BicycleModel Class Reference

This class implements the Bicycle Model. This model is used to predict the future state of the rover given a current state and control input. More...

#include <BicycleModel.hpp>

Classes
struct	Prediction
	This struct is used to store the predicted state of the bicycle. More...

Public Member Functions
	BicycleModel ()
	Construct a new Bicycle Model object.
	BicycleModel (const double dWheelbase, const double dXPosition, const double dYPosition, const double dTheta)
	Construct a new Bicycle Model object.
void	ResetState (const double dXPosition, const double dYPosition, const double dTheta)
	Resets the state of the model to a new position and heading.
void	ResetState ()
	Resets the state of the model to a default state.
void	UpdateState (const double dXPosition, const double dYPosition, const double dTheta)
	Update the state of the model, given a new position and heading. This method will automatically calculate the velocity of the rover base on the new and current position. The steering angle is also updated automatically based on the new and current heading.
void	Predict (const double dTimeStep, const int nNumPredictions, std::vector< Prediction > &vPredictions)
	Accessor for the State private member.
void	SetWheelbase (const double dWheelbase)
	Mutator for the Wheelbase private member.
void	SetXPosition (const double dXPosition)
	Mutator for the XPosition private member.
void	SetYPosition (const double dYPosition)
	Mutator for the YPosition private member.
void	SetTheta (const double dTheta)
	Mutator for the Theta private member.
void	SetSteeringAngle (const double dSteeringAngle)
	Mutator for the Steering Angle private member.
double	GetWheelbase () const
	Accessor for the Wheelbase private member.
double	GetXPosition () const
	Accessor for the XPosition private member.
double	GetYPosition () const
	Accessor for the YPosition private member.
double	GetTheta () const
	Accessor for the Theta private member.
double	GetVelocity () const
	Accessor for the Velocity private member.
double	GetSteeringAngle () const
	Accessor for the Steering Angle private member.

Private Attributes
double	m_dWheelbase
double	m_dXPosition
double	m_dYPosition
double	m_dTheta
double	m_dVelocity
double	m_dSteeringAngle
std::chrono::system_clock::time_point	m_tmLastUpdateTime

Detailed Description

This class implements the Bicycle Model. This model is used to predict the future state of the rover given a current state and control input.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

Constructor & Destructor Documentation

BicycleModel() [1/2]

BicycleModel::BicycleModel ( )

inline

Construct a new Bicycle Model object.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

        {
            // Initialize member variables.
            m_dWheelbase       = 0.0;
            m_dXPosition       = 0.0;
            m_dYPosition       = 0.0;
            m_dTheta           = 0.0;
            m_dVelocity        = -1.0;
            m_dSteeringAngle   = 0.0;
            m_tmLastUpdateTime = std::chrono::system_clock::now();
        }

BicycleModel() [2/2]

BicycleModel::BicycleModel ( const double  dWheelbase, const double  dXPosition, const double  dYPosition, const double  dTheta  )

inline

Construct a new Bicycle Model object.

Parameters

dWheelbase	- The distance between the front and rear axles of the rover.
dXPosition	- The x position of the rover.
dYPosition	- The y position of the rover.
dTheta	- The heading angle of the rover in degrees.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

        {
            // Initialize member variables.
            m_dWheelbase       = dWheelbase;
            m_dXPosition       = dXPosition;
            m_dYPosition       = dYPosition;
            m_dTheta           = dTheta;
            m_dVelocity        = -1.0;
            m_dSteeringAngle   = 0.0;
            m_tmLastUpdateTime = std::chrono::system_clock::now();
        }

Member Function Documentation

ResetState() [1/2]

void BicycleModel::ResetState ( const double  dXPosition, const double  dYPosition, const double  dTheta  )

inline

Resets the state of the model to a new position and heading.

Parameters

dXPosition	- The x position of the rover.
dYPosition	- The y position of the rover.
dTheta	- The heading angle of the rover in degrees.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

        {
            // Update member variables.
            m_dXPosition       = dXPosition;
            m_dYPosition       = dYPosition;
            m_dTheta           = dTheta;
            m_dSteeringAngle   = 0.0;
            m_dVelocity        = -1.0;
            m_tmLastUpdateTime = std::chrono::system_clock::now();
        }

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ResetState() [2/2]

void BicycleModel::ResetState ( )

inline

Resets the state of the model to a default state.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

        {
            // Update member variables.
            m_dXPosition       = 0.0;
            m_dYPosition       = 0.0;
            m_dTheta           = 0.0;
            m_dSteeringAngle   = 0.0;
            m_dVelocity        = -1.0;
            m_tmLastUpdateTime = std::chrono::system_clock::now();
        }

UpdateState()

void BicycleModel::UpdateState ( const double  dXPosition, const double  dYPosition, const double  dTheta  )

inline

Update the state of the model, given a new position and heading. This method will automatically calculate the velocity of the rover base on the new and current position. The steering angle is also updated automatically based on the new and current heading.

