ArGPS Class Reference

#include <ArGPS.h>

Inheritance diagram for ArGPS:

List of all members.

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Detailed Description

GPS Device Interface.

Connects to GPS device over a serial port or other device connection and reads data. Supports GPS devices sending standard NMEA format data (specifically the GPRMC, GPGGA, GPGSA, GPGRME, and optionally GPGSV, PGRMZ, PGRME, and HCHDG/T/M messages). If your GPS device supports several data formats or modes, select NMEA output in its configuration.

The preferred method of creating and setting up a new ArGPS object is to use ArGPSConnector, which creates an instance of ArGPS or a subclass, and creates and opens its device connection, based on command-line parameters. (To manually create an ArGPS object, create an ArDeviceConnection instance and call setDeviceConnection(), then open that device connection and call connect().

For either method, to get new data from the GPS, must call read() or readWithLock() periodically, ideally at a rate equal to or faster than your GPS sends data (usually one second). You can do this from a Sensor Intetrpretation Task in ArRobot, or a seperate thread. If you are calling read() from a loop in a new thread,

Here is an example of calling readWithLock() from a sensor interpretation task. The integer argument given to the functor constructor is a milisecond timeout that is passed to readWithLock() and prevents it from blocking too long if it doesn't read any data. It is important to do this in a robot task, or the robot task cycle will be blocked and cause problems.

    ArRetFunctor1C<ArGPS, int, unsigned int> gpsReadFunc(myGPS, &ArGPS::readWithLock, 10);
    myRobot->addSensorInterpretationTask("GPS read", 100, &gpsReadFunc);

If you use your own loop or thread, then it ought to include a call to ArUtil::sleep() for at least several hundred miliseconds to avoid starving other threads, since read() will return immediately if there is no data to read rather than blocking.

For each piece of data provided by this class, there is a flag indicating whether it was received from the GPS and set. Not all GPS models return all kinds of information, or it may be disabled in some way in a GPS's internal configuration, or the GPS may not yet have started sending the data (e.g. still acquiring satellites). Also, not all data will be received by one call to read(), and especially immediately after connecting and starting to read data, it may take a few seconds for data to be obtained. Furthermore, it may take some time for the GPS to calculate data with full accuracy.

See also:

gpsExample::cpp

gpsRobotTaskExample::cpp

This class is not inherently thread safe. Stored data is updated by read(), so if accessing from multiple threads, call lock() before calling any data accessor methods (methods starting with "get"), or read(), and call unlock() when done. You can also call readWithLock() to do a locked read in one function call.

Note:

ArGPS only provides access to the data reported by a GPS. The position reported by a GPS is in degrees on the surface of the earth (WGS84 datum), not in the cartesian coordinate system used by the robot odometry or ArMap. You can use the subclasses of Ar3DPoint (ArLLACoords, etc) to convert between different geographical coordinate systems, which may help you match GPS coordinates to the robot pose coordinate system.

