Description Usage Arguments Details Value Author(s) References Examples

calculate roll angle using measurements from a three-axis accelerometer. However, only two axes are required.

1 | ```
roll(y, z)
``` |

`y` |
a numeric vector of y-axis values. |

`z` |
a numeric vector of z-axis values. |

Roll angle is the angle between the left-right axis and the horizon. The angle is calculated assuming the NED
(north, east, down) frame of reference, where x is north, y is east, and z is down. Typically, this is measured with an accelerometer and is scaled from -1 to +1. Using NED, this means that when the accelerometer is measuring 1g, this is equal to -9.8 *m/s^2*. This also means that if the axis is aligned with the earth gravity vector (i.e. down, towards the center of the earth), it should have a value of +1. Roll angle is calcualted by

*roll = atan2(y,z)*

A downward movement of the y-axis gives a positive roll angle.

an object of roll values (in radians) from *-π ≤* `roll`

*≤ π*

Ed Farrell <[email protected]>

Ozyagcilar, T. (2012), Implementing a tilt-compensated eCompass using accelerometer and magnetometer sensors. Freescale semiconductor, AN 4248, Rev. 3.

Smith, K. J. (1998), *Essentials of Trigonometry*. Pacific Grove, CA: Brooks/Cole.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | ```
## Import the yaw, pitch and roll simulated calibration dataset. For
## an explanation of the data use help(yprsim).
data(yprsim)
## Assign accelerometer variables
ay <- yprsim$ay
az <- yprsim$az
## Calculate roll
theta <- roll(ay, az)
plot(theta*(180/pi),type='l',lty=1,lwd=2,xlab="time (s)",ylab="pitch (degrees)",
main="Roll Calculation (2 roll rotations)")
abline(v=c(126,252),lty=3,lwd=2)
legend(-10,110,legend=c("Roll","Change in \n Rotation"),
col=c("black","black"),lty=c(1,3),bty="n")
text(50,-70,"Yaw");text(175,-70,"Pitch");text(320,-70,"Roll")
``` |

animalTrack documentation built on May 29, 2017, 5:59 p.m.

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