CASS maintains three unique laboratories both inside the NWC and in the field that enable the design, fabrication, and maintenace of a host of autonomous systems. Additionally, these facilities allow for the collection of meaningful datasets on a variety of environmental topics as well as provide points for calibrating and validating the platforms themselves. Click the headers below to learn more about our laboratory facilities and the resources housed within them.
The CASS Sensors lab is located on the 5th floor of the National Weather Center and is a dedicated space for electronics development and systems integration. In addition to hand and small power tools, electronics development materials, oscilloscopes, and soldering stations, it has a 3D printing station which is outfitted with 2 LulzBot TAZ 6 desktop printers. Each chamber also has a thermistor to monitor the temperature of the print as well as a camera and Raspberry Pi set up so that jobs can be started, stopped and monitored remotely. The Sensors lab also has a large inventory of sensors, such as RGB and multispectral cameras, laser altimeters, multibeam acoustic doppler profiler, mini ADS-B transmitters, gas analyzers, particle counters, meteorological sensors, and GPS receivers that can be integrated into platforms depending on the mission. It also has ample space for individuals to perform vehicle maintenance and upkeep between deployments, plan missions, and develop new systems.
For larger builds, we utilize space as needed in the Radar Innovation Laboratory’s High Bay, which was CASS’s primary home from 2016-2018, or in the NWC Vehicle Bay.
The CASS Laboratory at North Campus (CASSL) is a 100,823-square foot wareyard and parking lot located off Industrial Blvd that is dedicated to the flight testing of unmanned systems. In the wareyard, the CASS team is in the process of erecting a 200’ x 240’ x 35’ net-enclosed flight field. This will provide the opportunity to test fly and refine systems without needing to obtain FAA permission to operate in the National Airspace System (NAS). It will also allow us a space to operate unattended so that we can explore the components needed for operational deployment of 3D mesonet stations out in the field as well as characterize the limitations of the system.
In addition to the netted facility, CASS has an outbuilding at the wareyard that provides shelter from the elements during operations at the facility, storage for extra supplies for the net, and serves as the long term hangar for some of our vehicles that are not currently being deployed on missions or have been retired from service.
CASS maintains a field laboratory on the north end of Kessler Atmospheric and Ecological Field Station, near the operations hub. This consists of a 30’ dual compartment cargo trailer; with the larger half serving as a small UAS repair space and field deployment staging zone while the smaller climate controlled office area acts as the operations office and houses communications and computer equipment for the detect and avoid radar, UAS ground stations, and the Weather Automation Testing and Environmental Research (WATER) Tower.
Recently, CASS partnered with WDSS International to install a Radiometrics MP300A microwave radiometer at the field lab. The microwave radiometer is a passive multi-channel sensor, which provides height profiles of the atmospheric temperature and humidity. Both WDSS International and Radiometrics Inc. are interested in conducting comparisons and validations between the measurements from the radiometer and our fleet of UAS. The use of ground-based remote sensors, such as the radiometer, can complement UAS operations when sampling the lower atmosphere in areas where flights are not practical, for example in urban areas or near airports.
In addition to the field laboratory, CASS, in collaboration with the Boundary Layer Integrated Sensing and Simulation (BLISS) collective in the OU School of Meteorology, has erected a 10 m tower about 45 m to the east of the trailer. The WATER Tower features four instrument booms at 2, 3, 5, and 10 m levels, a rugged desktop computer and communication system that allows for remote access to collected data from any internet connection, custom tilting base and guy wire system that allows for easier installation, and solar panel system that can allow for at least 1.5 days of operation without sunlight. Presently, it is equipped with three CSAT3 sonic anemometers (3, 5, and 10 m), a Lufft WS-500 Weather station (10 m), and a Li-840A gas analyzer measuring carbon dioxide at all four levels.
