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General Questions
WW-01 Questions


Designed for
servo motors

WW-02 Questions


Designed for
Solarbotics
GM-2/3/8/9 motors

WheelWatcherTM Encoder Frequently Asked Questions

General Questions

WW-01 Questions

WW-01
Designed for servo motors
  • Do I need to use the alignment tool?
    Yes, it is highly recommended. If the board's sensors are not aligned well with the codewheel sticker, the timing of the various signals will be strongly affected, to the point that you may end up not getting 128 clock pulses per rotation. Further, the time between each clock pulse will not be consistent, but will instead vary from pulse to pulse, usually with a pattern that repeats every 4 clocks. Severe misalignment may result in ChA and ChB not always being in phase with each other, resulting in inconsistent counts.

  • Do I need to use the adhesive on the back of the board? I might want to remove the WheelWatcher later.
    The adhesive helps prevent the board from falling into misalignment if the mounting screws come loose. We chose a type of adhesive that sticks well to many types of plastic, but not so well that you cannot remove the board if you need to.

  • Why am I not getting good counts from the encoders?
    Check the behavior of the LEDs while your servos are turning. Do this either by turning the wheels slowly by hand (rough turning can strip the gears in the servos, so be gentle!) with the power on to the WW-01s but off to the servos, or by using your own test program. The green LEDs should be solid on or off, and should only change state when the direction of wheel rotation changes. The red LEDs should blink on and off, once per stripe -- 32 times on and 32 off for each wheel rotation.

    If the green LED is flashing when it shouldn't be, or if the red LED is not pulsing 32 times per rotation, make sure your wheels are on tight. If the wheels are too high above the WW-01 PCBs, there won't be enough light reflected to the sensors on the boards. It is best to use the screws provided with your servos to hold the wheels in tight.
    If you are still having problems, check the alignment of the PCB with the AL-02 alignment tool with the wheel temporarily removed. Also, check that the codewheel stickers are flat against the wheel, without bubbles under them, and that they are clean.

  • What mounting hardware is provided?
    We provide four 4-40 x 7/8" flat head machine screws, with a 100 degree head angle so that the screw heads will not rub on the wheel. We also provide four 4-40 k-lock nuts, four .25" x .278" #4 custom spacers, and four .25" x .31" #4 spacers. See the product manual for suggested spacers to use with various popular servo models.

  • My robot uses DC motors and hand made wheels. Can I use the WheelWatcher WW-01 with it?
    Maybe. You will need to mount the WW-01 such that it is aligned with your motor's shaft, and place the codewheel sticker on a flat surface (your wheel or something attached to the motor shaft) so that it is parallel to the surface of the WW-01 PCB. The distance between the top of the 2 sensors on the WW-01 and the codewheel sticker must be close to 1.1 mm (0.043") for it to function.

    Beyond that, good luck. We can't support nonstandard motors, wheels, and mounting schemes -- the WW-01 is designed specifically for standard injection molded wheels and standard size RC servos. Let us know how it works for you, though.

WW-02 Questions

WW-02
Designed for Solarbotics GM2, GM3, GM–8, and GM9 motors
  • Why am I not getting good counts from the encoders?
    Check the behavior of the LEDs while your motors are turning. Do this either by turning the wheels slowly by hand (rough turning can strip the gears in the motors, so be gentle!) with the power on to the WW-02s but off to the motors, or by using your own test program. The green LEDs should be solid on or off, and should only change state when the direction of wheel rotation changes. The red LEDs should blink on and off, once per stripe -- 32 times on and 32 off for each wheel rotation.

    If the green LED is flashing when it shouldn't be, or if the red LED is not pulsing 32 times per rotation, make sure your wheels are on tight. If the wheels are too high above the WW-02 PCBs, there won't be enough light reflected to the sensors on the boards. It is best to use screws to hold the wheels in tight.

    If you are still having problems, check that the codewheel stickers are flat against the wheel, without bubbles under them, and that they are clean.

  • What mounting hardware is provided?
    The WW-02 is provided without mounting hardware at this time, as the appropriate hardware depends on the chassis to which the motor is attached.

  • My robot uses nonstandard motors and wheels. Can I use the WheelWatcher WW-02 with it?
    Maybe. You will need to mount the WW-02 such that it is aligned with your motor's shaft, and place the codewheel sticker on a flat surface (your wheel or something attached to the motor shaft) so that it is parallel to the surface of the WW-02 PCB. The distance between the top of the 2 sensors on the WW-02 and the codewheel sticker must be close to 1.1 mm (0.043") for it to function.

    Beyond that, good luck. We can't support nonstandard motors, wheels, and mounting schemes -- the WW-02 is designed specifically for standard injection molded wheels and Solarbotics GM-2, GM-3, GM-8, and GM-9 motors. Let us know how it works for you, though.

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