Public Types | Public Member Functions | Static Public Attributes | Private Member Functions | Private Attributes | Static Private Attributes
microstrain_3dmgx2_imu::IMU Class Reference

A class for interfacing to the microstrain 3dmgx2 and inertialink IMUs. More...

#include <3dmgx2.h>

List of all members.

Public Types

enum  cmd {
  CMD_RAW = 0xC1, CMD_ACCEL_ANGRATE = 0xC2, CMD_DELVEL_DELANG = 0xC3, CMD_CONTINUOUS = 0xC4,
  CMD_ORIENT = 0xC5, CMD_ATT_UPDATE = 0xC6, CMD_MAG_VEC = 0xC7, CMD_ACCEL_ANGRATE_ORIENT = 0xC8,
  CMD_WRITE_ACCEL_BIAS = 0xC9, CMD_WRITE_GYRO_BIAS = 0xCA, CMD_ACCEL_ANGRATE_MAG = 0xCB, CMD_ACCEL_ANGRATE_MAG_ORIENT = 0xCC,
  CMD_CAPTURE_GYRO_BIAS = 0xCD, CMD_EULER = 0xCE, CMD_EULER_ANGRATE = 0xCF, CMD_TEMPERATURES = 0xD1,
  CMD_GYROSTAB_ANGRATE_MAG = 0xD2, CMD_DELVEL_DELANG_MAG = 0xD3, CMD_DEV_ID_STR = 0xEA, CMD_STOP_CONTINUOUS = 0xFA
}
 Enumeration of possible IMU commands. More...
enum  id_string { ID_MODEL_NUMBER = 0, ID_SERIAL_NUMBER = 1, ID_DEVICE_NAME = 2, ID_DEVICE_OPTIONS = 3 }
 Enumeration of possible identifier strings for the getDeviceIdentifierString command. More...

Public Member Functions

void closePort ()
 Close the port.
bool getDeviceIdentifierString (id_string type, char id[17])
 Read one of the device identifier strings.
 IMU ()
 Constructor.
void initGyros (double *bias_x=0, double *bias_y=0, double *bias_z=0)
 Initial gyros.
void initTime (double fix_off)
 Initialize timing variables.
void openPort (const char *port_name)
 Open the port.
void receiveAccelAngrate (uint64_t *time, double accel[3], double angrate[3])
 Read a message of type "ACCEL_ANGRATE".
void receiveAccelAngrateMag (uint64_t *time, double accel[3], double angrate[3], double mag[3])
 Read a message of type "ACCEL_ANGRATE_MAG".
void receiveAccelAngrateMagOrientation (uint64_t *time, double accel[3], double angrate[3], double mag[3], double orientation[9])
 Read a message of type "ACCEL_ANGRATE_MAG_ORIENT".
void receiveAccelAngrateOrientation (uint64_t *time, double accel[3], double angrate[3], double orientation[9])
 Read a message of type "ACCEL_ANGRATE_ORIENTATION".
void receiveDelvelDelang (uint64_t *time, double delvel[3], double delang[3])
 Read a message of type "DELVEL_DELANG".
void receiveEuler (uint64_t *time, double *roll, double *pitch, double *yaw)
 Read a message of type "EULER".
void receiveRawAccelAngrate (uint64_t *time, double accel[3], double angrate[3])
 Read a message of type "CMD_RAW".
bool setContinuous (cmd command)
 Put the device in continuous mode.
void setFixedOffset (double fix_off)
 Set the fixed time offset.
void stopContinuous ()
 Take the device out of continous mode.
 ~IMU ()

Static Public Attributes

static const double G = 9.80665
 Gravity (m/sec^2)

Private Member Functions

uint64_t extractTime (uint8_t *addr)
 Extract time from a pointer into an imu buffer.
uint64_t filterTime (uint64_t imu_time, uint64_t sys_time)
 Run the filter on the imu time and system times.
int receive (uint8_t command, void *rep, int rep_len, int timeout=0, uint64_t *sys_time=NULL)
 Receive a particular message from the IMU.
int send (void *cmd, int cmd_len)
 Send a single packet frmo the IMU.
double toDouble (uint64_t time)
 Convert the uint64_t time to a double for numerical computations.
uint64_t toUint64_t (double time)
 Convert the double time back to a uint64_t.
int transact (void *cmd, int cmd_len, void *rep, int rep_len, int timeout=0)
 Send a command to the IMU and wait for a reply.

