massprop_skin {AvInertia} R Documentation

## Calculates the mass properties of skin or tertiaries

### Description

Calculate the moment of inertia of skin or tertiaries modeled as a flat triangular plate

### Usage

```massprop_skin(m, rho, pts)
```

### Arguments

 `m` Mass of skin (kg) `rho` Density of skin (kg/m^3) `pts` a 3x3 matrix that represent three points that define the vertices of the triangle. Frame of reference: VRP | Origin: VRP Must be numbered in a counterclockwise direction for positive area, otherwise signs will be reversed. each point should be a different of the matrix as follows: pt1x, pt1y, pt1z pt2x, pt1y, pt2z pt3x, pt3y, pt3z

### Value

This function returns a list that includes: point mass

• Ia 3x3 matrix representing the moment of inertia tensor of skin modeled as a flat triangular plate

• CGa 1x3 vector representing the center of gravity position of skin modeled as a flat triangular plate

• ma double that returns the input skin mass

### Warning

Parallel axis theorem does not apply between two arbitrary points. One point must be the object's center of gravity.

Caution: The skin frame of reference assumes that the z axis is normal to the incoming points.

Christina Harvey

### Examples

```# refer to the vignette
library(AvInertia)

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)

```

[Package AvInertia version 0.0.1 Index]