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Description: This is the Wheel Encoder Kit from DAGU, a simple add-on to any wheeled robot that can help measure the speed or distance the chassis travels. Each wheel encoder kit consists of two neodymium 8-pole magnets with rubber hubs and two hall-effect sensors terminated with 150mm cables and 3-pin female servo headers. These wheel encoders require a supply voltage of 3-24V with a supply current of 4mA.

Features:

  • Supply Voltage: 3-24V
  • Supply Current: 4mA per sensor
  • Output Voltage: 26V Max
  • Output Current: 25mA Continuous

Documents:

Comments 13 comments

  • What are the yellow strips shown in the picture? Do you have a part number or datasheet on the actual sensors?

  • Could these be used with servo motors, with the magnetic disc screwed on between the wheels and the servo axle (perhaps with longer screws)?

  • Accuracy can be thought of as how repeatable is each pulse. Consider the mythical monopole magnet and detect only the rising edge. If you label that as 0 degrees, will it always be 0 degrees, or will the reading wander from 359 to 1 degree? Will it wander from 350 to 10 degrees? How will RPM affect accuracy? I think it would be fun to build a car distributer that will use a knock sensor to advance timing for max engine efficiency under all conditions for a vintage engine. Part of that project would be to know where the crankshaft rotation is to less than a degree. I don’t have to measure each degree, I can interpolate if the readings have accurate repeatability.

  • These work very well with the cheap yellow motors. With some simple code my motors now have lots more torque. http://www.bajdi.com/adding-encoders-to-those-cheap-yellow-motors/

    • How would this give you Torque?

      • My guess is that he doesn’t talk about the torque of the motor since it is a motor spec, but the torque that is transferred to the ground (i.e. the wheels grip the ground better because of skid detection?). Just a thought.

  • What is the i/d of the magnet with the rubber hub removed? The motor drive on my robot uses 3/8" shafts. What is the o/d? I also suspect the magnet will pick up all sorts of cr_p from the ground if mounted to close to the ground. Fortunately my motor mounts are 6+“ above the base.

  • How accurate are these? How small an increment of rotation can be detected?

    • 8 poles and 2 encoders should give you 16 counts per revolution. 360/16 is 22.5 degrees per count. With 100 mm wheels (4") that would give you about 2 cm per count. I’d like to know what the output is – is it totally raw Hall sensors that need conditioning, or is there any clean-up of the signal to turn it into something nice? (Answered my own question: The outputs are open-drain, so all the clean-up needed is a pull-up resistor.)

      • You can get 32 counts per revolution with this configuration if you can detect rising and falling edges on both channels. Though I don’t know if these edges would be equally spaced with this magnetic encoder.

        • I don’t think so. I think the rise/fall is already included in the “poles.” 8 poles means 4 magnets. 4 magnets timesd two poles/states each (north and south, high-and-low) times two encoders equals 16 transitions/counts. I could be mis-understanding how the poles are counted, though.

    • I suspect 1/8 of a revolution based on the 8 poles of the magnet. Edit – I forgot there were 2 sensors. jwatte is correct!


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