Private Attributes

bool continuous
 Whether continuous mode is enabled.
unsigned int counter
 A counter used by the filter.
double d_offset
uint32_t diff_ticks
 The different in the number of ticks.
int fd
 The file descriptor.
double fixed_offset
 Variables used by the kalman computation.
bool is_gx3
 Is the IMU a GX3?
uint32_t last_ticks
 The last number of ticks for computing wraparound.
double offset
uint32_t offset_ticks
 The number of ticks the initial offset is off by.
double P_time_est [2][2]
 The covariances on time offset and driftrate.
unsigned long long start_time
 The time at which the imu was started.
double sum_meas
double time_est [2]
 The estimate of time offset and driftrate.
uint32_t wraps
 The number of times the imu has wrapped.

Static Private Attributes

static const double KF_K_1 = 0.00995031
 First KF term.
static const double KF_K_2 = 0.0000497506
 Second KF term.
static const unsigned int KF_NUM_SUM = 100
 Number of KF samples to sum over.
static const int MAX_BYTES_SKIPPED = 1000
 Maximum bytes allowed to be skipped when seeking a message.
static const int TICKS_PER_SEC_GX2 = 19660800
 IMU internal ticks/second.
static const int TICKS_PER_SEC_GX3 = 62500

Detailed Description

A class for interfacing to the microstrain 3dmgx2 and inertialink IMUs.

Note: This class is unreviewed and unsupported. It may change at any time without notice.

Many of the methods within this class may throw an microstrain_3dmgx2_imu::exception, timeout_exception, or corrupted_data_exception.

Before using the IMU, it must be opened via the open_port method. When finished using, it should be closed via the close_port method. Alternatively, close port will get called at destruction.

The library is primarily designed to be used in continuous mode, which is enabled with the set_continuous method, and then serviced with one of the receive methods.

Implementation of specific polled message transactions can be done with the transact method.

Because the timing related to the USB stack is fairly non-deterministic, but the IMU is internally known to be clocked to a 100hz clock, we have wrapped a Kalman filter around calls to get system time, and the internal imu time. This is only known to be reliable when operating in continuous mode, and if init_time is called shortly prior to beginning to get readings.

Example code:

   microstrain_3dmgx2_imu::IMU imu;
   imu.open_port("/dev/ttyUSB0");
   imu.init_time();
   imu.init_gyros();
   imu.set_continuous(microstrain_3dmgx2_imu::IMU::CMD_ACCEL_ANGRATE_ORIENT);
   while (int i = 0 ; i < 100; i++)
   {
     double accel[3];
     double angrate[3];
     double orientation[9];
     imu.receive_accel_angrate_orientation(&time, accel, angrate, orientation);
   }
   imu.close_port();

Definition at line 91 of file 3dmgx2.h.


Member Enumeration Documentation

Enumeration of possible IMU commands.

Enumerator:
CMD_RAW 
CMD_ACCEL_ANGRATE 
CMD_DELVEL_DELANG 
CMD_CONTINUOUS 
CMD_ORIENT 
CMD_ATT_UPDATE 
CMD_MAG_VEC 
CMD_ACCEL_ANGRATE_ORIENT 
CMD_WRITE_ACCEL_BIAS 
CMD_WRITE_GYRO_BIAS 
CMD_ACCEL_ANGRATE_MAG 
CMD_ACCEL_ANGRATE_MAG_ORIENT 
CMD_CAPTURE_GYRO_BIAS 
CMD_EULER 
CMD_EULER_ANGRATE 
CMD_TEMPERATURES 
CMD_GYROSTAB_ANGRATE_MAG 
CMD_DELVEL_DELANG_MAG 
CMD_DEV_ID_STR 
CMD_STOP_CONTINUOUS 

Definition at line 111 of file 3dmgx2.h.

Enumeration of possible identifier strings for the getDeviceIdentifierString command.

Enumerator:
ID_MODEL_NUMBER 
ID_SERIAL_NUMBER 
ID_DEVICE_NAME 
ID_DEVICE_OPTIONS 

Definition at line 136 of file 3dmgx2.h.


Constructor & Destructor Documentation

Constructor.

Definition at line 98 of file 3dmgx2.cc.

Definition at line 104 of file 3dmgx2.cc.


Member Function Documentation

Close the port.

