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Walk Sensor Test Rig Development Log

Added by J. Simmons over 9 years ago

As part of the development of v0.3 of the Holoseat, we want to improve the sensitivity of the "walk sensor(s)". See Testing Hall Effect Sensors for more details.

I am planning to build a sensor test rig to simplify the testing procedure and eliminate variation in test results. This thread will serve as a live "lab notebook" documenting the design and development of the test rig. The actual test process (including selection of sensors and magnets to test) will be captured in Testing Hall Effect Sensors.

Below is the block diagram for the test rig. It will use a stand alone Arduino to control a rotation source (planning to use a re-purposed stepper motor as that source) to run a small wheel over a range of speeds and then plot the values calculated with the sensor/magnet under test to the driven speeds (in RPMs). Note, a bike computer with cadence measurement (not shown) will be used to verify the stepper motor is driving the wheel to the correct speed.

sensor_test_rig_block_diagram.png (120.5 kB)


Replies (28)

RE: Walk Sensor Test Rig Development Log - Added by J. Simmons almost 8 years ago

Documenting the test definition file format. It is a JSON file of the following format.

{
  "ID": "CHAR01",
  "Description": "TR 08 characterization low rpm",
  "Sensor": "TR 08",
  "Magnet": "MAG.375",
  "Distance": "1.0",
  "Duration": "60",
  "Cadence": "20" 
}

RE: Walk Sensor Test Rig Development Log - Added by J. Simmons almost 8 years ago

Testing is complete. Here is a link to the full report. But, for those who just want to know the answer, here are the results.

  • Sensor = TR 08 (90G Trip, 65G Release Digital Hall Effect Sensor)
  • Magnet = MAG.375 (3/8" dia. x 1/8 thick, 5.46 lbs pull force magnet)
  • Max supported distance = 2.5 cm

I still need to capture the electronics for the test rig in Fritzing and I need to upload some analysis files to DMSF. Other than that, this task is finally wrapped up.

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