xsens_driver Documentation

xsens_driver

ROS Driver for XSens MT/MTi/MTi-G devices.

• Homepage: http://wiki.ros.org/xsens_driver

The xsens_driver package provides mtnode.py, a generic ROS node publishing the data streamed by an XSens imu (MT, MTi, MTi-G...).

Topics

The ROS node is a wrapper around the mtdevice::MTDevice class. It can publish the following topics, depending on the configuration of the device:

• /imu/data (sensor_msgs::Imu): orientation, angular velocity, linear acceleration,
• /fix (sensor_msgs::NavSatFix): longitude, latitude, altitude (from filtered/fused GPS and IMU),
• /raw_fix (sensor_msgs::NavSatFix): longitude, latitude, altitude (from ONLY GPS),
• /fix_extended (gps_common::GPSFix): more complete GPS information than /fix,
• /velocity (geometry_msgs::TwistStamped): angular velocity is in body frame, linear velocity is in world frame and fused with GPS measurement.
• /magnetic (geometry_msgs::Vector3Stamped): direction of magnetic field,
• /temperature (std_msgs::Float32): temperature,
• /pressure (std_msgs::Float32): pressure,
• /analog_in1 (std_msgs::UInt16): first analog input,
• /analog_in2 (std_msgs::UInt16): second analog input.

It can also publish diagnostics information.

Finally, it always publishes the decoded message as a std_msgs::String representing the Python dictionary on /imu_data_str.

If the IMU is set to raw mode, the values of the /imu/data, /velocity and /magnetic topics are the 16 bits output of the AD converters and therefore not in usual units.

The covariance information in the sensor_msgs::Imu message are filled with default values from the MTx/MTi/MTi-G documentation but may not be exact; it also does not correspond to the covariance of the internal XKF.

Parameters

The nodes can take the following parameters:

• ~device (auto): the path of the device file to connect to the imu; auto will look through all serial devices to find the first one.
• ~baudrate (0): the baudrate of the IMU (unused for auto device); 0 will try to auto-detect baudrate.
• ~timeout (0.002): the timeout for communication with the IMU.
• ~initial_wait (0.1): initial wait to allow the device to come up before trying to communicate.
• ~frame_id (/base_imu): the frame id of the IMU.
• ~frame_local (ENU): the desired frame orientation (ENU, NED, or NWU).
• ~no_rotation_duration (0): the int duration in seconds of the no-rotation calibration procedure at the start of the node (only for mark iv devices). If 0, the procedure is not launched.
• ~angular_velocity_covariance_diagonal ([0.0004, 0.0004, 0.0004]) diagonal elements of the covariance matrix on the angular velocity published on the /imu/data topic.
• ~linear_acceleration_covariance_diagonal ([0.0004, 0.0004, 0.0004]) diagonal elements of the covariance matrix on the linear acceleration published on the /imu/data topic.
• ~orientation_covariance_diagonal ([0.01745, 0.01745, 0.15708]) diagonal elements of the covariance matrix on the orientation published on the /imu/data topic.

Permissions

It might be necessary to add the user to the dialout group so that the node can communicate with the device.

Configuration using mtdevice.py

mtdevice.py can be used on the command line to configure or inspect the current configuration of the device, see usage below.

MT device driver.
Usage:
    ./mtdevice.py [commands] [opts]

Commands:
    -h, --help
        Print this help and quit.
    -r, --reset
        Reset device to factory defaults.
    -a, --change-baudrate=NEW_BAUD
        Change baudrate from BAUD (see below) to NEW_BAUD.
    -c, --configure=OUTPUT
        Configure the device (see OUTPUT description below).
    -e, --echo
        Print MTData. It is the default if no other command is supplied.
    -i, --inspect
        Print current MT device configuration.
    -x, --xkf-scenario=ID
        Change the current XKF scenario.
    -l, --legacy-configure
        Configure the device in legacy mode (needs MODE and SETTINGS arguments
        below).
    -v, --verbose
        Verbose output.
    -y, --synchronization=settings (see below)
        Configure the synchronization settings of each sync line (see below)
    -u, --setUTCTime=time (see below)
        Sets the UTC time buffer of the device

Generic options:
    -d, --device=DEV
        Serial interface of the device (default: /dev/ttyUSB0). If 'auto', then
        all serial ports are tested at all baudrates and the first
        suitable device is used.
    -b, --baudrate=BAUD
        Baudrate of serial interface (default: 115200). If 0, then all
        rates are tried until a suitable one is found.
    -t, --timeout=TIMEOUT
        Timeout of serial communication in second (default: 0.002).
    -w, --initial-wait=WAIT
        Initial wait to allow device to be ready in second (default: 0.1).