Definition at line 170 of file 3dmgx2.cc.

uint64_t microstrain_3dmgx2_imu::IMU::extractTime ( uint8_t *  addr) [private]

Extract time from a pointer into an imu buffer.

Definition at line 587 of file 3dmgx2.cc.

uint64_t microstrain_3dmgx2_imu::IMU::filterTime ( uint64_t  imu_time,
uint64_t  sys_time 
) [private]

Run the filter on the imu time and system times.

Definition at line 724 of file 3dmgx2.cc.

Read one of the device identifier strings.

Parameters:
typeIndicates which identifier string to read
idArray that gets filled with the identifier string
Returns:
True if successful

Definition at line 476 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::initGyros ( double *  bias_x = 0,
double *  bias_y = 0,
double *  bias_z = 0 
)

Initial gyros.

This call will prompt the IMU to run its gyro initialization routine.

NOTE: THE IMU MUST BE STATIONARY WHEN THIS ROUTINE IS CALLED

Parameters:
bias_xPointer to double where x bias will be placed.
bias_yPointer to double where y bias will be placed.
bias_zPointer to double where z bias will be placed.

Definition at line 224 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::initTime ( double  fix_off)

Initialize timing variables.

This call determines the initial offset of the imu relative to system clock time, and resets the kalman filter state.

Parameters:
fix_offthis fixed offset will be added to the timestamp of the imu

Definition at line 196 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::openPort ( const char *  port_name)

Open the port.

This must be done before the imu can be used.

Parameters:
port_nameA character array containing the name of the port
Todo:
tcsetattr returns true if at least one attribute was set. Hence, we might not have set everything on success.

Definition at line 113 of file 3dmgx2.cc.

int microstrain_3dmgx2_imu::IMU::receive ( uint8_t  command,
void *  rep,
int  rep_len,
int  timeout = 0,
uint64_t *  sys_time = NULL 
) [private]

Receive a particular message from the IMU.

Definition at line 671 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::receiveAccelAngrate ( uint64_t *  time,
double  accel[3],
double  angrate[3] 
)

Read a message of type "ACCEL_ANGRATE".

Parameters:
timePointer to uint64_t which will receive time
accelarray of accelerations which will be filled
angratearray of angular rates which will be filled

Definition at line 389 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::receiveAccelAngrateMag ( uint64_t *  time,
double  accel[3],
double  angrate[3],
double  mag[3] 
)

Read a message of type "ACCEL_ANGRATE_MAG".

Parameters:
timePointer to uint64_t which will receive time
accelarray of accelerations which will be filled
angratearray of angular rates which will be filled
magarray of magnetometer orientations which will be filled

Definition at line 304 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::receiveAccelAngrateMagOrientation ( uint64_t *  time,
double  accel[3],
double  angrate[3],
double  mag[3],
double  orientation[9] 
)

Read a message of type "ACCEL_ANGRATE_MAG_ORIENT".

Parameters:
timePointer to uint64_t which will receive time
accelarray of accelerations which will be filled
angratearray of angular rates which will be filled
magarray of magnetometer orientations which will be filled
orientationorientation matrix which will be filled

Definition at line 505 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::receiveAccelAngrateOrientation ( uint64_t *  time,
double  accel[3],
double  angrate[3],
double  orientation[9] 
)

Read a message of type "ACCEL_ANGRATE_ORIENTATION".

Parameters:
timePointer to uint64_t which will receive time
accelarray of accelerations which will be filled
angratearray of angular rates which will be filled
orientationorientation matrix which will be filled

Definition at line 346 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::receiveDelvelDelang ( uint64_t *  time,
double  delvel[3],
double  delang[3] 
)

Read a message of type "DELVEL_DELANG".

Parameters:
timePointer to uint64_t which will receive time
delvelarray of accelerations which will be filled
delangarray of angular rates which will be filled

Definition at line 422 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::receiveEuler ( uint64_t *  time,
double *  roll,
double *  pitch,
double *  yaw 
)

Read a message of type "EULER".

Parameters:
timePointer to uint64_t which will receive time
rollPointer to roll value which will be filled
pitchPointer to pitch value which will be filled
yawPointer to yaw value which will be filled

Definition at line 456 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::receiveRawAccelAngrate ( uint64_t *  time,
double  accel[3],
double  angrate[3] 
)

Read a message of type "CMD_RAW".

