Motion Laboratory

Mission

Build this

Build a small courtroom for PIR, tilt, and GY-6500 evidence, with a display for raw clues and a gesture for the combined verdict.

Bill of materials

Parts

Disconnect USB before rewiring. Motors, the relay, and the servo need appropriate power and a shared ground. Never drive an actuator from the ESP32 3V3 pin.

The central idea

A sensor does not detect “motion.” It detects its own clue.

A person walking past can trigger the PIR while leaving the table perfectly still. A tap can wake the tilt switch and motion module while the PIR sees no warm body crossing. A slow tilt may change orientation without creating a sharp acceleration.

Predictions, not answers. Your trials decide what “likely” means for your setup.

Design the courtroom

Define the event before judging the sensor

“Motion happened” is too vague for a fair test. Mark where the person walks, how the table is tapped, how far the sensor sits, and when each trial begins and ends.

This four-box record is a confusion table. Its purpose is not to confuse you. It stops one impressive success from hiding five quiet failures.

Wiring

Introduce the witnesses one at a time

Read the PIR first, then the tilt switch, then the GY-6500. Let the OLED show each raw witness before your combined rule replaces them with one verdict.

The power rule: The GY-6500 and OLED use 3V3. The common PIR module uses 5 V but returns 3.3 V logic. The servo uses a separate 5 V supply. Join all grounds.

Give agreement a body

One clue should not look like three clues

Your trial programme

Rehearse both movement and stillness

1. Write four scenes.

   Include at least two motions and two no-motion conditions that could fool a sensor.

2. Predict the witnesses.

   Write which sensors you expect before running the trial.

3. Run twenty repetitions per scene.

   Keep placement and timing fixed. Record every witness, delay, and final verdict.

4. Tune once, then stop.

   Use one run to design the rule and a fresh run to evaluate it. Do not keep moving the goalposts.

When witnesses behave strangely

Disagreement is often the result you need

Choose your laboratory

What kind of motion scientist will you become?

A calm way through the build

Collect four small wins

1. mb-01 says hello.

   Prove the garden connection first.

2. Each witness has a raw display.

   Test PIR, tilt, and GY-6500 separately.

3. One fixed scene produces a repeatable record.

   Build the trial loop before inventing the fusion rule.

4. The verdict survives fresh trials.

   Freeze the rule, add the servo gesture, and evaluate it without retuning.

The garden handshake

Share what you found

These names are the rigid part of the project. They let another team find your work without knowing what you called the variables in your code.

Finish line

Ready to introduce to the garden

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  mb-01 stays online and publishes motion verdict and event count.

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  The reject feed stays clear after the final code starts.

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  The device reads the Gate Keeper count topic.

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  The display and servo distinguish raw clues from the combined verdict without blocking messages.

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  The build log contains defined scenes, at least twenty trials per condition, delays, misses, false alarms, and an untouched evaluation run.

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  All sensors are fixed, the servo is safely powered, and the device label can be scanned.

The goal is not to make three sensors agree. It is to understand what each witness can see, then build a rule that deserves its confidence.