chrono::vehicle::ChPathSteeringControllerStanley Class Reference

Description

"Stanley" path-following ontroller named after an autonomous vehicle called Stanley.

It minimizes lateral error and heading error. Time delay of the driver's reaction is considered. This driver can be parametrized by a PID json file. It can consider a dead zone left and right to the path, where no path information is recognized. This can be useful when the path information contains lateral disturbances, that could cause bad disturbances of the controller. dead_zone = 0.05 means: 0 <= lat_err <= 0.05 no driver reaction 0.05 < lat_err <= 2*0.05 smooth transition interval to complete controller engagement The Stanley driver should find 'always' back to the path, despite of great heading or lateral error. If an integral term is used, its state is getting reset every 30 secs to avoid controller wind-up.

The algorithm comes from from : Gabriel M. Hoffmann, Claire J. Tomlin, Michael Montemerlo, Sebastian Thrun: "Autonomous Automobile Trajectory Tracking for Off-Road Driving", 2005, Stanford University, USA

#include <ChSteeringController.h>

Inheritance diagram for chrono::vehicle::ChPathSteeringControllerStanley:
Collaboration diagram for chrono::vehicle::ChPathSteeringControllerStanley:

Public Member Functions

 ChPathSteeringControllerStanley (std::shared_ptr< ChBezierCurve > path, bool isClosedPath=false, double max_wheel_turn_angle=0.0)
 Construct a steering controller to track the specified path. More...
 
 ChPathSteeringControllerStanley (const std::string &filename, std::shared_ptr< ChBezierCurve > path, bool isClosedPath=false, double max_wheel_turn_angle=0.0)
 Construct a steering controller to track the specified path. More...
 
void SetGains (double Kp, double Ki, double Kd)
 Set the gains for the PID controller.
 
void SetDeadZone (double dead_zone=0.0)
 
virtual double Advance (const ChVehicle &vehicle, double step) override
 Advance the state of the Stanley controller.
 
virtual void Reset (const ChVehicle &vehicle) override
 Reset the PID controller. More...
 
virtual void CalcTargetLocation () override
 Calculate the current target point location. More...
 
double CalcHeadingError (ChVector<> &a, ChVector<> &b)
 
- Public Member Functions inherited from chrono::vehicle::ChSteeringController
virtual ~ChSteeringController ()
 Destructor.
 
void SetLookAheadDistance (double dist)
 Specify the look-ahead distance. More...
 
const ChVectorGetSentinelLocation () const
 Return the current location of the sentinel point. More...
 
const ChVectorGetTargetLocation () const
 Return the current value of the target point. More...
 
std::shared_ptr< ChBezierCurveGetPath () const
 Return a pointer to the Bezier curve.
 
void StartDataCollection ()
 Start/restart data collection.
 
void StopDataCollection ()
 Suspend/stop data collection.
 
bool IsDataCollectionEnabled () const
 Return true if data is being collected.
 
bool IsDataAvailable () const
 Return true if data is available for output.
 
void WriteOutputFile (const std::string &filename)
 Output data collected so far to the specified file.
 

Additional Inherited Members

- Protected Member Functions inherited from chrono::vehicle::ChSteeringController
 ChSteeringController (std::shared_ptr< ChBezierCurve > path)
 Construct a steering controller with default parameters.
 
- Protected Attributes inherited from chrono::vehicle::ChSteeringController
std::shared_ptr< ChBezierCurvem_path
 tracked path (piecewise cubic Bezier curve)
 
double m_dist
 look-ahead distance
 
ChVector m_sentinel
 position of sentinel point in global frame
 
ChVector m_target
 position of target point in global frame
 
double m_err
 current error (signed distance to target point)
 
double m_errd
 error derivative
 
double m_erri
 integral of error
 
utils::CSV_writer * m_csv
 CSV_writer object for data collection.
 
bool m_collect
 flag indicating whether or not data is being collected
 

Constructor & Destructor Documentation

◆ ChPathSteeringControllerStanley() [1/2]

chrono::vehicle::ChPathSteeringControllerStanley::ChPathSteeringControllerStanley ( std::shared_ptr< ChBezierCurve path,
bool  isClosedPath = false,
double  max_wheel_turn_angle = 0.0 
)

Construct a steering controller to track the specified path.

This version uses default controller parameters (zero gains). The user is responsible for calling SetGains and SetLookAheadDistance.

◆ ChPathSteeringControllerStanley() [2/2]

chrono::vehicle::ChPathSteeringControllerStanley::ChPathSteeringControllerStanley ( const std::string &  filename,
std::shared_ptr< ChBezierCurve path,
bool  isClosedPath = false,
double  max_wheel_turn_angle = 0.0 
)

Construct a steering controller to track the specified path.

This version reads controller gains and lookahead distance from the specified JSON file.

Member Function Documentation

◆ CalcTargetLocation()

void chrono::vehicle::ChPathSteeringControllerStanley::CalcTargetLocation ( )
overridevirtual

Calculate the current target point location.

The target point is the point on the associated path that is closest to the current location of the sentinel point.

Implements chrono::vehicle::ChSteeringController.

◆ Reset()

void chrono::vehicle::ChPathSteeringControllerStanley::Reset ( const ChVehicle vehicle)
overridevirtual

Reset the PID controller.

This function resets the underlying path tracker using the current location of the sentinel point.

Reimplemented from chrono::vehicle::ChSteeringController.


The documentation for this class was generated from the following files:
  • /builds/uwsbel/chrono/src/chrono_vehicle/utils/ChSteeringController.h
  • /builds/uwsbel/chrono/src/chrono_vehicle/utils/ChSteeringController.cpp