ArUco marker landing in Drone Programming - Step-by-Step Execution

Concept Flow - ArUco marker landing

Start Drone

↓

Search for ArUco Marker

↓

Marker Detected?

No→Keep Searching

Yes↓

Calculate Marker Position

↓

Adjust Drone Position

↓

Is Drone Aligned?

No→Adjust Position Again

Yes↓

Descend Slowly

↓

Landing Complete

↓

Stop Drone

The drone starts, searches for the ArUco marker, detects it, calculates its position, aligns itself, descends, and lands.

Execution Sample

Drone Programming

while not landed:
    detect_marker()
    if marker_found:
        position = get_marker_position()
        align_to_marker(position)
        if aligned:
            descend()
            if on_ground:
                landed = True

This code makes the drone detect the ArUco marker, align to it, and descend until it lands.

Execution Table

Step	Action	Marker Found?	Position Calculated	Aligned?	Descend?	Landed?
1	Start drone and search	No	N/A	No	No	No
2	Search again	No	N/A	No	No	No
3	Marker detected	Yes	Calculate position (x=2,y=3)	No	No	No
4	Align to marker	Yes	Position (2,3)	Yes	No	No
5	Descend	Yes	Position (2,3)	Yes	Yes	No
6	Check if on ground	Yes	Position (2,3)	Yes	Yes	Yes
7	Landing complete	Yes	Position (2,3)	Yes	No	Yes

💡 Drone lands when it is aligned and on the ground, setting landed to True.

Variable Tracker

Variable	Start	After Step 3	After Step 4	After Step 5	After Step 6	Final
marker_found	False	True	True	True	True	True
position	None	(2,3)	(2,3)	(2,3)	(2,3)	(2,3)
aligned	False	False	True	True	True	True
descend	False	False	False	True	True	False
landed	False	False	False	False	True	True

Key Moments - 3 Insights

Why does the drone keep searching even after starting?

Because marker_found is False at first (see step 1 and 2 in execution_table), so the drone continues searching until it detects the marker.

What happens if the drone is not aligned after detecting the marker?

The drone will keep adjusting its position and will not descend until aligned is True (see step 3 and 4).

When does the drone stop descending and consider landing complete?

When the drone is aligned and on_ground becomes True (step 6), it sets landed to True and stops descending.

Visual Quiz - 3 Questions

Look at the execution_table, at which step does the drone first detect the marker?

A Step 1

B Step 5

C Step 3

D Step 7

💡 Hint

Check the 'Marker Found?' column in execution_table rows.

According to variable_tracker, what is the value of 'aligned' after Step 4?

A True

B None

C False

D Not set

💡 Hint

Look at the 'aligned' row under 'After Step 4' in variable_tracker.

If the drone never aligns, what will happen to the 'descend' variable in execution_table?

A It will become True anyway

B It will stay False

C It will toggle between True and False

D It will cause an error

💡 Hint

Refer to the 'Aligned?' and 'Descend?' columns in execution_table rows 3 and 4.

Concept Snapshot

ArUco marker landing process:
1. Start drone and search for marker.
2. Detect marker and calculate position.
3. Align drone to marker position.
4. Descend only when aligned.
5. Land when on ground and aligned.
6. Stop drone after landing.

Full Transcript

This visual execution shows how a drone uses an ArUco marker to land. The drone starts by searching for the marker. If the marker is not found, it keeps searching. Once detected, it calculates the marker's position and aligns itself. The drone only descends when aligned. When it reaches the ground, it sets landed to True and stops. Variables like marker_found, position, aligned, descend, and landed change step-by-step to guide the drone's behavior.