Just to the south of the trailer is a detect and avoid radar, which is being developed under the leadership of Dr. Yeary to assist with deconfliction of the airspace during attended or unattended operations. The radar's primary specifications are: 5.6 GHz operating frequency, 10 MHz to 20 MHz of operating bandwidth, 6.3 kW peak transmit power, maximum duty cycle = 10%, range = 5 km, probability of detection within range = 99.9%. As such, the radar scans continuously, aiming for a high probability of detecting targets entering within a 5 km range. Power supplies, a processing unit, an antenna, and radio frequency components for both transmitting and receiving signals have been designed for the radar. Software is being developed to visualize the radar output, send alerts to the ground station to warn of incoming manned aircraft, and provide evasive action commands as needed.
The Center’s fleet is comprised of both of fixed and rotary wing platforms that are either custom built, assembled from off the shelf kits, or commercially available. Click the headers below to learn more about our platforms, current and retired.
The CopterSonde was the first weather uncrewed aerial vehicle (WxUAV) fully designed and manufactured by CASS for the express purpose of taking atmospheric measurements in the boundary layer in a profiling mode of operations. The name CopterSonde is meant to be reminiscent of a radiosonde, as this platform is designed to be able to be deployed as a reusable weather balloon, taking measurements of atmospheric thermodynamics and kinematics in a repeatable way in the lowest 1-2 kilometers of the atmosphere.
The platform was constructed out of carbon fiber tube and plate as well as a custom-welded-aluminum lid to protect the electronics from water and hail. It was equipped with four temperature and four humidity sensors, which were placed in vertical solar shields under the propellers to ensure consistent aspiration. Pressure was also measured using a barometer imbedded in the flight controller, and wind speed and direction were derived using the roll, pitch, and yaw of the inertial measurement unit.
A trio of units were fabricated and deployed in support of the Environmental Profiling and Initiation of Convection (EPIC) and Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics (CLOUD-MAP) campaigns in 2017. It was retired from operations in the middle of 2018 and lessons learned from this platform has paved the way for several other iterations of systems in the CopterSonde series.
- Frame size: 650 mm
- All-up weight: 7.0 kg
- Maximum wind speed tolerance: 20 m/s
- Maximum altitude above ground: 760 m
- Flight Endurance: 20 min
- Operating temperature: -20 C to 40 C
The CopterSonde 2 is a unique and highly flexible platform for in situ atmospheric boundary layer measurements with high spatial and temporal resolution, suitable for meteorological applications and research. The structure of the quadcopter is made of G10 fiberglass plates, carbon fiber tubes, aluminum tube-clamps and stand-offs. The battery has its own compartment inside the CopterSonde to avoid exposing it to extreme environments and protect it from external hazards. The shell of the CopterSonde was designed using a CAD software and 3D printed with highly durable PLA material. Flow simulations were also conducted using the CAD model to find the optimal sensor location and improve the aerodynamic characteristics.
The arrangement of the electronic components within the CopterSonde was carefully planned to increase its modularity and facilitate performing routine maintenance and calibration. In particular, the payload was strategically placed at the frontmost section of the CopterSonde to optimize air sampling. Such payload consists of three iMet temperature beads and three HYT271 capacitive humidity sensors which are housed inside a sun shield scoop and aspirated by a fan. The CopterSonde’s autopilot runs a custom version of the open-source ArduPilot code developed in-house. The modified code includes the seamless integration of custom functions and protocols for the acquisition, storage, and distribution of atmospheric data along with the flight control data.
The first version of this platform was manfufactured for and deployed as a part of (ISOBAR). The mature version of this platform, lovingly dubbed the CopterSonde 2.5, is now the workhorse of the CASS fleet and has been featured in the Lower Atmospheric Process Studies at Elevation - a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE), Flux Capacitor, and the upcoming Oklahoma UAS Targeted Flights for Low-level Observations of Weather (OUTFLOW) campaigns.
