# Obstacle Avoidance

Compute obstacle-free direction using range sensor data and target position

*Since R2021b*

**Libraries:**

UAV Toolbox /
Algorithms

## Description

The Obstacle Avoidance block computes an obstacle-free direction using range sensor data and target position.

## Examples

## Ports

### Input

**Position** — Position of UAV

vector

Position of the UAV, specified as a vector of the form
`[`

, in meters.*x*; *y*;
*z*]

**Example: **
`[1; 1; 1]`

**Data Types: **`double`

**Orientation** — Orientation of UAV

vector

Orientation of the UAV, specified as a quaternion vector of the form
`[`

.*w*; *x*; *y*;
*z*]

**Example: **`[1; 0; 0; 0]`

**Data Types: **`double`

**ObstaclePoints** — Positions of obstacles

matrix

Positions of the obstacles, specified as an *N*-by-3 matrix with
rows of the form `[`

, in meters. *x*
*y*
*z*]*N* is the number of
obstacle points.

**Example: **`[1 1 1; 2 2 2]`

**Data Types: **`double`

**TargetPostion** — Position of target

vector

Position of the target, specified as a vector of the form
`[`

, in meters.*x*; *y*;
*z*]

**Example: **`[2; 3; 4]`

**Data Types: **`double`

### Output

**DesiredDirection** — Desired direction

vector

Desired direction, returned as a vector of the form
`[`

, in meters.*x*; *y*;
*z*]

**Data Types: **`double`

**DesiredYaw** — Desired yaw

scalar

Desired yaw, returned as numeric scalar in radians in the range of ```
[-pi,
pi]
```

.

**Data Types: **`double`

**Status** — Status of obstacle-free direction

`0`

| `1`

| `2`

| `3`

Status of the obstacle-free direction, returned as `0`

,
`1`

, `2`

, or `3`

.

`0`

— An obstacle-free direction is found.`1`

— No obstacle-free direction is found.`2`

— An obstacle-free direction is found but is close to the obstacle.`3`

— No obstacle-free direction is found and is close to obstacle.

**Data Types: **`uint8`

## Parameters

**Main**

**Sensor range limits (m)** — Limits of range sensor

`[0.2 10]`

(default) | vector of form `[`*min*
*max*]

*min*

*max*]

Specify the minimum and maximum limits of the range sensor as a vector of the form
`[`

, with values in meters.*min*
*max*]

**Data Types: **`double`

**Sensor horizontal field of view (deg)** — Horizontal field of view limits of range sensor

`[-60 60]`

(default) | vector of form `[`*min*
*max*]

*min*

*max*]

Specify the minimum and maximum horizontal field of view limits of the range sensor
as a vector of the form `[`

, with values in degrees.*min*
*max*]

**Data Types: **`double`

**Sensor vertical field of view (deg)** — Vertical field of view limits of range sensor

`[-30 30]`

(default) | vector of form `[`*min*
*max*]

*min*

*max*]

Specify the minimum and maximum vertical field of view limits of the range sensor as
a vector of the form `[`

, with values in degrees.*min*
*max*]

**Data Types: **`double`

**Sensor location [X, Y, Z] (m)** — Sensor mounting location on UAV

`[0 0 0]`

(default) | vector of form `[`*x*
*y*
*z*]

*x*

*y*

*z*]

Specify the mounting location of the sensor on the UAV as a vector of the form
`[`

, with values in meters.*x*
*y*
*z*]

**Data Types: **`double`

**Sensor orientation [Roll, Pitch, Yaw] (deg)** — Orientation of sensor mounted on UAV

`[0 0 0]`

(default) | vector of form `[`*roll*
*pitch*
*yaw*]

*roll*

*pitch*

*yaw*]

Specify the orientation of the sensor mounted on the UAV as a vector of the form
`[`

, with values in degrees.*roll*
*pitch*
*yaw*]

**Data Types: **`double`

**Vehicle radius (m)** — Radius of UAV

`1`

(default) | numeric scalar

This dimension defines the smallest circle that can circumscribe your vehicle, in meters. The vehicle radius is used to account for vehicle size when computing the obstacle-free direction.

**Data Types: **`double`

**Minimum distance to obstacle (m)** — Safety distance around UAV to obstacle

`1`

(default) | numeric scalar

The safety distance specifies, in meters, the space accounted for between the UAV and obstacles in addition to the vehicle radius. The vehicle radius and safety distance are used to compute the obstacle-free direction.

**Data Types: **`double`

**Simulate using** — Type of simulation to run

`Interpreted execution`

(default) | `Code generation`

Specify whether to simulate the model using `Interpreted execution`

or `Code generation`

.

`Interpreted execution`

— Simulate the model using the MATLAB^{®}interpreter. This option reduces startup time, but has a slower simulation speed than`Code generation`

. In this mode, you can debug the source code of the block.`Code generation`

— Simulate the model using generated C code. The first time you run a simulation, Simulink^{®}generates C code for this block. The C code is reused for subsequent simulations, as long as the model does not change. This option requires additional startup time, but the speed of subsequent simulations is comparable to`Interpreted execution`

.

**Tunable: **No

**Histogram**

**Histogram resolution (deg)** — Histogram grid resolution

`5`

(default) | `1`

| `3`

| `6`

| `10`

| `15`

| `18`

| `30`

| `45`

| `60`

To change the histogram grid resolution, select a value from the list. All values are in degrees.

**Histogram window size** — Histogram window size

`1`

(default) | odd integer

The histogram window size determines the angular width of an obstacle-free opening in the azimuth and elevation directions. This value is unitless.

**Data Types: **`uint8`

**Histogram threshold** — Threshold for computing histogram

`1`

(default) | positive integer

The threshold for computing the histogram specifies the minimum number of obstacle points that should be in an histogram cell to be considered as obstacle. If a cell contains fewer than this number of obstacle points, the cell is considered as obstacle-free.

**Data Types: **`uint8`

**Maximum age of obstacle point** — Maximum age of remembered obstacle point

`0`

(default) | numeric scalar

Specifies the maximum age of a remembered obstacle point as a numeric scalar. This value specify the number of previous time steps for which the obstacle points from those time steps is remembered.

**Data Types: **`double`

**Cost**

**Target direction weight** — Cost function weight for target direction

`5`

(default) | numeric scalar

Specifies the function weight for moving toward the target direction. To follow a
target direction, set this weight to be greater than the sum of ```
Current direction
weight
```

and ```
Previous direction
weight
```

. To ignore the target direction cost, set this weight to
`0`

.

**Data Types: **`double`

**Current direction weight** — Cost function weight for current direction

`2`

(default) | numeric scalar

Specifies the function weight for moving the vehicle in the current heading
directions. Higher values of this weight produce efficient paths. To ignore the current
direction cost, set this weight to `0`

.

**Data Types: **`double`

**Previous direction weight** — Cost function weight for previous direction

`2`

(default) | numeric scalar

Specifies the function weight for moving in the previously selected steering
direction. Higher values of this weight produce smoother paths. To ignore the previous
direction cost, set this weight to `0`

.

**Data Types: **`double`

## Extended Capabilities

### C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

## Version History

**Introduced in R2021b**

## See Also

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