enum	FixType {   NoFix, BadFix, GPSFix, DGPSFix,   PPSFix, RTKinFix, FloatRTKinFix, DeadReckFix,   ManualFix, SimulatedFix, UnknownFixType, OmnistarConverging = FloatRTKinFix,   OmnistarConverged = RTKinFix }
	Access the last received data from the GPS. More...
double	getCompassHeadingMag () const
	Heading from magnetic north.
double	getCompassHeadingTrue () const
	Heading from true north.
const ArGPS::Data &	getCurrentDataRef () const
unsigned short	getDGPSStationID () const
FixType	getFixType () const
const char *	getFixTypeName () const
double	getGarminPositionError () const
double	getGarminVerticalPositionError () const
	GPS device's error estimation in meters.
ArTime	getGPSPositionTimestamp () const
double	getLatitude () const
double	getLongitude () const
int	getNumSatellitesTracked () const
double	getSpeed () const
ArTime	getTimeReceivedPosition () const
bool	haveCompassHeadingMag () const
	Have a compass heading value relative to magnetic north.
bool	haveCompassHeadingTrue () const
	Have a compass heading value relative to true north (using device's configured declination).
bool	haveDGPSStation () const
bool	haveGarminPositionError () const
bool	haveGarminVerticalPositionError () const
bool	haveLatitude () const
bool	haveLongitude () const
bool	havePosition () const
bool	haveSpeed () const
void	setCompassHeadingMag (double val)
void	setCompassHeadingMagWithLock (double val)
void	setCompassHeadingTrue (double val)
void	setCompassHeadingTrueWithLock (double val)
static const char *	getFixTypeName (FixType type)
Public Types
enum	{ ReadFinished = ArNMEAParser::ParseFinished, ReadError = ArNMEAParser::ParseError, ReadData = ArNMEAParser::ParseData, ReadUpdated = ArNMEAParser::ParseUpdated }
	Flags to indicates what the read() method did. i.e. If nothing was done, then the result will be 0. To check a read() return result result to see if data was updated, use (result & ReadUpdated). To check if there was an error, use (result & ReadError). More...
Public Member Functions
void	addNMEAHandler (const char *message, ArNMEAParser::Handler *handler)
bool	blockingConnect (unsigned long connectTimeout=10000)
virtual bool	connect (unsigned long connectTimeout=10000)
	Check that the device connection (e.g. serial port) is open, and that data is being received from GPS.
double	getAltimeter () const
double	getAltitude () const
	Calculated from GPS.
ArDeviceConnection *	getDeviceConnection () const
	Return device connection in use (or NULL if none).
double	getHDOP () const
double	getMeanSNR () const
	dB
double	getPDOP () const
double	getVDOP () const
bool	haveAltimeter () const
bool	haveAltitude () const
	Calculated from GPS.
bool	haveHDOP () const
bool	havePDOP () const
bool	haveSNR () const
bool	haveVDOP () const
void	lock ()
void	logData () const
	Log last received data using ArLog.
void	printData (bool labels=true) const
void	printDataLabelsHeader () const
virtual int	read (unsigned long maxTime=0)
	Read some data from the device connection, and update stored data as complete messages are received.
int	readWithLock (unsigned int maxTime)
void	removeNMEAHandler (const char *message)
void	setDeviceConnection (ArDeviceConnection *deviceConn)
	Set device connection to use.
void	setIgnoreChecksum (bool ignore)
	Set whether checksum sent with NMEA messages is ignored.
void	unlock ()
double	getAltitudeError () const
	Standard deviation of altitude error, meters.
double	getInputsRMS () const
double	getLatitudeError () const
ArPose	getLatLonError () const
double	getLongitudeError () const
bool	haveAltitudeError () const
bool	haveInputsRMS () const
bool	haveLatLonError () const
unsigned short	getBeaconChannel () const
double	getBeaconFreq () const
	kHz
double	getBeaconSignalStrength () const
	dB
double	getBeaconSNR () const
	dB
unsigned short	getBecaonBPS () const
	bitrate (bits per second)
bool	haveBeaconInfo () const
ArPose	getErrorEllipse () const
bool	haveErrorEllipse () const
Public Attributes
enum ArGPS:: { ... }	ReadFlags
	Flags to indicates what the read() method did. i.e. If nothing was done, then the result will be 0. To check a read() return result result to see if data was updated, use (result & ReadUpdated). To check if there was an error, use (result & ReadError).
Protected Member Functions
void	handleGPGGA (ArNMEAParser::Message msg)
void	handleGPGSA (ArNMEAParser::Message msg)
void	handleGPGST (ArNMEAParser::Message msg)
void	handleGPGSV (ArNMEAParser::Message msg)
void	handleGPMSS (ArNMEAParser::Message msg)
void	handleGPRMC (ArNMEAParser::Message msg)
void	handleHCHDx (ArNMEAParser::Message msg)
void	handlePGRME (ArNMEAParser::Message msg)
void	handlePGRMZ (ArNMEAParser::Message msg)
virtual bool	initDevice ()
bool	readFloatFromString (std::string &str, double *target, double(*convf)(double)=NULL) const
bool	readFloatFromStringVec (std::vector< std::string > *vec, size_t i, double *target, double(*convf)(double)=NULL) const
bool	readUShortFromString (std::string &str, unsigned short *target, unsigned short(*convf)(unsigned short)=NULL) const
bool	readUShortFromStringVec (std::vector< std::string > *vec, size_t i, unsigned short *target, unsigned short(*convf)(unsigned short)=NULL) const
bool	waitForData (unsigned long timeout)
Static Protected Member Functions
static double	feetToMeters (double f)
static double	gpsDegminToDegrees (double degmin)
static double	knotsToMPS (double knots)
static double	metersToFeet (double m)
static double	mpsToMph (double mps)
Protected Attributes
ArArgumentParser *	myArgParser
bool	myCreatedOwnDeviceCon
Data	myData
ArDeviceConnection *	myDevice
ArFunctor1C< ArGPS, ArNMEAParser::Message >	myGPGGAHandler
ArFunctor1C< ArGPS, ArNMEAParser::Message >	myGPGSAHandler
ArFunctor1C< ArGPS, ArNMEAParser::Message >	myGPGSTHandler
ArFunctor1C< ArGPS, ArNMEAParser::Message >	myGPGSVHandler
ArFunctor1C< ArGPS, ArNMEAParser::Message >	myGPMSSHandler
ArFunctor1C< ArGPS, ArNMEAParser::Message >	myGPRMCHandler
ArFunctor1C< ArGPS, ArNMEAParser::Message >	myHCHDxHandler
ArMutex	myMutex
ArNMEAParser	myNMEAParser
ArRetFunctorC< bool, ArGPS >	myParseArgsCallback
ArFunctor1C< ArGPS, ArNMEAParser::Message >	myPGRMEHandler
ArFunctor1C< ArGPS, ArNMEAParser::Message >	myPGRMZHandler
unsigned short	mySNRNum
unsigned int	mySNRSum

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Member Enumeration Documentation

anonymous enum

Flags to indicates what the read() method did. i.e. If nothing was done, then the result will be 0. To check a read() return result result to see if data was updated, use (result & ReadUpdated). To check if there was an error, use (result & ReadError).

These happen to match the flags in ArNMEAParser.

enum ArGPS::FixType

Access the last received data from the GPS.