Configuration option:
    OUTPUT
        The format is a sequence of "<group><type><frequency>?<format>?"
        separated by commas.
        The frequency and format are optional.
        The groups and types can be:
            t  temperature (max frequency: 1 Hz):
                tt  temperature
            i  timestamp (max frequency: 2000 Hz):
                iu  UTC time
                ip  packet counter
                ii  Integer Time of the Week (ITOW)
                if  sample time fine
                ic  sample time coarse
                ir  frame range
            o  orientation data (max frequency: 400 Hz):
                oq  quaternion
                om  rotation matrix
                oe  Euler angles
            b  pressure (max frequency: 50 Hz):
                bp  baro pressure
            a  acceleration (max frequency: 2000 Hz (see documentation)):
                ad  delta v
                aa  acceleration
                af  free acceleration
                ah  acceleration HR (max frequency 1000 Hz)
            p  position (max frequency: 400 Hz):
                pa  altitude ellipsoid
                pp  position ECEF
                pl  latitude longitude
            n  GNSS (max frequency: 4 Hz):
                np  GNSS PVT data
                ns  GNSS satellites info
            w  angular velocity (max frequency: 2000 Hz (see documentation)):
                wr  rate of turn
                wd  delta q
                wh  rate of turn HR (max frequency 1000 Hz)
            g  GPS (max frequency: 4 Hz):
                gd  DOP
                gs  SOL
                gu  time UTC
                gi  SV info
            r  Sensor Component Readout (max frequency: 2000 Hz):
                rr  ACC, GYR, MAG, temperature
                rt  Gyro temperatures
            m  Magnetic (max frequency: 100 Hz):
                mf  magnetic Field
            v  Velocity (max frequency: 400 Hz):
                vv  velocity XYZ
            s  Status (max frequency: 2000 Hz):
                sb  status byte
                sw  status word
        Frequency is specified in decimal and is assumed to be the maximum
        frequency if it is omitted.
        Format is a combination of the precision for real valued numbers and
        coordinate system:
            precision:
                f  single precision floating point number (32-bit) (default)
                d  double precision floating point number (64-bit)
            coordinate system:
                e  East-North-Up (default)
                n  North-East-Down
                w  North-West-Up
        Examples:
            The default configuration for the MTi-1/10/100 IMUs can be
            specified either as:
                "wd,ad,mf,ip,if,sw"
            or
                "wd2000fe,ad2000fe,mf100fe,ip2000,if2000,sw2000"
            For getting quaternion orientation in float with sample time:
                "oq400fw,if2000"
            For longitude, latitude, altitude and orientation (on MTi-G-700):
                "pl400fe,pa400fe,oq400fe"

Synchronization settings:
    The format follows the xsens protocol documentation. All fields are required
    and separated by commas.
    Note: The entire synchronization buffer is wiped every time a new one
          is set, so it is necessary to specify the settings of multiple
          lines at once.
    It also possible to clear the synchronization with the argument "clear"

        Function (see manual for details):
             3 Trigger indication
             4 Interval Transition Measurement
             8 SendLatest
             9 ClockBiasEstimation
            11 StartSampling
        Line (manual for details):
            0 ClockIn
            1 GPSClockIn (only available for 700/710)
            2 Input Line (SyncIn)
            4 SyncOut
            5 ExtTimepulseIn (only available for 700/710)
            6 Software (only available for SendLatest with ReqData message)
        Polarity:
            1 Positive pulse/ Rising edge
            2 Negative pulse/ Falling edge
            3 Both/ Toggle
        Trigger Type:
            0 multiple times
            1 once
        Skip First (unsigned_int):
            Number of initial events to skip before taking actions
        Skip Factor (unsigned_int):
            Number of events to skip before taking action again
            Ignored with ReqData.
        Pulse Width (unsigned_int):
            Ignored for SyncIn.
            For SyncOut, the width of the generated pulse in 100 microseconds
            unit. Ignored for Toggle pulses.
        Delay:
            Delay after receiving a sync pulse to taking action,
            100 microseconds units, range [0...600000]
        Clock Period:
            Reference clock period in milliseconds for ClockBiasEstimation
        Offset:
            Offset from event to pulse generation.
            100 microseconds unit, range [-30000...+30000]