Parameters:
timePointer to uint64_t which will receive time
accelarray of accelerations which will be filled
angratearray of angular rates which will be filled

Definition at line 553 of file 3dmgx2.cc.

int microstrain_3dmgx2_imu::IMU::send ( void *  cmd,
int  cmd_len 
) [private]

Send a single packet frmo the IMU.

Definition at line 620 of file 3dmgx2.cc.

Put the device in continuous mode.

This call puts the IMU into a mode where it is continuously outputting a particular message.

Parameters:
commandThe type of message to be output.
Returns:
Whether or not continuous mode was enabled successfully.

Definition at line 252 of file 3dmgx2.cc.

void microstrain_3dmgx2_imu::IMU::setFixedOffset ( double  fix_off) [inline]

Set the fixed time offset.

Parameters:
fix_offFixed time offset in seconds

Definition at line 262 of file 3dmgx2.h.

Take the device out of continous mode.

Definition at line 277 of file 3dmgx2.cc.

double microstrain_3dmgx2_imu::IMU::toDouble ( uint64_t  time) [private]

Convert the uint64_t time to a double for numerical computations.

Definition at line 750 of file 3dmgx2.cc.

uint64_t microstrain_3dmgx2_imu::IMU::toUint64_t ( double  time) [private]

Convert the double time back to a uint64_t.

Definition at line 760 of file 3dmgx2.cc.

int microstrain_3dmgx2_imu::IMU::transact ( void *  cmd,
int  cmd_len,
void *  rep,
int  rep_len,
int  timeout = 0 
) [private]

Send a command to the IMU and wait for a reply.

Definition at line 608 of file 3dmgx2.cc.


Member Data Documentation

Whether continuous mode is enabled.

Definition at line 319 of file 3dmgx2.h.

unsigned int microstrain_3dmgx2_imu::IMU::counter [private]

A counter used by the filter.

Definition at line 322 of file 3dmgx2.h.

Definition at line 325 of file 3dmgx2.h.

The different in the number of ticks.

Definition at line 307 of file 3dmgx2.h.

The file descriptor.

Definition at line 295 of file 3dmgx2.h.

Variables used by the kalman computation.

Definition at line 325 of file 3dmgx2.h.

const double microstrain_3dmgx2_imu::IMU::G = 9.80665 [static]

Gravity (m/sec^2)

Definition at line 108 of file 3dmgx2.h.

Is the IMU a GX3?

Definition at line 328 of file 3dmgx2.h.

const double microstrain_3dmgx2_imu::IMU::KF_K_1 = 0.00995031 [static, private]

First KF term.

Definition at line 101 of file 3dmgx2.h.

const double microstrain_3dmgx2_imu::IMU::KF_K_2 = 0.0000497506 [static, private]

Second KF term.

Definition at line 103 of file 3dmgx2.h.

const unsigned int microstrain_3dmgx2_imu::IMU::KF_NUM_SUM = 100 [static, private]

Number of KF samples to sum over.

Definition at line 99 of file 3dmgx2.h.

The last number of ticks for computing wraparound.

Definition at line 304 of file 3dmgx2.h.

const int microstrain_3dmgx2_imu::IMU::MAX_BYTES_SKIPPED = 1000 [static, private]

Maximum bytes allowed to be skipped when seeking a message.

Definition at line 97 of file 3dmgx2.h.

Definition at line 325 of file 3dmgx2.h.

The number of ticks the initial offset is off by.

Definition at line 301 of file 3dmgx2.h.

The covariances on time offset and driftrate.

Definition at line 316 of file 3dmgx2.h.

unsigned long long microstrain_3dmgx2_imu::IMU::start_time [private]

The time at which the imu was started.

Definition at line 310 of file 3dmgx2.h.

Definition at line 325 of file 3dmgx2.h.

const int microstrain_3dmgx2_imu::IMU::TICKS_PER_SEC_GX2 = 19660800 [static, private]

IMU internal ticks/second.

Definition at line 94 of file 3dmgx2.h.

const int microstrain_3dmgx2_imu::IMU::TICKS_PER_SEC_GX3 = 62500 [static, private]

Definition at line 95 of file 3dmgx2.h.

The estimate of time offset and driftrate.

Definition at line 313 of file 3dmgx2.h.

The number of times the imu has wrapped.

Definition at line 298 of file 3dmgx2.h.


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


microstrain_3dmgx2_imu
Author(s): Jeremy Leibs, Blaise Gassend
autogenerated on Thu Apr 24 2014 15:26:55