Data accessors

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Member Function Documentation

void ArGPS::addNMEAHandler	(	const char *	message,
		ArNMEAParser::Handler *	handler
	)			[inline]

Set a handler for an NMEA message. Mostly for internal use or to be used by related classes, but you could use for ususual or custom messages emitted by a device that you wish to be handled outside of the ArGPS class.

bool ArGPS::blockingConnect

(

unsigned long

connectTimeout = 10000

)

[inline]

Same as connect(). See connect().

virtual bool ArGPS::connect

(

unsigned long

connectTimeout = 10000

)

[virtual]

Check that the device connection (e.g. serial port) is open, and that data is being received from GPS.

Subclasses may override this method so that device-specific initialization commands may be sent.

Returns:

false if there is no device connection or the device connection is not open, or if there is an error sending device initialization commands, or if no data is received after calling read() every 100 ms for connectTimeout ms. Otherwise, return true.

See also:

blockingConnect()

double ArGPS::getGarminPositionError

(

)

const [inline]

GPS device's error estimation in meters

double ArGPS::getLatitude

(

)

const [inline]

Returns:

latitude in decimal degrees

double ArGPS::getLongitude

(

)

const [inline]

Returns:

longitude in decimal degrees

double ArGPS::getSpeed

(

)

const [inline]

Returns:

GPS' measured speed converted to meters per second

ArTime ArGPS::getTimeReceivedPosition

(

)

const [inline]

Returns:

copy of an ArTime object set to the time that ArGPS read and received latitude and longitude data from the GPS.

bool ArGPS::haveBeaconInfo

(

)

const [inline]

DGPS stationary beacon info

bool ArGPS::haveErrorEllipse

(

)

const [inline]

Standard deviation of position error, meters. Theta in ArPose is orientation of ellipse from true north, Y is the length of the major axis on that orientation, X the minor.

Note:

Values may be inf or NaN (if GPS supplies "Inf" or "NAN")

bool ArGPS::haveGarminPositionError

(

)

const [inline]

Returns:

whether GPS provided a distance error estimation (only some Garmins do)

bool ArGPS::haveGarminVerticalPositionError

(

)

const [inline]

Returns:

whether GPS provided an altitude error estimation (only some device models do)

bool ArGPS::haveLatLonError

(

)

const [inline]

Standard deviation of latitude and longitude error, meters. Theta value in ArPose is unused.

Note:

May only be provided by GPS in certain fix modes (e.g. Trimble AgGPS provides it in Omnistar and RTK modes, but not in GPS or DGPS modes).

Values may be inf or NaN (if GPS supplies "Inf" or "NAN")

virtual bool ArGPS::initDevice

(

)

[inline, protected, virtual]

Subclasses may override to send device initialization/configuration commands and set up device-specific message handlers. (Default behavior is to do nothing and return true.)

void ArGPS::lock

(

)

[inline]

Locks a mutex object contained by this class. No other method (except readWithLock()) in ArGPS locks or unlocks this mutex, it is provided for you to use when accessing ArGPS from multiple threads.

void ArGPS::printData

(

bool

labels = true

)

const

Print basic navigation data on one line to standard output, with no newline at end.

virtual int ArGPS::read

(

unsigned long

maxTime = 0

)

[virtual]

Read some data from the device connection, and update stored data as complete messages are received.

Parameters:

maxTime

If nonzero, return when this time limit is reached, even if there is still data available to read. If zero, then don't return until all available data has been exhausted or an error occurs. Be careful setting this parameter to 0: read() could block for an arbitrary amount of time, even forever if for some reason data is recieved from the device faster than read() can read and parse it.

Returns:

A mask of ReadFlags codes, combined with bitwise or (|), or 0 if no attempt to read from the device occured (for example because the maxTime timeout was reached before the first attempt to read occured). The flags will include ReadError if there was as error reading from the device connection, ReadData if some data was read, ReadUpdated if data was read and a full message was successfully read and stored data was updated in ArGPS, ReadFinished if all available data was read.

int ArGPS::readWithLock

(

unsigned int

maxTime

)

[inline]

Calls lock(), calls read(maxTime), then calls unlock(). Note, this could end up keeping ArGPS locked until maxTime is reached, or for any amount of time if maxTime is 0, so watch out for that.

void ArGPS::setCompassHeadingMag

(

double

val

)

[inline]

Manually set compass values.

void ArGPS::unlock

(

)

[inline]

Unlocks a mutex object contained by this class. No other method (except readWithLock()) in ArGPS locks or unlocks this mutex, it is provided for you to use when accessing ArGPS from multiple threads.

bool ArGPS::waitForData

(

unsigned long

timeout

)

[protected]

Block until data is read from GPS. Waits by calling read() every 100 ms for timeout ms.

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Member Data Documentation

enum { ... } ArGPS::ReadFlags

Flags to indicates what the read() method did. i.e. If nothing was done, then the result will be 0. To check a read() return result result to see if data was updated, use (result & ReadUpdated). To check if there was an error, use (result & ReadError).

These happen to match the flags in ArNMEAParser.

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

• ArGPS.h

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