    Examples:
        For changing the sync setting of the SyncIn line to trigger indication
        with rising edge, one time triggering and no skipping and delay. Enter
        the settings as:
            "3,2,1,1,0,0,0,0"

        Note a number is still in the place for pulse width despite it being
        ignored.

        To set multiple lines at once:
        ./mtdevice.py -y 3,2,1,0,0,0,0,0 -y 9,0,1,0,0,0,10,0

        To clear the synchronization settings of MTi
        ./mtdevice.py -y clear

SetUTCTime settings:
    There are two ways to set the UTCtime for the MTi.
    Option #1: set MTi to the current UTC time based on local system time with
               the option 'now'
    Option #2: set MTi to a specified UTC time
        The time fields are set as follows:
            year: range [1999,2099]
            month: range [1,12]
            day: day of the month, range [1,31]
            hour: hour of the day, range [0,23]
            min: minute of the hour, range [0,59]
            sec: second of the minute, range [0,59]
            ns: nanosecond of the second, range [0,1000000000]
            flag:
                1: Valid Time of Week
                2: Valid Week Number
                4: valid UTC
            Note: the flag is ignored for setUTCTime as it is set by the module
                  itself when connected to a GPS

    Examples:
        Set UTC time for the device:
        ./mtdevice.py -u now
        ./mtdevice.py -u 1999,1,1,0,0,0,0,0

Legacy options:
    -m, --output-mode=MODE
        Legacy mode of the device to select the information to output.
        This is required for 'legacy-configure' command.
        MODE can be either the mode value in hexadecimal, decimal or
        binary form, or a string composed of the following characters
        (in any order):
            t  temperature, [0x0001]
            c  calibrated data, [0x0002]
            o  orientation data, [0x0004]
            a  auxiliary data, [0x0008]
            p  position data (requires MTi-G), [0x0010]
            v  velocity data (requires MTi-G), [0x0020]
            s  status data, [0x0800]
            g  raw GPS mode (requires MTi-G), [0x1000]
            r  raw (incompatible with others except raw GPS), [0x4000]
        For example, use "--output-mode=so" to have status and
        orientation data.
    -s, --output-settings=SETTINGS
        Legacy settings of the device. This is required for 'legacy-configure'
        command.
        SETTINGS can be either the settings value in hexadecimal,
        decimal or binary form, or a string composed of the following
        characters (in any order):
            t  sample count (excludes 'n')
            n  no sample count (excludes 't')
            u  UTC time
            q  orientation in quaternion (excludes 'e' and 'm')
            e  orientation in Euler angles (excludes 'm' and 'q')
            m  orientation in matrix (excludes 'q' and 'e')
            A  acceleration in calibrated data
            G  rate of turn in calibrated data
            M  magnetic field in calibrated data
            i  only analog input 1 (excludes 'j')
            j  only analog input 2 (excludes 'i')
            N  North-East-Down instead of default: X North Z up
        For example, use "--output-settings=tqMAG" for all calibrated
        data, sample counter and orientation in quaternion.
    -p, --period=PERIOD
        Sampling period in (1/115200) seconds (default: 1152).
        Minimum is 225 (1.95 ms, 512 Hz), maximum is 1152
        (10.0 ms, 100 Hz).
        Note that for legacy devices it is the period at which sampling occurs,
        not the period at which messages are sent (see below).

Deprecated options:
    -f, --deprecated-skip-factor=SKIPFACTOR
        Only for mark III devices.
        Number of samples to skip before sending MTData message
        (default: 0).
        The frequency at which MTData message is send is:
            115200/(PERIOD * (SKIPFACTOR + 1))
        If the value is 0xffff, no data is send unless a ReqData request
        is made.