Robust Adaptive Controls for Shipboard Landing of Multi-Rotor Unmanned Aerial Vehicles

Alex Bryant and Lauren Ingmire in the lab.

A newly funded project in the School of Aerospace and Mechanical Engineering makes use of close collaboration between researchers in different fields to improve a critical technology for national defense. Dr. Keith Walters and Dr. Andrea L’Afflitto (now a faculty member at Virginia Tech) are combining their respective expertise in aerodynamics and controls to address a difficult challenge for unmanned aerial vehicles (UAVs).

It is well known that UAVs are increasingly being used for both commercial and military applications. The United States Department of Defense (DoD) currently employs multi-rotor helicopters (quadcopters) for remote sensing missions, such as surveillance and search and rescue. In the future, they will support troops by performing tactical tasks, such as picking up and dropping off payloads and surveying cluttered environments. Of particular interest are vehicles that operate autonomously, that is without any direct control by human pilots. These vehicles use onboard computers and mathematical control algorithms to perform necessary aerial maneuvers, travel to desired locations, avoid obstacles, and perform whatever tasks are required of their mission. The development of new and improved control algorithms is, therefore, an active area of research with the potential for substantial impact on next-generation UAVs.

This project focuses on the development of improved control algorithms specifically designed for the landing of UAVs on U.S. Navy ships. Shipboard landing is a complex task for UAVs because 1) the deck is highly unsteady in rough seas; 2) adverse sea conditions are often accompanied by adverse weather and high winds; 3) the superstructure of a moving ship induces a wake in the air, which further perturbs the UAVs landing on its deck; 4) near hard surfaces, the ‘ground effect’ alters the thrust produced by the propellers; and 5) UAVs returning from a mission may be damaged. To land on the deck of a ship, a UAV’s control system regulates the thrust forces of each propeller so that the aircraft approaches the ship with some desired relative velocity and orientation, leading to (hopefully) a gentle touch down in the appropriate location.

The primary objective of this research is to design a robust adaptive control system for multi-rotor UAVs that allows precise landing on the deck of moving ships. The work builds on prior research by former AME faculty member Andrea L’Afflitto and will make use of a model reference adaptive control (MRAC) architecture. Such an approach guarantees robustness of the closed-loop feedback system to both uncertainties in system parameters and unknown state-dependent disturbances that affect the control inputs, such as wind gusts or the swinging of an attached cargo payload.

The control algorithm will also be improved by adopting more realistic functional relationships between propeller rotational speed (RPM) and the generated thrust. Currently, it is assumed that thrust is simply proportional to RPM squared under all conditions. While this is often nearly true when a UAV is hovering in calm air, it does not hold during complex aerial maneuvers, under the action of strong wind disturbances, or when the vehicle is close to a solid surface such as the deck of a ship. Keith Walters and his students will perform computational fluid dynamics (CFD) simulations of quadrotor propellers to more accurately determine the relationship between thrust and RPM under these conditions. The simulations will be used to develop an analytical function that will be included in the control algorithm developed by Dr. L’Afflitto.

The scientific advances made by this project will be disseminated in the technical literature and will provide opportunities for graduate students to participate in national or international conferences. The improvement to UAV performance during shipboard landing will be critical to increasing the value of these vehicles to U.S. Navy missions, and the technology can be translated to other branches of the armed forces to improve design and operation of their next-generation UAV systems. Eventually, the research may be adopted by the commercial sector to improve, for example, the use of UAVs for package delivery or remote sensing in adverse weather conditions.

AME Graduate Students Create Evaluation App

Sam Jett, a mechanical engineering graduate, and Zach Schuermann, a mechanical engineering and computer engineering graduate created an app for students to evaluate professors and courses. In the video below, Sam Jett gives a tutorial for The Student-Teacher Evaluation Visualization app (STEV) and explains why they decided to create it.

Click here to visit the STEV web app.

 

 

Development of Zero-Liquid Discharge Freeze System to Remove Dissolved Salt from Contaminated Water

Management of waste water is a challenging issue in many municipal and industrial sectors. The oil and gas industry produces a massive amount of waste water during production. The production of one barrel of oil results in approximately nine barrels of water that is contaminated with salt, heavy metals, and organic compounds. The development of methods for cost-efficient disposal and re-use of produced water without damage to the environment is a critical need for the oil and gas industry. Also, re-use of the water for agricultural purposes will be helpful because the agricultural sector is a primary consumer of increasingly scarce freshwater (accounting for 63% of U.S. surface water withdrawals, according to the U.S. Geological Survey).

