ulogreader

Read messages from ULOG file

Description

The ulogreader object reads a ULOG file (.ulg). The object stores information about the file, including start and end logging times, summary of available topics, and dropout intervals.

Creation

Syntax

ulogOBJ = ulogreader(filePath)

Description

ulogOBJ = ulogreader(filePath) reads the ULOG file from the specified path and returns an object containing information about the file. The information in filePath is used to set the FileName property.

example

Properties

expand all

`FileName` — Name of ULOG file
Read-only: string scalar | character vector

This property is read-only.

Name of the ULOG file, specified as a string scalar or character vector. The FileName is the path specified in the filePath input.

Data Types: char | string

`StartTime` — Start time of logging
Read-only: `duration` object

This property is read-only.

Start time of logging offset from the system start time in the ULOG file, specified as a duration object in the 'hh:mm:ss.SSSSSS' format.

Data Types: duration

`EndTime` — Timestamp of last timestamped message
Read-only: `duration` object

This property is read-only.

Timestamp of the last timestamped message logged in the ULOG file, specified as a duration object in the 'hh:mm:ss.SSSSSS' format.

Data Types: duration

`AvailableTopics` — Table of all logged topics
Read-only: table

This property is read-only.

Summary of all the logged topics, specified as a table that contains the columns:

TopicNames
InstanceID
StartTimestamp
LastTimestamp
NumMessages

Data Types: table

`DropoutIntervals` — Time intervals in which messages were dropped while logging
Read-only: n-by-2 matrix

This property is read-only.

Time intervals in which messages were dropped while logging, specified as an n-by-2 matrix of duration arrays in the 'hh:mm:ss.SSSSSS' format, where n is the number of dropouts.

Data Types: duration

Object Functions

`readTopicMsgs`	Read topic messages
`readSystemInformation`	Read information messages
`readParameters`	Read parameter values
`readLoggedOutput`	Read logged output messages

Examples

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Read Messages from ULOG File

Open Live Script

Load the ULOG file. Specify the relative path of the file

ulog = ulogreader('flight.ulg');

Read all topic messages.

msg = readTopicMsgs(ulog);

Specify the time interval between which to select messages.

d1 = ulog.StartTime;
d2 = d1 + duration([0 0 55],'Format','hh:mm:ss.SSSSSS');

Read messages from the topic 'vehicle_attitude' with an instance ID of 0 in the time interval [d1 d2].

data = readTopicMsgs(ulog,'TopicNames',{'vehicle_attitude'}, ... 
'InstanceID',{0},'Time',[d1 d2]);

Extract topic messages for the topic.

vehicle_attitude = data.TopicMessages{1,1}

vehicle_attitude=1066×3 timetable
       timestamp                             q                                              delta_q_reset                       quat_reset_counter
    _______________    ______________________________________________    ___________________________________________________    __________________

    00:00:01.952000    0.68231    0.0017879    -0.014252      0.73092    0.6823     2.1123e-10     6.8316e-10        0.73107            1         
    00:00:01.956000    0.68231    0.0017974    -0.014259      0.73092    0.6823     2.1123e-10     6.8316e-10        0.73107            1         
    00:00:02.004000    0.68126     0.001916    -0.014383      0.73189         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.052000    0.68112    0.0019686    -0.014534      0.73202         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.104000    0.68092     0.002101    -0.014752      0.73221         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.152000    0.68067    0.0022023    -0.014936      0.73243         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.204000    0.68045    0.0023886    -0.015088      0.73263         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.252000    0.68016    0.0025014    -0.015266       0.7329         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.304000    0.67995    0.0026582    -0.015413      0.73309         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.352000    0.67983    0.0027451    -0.015558       0.7332         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.404000    0.67979    0.0028021    -0.015723      0.73323         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.452000    0.67975    0.0029118    -0.015801      0.73327         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.504000    0.67972     0.002982    -0.015947      0.73329         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.552000    0.67975    0.0030121    -0.016096      0.73326         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.604000     0.6798    0.0030043    -0.016209      0.73321         1              0    -2.2119e-09      0.0013563            2         
    00:00:02.652000    0.67985    0.0030682    -0.016367      0.73317         1              0    -2.2119e-09      0.0013563            2         
      ⋮

Read all system information.

systeminfo = readSystemInformation(ulog)

systeminfo=12×2 table
       InformationField                          Value                   
    _______________________    __________________________________________

