# parallelaxis: Parallel axis theory In AvInertia: Calculate the Inertial Properties of a Flying Bird

## Description

Reads in an initial tensor and an offset to compute the transformed tensor. Will be in the same frame of reference as the input tensor.

## Usage

 `1` ```parallelaxis(I, offset_vec, m, cg_a) ```

## Arguments

 `I` a 3x3 matrix representing the moment of inertia tensor about the center of gravity of the object (kg-m^2). `offset_vec` a 1x3 vector representing the distance (x,y,z) between the objects CG and the arbitrary pt A (m). Vector should always point from the CG to the arbitrary point A. `m` Mass of the object (kg). `cg_a` If input I is about the CG enter "CG" or if I is about an arbitrary axis enter "A".

## Value

a 3x3 matrix representing the transformed moment of inertia tensor after a solid body translation defined by the offset vector.

Christina Harvey

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31``` ```# refer to the vignette library(AvInertia) # load data data(dat_id_curr, package = "AvInertia") data(dat_bird_curr, package = "AvInertia") data(dat_feat_curr, package = "AvInertia") data(dat_bone_curr, package = "AvInertia") data(dat_mat, package = "AvInertia") data(clean_pts, package = "AvInertia") # 1. Determine the center of gravity of the bird's torso (including the legs) dat_torsotail_out = massprop_restbody(dat_id_curr, dat_bird_curr) # 2. Calculate the inertia of the flight feathers about the tip of the calamus feather_inertia <- compute_feat_inertia(dat_mat, dat_feat_curr, dat_bird_curr) # 3. Determine the center of gravity of one of the bird's wings dat_wing_out = massprop_birdwing(dat_id_curr, dat_bird_curr, dat_bone_curr, dat_feat_curr, dat_mat, clean_pts, feather_inertia, plot_var = 0) # Visualize the center of gravity of each wing component in the x and y axis dat_wing_out = massprop_birdwing(dat_id_curr, dat_bird_curr, dat_bone_curr, dat_feat_curr, dat_mat, clean_pts, feather_inertia, plot_var = "yx") # or the y and z axis dat_wing_out = massprop_birdwing(dat_id_curr, dat_bird_curr, dat_bone_curr, dat_feat_curr, dat_mat, clean_pts, feather_inertia, plot_var = "yz") # 4. Combine all data and obtain the center of gravity, moment of inertia # and principal axes of the bird curr_full_bird = combine_inertialprop(dat_torsotail_out,dat_wing_out, dat_wing_out, dat_id_curr, dat_bird_curr, symmetric=TRUE) ```

AvInertia documentation built on July 22, 2021, 9:08 a.m.