Debugging Drone Flight Controllers: A Technical Deep Dive

Working with drone flight management systems presents unique challenges, especially when dealing with flight log timestamps and mission planning data.

Recently, while developing our drone fleet management platform, I encountered an interesting bug in our flight scheduling validation system.

When scheduling drone missions, there are two critical timestamps that need validation:

• The mission start time (when the drone should begin its flight)
• The mission completion deadline (when the drone must return to base)

The validation logic seemed straightforward:

• Ensure the start time isn’t in the past
• Ensure the deadline isn’t in the past
• Verify the start time comes before the deadline

Here’s the initial implementation:

startTime, _ := time.Parse("2006-01-02T15:04:05", req.MissionStart)
deadlineTime, _ := time.Parse("2006-01-02T15:04:05", req.MissionDeadline)

if startTime.Before(time.Now()) || deadlineTime.Before(time.Now()) {
    c.JSON(http.StatusBadRequest, gin.H{"message": "Mission times cannot be in the past"})
    return
}   

if startTime.After(deadlineTime) {
    c.JSON(http.StatusBadRequest, gin.H{"message": "Mission start cannot be after deadline"})
    return
}

The Problem

The validation was incorrectly rejecting missions scheduled for “today” because startTime.Before(time.Now()) compares exact timestamps, not just dates. A mission scheduled for today at 2 PM would be rejected if the current time was 3 PM, even though the mission was validly scheduled for the future.

This was particularly problematic for our agricultural monitoring drones that often have same-day mission schedules.

The Solution

For date-only comparisons in drone mission planning, we need to truncate timestamps to the day level:

startTime, _ := time.Parse("2006-01-02T15:04:05", req.MissionStart)
deadlineTime, _ := time.Parse("2006-01-02T15:04:05", req.MissionDeadline)

currentDate := time.Now().Truncate(24 * time.Hour)
missionDate := startTime.Truncate(24 * time.Hour)

if missionDate.Before(currentDate) {
    c.JSON(http.StatusBadRequest, gin.H{"message": "Cannot schedule missions for past dates"})
    return
}

This fix ensures our drone operators can schedule missions for today without timestamp precision issues affecting the validation logic.

Key Takeaway

When working with drone flight systems, always consider whether you’re validating exact timestamps or date ranges. The distinction is crucial for mission-critical aviation software where scheduling precision matters.