Researchers Discuss Equipment with Assistants Castillo Alejandro and Aly Elhefny

In this project sponsored by the US Department of Energy, Drs. Shabgard, Cai and Parthasarathy are working on the development of a novel, zero-liquid discharge freeze system to remove dissolved salt from contaminated water. Freeze-desalination processes are well suited for these situations because pure ice crystals can be produced even in highly concentrated brine. However, current freeze-desalination technologies have some deficiencies that hinder their widespread use. A new method of eutectic freeze desalination will be used with a cooling approach that maximizes efficiency. Thus, the need for energy-intensive evaporation methods is avoided. The density differences between water, ice, and salty brine are used to separate the components. The system will operate under atmospheric pressure and be capable of treating highly concentrated/contaminated water. If successful, the treated water will be suitable for agricultural use, providing an abundant new water source. The goal is to develop a zero-liquid discharge (ZLD) freeze-desalination system capable of treating water with total dissolved solids (TDS) values up to 250,000 mg/l (milligrams per liter). For comparison, the TDS content of seawater is approximately 35,000 mg/l.

The proposed system offers a sustainable solution for the increasing water demand in industrial and oil and gas sectors by recycling the otherwise wasted water, without putting pressure on increasingly scarce freshwaterresources also in demand by local communities for agricultural and municipal purposes. Also, the environmental concerns related to disposing highly contaminated water are avoided by the use of the proposed ZLD desalination system.

Brooke Owens Fellowship Recipient Encourages Others to Apply

This summer, aerospace engineering student Kaley Hassell participated in the Brooke Owens Fellowship Program. Now, she is encouraging other students to apply.

Hassell decided to apply for the Brooke Owens Fellowship program when she saw that it offered opportunities to work with amazing aerospace companies. She said, “the program is absolutely amazing for undergraduate women in aerospace.” Applications for the fellowship are open, and they close on November 12th.

As a selected fellow, Kaley Hassel worked with the engineering department at Sierra Nevada Corporation on the Dream Chaser spacecraft. She also got the opportunity to work with astronauts and CEOs.

Part of the Brooke Owens Fellowship Summit was the grand challenge presentation held in Washington D.C. “All of us were divided into groups and solved a grand challenge-or humanity’s next biggest feat,” Hassell said. “We got to present and network with a lot of cool people! We were tasked with solving how we could create a collaborative lunar economy. It was a lot of fun.”

 

 

Part of the Fellowship is being assigned a professional mentor. “Mine was Mr. Tory Bruno, CEO of the United Launch Alliance,” Hassell said. “It was really awesome getting to know and learn from him. He even invited me to observe mission control on the recent AEHF5 launch on August 8th!”

 

 

 

Kaley Hassell’s Experiences

 

NASA Administrator Mr. Jim Bridenstine keynote spoke to the Brookies at one of the fellowship dinners. “It was really cool,” Hassell said. “I learned a lot about how policy goes into the aerospace world and even got to ask him a question face to face!”

 

 

 

 

Hassell said the Brookies are definitely a family. She got to make some great connections with women from around the world who are passionate about making a change in the world of aerospace.

 

 

 

 

 

They also got to have a fireside chat with NASA Chief of Staff Janet Karika.

 

 

 

 

 

 

They also got to meet Oklahoma Representative Kendra Horn, and have a fireside chat with her about different space issues as well as learn from her successes and experience.

 

 

 

 

 

Kaley Hassell and her friend Ivy (another Brookie) with the Dream Chaser spacecraft. “I worked in the Systems Engineering department, solving problems and integrating between different systems,” Hassell said.

 

 

 

Pictured is the Brookie Class of 2019 at the Udvar-Hazy Center of the National Air and Space Museum. The Discovery space shuttle is in the background. “It was really cool to see it in person since I was basically working on a mini version of the Shuttle at SNC this summer!” Hassell said.

 

Sooner Off-Road Participates in Midnight Mayhem Competition

On September 21, Sooner Off-Road participated in the Midnight Mayhem competition at the Drop Forge Proving Grounds at the University of Louisville. They competed against 100 other teams in the competition and finished with successful results.

Twelve Sooner Off-Road members attended the competition and all of them had the opportunity to drive. They took two vehicles to the competition, the 2019 competition vehicle, Isabella #12, and the 2018 competition vehicle, Valerie #41.

