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3DOF Jerky Jerky Motors

Discussion in 'New users start here - FAQ' started by DukeLeather, Dec 1, 2025 at 02:40.

  1. DukeLeather

    DukeLeather New Member Gold Contributor

    Joined:
    Mar 17, 2023
    Messages:
    3
    Balance:
    - 57Coins
    Ratings:
    +1 / 0 / -0
    My Motion Simulator:
    3DOF
    Trying to calibrate my traction loss motor. This being the first of the 3 DOF. I've been fighting with this for over a week and can't seem to make any headway. Below I've listed all the specs of electronics I've used as well as all of the diagnostics I've attempted so far. I started with 3-IBT2 and then moved to a sabertooth 2x32 for the front motors. I've tested the traction loss motor with the sabertooth as well. I've also included photos and links to video of what is happening. Any suggestions would be greatly appreciated! Thank you!


    3DOF ELECTRONICS SPEC SHEET

    3 - MOTORS:
    (2) ElectroCraft Wheel Chair Motors
    o 22.5v
    o 275 watt (1000 watt peak)
    o Gear Ratio 32.79:1
    o Output Shaft 116 RPM

    (1) Pride Quantum Wheel Chair Motor
    o 24.0v
    o 200 watt (1000 watt peak)
    o Gear Ratio 29:1
    o Output Shaft 186 RPM

    3 - POWER SUPPLIES (one for each motor)
    - AC 170-250V to DC 24V 41.6A 1000W
    - Dialed in to exactly 22.5v
    - (12v 20A Computer Power Supply for low voltage testing)

    2 - ARDUINO
    2 - ELGATO UNO R3
    2 - ElectroCookie Uno Terminal Block

    3 – HALL SENSORS - 6127V1A180L.5FS

    3 - MOTOR DRIVER MODULES
    - IBT-2 BTS7960 43A H-bridge Double Motor Driver Module (Traction Loss Motor)
    - Sabertooth Dual 32A 6V-24V DC Motor Driver (2 Main Motors)

    SOFTWARE
    SABERTOOTH
    - SabertoothArduinoLibraries
    - SPS_8.2_softstart (Sketch) – Set to MODE 3

    IBT-2
    - SMC3 v1.0 (Sketch) – Set to MODE 2

    SMC UTILITIES
    - SMC3Utils v1.01


    DIAGNOSTIC TESTING – Jerkiness of Traction Loss Motor (all resulted in little to no change of issue)
    - Different computers
    - Different cables
    - Triple checked then checked again the connections to Uno
    - Shorter length of wire to Hall Sensors
    - Swapped Hall Sensors
    - Tested voltage at Sensors
    - Swap Uno R3 unit
    - Added power supply to Uno R3 for increased power instead of relying on the PC to provide power
    - Changed multiple IBT2 controllers
    - Changed to Sabertooth 2x32 controller
    - I tried different motors (same and different models)
    - Swapped 24v power supply for another
    - Changed out 24v power supply to 12v power supply
    - Tested voltages to controllers from power supply - constant
    - Tried 2:1 gearing and 1:1 gearing of Hall Sensor to motor shaft
    - Tried Fpwm Freq from 15kHz to 30kHz
    - High and low Kp testing varied the strength, but jerkiness would still happen to different degrees
    - Various PWMmin and PWMrev with little to no change
    - Tried all Fpid settings with no change other than motor hum


    VIDEO LINKS
    IBT2 with load:
    IBT2 no load:

    Sabertooth KP200:
    Sabertooth KP400:

    Attached Files:

    DukeLeather, Dec 1, 2025 at 02:40
    #1
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    21,869
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    Tasmania, Australia
    Balance:
    152,845Coins
    Ratings:
    +11,111 / 56 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    Just a guess but try setting PWMmin=0, PWMmax=200 and PWMrev=120, rerun the Sine test and please post the result.
    noorbeast, Dec 1, 2025 at 03:57
    #2