DiffDriveOdometry Class Reference

Computes odometry values based on a set of kinematic properties and wheel speeds for a diff-drive vehicle. More...

#include <ignition/math/DiffDriveOdometry.hh>

Public Member Functions
	DiffDriveOdometry (size_t _windowSize=10)
	Constructor. More...
	~DiffDriveOdometry ()
	Destructor. More...
const Angle &	AngularVelocity () const
	Get the angular velocity. More...
const Angle &	Heading () const
	Get the heading. More...
void	Init (const clock::time_point &_time)
	Initialize the odometry. More...
bool	Initialized () const
	Get whether Init has been called. More...
double	LinearVelocity () const
	Get the linear velocity. More...
void	SetVelocityRollingWindowSize (size_t _size)
	Set the velocity rolling window size. More...
void	SetWheelParams (double _wheelSeparation, double _leftWheelRadius, double _rightWheelRadius)
	Set the wheel parameters including the radius and separation. More...
bool	Update (const Angle &_leftPos, const Angle &_rightPos, const clock::time_point &_time)
	Updates the odometry class with latest wheels and steerings position. More...
double	X () const
	Get the X position. More...
double	Y () const
	Get the Y position. More...

Detailed Description

Computes odometry values based on a set of kinematic properties and wheel speeds for a diff-drive vehicle.

A vehicle with a heading of zero degrees has a local reference frame according to the diagram below.

  Y
  ^
  |
  |
  O--->X(forward)

Rotating the right wheel while keeping the left wheel fixed will cause the vehicle to rotate counter-clockwise. For example (excuse the lack of precision with ASCII art):

Y     X(forward)
^     ^
 \   /
  \ /
   O

Example Usage

DiffDriveOdometry odom;
odom.SetWheelParams(2.0, 0.5, 0.5);
odom.Init(std::chrono::steady_clock::now());
 
// ... Some time later
 
// Both wheels have rotated the same amount
odom.Update(IGN_DTOR(2), IGN_DTOR(2), std::chrono::steady_clock::now());
 
// ... Some time later
 
// The left wheel has rotated, the right wheel did not rotate
odom.Update(IGN_DTOR(4), IGN_DTOR(2), std::chrono::steady_clock::now());

Constructor & Destructor Documentation

DiffDriveOdometry()

DiffDriveOdometry ( size_t  _windowSize = 10 )

explicit

Constructor.

Parameters

[in]

_windowSize

Rolling window size used to compute the velocity mean

~DiffDriveOdometry()

~DiffDriveOdometry

(

)

Destructor.

Member Function Documentation

AngularVelocity()

const Angle& AngularVelocity

(

)

const

Get the angular velocity.

Returns

The angular velocity in radian/second.

Heading()

const Angle& Heading

(

)

const

Get the heading.

Returns

The heading in radians.

Init()

void Init

(

const clock::time_point &

_time

)

Initialize the odometry.

Parameters

[in]

_time

Current time.

Initialized()

bool Initialized

(

)

const

Get whether Init has been called.

Returns

True if Init has been called, false otherwise.

LinearVelocity()

double LinearVelocity

(

)

const

Get the linear velocity.

Returns

The linear velocity in meter/second.

SetVelocityRollingWindowSize()

void SetVelocityRollingWindowSize

(

size_t

_size

)

Set the velocity rolling window size.

Parameters

[in]

_size

The Velocity rolling window size.

SetWheelParams()

void SetWheelParams	(	double	_wheelSeparation,
		double	_leftWheelRadius,
		double	_rightWheelRadius
	)

Set the wheel parameters including the radius and separation.

Parameters

[in]	_wheelSeparation	Distance between left and right wheels.
[in]	_leftWheelRadius	Radius of the left wheel.
[in]	_rightWheelRadius	Radius of the right wheel.

Update()

bool Update	(	const Angle &	_leftPos,
		const Angle &	_rightPos,
		const clock::time_point &	_time
	)

Updates the odometry class with latest wheels and steerings position.

Parameters

[in]	_leftPos	Left wheel position in radians.
[in]	_rightPos	Right wheel postion in radians.
[in]	_time	Current time point.

Returns

True if the odometry is actually updated.

X()

double X

(

)

const

Get the X position.

Returns

The X position in meters

Y()

double Y

(

)

const

Get the Y position.

Returns

The Y position in meters.

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The documentation for this class was generated from the following file:

• gz/math/DiffDriveOdometry.hh