Failsafe actions (RTL, Land, SmartRTL) in Drone Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the drone's failsafe action to Return To Launch (RTL).

Drone Programming

drone.setFailsafeAction([1])

Drag options to blanks, or click blank then click option'

AFailsafeAction.SMART_RTL

BFailsafeAction.LAND

CFailsafeAction.RTL

DFailsafeAction.HOVER

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing LAND instead of RTL will make the drone land immediately instead of returning.

SMART_RTL is a different mode that may not be supported everywhere.

The correct failsafe action to make the drone return to its launch point is FailsafeAction.RTL.

2fill in blank

medium

Complete the code to make the drone land immediately as a failsafe action.

Drone Programming

drone.setFailsafeAction([1])

Drag options to blanks, or click blank then click option'

AFailsafeAction.LAND

BFailsafeAction.HOVER

CFailsafeAction.SMART_RTL

DFailsafeAction.RTL

Attempts:

3 left

💡 Hint

Common Mistakes

Using RTL will make the drone fly back instead of landing.

SMART_RTL is a smarter return mode, not immediate landing.

To make the drone land immediately on failsafe, use FailsafeAction.LAND.

3fill in blank

hard

Fix the error in the code to set the failsafe action to Smart Return To Launch (SmartRTL).

Drone Programming

drone.setFailsafeAction([1])

Drag options to blanks, or click blank then click option'

AFailsafeAction.SMART_RTL

BFailsafeAction.LAND

CFailsafeAction.RTL

DFailsafeAction.HOVER

Attempts:

3 left

💡 Hint

Common Mistakes

Using RTL instead of SMART_RTL misses the smart features.

LAND will cause the drone to land immediately, not return.

The correct constant for Smart Return To Launch is FailsafeAction.SMART_RTL.

4fill in blank

hard

Fill both blanks to check if the failsafe action is set to RTL or Land.

Drone Programming

if drone.getFailsafeAction() == [1] or drone.getFailsafeAction() == [2]:
    drone.alertPilot()

Drag options to blanks, or click blank then click option'

AFailsafeAction.RTL

BFailsafeAction.LAND

CFailsafeAction.SMART_RTL

DFailsafeAction.HOVER

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for SMART_RTL instead of RTL or LAND.

Using HOVER which is not a failsafe action here.

This code checks if the failsafe action is either RTL or LAND, then alerts the pilot.

5fill in blank

hard

Fill all three blanks to create a dictionary mapping failsafe actions to their descriptions.

Drone Programming

failsafe_descriptions = {
    [1]: "Return To Launch",
    [2]: "Land Immediately",
    [3]: "Smart Return To Launch"
}

Drag options to blanks, or click blank then click option'

AFailsafeAction.RTL

BFailsafeAction.LAND

CFailsafeAction.SMART_RTL

DFailsafeAction.HOVER

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the constants and descriptions.

Including HOVER which is not part of the failsafe descriptions here.

This dictionary links each failsafe action constant to a clear description string.

Practice

1. What does the RTL failsafe action do when triggered on a drone?

easy

A. The drone returns to its takeoff point automatically.

B. The drone immediately lands at its current location.

C. The drone hovers in place until manual control is regained.

D. The drone performs a pre-programmed flight path before landing.

Solution

1. Step 1: Understand RTL meaning

   RTL stands for "Return To Launch," meaning the drone flies back to where it took off.

2. Step 2: Compare with other failsafe actions

   Unlike Land or SmartRTL, RTL specifically returns the drone to the takeoff point automatically.

3. Final Answer:

   The drone returns to its takeoff point automatically. -> Option A

4. Quick Check:

   RTL = Return To Launch [OK]

Hint: RTL always means return to the starting point [OK]

Common Mistakes:

• Confusing RTL with immediate landing
• Thinking RTL means hovering
• Assuming RTL follows a custom path

2. Which of the following is the correct syntax to set the failsafe action to Land in a drone programming script?

easy

A. set_failsafeAction('Land')

B. setFailsafeAction(Land)

C. setFailsafeAction("Land")

D. setFailsafeAction('land')

Solution

1. Step 1: Identify string syntax in code

   Failsafe actions are usually passed as strings, so quotes are needed around the word Land.

