Unit 14 · lesson
Test Perception at Its Boundaries
A perception demo in perfect lighting tells you almost nothing about robustness.
Boundary testing changes one condition at a time and watches where performance changes.
Conditions worth testing
Depending on the system:
- bright/dim lighting;
- backlighting;
- target distance;
- target rotation;
- partial occlusion;
- motion blur;
- background similarity;
- camera vibration;
- multiple similar objects.
The goal is not to make the detector fail for entertainment. It is to discover the operating envelope.
Example test matrix
| Trial | Distance | Light | Occlusion | Expected | Observed |
|---|---|---|---|---|---|
| A | 1 m | normal | none | detect | detect |
| B | 2 m | normal | none | detect | detect |
| C | 2 m | dim | none | detect | missed |
| D | 1 m | normal | partial | detect | unstable |
Now the statement "vision works" can be replaced with something useful:
Detection was reliable in the tested normal-light cases to 2 m, but performance degraded in the dim-light trial.
Separate model failure from pipeline failure
A missing detection can come from:
- camera not producing frames;
- exposure problem;
- image transport delay;
- preprocessing error;
- model inference;
- threshold logic;
- coordinate transform.
Do not blame "AI" until you know which layer failed.
Build a boundary report
Use supplied outputs, a simulator, a safe camera test, or a clearly labeled hypothetical dataset.
Change at least three conditions.
Record:
- expected behavior;
- observed output;
- failure point;
- whether the robot should continue, degrade, request help, or stop.
End with an operating-boundary statement for the perception system.
Build a boundary test matrix
A perception demo under perfect lighting proves very little about operating limits.
Change one condition at a time:
| Trial | Lighting | Distance | Occlusion | Expected | Observed |
|---|---|---|---|---|---|
| A | bright | 1 m | none | detect | detect |
| B | dim | 1 m | none | detect | miss |
| C | bright | 3 m | none | detect | detect |
| D | bright | 1 m | partial | detect | wrong label |
The table is valuable even when you use a supplied dataset rather than a live camera.
Find the first boundary
If Trial B fails, do not immediately conclude "the model is bad." Repeat or narrow the condition:
100% light → pass
70% light → pass
50% light → pass
40% light → intermittent
30% light → fail
Now you have an approximate operating boundary to investigate.
Design the system around uncertainty
A robust robot can respond to low-confidence or missing perception by:
- reducing speed;
- requesting another observation;
- switching sensor sources;
- stopping;
- handing authority to a person.
Perception quality and robot policy belong in the same safety conversation. The model can be uncertain while the system response remains deliberate.