Michael

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Viewing 15 posts - 1 through 15 (of 22 total)
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  • in reply to: How to convert "Data" correctly? #2230
    Michael
    Michael
    Keymaster

    Hi Johnson,

    What language are you using?
    You could look through the UMJ github repo, and see how we parsed the data.
    https://github.com/redshifting/UM7J
    Also the datasheet for the UM7 contains useful information on how to parse data in binary mode from the UM7.
    UM7 Datasheet V1.6

    Regards,
    Michael

  • in reply to: UM7 Calibration Procedure #1931
    Michael
    Michael
    Keymaster

    Hi Benjamin,
    Usually you wont need to calibrate a unit if its been factory calibrated.
    However because the unit is factory calibrated either in Australia or the USA, the magnetic field will be different in your locality, I assume France?
    I would test the unit and see if it is working as expected if you are getting some strange results, definitely re calibrate.
    Once you have done a successful calibration you shouldn’t need to do it again. One thing to note is: I would recommend resetting the EKF upon boot from within your application. 

    When a reset of EKF is performed make sure the robot and or sensor if attached to robot, is not moved until the EKF converges this can take about 20-30 seconds. 
You do not necessarily have to reset the EKF upon boot but it may help especially if the sensor has been exposed to ferrous materials.


    some useful information.

    If you are seeing a saw-tooth waveform on the yaw output from within the serial interface software, then the magnetic field has been disturbed and this can blow the yaw errors out exponentially. I would recommend re-calibrating your unit following the steps outlined here:
    https://www.redshiftlabs.com.au/um7-calibration-procedure

    When you first start the unit up (after calibration), make sure you don’t bump the unit, allow a small amount of time (20 – 30 seconds) for the kalman filters to converge, if you move the unit upon boot or after resetting the EKF, it can also loose its heading and go haywire for up to 60 seconds until the Kalman filter re-converges.

    Tuning the Kalman filter.
    You can minimize dynamic distortions (i.e. cables carrying variable current loads) that will affect the yaw data and if they can be accounted for. You can lower the magnetometer variance and bump up the gyro variance (i.e. gyro:1, acc=0.01, mag=0.0002) to rely less on the magnetometer.

    To do this fire up the serial interface software.
    Connect to your device.
    Click In the configurations tab, now press Read
    Now tick the checkbox named Show advanced settings
    There should be a drop down list called Sensor variance settings
    You can tune the EKF from here using the instructions mentioned above.

    To enable the Magnetometer.
    Click In the configurations tab, now press Read
    Locate the Filter Settings drop down list.
    Make sure that Magnetometer Updates Enabled is set to Enabled

    Videos
    https://www.redshiftlabs.com.au/um7-calibration-procedure
    File downloads
    Resources
    UM7 datasheet (2MB pdf)
        •        Datasheet V1.6, released 1 October 2016, for the Redshift
    Labs UM7 orientation sensor
    https://www.redshiftlabs.com.au/media/documents/UM7%20Datasheet_v1-6_10.1.2016.pdf

    UM7 Quick-Start Guide
    https://www.redshiftlabs.com.au/um7-quick-start-guide

    UM7 U71D, U72A Calibration Procedure explained
    https://www.redshiftlabs.com.au/um7-calibration-procedure

    Recommended links
    https://www.redshiftlabs.com.au/serial-interface-software

    Redshift Labs UM7 orientation sensor product page
        •        Additional information and resources for the UM7
    orientation sensor can be found on its product page on the Redshift
    Labs website.

    https://www.redshiftlabs.com.au/sensors/um7-orientation-sensor

    UM7 Content library
        •        The UM7 content library provides some background on how
    their orientation sensors work, including the principles and
    mathematics behind their operation.

    https://www.redshiftlabs.com.au/um7-content-library

    Support Forum
    Redshift Labs is presently supporting the CH Robotics support forum,
    the best place to get in-depth technical support for the UM7.

    Regards,
    Michael Malloy
    http://www.redshiftlabs.com.au

  • in reply to: Low voltage on MISO um7 #1930
    Michael
    Michael
    Keymaster

    Hi John,
    Looks like a fried pin on either the UM7 or your hardware.
    can you test the UM7 not connected to anything?

    Regards,
    Michael Malloy

  • in reply to: Purpose for set home position and its usage #1746
    Michael
    Michael
    Keymaster

    Hi Chris,
    Set home position is used when using a GPS concurrently with your UM7.
    The home position is the longitude and latitude that is recorded when you run this command when using a GPS.

    Regards,
    Michael

  • in reply to: Unable to connect to UM-7 AHRS #1745
    Michael
    Michael
    Keymaster

    Hi Naveen,

    It definitely seems like you are transmitting NMEA type packets, anything starting with a “$PCHR…” is a NMEA packet type.
    Can you please turn these off using the serial interface software, and let me know if this helps.

    Regards
    Michael

  • in reply to: Unable to connect to UM-7 AHRS #1638
    Michael
    Michael
    Keymaster

    Naveen,

    Also looks like you have NMEA packets and binary data being transmitted?

    Regards,
    Michael

  • in reply to: Unable to connect to UM-7 AHRS #1637
    Michael
    Michael
    Keymaster

    Hi Naveen,

    Sounds like a driver issue, did you install the latest FTDI drivers from the FTDI web site?

