Finally, an easy and affordable encoder disc system for desktop robotics.
Wheel encoders keep your robot headed where it's supposed to be going. Here's how they work: Stripes or holes in a pattern attached to the motor or wheel are used to monitor speed and revolutions. Your robot's control program keeps track of the pattern, and adjusts motor output accordingly. The idea isn't terribly complicated, but commercial wheel encoders can be expensive, and homebrew can be unpolished and prone to error.
How wheel encoders work: Light from an infrared LED
reflects off a pattern attached to the inside of the
robot's wheels, and into a photo detector. The pattern
produces a series of pulses to indicate wheel motion.
The new Budget Robotics EZ-Encoder patterns are quality die-cut decals that you apply to your robot's wheels (wheels not included). They come in a variety of sizes and variations to suit the requirements of your bot and its control electronics. We provide the codewheel pattern; you must add the wheel and reflective infrared sensor to complete the system. Depending on the components you use, the cost per wheel is from $3 to $5, far less than most other encoders!
The decal material is especially selected for its durability. It's water resistant, and once applied to your robot's wheels will stay there until you purposely remove it. These are NOT cheapo patterns printed on paper and cut out with a pair of scissors. They're made on a servo-operated CAD machine using long-lasting adhesive-backed vinyl material.
Most encoder systems for amateur and educational robotics rely on small patterns, which in turn require special and sub-miniature sensors. These can be hard to work with. Our codewheel patterns are intentionally made large -- they fill as much of the inside wheel surface as possible. That makes it much easier to add your own sensors. You can use ready-made infrared emitter/detector boards (about $3 each from SparkFun and Pololu), or save even more by constructing your own using inexpensive components.
EZ-Encoder discs are available for the following common desktop robot wheels (you supply the wheels):
- Budget Robotics X-Wheels (or other generic wheel with a smooth, flat black surface for mounting)
- Pololu 2-5/8" wheel with rubber tire
- Parallax BOE-Bot wheels
- Solarbotics 2-5/8" wheel (servo or GM motor) with high-traction tire
- Other wheels size-compatible with the above
EZ-Encoder codewheels are provided in pairs. Application is easy, and takes less than a minute per wheel. Full instructions are provided.
Encoder patterns and inserts are provided for a variety of popular wheels for desktop robots.
The Budget Robotics X-Wheels already use a jet-black inner wheel; just apply the pattern decal to the wheel and you're all set! For the Parallax, Pololu, and Solarbotics wheels, you also get polystyrene inserts that provide a contrasting background for the white pattern decal. Apply the decal to the insert, and then mount the insert to the wheel. The inserts are held in place using Glue Dots (not included).
Adding an EZ-Encoder disc to the Parallax BOE-Bot wheel (you supply):
Apply the white pattern decal to the insert, then drop the insert
over the hub of the wheel.
The latest Solarbotics wheels for servos and GM gear motors incorporate their own molded-in encoder pattern. The Budget Robotics EZ-Encoder discs don't rely on specific sensor hardware, and because the pattern occupies a greater area of the wheel, is easier to use with components you add yourself. That saves you money.
EZ-Encoder codewheel added to the Solarbotics (you supply) high traction
wheels. These wheels are available for
both Futaba and Futaba-compatible servos, and the Solarbotics
"GM" series miniature gear motors.
Choose from among five pattern styles, consisting of 6, 8, 12, 16, and 24 "stripes." Choose the stripe density based on the capabilities of your robot's control electronics. More stripes aren't always better. If you're not sure of the stripe density you need get a set of all five pattern styles, and experiment. Each combo set comes with two of each pattern style -- 10 codewheel decals in all.
Choose the wheel type and pattern style from below. Remember: EZ-Encoder discs are provided in pairs. You get a set of two pattern decals, one for each of your bot's wheels, plus one pair of polystyrene inserts (for Parallax, Pololu, and Solarbotics wheels). NOTE Wheels and sensor electronics are not included.