Holoseat Magnet/Sensor Test Plan

The goal of the Holoseat magnet/sensor test plan is to determine the best magnet/sensor combination for the Holoseat cadence (the user’s pedaling speed measured in RPM) detection. A good magnet/sensor pairing is one which works reliably for a wide range of physical configurations.  Reliability for this pairing means low to no noise in the sensor signal and sufficient sensor detection signal from the magnet over a wide range of distances between the magnet and the sensor.

The test plan is broken into three phases:  setup, characterization, and design of experiments (DOE).  The setup phase includes all steps required to prepare the test rig.  The characterization phase gathers data about the general behavior of the sensors and magnets for three cadences (lo:20, mid:36, and hi:54).  The product of the characterization phase is a report showing the performance of the sensors and magnets at each cadence and recommending which sensors and magnets to continue researching.  The DOE phase simulates the calculation of cadence for each remaining pairing of magnet and sensor over varying cadences and distances to arrive at a recommended pairing for the Holoseat.

Test Plan Steps

Setup Phase

1. Prepare the work test rig

1. Clear the workspace
2. Set up the stepper motor mount and Arduino (making sure to remove temp test magnets from the test rig arm if necessary)
3. Set up the Raspberry Pi

1.  Plug in the USB cables for the Arduino, keyboard, and mouse
2. Plug in the display cable
3. Plug in the Ethernet cable
4. Plug in the power cable
5. Log in to the Raspberry Pi
6. Start a terminal shell and change to the test scripts directory

2. Prepare sensors

1. Clear a space for the sensors
2. Lay out the sensors in their packaging so they are within easy reach of the work area

3. Prepare the magnets

1. Clear a space for the magnets (ensure the space has no metal or magnets in it)
2. Lay out the magnets in their packaging so they are within easy reach of the work area and are not attached to each other

4. Prepare ODE

1. Log into ODE from the Raspberry Pi
2. Navigate to Holoseat’s DMSF repository
3. Create a directory structure for storing the test results

Characterization Phase

The characterization phase uses the run-char-test.js test script.

1. Generate the test definition files for Phase 1.1 (sensor characterization) from the test definition spreadsheet for Phase 1.1 by running the test generator script
2. Run the test cases for Phase 1.1 using the instructions in the Individual Test Procedure section
3. Write Section 1.1 of the test report

1. Create line plots for each cadence+sensor and each cadence+all sensors
2. For each plot, comment on the results (were some sensors prone to noise, if so for which cadence(s)?)
3. Note whether it makes sense at this time to continue testing the analog sensor
4. Note if any sensors perform reliably across all of the tests
5. Select which sensor(s) will move to later stages of testing

4. Update the test definitions for Phase 1.2 (magnet characterization) based on results from Phase 1.1
5. Generate the test definition files for Phase 1.2 from the test definition spreadsheet for Phase 1.2 by running the test generator script
6. Run the test cases for Phase 1.2 using the instructions in the Individual Test Procedure section
7. Write Section 1.2 of the test report

1. Create line plots for each cadence+magnet and each cadence+all magnets
2. For each plot, comment on the results (were some magnets prone to noise, if so for which cadence(s)?)
3. Note if any magnets perform reliably across all of the tests
4. Select which magnet(s) will move to later stages of testing

8. Write test definition for Phase 1.3 (distance sweep) using the smallest viable magnet from Phase 1.2, the sensor with the widest “on” range, the mid cadence speed, and the default distance.
9. Run tests for Phase 1.3 using the instructions in the Individual Test Procedure section, doubling the distance for each test case (check results after each test for when the sensor signal becomes unreliable and then stop)
10. Write Section 1.3 of the test report

1. Create a line plot showing the results for all of the test cases in Phase 1.3
2. Identify the max distance where the sensor and magnet pair worked reliably, this is the max distance for Phase 2 testing
3. Catalog the final results of Phase 1

1. Sensors to study in the DOE
2. Magnets to study in the DOE
3. Min and max distance for tests in the DOE

DOE Phase

The characterization phase uses the run-doe-test.js test script.

1. Update the test definitions for Phase 2.1 (DOE) based on results from Section 1.3 of the test report (include 3 replicates)
2. Generate the test definition files for Phase 2.1 from the test definition spreadsheet for Phase 2.1by running the test generator script
3. Run the test cases for Phase 2.1 using the instructions in the Individual Test Procedure section
4. Write Section 2.1 of the test report

1. For each cadence, distance, and magnet/sensor pairing

1. Create a line plot of measured cadence (in RPMs) vs time (in seconds), including a horizontal line at the specified cadence to use as a comparison with the measured cadence; each replicate should be its own series
2. Calculate the overall error for the magnet/sensor pairing using the specified cadence as the truth (use the data from all replicates)

2. Summarize results in a table of cadence, distance, and magnet/sensor error value
3. Recommend a specific magnet/sensor pairing based on these results (looking for lowest consistent error values over all the DOE tests

5. Write test definition for Phase 2.1 (distance sweep) using the recommended magnet/sensor pair, the mid cadence speed, and the default distance.
6. Run tests for Phase 2.1 using the instructions in the Individual Test Procedure section, doubling the distance for each test case (calculate the error value for each test case, and stop when it is 1.5 times the average error value from the DOe for this pairing)
7. Write Section 2.2 of the test report

1. Create a line plot showing the results for all of the test cases in Phase 2.1
2. Identify the max distance for the magnet/sensor pair based on plots and error table (distance, error)
3. Summarize the results of the DOE

1. Recommended magnet
2. Recommended sensor
3. Max distance supported by this pair

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Individual Test Procedure

This procedure is run any time we are collecting data.

1. Randomly select next test case (roll a die, etc) until all CHAR tests for this phase have been run once - for doe just follow table (when practical for experiment set up - some configurations may be difficult to set up, when this happens, group experiments)
2. Pull required sensor from inventory
3. Attach sensor to leads (be sure to select appropriate set of leads based on digital vs analog sensor)
4. Mount sensor to helping hands
5. Position sensor at specified distance above magnet mounting plates
6. Pull required magnets (2) from inventory
7. Attach magnets to test rig (verify polarity by running sudo node hall-read.js, reversing the magnet if it does not trigger the sensor to report a value of 0)
8. Start the stepper motor to required cadence (run sudo node set-cadence.js <cadence>)
9. Verify stepper motor is running at the required cadence with the bike computer
10. Run test script for selected test case file
11. Review test description and confirm test is set up correctly
12. Begin test
13. Wait for test to complete
14. Stop the stepper motor (run sudo node set-cadence.js 0)
15. Upload results file to ODE
16. Remove and store the sensor
17. Remove and store the magnets

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