UAS 231 Module 2 Outline

Module 2 Overview

  • Focus on flight testing sUAS (small Unmanned Aerial Systems)

  • Emphasis on conducting initial test flight of a new aircraft

  • Importance of understanding flight control algorithms for stability and various flight modes prior to testing

  • Exploration of preparatory measures for the first-flight scenario

  • Discussion of a comprehensive flight test plan and test card

  • Consideration of subsequent testing of basic flight performance factors

  • Initial live flight-testing phase of an aircraft under development6

  • Contents include:

    • First Flight and Performance

    • Conducting First Flight Tests

    • Basic Maneuvers

    • Ground Testing

    • Performance Testing

Lesson 1: First Flight and Performance

  • Learning Objectives

    • Understand the process for sUAS test flights

    • Conduct CONOPs (Concept of Operations) reviews

    • Grasp control algorithms and perform necessary ground testing for safety

Lesson 2: Learning Objectives

  1. Pre-flight testing sequence overview for sUAS:

    • CONOPs review

    • Understanding control algorithms

    • Ground testing for safe flight operations

  2. Explanation of PID control algorithms in UAVs (both fixed-wing and multicopter):

    • Role in maintaining stability through sensor data and motor/control surface adjustments

  3. Assessment of aerodynamic factors affecting UAV performance:

    • Importance of stalling conditions and recovery strategies for fixed-wing and multicopter platforms

Flight Testing Process

  • Begins after design phase completion

  • Document review and test planning are critical aspects of transitioning from design to testing phase

  • Key Documents:

    • CONOPs: Outlines the use case, operations profile, and aircraft flight profile

    • Defines operational requirements

    • Aircraft Design Matrix (ADM): Helps understand performance and feature requirements

    • Lists performance and feature requirements

    • Connects to end-user needs

    • Bill of Materials (BOM): Technical specifications for UAS components and subsystems

Documentation Review Process

  • Days 1-3: Documentation package review

    • FTEs examine the operational requirements, design specifications, and technical details of the aircraft

    • Analyze CONOPs, ADM, and BOM for necessary insights

  • Identification and documentation of questions and potential technical concerns

Pre-Test Validation Method

  • A structured method is utilized to validate the aircraft before live-flight testing:

    • Ground testing to verify basic systems

    • Bench testing to evaluate components

  • Each testing step is designed to build confidence in the functionality of the system

  • The method encourages ground testing, bench testing, and simulation testing prior to live flight

Flight Test Preparation Steps

  • Day 4: Team holds technical briefing with systems engineers and design teams to review findings

    • Review initial flight test briefing and examine the physical aircraft

Test Preparation and FTE Training

  • FTEs and discipline engineers conduct a thorough review of all systems and components prior to flight

  • Emphasis on PID Tuning of the PX4 firmware

  • Understanding manual, semi-autonomous, and autonomous flight behavior is critical

Control Algorithms Overview

  • Firmware: Defined as "software that is permanently programmed into read-only memory"

    • Compares to an operating system managing a computer's tasks

  • Flight Control Algorithms: Activate in various flight modes, managing aircraft stability

  • PID (Proportional Integral Derivative) Controllers: Handles specific flight stability and navigation aspects

    • Components of the flight control algorithm:

    • Kp (Proportional): Adjusts controller’s responsiveness

    • Ki (Integral): Reduces steady state error over time

    • Kd (Derivative): Damps oscillations and enhances stability

PID Control Loop Structure

  • The PID controller employs multiple sensors (gyroscopes, accelerometers)

  • Adjusts motor outputs based on environmental data

  • The PID controller's algorithm processes information to maintain level flight

  • Applications in Multicopters vs. Fixed-Wing Aircraft: Differences in output control mechanisms

Planning the Ground Test

  • Establishing a ground test plan and test card

  • Involvement of FTEs in identifying test structures based on prior documentation reviews

  • Collaboration vital between firmware engineers and flight test engineers for optimal performance

Ground Test Briefing

  • Review specifics for test procedures, personnel, location, and equipment

  • Safety protocols and identification of risk analysis critical before testing

Test Sequence Execution

  • Involves executing the test card sequence engaged by the designated test conductor

  • Validation phase: documents created can be adjusted as the aircraft development process advances

    • Preparation for when the aircraft transitions to production stages

Ground Test Safety Measures

  • A rigorous approach to safety is equally important during ground test as in live flight

    • Install safety nets around active components (propellers)

    • Maintain adequate distancing during testing

Risk/Hazard Register

  • A register used for managing risks associated with flight tests

  • Essential as the aircraft progresses toward commercial operations

First Live Flight Test Preparation

  • Objectives focus on confirming aircraft functionality; not pushing performance limits

  • Tasks for multicopters include:

    • Taking off, briefly hovering, and landing

  • Tasks for fixed-wing may involve takeoff, low altitude gliding, and landing

  • Important to include transitional challenges for VTOL/hybrid sUAVs in flight testing plan

Flight Performance Testing

  • Evaluates ability to navigate while meeting mission requirements

  • Essential considerations include:

    1. Speed capacity

    2. Maximum altitude

    3. Flight endurance and payload capacity

    4. Takeoff and landing requirements

Aerodynamic Fundamentals

  • Critical to understand key aerodynamic principles affecting UAS flight testing

  • Concepts of air mass and its properties:

    • Pressure, temperature, density, velocity

  • Stall Speed: Minimum speed to maintain controlled flight during takeoff and landing

  • Analysis of stall conditions and recovery necessary for validation of flight safety

Summary and References

  • Reviews materials related to PID control algorithms and flight testing processes

  • Essential literature cited include FAA guidelines, academic sources, and developer documentation

What's Next

  • Exploration of further performance factors and initiation of testing UAV autonomous fail safes.