- Frame size: 500 mm
- All-up weight: 2.3 kg
- Maximum wind speed tolerance: 22 m/s
- Maximum ascent rate: 12.2 m/s
- Maximum descent rate: 6.5 m/s
- Maximum altitude above ground: 1800 m
- Flight Endurance: 18 min
- Operating temperature: -20C to 40 C
The CopterSonde 3 is a custom-built Y6 style hexcopter that was developed for the express purpose of providing a testbed for sensors prior to their final integration into an operational system like the CopterSonde 2 or the Tuffwing. The Y6 coaxial design has the minimal layout of a tri copter facilitating sensor isolation along with the redundancy benefits of a hexacopter, making it an ideal choice for this open-concept testbed. To date it has been used to test a variety of onboard components such as companion computing units, lidar range finders, carbon dioxide payloads, platform agnostic thermodynamic scoops, and more.
Like others in the CopterSonde series, the CopterSonde 3 body is constructed out of carbon fiber plate and tubing and features the same core electronic package as the CopterSonde 2 to facilitate easy integration of new senor payloads into the software architecture.
The Omni-Directional Watercraft was designed and built to support bathymetric and river/stream discharge measurements in aqueous environments using a Sontek RiverSurveyor S5. The vehicle is radially symmetric, which facilitates omni-directional travel while maintaining heading. It is fabricated out of marine grade aluminum and utilizes an innertube for flotation and adjustable buoyancy.
Two watertight compartments are located on top of the platform to hold the batteries, control systems, and a Latte Panda computer that compliments sensing payloads and facilitates the automation of data collection. The Pixhawk uses the Rover Omni-X firmware to control the four inclined thrusters in such a way that the platform uses its heading to ideally situate a sensing payload, regardless of the direction of travel.
- Maximum Speed: 1 m/s
- Sampling Speed: 0.5 m/s
- Diameter: 1.3 m
- Maximum Weight: 35 kg
- Endurance: 6 hr
The following video compilation highlights the Omni-Directional Watercraft’s capabilities, including its zero-degree turning radius and redundant flotation systems.
The CASS team also has a DJI Phantom 4 Pro v2 in its fleet that tags along for many fof our missions. In addition to using it as a videography platform to document our field campaigns, it is also utilized as a tool to inspect the CASS Field Laboratory periodically. It also can be used to conduct photogrammetry missions with its own 20 MP RGB camera or through interfacing with a five-channel multispectral camera.
- Frame size: 350 mm
- All-up weight: 1.4 kg
- Maximum wind speed tolerance: 10 m/s
- Maximum ascent rate: 6 m/s
- Maximum descent rate: 4 m/s
- Flight Endurance: 25 min
- Operating temperature: 0 C to 40 C
In addition to the variety of rotary wing vehicles, CASS also uses a rugged flying wing platform for a variety of other missions such as transect missions to study the evolution of thermodynamic variables, examining the vertical structure of various atmospheric chemistry variables, and conducting photogrammetry surveys.
The current workhorse platform, the Tuffwing, is a belly lander is made of expanded polypropylene, which gives this platform significantly higher impact resistance compared to traditional foam fixed wings. The team assembles it from a kit in house and outfits it with our preferred set of electronic components.
CASS currently has two dedicated versions of this craft and their payloads are outlined below.
The atmospheric chemistry Tuffwing carries the same thermodynamics payload as the CS 2, composed of three bead thermistors, three capacitive relative humidity sensors, and the autopilot's pressure sensor. Additionally, the atmospheric chemistry fixed-wing carries two fast response non-dispersive infrared (NDIR) Carbon Dioxide sensors (SenseAir K30-FR). The combination of the thermodynamics and carbon dioxide payloads allows CASS's scientists to study how the structure of the atmospheric boundary layer affects the spatial distribution of carbon dioxide concentrations.
The photogrammetry Tuffwing can perform photogrammetry surveys with either RBG or Multispectral cameras utilizing real-time or post-processed kinematic GPS. The resulting datasets can be used for Structure from Motion, creating digital elevation maps, estimating depths of shallow water bodies, and much more.
- Wingspan: 1.22 m
- All-up Weight: 2.0 kg
- Maximum wind speed tolerance: 20 m/s
- Minimum air speed: 17 m/s
- Maximum flight ceiling (AGL): 1,500 m (5,000 ft)
- Typical Flight Endurance: 25-30 min
- Operating Temperature: -20 – 40 °C