    Regards,
    Michael

  • in reply to: euler angles become NaN after some time #1463
    Michael
    Michael
    Keymaster

    Hi Till,
    Thanks for this update it’s greatly appreciated.

    Can you please contact the support team at Redshift labs.
    They would like to discuss this further and possibly gather some more information from you.

    Regards,
    Michael Malloy

  • in reply to: Compass Reading near North Pole #1212
    Michael
    Michael
    Keymaster

    Hi Bolek,
    This is a very interesting question I have had similar thoughts about using the sensor at the equator, but thats another story.

    To be safe I think you should calibrate your unit in the local magnetic surroundings, and the sensor should operate as specified.
    Are you able to perform Calibration on site, or are these being deployed from a test platform, and delivered to the area you mentioned?

    However the UM7’s only limitation is the sensor itself, its sensitivity is ±4800 uT at full scale range.
    so this gives the sensor about (9600 uT/ 2^14 bits) = apx 585.98 nT resolution.

    However the figures you have posted look within these values, so I don’t think this would be an issue.

    Regards,
    Michael Malloy

  • in reply to: UM7 factory configuration #1209
    Michael
    Michael
    Keymaster

    Hi Till,

    Try downloading the new interface software.
    https://www.redshiftlabs.com.au/serial-interface-software

    there should be a default U71D config file deployed with software package

    Regards,
    Michael Malloy

  • in reply to: UM7 register 137 #1143
    Michael
    Michael
    Keymaster

    Hi Jose,

    please see here

    Regards,
    Michael

  • in reply to: UM7 register 137 #1129
    Michael
    Michael
    Keymaster

    Hi Rocky

    “I would like to know if there are any other differences in the two U71D versions”

    No, there are no other differences in the U71D.xml file.

    The newer firmware version U71D has had added real time gyro bias estimates, these are located in registers 137, 138 & 139. The xml files are a mapping file which tell the serial software what settings should be displayed to the users and similarly what commands to send to the UM7 to perform functions on those registers, however the information for these new registers 137,138 & 139 had not been added. You should be using the newer U71D.xml file as it has been updated to reflect the changes in the firmware, this is not a temporary version it will be the version deployed in the new serial software which will be released this week, I will post the link here when its ready.

    “and also to know what the differences were between U71C and U71D (first version).”

    The differences between U71C and U71D.

    U71D added the following functionality which U71C did not have
    – Adds real-time gyro bias estimation, with ability to tune bias convergence rate, and broadcast bias estimates.
    – Modifies filter to run in-place to improve efficiency.
    – Modified magnetometer code so that after rotating the measurement into the v1 frame (Euler-Angle mode), it computes
    the yaw angle and uses the ref vector to subtract the declination. Provides more robust yaw measurements.

    “We have several products where we plan on using the gyro, but need to have a stable version to go forward.”

    I understand there isn’t an issue with the firmware there just hadn’t been a way to turn these registers off/on. An updated set of serial interface software V3.1.3 will be released this week. This will have the new U71D.xml file deployed within the software so users will not need to run through the workaround process discussed a few threads earlier. Also the datasheet/documentation has been updated and will also be released this week, which explains registers 137,138 & 139 functionality.

    I hope this helps!

    Regards,
    Michael

    • This reply was modified 1 year, 7 months ago by Michael Michael.
    • This reply was modified 1 year, 7 months ago by Michael Michael.
  • in reply to: UM7 register 137 #1126
    Michael
    Michael
    Keymaster

    Hi Peter

    “Is the firmware also responsible for the graphs no longer working in the CHR serial interface?”

    Can you please be more specific which graphs are not working? I am unaware of this issue.

    The firmware is not responsible for the graphing functionality that is handled on the PC side.
    The firmware does all the heavy lifting on the UM7 pcb, including the transfer of data to and from the UM7.

    Regards,
    Michael

    • This reply was modified 1 year, 7 months ago by Michael Michael.
    • This reply was modified 1 year, 7 months ago by Michael Michael.
  • in reply to: Position & Velocity data #2252
    Michael
    Michael
    Keymaster

    Hi Tanis,

    Without a GPS connected you wont be able to obtain longitude or latitude.
    The UM7 simply parses GPS data and does perform some simple calculations however, you would need data constantly being fed into the UM7.

    Regards,
    Michael

  • in reply to: Quaternion Output Drift #1941
    Michael
    Michael
    Keymaster

    Hi Tanis,
    I cannot see any easy way to calibrate your unit without connecting to the serial interface software. To do so, you will need any USB to TTL converter, we recommend something with an FTDI chip set.
    like ours
    https://www.redshiftlabs.com.au/sensors/usb-expansion-board

    I would suggest buying a USB expansion board it will make your life so much easier, although it would be a fun project to do, it really depends on the time you have to commit to the implementation.

    The issue with calibrating and parsing the data with an Arduino is you would need to write a full parser and interface then pipe that through a VCOM port.

    With that said redshift labs will be releasing a full Arduino interface in the coming months, however that wont help you now, but keep it in mind.

    Regards,
    Michael Malloy

Viewing 15 posts - 1 through 15 (of 22 total)