2. Step 2: Check correct string format

   Double quotes or single quotes can be used, but the option with double quotes and correct capitalization is standard.

3. Final Answer:

   setFailsafeAction("Land") -> Option C

4. Quick Check:

   String with quotes and correct case = setFailsafeAction("Land") [OK]

Hint: Use quotes and correct capitalization for string parameters [OK]

Common Mistakes:

• Omitting quotes around the string
• Using wrong capitalization
• Passing the action as a variable without quotes

3. Given the following code snippet, what will be the drone's behavior if the failsafe is triggered?

failsafe = 'SmartRTL'
if failsafe == 'RTL':
    action = 'Return to launch point'
elif failsafe == 'Land':
    action = 'Land immediately'
elif failsafe == 'SmartRTL':
    action = 'Return home avoiding obstacles'
else:
    action = 'Hover in place'
print(action)

medium

A. Return home avoiding obstacles

B. Land immediately

C. Return to launch point

D. Hover in place

Solution

1. Step 1: Check the value of failsafe variable

   The variable failsafe is set to 'SmartRTL'.

2. Step 2: Follow the if-elif conditions

   The code matches the 'SmartRTL' condition and sets action to 'Return home avoiding obstacles'.

3. Final Answer:

   Return home avoiding obstacles -> Option A

4. Quick Check:

   SmartRTL triggers obstacle-avoiding return [OK]

Hint: Match variable value to condition branches carefully [OK]

Common Mistakes:

• Choosing the default else action
• Confusing SmartRTL with simple RTL
• Ignoring case sensitivity in strings

4. Identify the error in this failsafe action code snippet:

def set_failsafe(action):
    if action = 'RTL':
        return 'Returning home'
    elif action == 'Land':
        return 'Landing now'
    else:
        return 'Hovering'

medium

A. Missing colon after the else statement

B. Using single equals (=) instead of double equals (==) in the if condition

C. Incorrect indentation of the return statements

D. Using single quotes instead of double quotes for strings

Solution

1. Step 1: Check the if condition syntax

   The if condition uses a single equals sign (=), which is assignment, not comparison.

2. Step 2: Confirm correct comparison operator

   Comparison requires double equals (==) to check equality.

3. Final Answer:

   Using single equals (=) instead of double equals (==) in the if condition -> Option B

4. Quick Check:

   Comparison needs '==' not '=' [OK]

Hint: Use '==' for comparison, '=' is assignment [OK]

Common Mistakes:

• Confusing assignment and comparison operators
• Ignoring syntax errors from missing colons
• Assuming quotes style causes errors

5. Given the following code snippet, what failsafe action will be selected?

battery = 15  # percentage
gps_signal = False

if battery < 20 and gps_signal:
    failsafe = 'SmartRTL'
elif battery < 20 and not gps_signal:
    failsafe = 'Land'
else:
    failsafe = 'RTL'

print(failsafe)

hard

A. The drone will choose 'RTL' because battery is sufficient.

B. The drone will choose 'SmartRTL' because battery is low and GPS signal is present.

C. The drone will choose 'Land' because GPS signal is present.

D. The drone will choose 'Land' because battery is low and GPS signal is missing.

Solution

1. Step 1: Analyze battery and GPS conditions

   Battery is 15% (less than 20) and GPS signal is False (missing).

2. Step 2: Follow the if-elif-else logic

   Since battery < 20 and gps_signal is False, the elif condition matches and sets failsafe to 'Land'.

3. Final Answer:

   The drone will choose 'Land' because battery is low and GPS signal is missing. -> Option D

4. Quick Check:

   Low battery + no GPS = Land [OK]

Hint: Check conditions in order: battery then GPS [OK]

Common Mistakes:

• Assuming SmartRTL without GPS signal
• Ignoring battery level in decision
• Mixing up elif and else conditions