Winch-Controlled UAV Hover Test System
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Solution Overview
Problem
Existing test systems for Vertical Take-off and Landing (VTOL) aircraft, such as UAVs, face challenges in controlling the ascent and hover of new or modified designs, as they can impose excessive loads and mechanical disturbances on the flight control system, especially during early development, and lack effective restraint mechanisms for indoor testing without GPS.
Innovation Solution
A test system utilizing a winch with a cable to maintain tension and control the UAV's ascent and hover position, combined with a mounting tree assembly that allows five degrees of freedom, enabling controlled altitude and position hold during flight testing, even in indoor environments without GPS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If slack tethers, spring tethers, or short taut tethers are used to restrain the UAV, then uncontrolled movements are mitigated, but excessive loads are imposed at the attach point on the UAV and mechanical disturbances are created beyond the capability of the flight control system
Solution Approach 1:
The patent introduces a winch system as an intermediary device between the tether and the UAV. The winch actively controls the tether tension, allowing it to remain taut without imposing excessive loads on the UAV. The winch acts as a mediator that can dynamically adjust the restraint force, providing stability while protecting the UAV's flight control system from harmful mechanical disturbances.
Solution Approach 2:
The system transitions from static tether configurations (slack, spring, or fixed-tension taut tethers) to a dynamic winch-controlled system. The winch can actively adjust the tether length and tension in real-time, optimizing the balance between restraining uncontrolled movements and minimizing loads on the UAV. This dynamic control allows the system to adapt to different flight phases and conditions.
2Ease of operation
If the UAV is allowed free movement during ascent, then flight control system capability is preserved, but uncontrolled movements create hazards for the UAV and test team
Solution Approach 1:
The winch system serves as a safety intermediary that prevents hazardous uncontrolled movements without directly interfering with the UAV's flight control operations. By controlling the tether tension and length, the winch creates a safety boundary that limits the UAV's movement envelope, preventing it from reaching hazardous positions while allowing the flight control system to operate normally within safe parameters.
Solution Approach 2:
The system applies preliminary restraint through the winch-controlled tether before hazardous uncontrolled movements can occur. The winch anticipates potential safety issues by maintaining appropriate tether tension and readiness to reel in or pay out line, preventing the UAV from entering hazardous flight conditions rather than reacting after problems arise.
3Reliability
If indoor testing environment is used without GPS, then controlled environment for testing is provided, but position hold capability is lost
Solution Approach 1:
The patent replaces the electronic GPS-based position holding system with a mechanical winch-controlled tether system. The winch uses mechanical feedback from tether tension and length to maintain the UAV at the desired hover position. This mechanical substitution works effectively in indoor environments where GPS signals are unavailable, providing reliable position hold through physical restraint rather than electronic navigation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides a safe and controlled environment for UAV testing by minimizing shock loads and mechanical disturbances, allowing precise control over ascent rate and altitude, and enabling evaluation of UAV performance with multiple axis movement, thus enhancing the effectiveness and safety of hover flight testing.
Implementation Method 1
The winch is configured to maintain tension on the cable to provide for a controlled ascent of the UAV to a hover position
Implementation Method 2
The mounting tree assembly comprises a frame member pivotally coupled to the cable to pivot about a first horizontal axis. The mounting tree assembly further comprises a first connecting arm having a first end pivotally coupled to the frame member to pivot about a second horizontal axis
Data Source
AI summary
Test systems and methods for testing hover flight of an Unmanned Aerial Vehicle (UAV). In one embodiment, a test system includes a winch having a cable, and a mounting tree assembly configured to attach to the cable of the winch and to attach to the UAV. The winch is configured to restrain an altitude of the UAV during hover flight while the mounting tree assembly permits five degrees of freedom for the UAV.