Nubotics WW-02-WheelWatcher Encoder

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Product Manual || Frequently Asked Questions || Product Brief || Nubotics Code Examples || LS7084 Quadrature Decoder || Photomicrosensor

For an explanation of how encoders actually work visit John Schimmels encoder sensor report and also go to Wikipedia. For an overview of how this sensor was used in the project please go to the Ramps link. For the code on this wiki please go to RampsMouse

The Nubotics WW-02-WheelWatcher Encoder is an optical quadrature encoder that senses direction, distance, velocity and acceleration. It is manufactured by Nubotics and sold by Acroname for robotics for a single wheel for $21.95or as a two wheel set for $41.95. It comes in a small plastic bag with the following components:

  • Printed circuit board, preassembled
  • Self-adhesive codewheel
  • 6" four lead color-coded cable
  • A direction booklet
  • Two extra wires provided for use with raw-quadrature output
  • Motor and wheel not included (its intended usage)

For my project I also ended up buying their CS-100 codewheel spacer also from acroname, a one eighth inch laser-cut plexiglas disc:

It is designed to go an a gear motor to control robotic functions - the following is a picture of it's intended applicationon on a gear motor:

Timing Diagram The following diagram illustrates the behavior of the ChA, ChB, Dir, and Clk signals as the wheel slows down and changes direction, then speeds back up.

Specifications (PRELIMINARY)

  • Supply Voltage (Vcc) +4.5v to +5.5v
  • Supply Current (Icc) 30mA MAX (TBD)
  • DC Output Voltage 0v to Vcc
  • DC Output Current (pins 1, 3) +/- 50mA
  • DC Output Current (pins 5, 7) +1.0mA (Vout 4.5v), -1.75mA (Vout 0.4v)
  • Clock pulse width 25us
  • Radial misalignment TBD
  • Tangential misalignment TBD
  • Angular misalignment TBD
  • Codewheel tilt TBD
  • Phase error TBD
  • detector top to codewheel 0.8mm (0.031") - 1.1mm (0.043")

NOMINAL SPACING

  • MIN 0.5mm (0.02") (TBD)
  • MAX 2mm (0.08") (TBD)

BLOCK DIAGRAM

The LS7084 Datasheet

From the EE-SY125 datasheet:

Features of Photomicrosensors: The Photomicrosensor is a compact optical sensor that senses objects or object positions with an optical beam. The transmissive Photomicrosensor and reflective Photomicrosensor are typical Photomicrosensors. The transmissive Photomicrosensor incorporates an emitter and a transmissive that face each other as shown in Figure 1. When an object is located in the sensing position between the emitter and the detector, the object intercepts the optical beam of the emitter, thus reducing the amount of optical energy reaching the detector. The reflective Photomicrosensor incorporates an emitter and a detector as shown in Figure 2. When an object is located in the sensing area of the reflective Photomicrosensor, the object reflects the optical beam of the emitter, thus changing the amount of optical energy reaching the detector. “Photomicrosensor” is an OMRON product name. Generally, the Photomicrosensor is called a photointerrupter.

Reflective Photomicrosensor:

ChA and ChB are 50% duty cycle, 90° out of phase signals, created by having two Omron EE-SY125 (or equivalent) photodetector packages spaced at a very specific angle with respect to each other, at a specific radius from the center of the axis of rotation, and expect to be used with a 32 stripe codewheel with a 50% silver/50% black radial stripe pattern.

Product Manual || Frequently Asked Questions || Product Brief || Nubotics Code Examples || LS7084 Quadrature Decoder || Photomicrosensor

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