    "ver_sw"                   "8763d71bf0b603e0da42ea16fceae7fd2590546f"
    "ver_sw_release"           "v1.11.0.RC"                              
    "ver_vendor_sw_release"    "192"                                     
    "ver_hw"                   "PX4_SITL"                                
    "sys_name"                 "PX4"                                     
    "sys_os_name"              "Linux"                                   
    "ver_sw_branch"            "master"                                  
    "sys_os_ver_release"       "84148479"                                
    "sys_toolchain"            "GNU GCC"                                 
    "sys_toolchain_ver"        "9.3.0"                                   
    "ver_data_format"          "1"                                       
    "time_ref_utc"             "0"

Read all initial parameter values.

params = readParameters(ulog)

params=631×2 table
       Parameters        Values
    _________________    ______

    "ASPD_BETA_GATE"          1
    "ASPD_BETA_NOISE"       0.3
    "ASPD_DO_CHECKS"          0
    "ASPD_FALLBACK"           0
    "ASPD_FS_INNOV"           1
    "ASPD_FS_INTEG"          -1
    "ASPD_FS_T1"              3
    "ASPD_FS_T2"            100
    "ASPD_PRIMARY"            1
    "ASPD_SCALE"              1
    "ASPD_SCALE_EST"          0
    "ASPD_SC_P_NOISE"    0.0001
    "ASPD_STALL"             10
    "ASPD_TAS_GATE"           3
    "ASPD_TAS_NOISE"        1.4
    "ASPD_W_P_NOISE"        0.1
      ⋮

Read logged output messages in the time interval.

log = readLoggedOutput(ulog,'Time',[d1 d2])

log=23×2 timetable
       timestamp       LogLevel                                          Messages                                       
    _______________    ________    _____________________________________________________________________________________

    00:00:00.176000     "INFO"     "[logger] [logger] ./log/2020-07-07/15_07_10.ulg"                                    
    00:00:00.176000     "INFO"     "[logger] Opened full log file: ./log/2020-07-07/15_07_10.ulg"                       
    00:00:00.176000     "INFO"     "[mavlink] MAVLink only on localhost (set param MAV_BROADCAST = 1 to enable network)"
    00:00:00.184000     "INFO"     "[px4] Startup script returned successfully"                                         
    00:00:01.044000     "INFO"     "[mavlink] partner IP: 127.0.0.1"                                                    
    00:00:01.096000     "INFO"     "[ecl/EKF] 888000: GPS checks passed"                                                
    00:00:01.948000     "INFO"     "[ecl/EKF] 1780000: reset position to last known position"                           
    00:00:01.948000     "INFO"     "[ecl/EKF] 1780000: reset velocity to zero"                                          
    00:00:05.548000     "INFO"     "[ecl/EKF] 5380000: reset velocity to GPS"                                           
    00:00:05.548000     "INFO"     "[ecl/EKF] 5380000: starting GPS fusion"                                             
    00:00:26.668000     "INFO"     "[commander] ARMED by Arm/Disarm component command"                                  
    00:00:31.268000     "INFO"     "[fw_pos_control_l1] Takeoff on runway"                                              
    00:00:31.360000     "INFO"     "[commander] Takeoff detected"                                                       
    00:00:31.688000     "INFO"     "[runway_takeoff] #Takeoff airspeed reached"                                         
    00:00:33.548000     "INFO"     "[runway_takeoff] #Climbout"                                                         
    00:00:34.088000     "INFO"     "[runway_takeoff] #Navigating to waypoint"                                           
      ⋮

References

[1] PX4 Developer Guide. "ULog File Format." Accessed December 6, 2019. https://docs.px4.io/main/en/dev_log/ulog_file_format.html.

Version History

Introduced in R2020b

ulogreader

Description

Creation

Syntax

Description

Properties

FileName — Name of ULOG file Read-only: string scalar | character vector

StartTime — Start time of logging Read-only: duration object

EndTime — Timestamp of last timestamped message Read-only: duration object

AvailableTopics — Table of all logged topics Read-only: table

DropoutIntervals — Time intervals in which messages were dropped while logging Read-only: n-by-2 matrix

Object Functions

Examples

Read Messages from ULOG File

References

Version History

See Also

`FileName` — Name of ULOG file
Read-only: string scalar | character vector

`StartTime` — Start time of logging
Read-only: `duration` object

`EndTime` — Timestamp of last timestamped message
Read-only: `duration` object

`AvailableTopics` — Table of all logged topics
Read-only: table

`DropoutIntervals` — Time intervals in which messages were dropped while logging
Read-only: n-by-2 matrix