Collision avoidance in swarms in Drone Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of simple collision avoidance logic

Consider a swarm of drones where each drone checks the distance to its neighbors and adjusts its velocity to avoid collisions. What is the output of the following code snippet simulating one drone's velocity adjustment?

Drone Programming

neighbors = [(2, 3), (5, 5), (1, 1)]
current_position = (3, 3)
velocity = [1, 1]

for nx, ny in neighbors:
    dx = current_position[0] - nx
    dy = current_position[1] - ny
    dist_sq = dx*dx + dy*dy
    if dist_sq < 5:
        velocity[0] += dx
        velocity[1] += dy

print(tuple(velocity))

A (3, 3)

B (1, 1)

C (0, 0)

D (2, 1)

💡 Hint

Check which neighbors are within the distance threshold and how velocity changes.

The drone checks neighbors within distance squared less than 5. Only neighbor at (2,3) is close enough (dist_sq=(3-2)^2 + (3-3)^2 = 1 < 5). Neighbors at (5,5) and (1,1) have dist_sq=20 >=5. Velocity is adjusted by adding dx=1, dy=0 to [1,1], resulting in (2,1).

🧠 Conceptual

intermediate

Key principle behind collision avoidance in swarms

What is the main principle that allows drones in a swarm to avoid collisions while moving together?

A Each drone moves randomly without considering others

B Each drone maintains a minimum distance from neighbors by adjusting velocity

C Drones stop moving when they detect others nearby

D Drones follow a fixed path ignoring neighbors

💡 Hint

Think about how drones keep safe space around themselves.

Collision avoidance relies on drones sensing neighbors and adjusting their velocity to keep a safe distance, preventing crashes while moving cohesively.

🔧 Debug

advanced

Identify the error causing collision in swarm simulation

The following code is intended to prevent collisions by adjusting drone velocities. However, collisions still occur. What is the bug?

Drone Programming

def avoid_collision(position, neighbors):
    velocity = [0, 0]
    for nx, ny in neighbors:
        dx = position[0] - nx
        dy = position[1] - ny
        dist_sq = dx*dx + dy*dy
        if dist_sq < 4:
            velocity[0] -= dx
            velocity[1] -= dy
    return velocity

# Drone at (3,3) with neighbors
print(avoid_collision((3,3), [(2,3), (4,4), (3,5)]))

A The velocity update should add dx and dy instead of subtracting

B The distance threshold is too large causing false positives

C The distance calculation uses wrong signs causing incorrect velocity adjustment

D The function does not normalize the velocity vector

💡 Hint

Check how dx and dy are calculated and used to update velocity.

The code calculates dx and dy as position minus neighbor, but then subtracts dx and dy from velocity, which reverses the intended avoidance direction. This causes drones to move toward neighbors instead of away, causing collisions.

📝 Syntax

advanced

Syntax error in collision avoidance velocity update

Which option contains the correct syntax for updating a drone's velocity to avoid neighbors within a threshold?

Drone Programming

neighbors = [(1,2), (3,4)]
position = (2,2)
velocity = [0,0]
for nx, ny in neighbors:
    dx = position[0] - nx
    dy = position[1] - ny
    dist_sq = dx*dx + dy*dy
    if dist_sq < 5
        velocity[0] += dx
        velocity[1] += dy
print(velocity)

A Add colon after if condition: if dist_sq < 5:

B Replace parentheses with brackets in if condition: if [dist_sq < 5]:

C Change if to while: while dist_sq < 5:

D Remove indentation before velocity updates

💡 Hint

Check the syntax of the if statement.

Python requires a colon at the end of an if statement. Missing colon causes SyntaxError. Other options cause syntax or logic errors.

🚀 Application

expert

Calculate number of drones avoiding collision in a swarm

Given a swarm of 5 drones at positions [(0,0), (1,1), (3,3), (5,5), (1,0)], each drone avoids neighbors closer than distance 2 by adjusting velocity. How many drones will adjust their velocity in one update cycle?

A 3

B 4

C 2

D 5

💡 Hint

Check pairs of drones closer than distance 2 and count how many have at least one neighbor that close.

Drones at (0,0), (1,1), and (1,0) have neighbors within distance 2, so they adjust velocity. Drones at (3,3) and (5,5) are too far from others to adjust. So 3 drones adjust velocity.