Parameters

dXPosition	- The x position of the rover.
dYPosition	- The y position of the rover.
dTheta	- The heading angle of the rover in degrees.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

        {
            // Check if this is our first update.
            if (m_dVelocity == -1.0)
            {
                // Set the velocity to zero.
                m_dVelocity = 0.0;
            }
            // Calculate the velocity of the rover as long as the new position is different from the current position.
            else if (dXPosition != m_dXPosition || dYPosition != m_dYPosition)
            {
                // Calculate the velocity of the rover.
                std::chrono::system_clock::time_point tmCurrentTime = std::chrono::system_clock::now();
                double dTimeElapsed = std::chrono::duration_cast<std::chrono::milliseconds>(tmCurrentTime - m_tmLastUpdateTime).count() / 1000.0;
                m_dVelocity         = std::sqrt(std::pow(dXPosition - m_dXPosition, 2) + std::pow(dYPosition - m_dYPosition, 2)) / dTimeElapsed;
 
                // Update the last update time.
                m_tmLastUpdateTime = tmCurrentTime;
            }
 
            // Calculate the steering angle of the rover.
            m_dSteeringAngle = (std::atan2(dYPosition - m_dYPosition, dXPosition - m_dXPosition) * 180.0 / M_PI) - m_dTheta;
            // Ensure the steering angle stays within 0-360 degrees.
            m_dSteeringAngle = numops::InputAngleModulus(m_dSteeringAngle, 0.0, 360.0);
 
            // Update member variables.
            m_dXPosition = dXPosition;
            m_dYPosition = dYPosition;
            m_dTheta     = dTheta;
        }

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Predict()

void BicycleModel::Predict ( const double  dTimeStep, const int  nNumPredictions, std::vector< Prediction > &  vPredictions  )

inline

Accessor for the State private member.

Parameters

dTimeStep	- The time step to predict the future state. How far into the future to predict.
nNumPredictions	- The number of predictions to make.
vPredictions	- The vector of predictions to store the predicted states.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

        {
            // Start from the current state.
            double dXPredicted     = m_dXPosition;
            double dYPredicted     = m_dYPosition;
            double dThetaPredicted = m_dTheta;
 
            // Perform prediction for a specified number of time steps.
            for (int nIter = 0; nIter < nNumPredictions; ++nIter)
            {
                // Convert theta from degrees to radians for calculation.
                double dThetaRad         = dThetaPredicted * M_PI / 180.0;
                double dSteeringAngleRad = m_dSteeringAngle * M_PI / 180.0;
 
                // Calculate the new state.
                dXPredicted += m_dVelocity * std::sin(dThetaRad) * dTimeStep;
                dYPredicted += m_dVelocity * std::cos(dThetaRad) * dTimeStep;
                dThetaPredicted += (m_dVelocity / m_dWheelbase) * std::tan(dSteeringAngleRad - M_PI_2) * dTimeStep;
 
                // Ensure theta stays within 0-360 degrees.
                dThetaPredicted = numops::InputAngleModulus(dThetaPredicted, 0.0, 360.0);
 
                // Store the new state.
                Prediction stPrediction{dXPredicted, dYPredicted, dThetaPredicted};
                vPredictions.push_back(stPrediction);
            }
        }

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SetWheelbase()

void BicycleModel::SetWheelbase ( const double  dWheelbase )

inline

Mutator for the Wheelbase private member.

Parameters

dWheelbase

- The distance between the front and rear axles of the rover.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ m_dWheelbase = dWheelbase; }

SetXPosition()

void BicycleModel::SetXPosition ( const double  dXPosition )

inline

Mutator for the XPosition private member.

Parameters

dXPosition

- The x position of the rover.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ m_dXPosition = dXPosition; }

SetYPosition()

void BicycleModel::SetYPosition ( const double  dYPosition )

inline

Mutator for the YPosition private member.

Parameters

dYPosition

- The y position of the rover.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ m_dYPosition = dYPosition; }

SetTheta()

void BicycleModel::SetTheta ( const double  dTheta )

inline

Mutator for the Theta private member.

Parameters

dTheta

- The heading angle of the rover in degrees.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ m_dTheta = dTheta; }

SetSteeringAngle()

void BicycleModel::SetSteeringAngle ( const double  dSteeringAngle )

inline

Mutator for the Steering Angle private member.

Parameters

dSteeringAngle

- The steering angle of the rover in degrees.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ m_dSteeringAngle = dSteeringAngle; }

GetWheelbase()

double BicycleModel::GetWheelbase ( ) const

inline

Accessor for the Wheelbase private member.

Returns

double - The distance between the front and rear axles of the rover.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ return m_dWheelbase; }

GetXPosition()

double BicycleModel::GetXPosition ( ) const

inline

Accessor for the XPosition private member.

Returns

double - The x position of the rover.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ return m_dXPosition; }

GetYPosition()

double BicycleModel::GetYPosition ( ) const

inline

Accessor for the YPosition private member.

Returns

double - The y position of the rover.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ return m_dYPosition; }

GetTheta()

double BicycleModel::GetTheta ( ) const

inline

Accessor for the Theta private member.

Returns

double - The heading angle of the rover in degrees.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ return m_dTheta; }

GetVelocity()

double BicycleModel::GetVelocity ( ) const

inline

Accessor for the Velocity private member.

Returns

double - The velocity of the rover.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ return m_dVelocity; }

GetSteeringAngle()

double BicycleModel::GetSteeringAngle ( ) const

inline

Accessor for the Steering Angle private member.

Returns

double - The steering angle of the rover in degrees.

Author

clayjay3 (clayt.nosp@m.onra.nosp@m.ycowe.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om)

Date

2025-01-10

{ return m_dSteeringAngle; }

---

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

• src/algorithms/kinematics/BicycleModel.hpp