WindiWing: Atmospheric Data Collection Line Climber

Increasing demand for smaller UAVs (e.g., sometimes with wingspans on the order of six inches and weighing less than one pound) generated a need for much smaller flight and sensing equipment. NASA Langley's new sensing and flight control system for small UAVs includes both an active flight control board and an avionics sensor board. Together, these compare the status of the UAVs position, heading, and orientation with the pre-programmed data to determine and apply the flight control inputs needed to maintain the desired course. To satisfy the small form-factor system requirements, micro-electro-mechanical systems (MEMS) are used to realize the various flight control sensing devices. MEMS-based devices are commercially available single-chip devices that lend themselves to easy integration onto a circuit board. The system uses less energy than current systems, allowing solar panels planted on the vehicle to generate the systems power. While the lightweight technology was designed for smaller UAVs, the sensors could be distributed throughout larger UAVs, depending on the application.

The technology presents an on-board estimation, navigation and control architecture for multi-rotor drones flying in an urban environment. It consists of adaptive algorithms to estimate the vehicle's aerodynamic drag coefficients with respect to still air and urban wind components along the flight trajectory, with guaranteed fast and reliable convergence to the true values. Navigation algorithms generate feasible trajectories between given way-points that take into account the estimated wind. Control algorithms track the generated trajectories as long as the vehicle retains a sufficient number of functioning rotors that are capable of compensating for the estimated wind. The technology provides a method of measuring wind profiles on a drone using existing motion sensors, like the inertial measurement unit (IMU), rate gyroscope, etc., that are observably necessary for any drone to operate. The algorithms are used to estimate wind around the drone. They can be used for stability or trajectory calculations, and are adaptable for use with any UAV regardless of the knowledge of weight and inertia. They further provide real-time calculations without additional sensors. The estimation method is implemented using onboard computing power. It rapidly converges to true values, is computationally inexpensive, and does not require any specific hardware or specific vehicle maneuvers for the convergence. All components of this on-board system are computationally effective and are intended for a real time implementation. The method's software is developed in a Matlab/Simulink environment, and has executable versions, which are suitable for majority of existing onboard controllers. The algorithms were tested in simulations.

The AeroPods design for steadying and damping payloads includes the use of a tail boom and fin combination. It is a novel design and provides a relatively simple alternative to the traditional methods for suspending equipment from kites or blimps. The AeroPod is superior to the traditional Picavet pulley-style suspension system for kite-flight because its light weight, simple to construct, and has no moving parts. Furthermore, the AeroPod design is advantageous to the traditional tethered blimp suspension technique where tether motion is translated directly to the sensor system because the AeroPod is free of direct motions of the tether.

The ActiVator is a rigid-wing system designed to transport sensor or instrument packages along a kite line using the lift generated by apparent wind. Unlike flexible, sail-like structures, the ActiVator maintains its aerodynamic shape throughout its flight, except for a movable elevator control surface that adjusts the angle of attack to regulate aerodynamic lift. The structural design leverages principles from aircraft wing engineering, incorporating a reinforced spar capable of withstanding lift-induced bending and drag forces, an aerodynamically optimized leading edge, and a thin trailing edge to achieve higher lift coefficients than typical sail-based designs. The ActiVator can be constructed using a variety of materials, including wood with plastic covering, molded foam with reinforcements, or other lightweight composites tailored for both aerodynamic performance and structural integrity. The control system mirrors conventional aircraft design, using a movable surface for pitch control, thereby adjusting lift to facilitate climbing or descending. Currently, the ActiVator operates via radio-controlled inputs, but it can also be configured for preprogrammed flight sequences, allowing autonomous operation without active user control. By offering a stable, compact, and lightweight platform, the ActiVator enables high-performance instrument deployment across diverse wind conditions. Potential applications include air-quality monitoring, atmospheric boundary layer research, distributed weather observations, and remote sensing, such as optimizing the field of view and resolution of a fixed-lens camera. The technology is at Technology Readiness Level (TRL) 4 (validated in a laboratory environment) and is available for patent licensing.

Langley has developed various technologies to enable the portable detection system, including: - 3-inch electret condenser microphone - unprecedented sensitivity of -45 dB/Hz - compact nonporous windscreen - suitable for replacing spatially demanding soaker hoses in current use - infrasonic calibrator for field use - piston phone with a test signal of 110 dB at 14Hz. - laboratory calibration apparatus - to very low frequencies - vacuum isolation vessel - sufficiently anechoic to permit measurement of background noise in microphones at frequencies down to a few Hz - mobile source for reference - a Helmholtz resonator that provides pure tone at 19 Hz The NASA system uses a three-element array in the field to locate sources of infrasound and their direction. This information has been correlated with PIREPs available in real time via the Internet, with 10 examples of good correlation.