage reading to read zero, I have sort of adjust the length of the four sides of the circuit so that the voltage is zero when it is on a leveled surface.

    The circuit came with a calibration curve fit equation
    theta = a + bV +cV**2+dV**3+eV**4+fV**5

    where V is the X or Y output

    and a,b,c,d,e,f is given for both the x-axis and the y-axis.

    I calculated the angles using the voltage values I found when the circuit was leveled on the surface.

    The voltage when the circuit is horizontal is 0.1999 arc degrees for the x-axis and -1.023 arc degrees for the y-axis. Using these values, I have to determine a correction factor for the four sides of the circuit, so I can make four stands to make the voltage zero when it's on a leveled surface. I'd appreciate if someone could give me some input on how I should do this. I know I have to use the angles I calculated somehow.
     
    Last edited: Jun 21, 2006
  2. jcsd
  3. Jun 21, 2006 #2

    berkeman

    User Avatar

    Staff: Mentor

    Woof. What in the world are you talking about devildoll? Voltage does not have units of arc-degrees for starters. What is the device you are trying to calibrate? It sounds like it is some kind of tilt meter sensor?
     
  4. Jun 21, 2006 #3
    Oops sorry. I meant the calculated theta (angle) from the equation above equals 0.1999 arc degrees for the x-axis and -1.023 arc degrees for y-axis. The measured voltages were 0.026 V for the x-axis and the -0.243 V for y-axis. I suppose the the value for the x-axis is close to zero, but the value for the y-axis is way off. So, I have to build four little stands of appropriate length so that when the device is on a leveled surface, the voltage reads zero. Yeah, I suppose you could say it's a title meter sensor, and it is going to be on a magnetometer.
     
    Last edited: Jun 21, 2006
  5. Jun 22, 2006 #4

    berkeman

    User Avatar

    Staff: Mentor

    Not knowing exactly what the setup is, it's hard for me to make much of a suggestion. Can you just tilt the thing by hand until you get zero, and measure that angle? It sounds like you are wanting to make an adapter pre-tilt thing to get zero out when the adapter+sensor are placed on a level surface, so just tilt the sensor until you get zero, and make something that provides that tilt. Better yet, squish the sensor down in some soft putty on a level surface and tilt it to get zero, then let the putty dry into a permanent adapter.
     
  6. Jun 22, 2006 #5
    Yeah, I guess when I tilt the tiltmeter, I can get a zero voltage for both x and y. However, in order to make something that makes the tilt, my advisor wants me to calculate by how much for each side. So, since I have the x and y angles (calculated from the calibration curve fit equation which came with the device), and the length of each side, I guess I could use trig, maybe, the tan function to calculate the required height to make the correction right?

    By the way, here's a link of the device

    http://www.geosystems.com.au/pdpm02.html [Broken]
     
    Last edited by a moderator: May 2, 2017
  7. Jun 22, 2006 #6

    berkeman

    User Avatar

    Staff: Mentor

    Sounds right. Looks like a fun project!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Calculating a correction factor
  1. Is this correct? (Replies: 3)

Loading...