 

Valerie #41 results:

50th Acceleration 5.32 seconds over 150ft

50th Maneuverability

50th Baja Cross, a suspension testing event

 

Isabella #12 results:

20th Acceleration at 4.77 seconds over 150ft

37th Maneuverability

10th Baja Cross, a suspension testing event

 

In the 4-hour endurance race:

Car #12 peaked in 3rd place before it broke a rear suspension component. They were able to repair the vehicle and get back on track and complete a few more laps before the end of the race. The car’s final place was 24th with a final lap time of 2 minutes and 51 seconds.

Car #41 peaked in 15th place before breaking a front suspension component and coming out of the race for the remainder of the time. The car’s final place was 41st with a best lap time of 3 minutes and 11 seconds.

AME Graduates Featured in The OU Daily for Their New App

Sam Jett (pictured), a mechanical engineering graduate, Zach Schuermann, a mechanical engineering and computer engineering graduate, and Joseph Lovoi, a finance, entrepreneurship and venture management graduate, were featured in the OU Daily for their new app. The app is called STEV (Student-Teacher Evaluation Visualizations), and it’s a new way for students to evaluate their teachers.

Click here to read the full article on the OU Daily Website.

Meet Dr. Kazempoor, an Assistant Professor new to the University of Oklahoma

Dr. Pejman Kazempoor started working at OU as an Assistant Professor in Mechanical Engineering at the beginning of this semester. Dr. Kazempoor’s research interests include driving sustainable performance in the Oil and Gas industry; Process modeling, simulation, and optimization; Natural gas transmission and processing; Energy storage, Fuel cells, and Batteries; Advanced sensor technologies; Data analytics and machine learning.

Dr. Kazempoor believes that OU is a well-respected, and comprehensive global university and has an incredible diversity on campus. He also said that OU stands out as a leader in many sciences, engineering, and medical fields. It has been providing students with a world-class education for over 100 years. He said OU is also the leading arts and cultural center in the state of Oklahoma.

He’s looking forward to developing innovative and multi-disciplinary research projects related to the oil and gas industry. He is broadly interested in sustainable energy for the O&G industry with the main objectives to increase energy efficiency and reduce carbon emissions.

Dr. Kazempoor is from the city of Isfahan located in central Iran. The city is renowned for its outstanding Islamic and Iranian architecture. The city was once one of the largest and most important cities in Central Asia. French poet Renier visited Isfahan for the first time; and called it “Half of the World.”

Dr. Kazempoor enjoys fine arts especially Western and Native-American paintings and bronze sculptures. He was a marathon runner when he was younger, but now he enjoys more hiking, fishing, camping and spending time with his family and friends. Dr. Kazempoor also plays two traditional music instruments –Tar and Setar.

Shell Fall Festival Gives Students an Opportunity to Get Involved in AME Organizations

Shell Fall Festival occurred in the engineering quad on August 23 where new and returning students had the opportunity to learn about several student organizations. Students also enjoyed a dunk tank and other carnival games, free hamburgers, snow cones and t-shirts, and networking opportunities with Shell and Schlumberger. Below are some of the student organizations that participated in the festival!

Sooner Rover Team is an OU Engineering competition team composed of Mechanical, Electrical, Aerospace, and Computer Engineers. The team designs, builds, and documents a rover for the University Rover Challenge competition.

Sooner Rover Team Facebook: https://www.facebook.com/SoonerRover/

Sooner Rover Team Website: http://ou.edu/soonerrover/

Boomer Rocket Team is a group of multidisciplinary engineering students at the University of Oklahoma dedicated to the design, construction, and launch of high powered rockets.

Boomer Rocket Team Facebook: https://www.facebook.com/oubrt/

Boomer Rocket Team Website: brt.ou.edu

Sooner Off-Road is an organization that builds an off-road style vehicle for competition. During their competitions, engineering students are given a mission to design and build a vehicle that will survive the severe punishment of rough terrain and sometimes water.

Sooner Off-Road Facebook: https://www.facebook.com/SoonerOffRoad/

Sooner Off-Road Website:  http://www.ou.edu/offroad/history.html

The Sooner Racing Team is a competition team at the University of Oklahoma. Their goal is to build a Formula SAE race car to participate in events across the United States and around the world. Teams are judged on criteria involving engineering design, material and manufacturing cost, marketing analysis, and final product performance and reliability.

Sooner Racing Team Facebook: https://www.facebook.com/soonerracingteam/

Sooner Racing Team Website: https://sae.ou.edu/

(Combined booth: AIAA and DBF Crimson Skies)

AIAA is the leading professional society for America’s aerospace engineers, offering its members exclusive industry news, business and academic relationships and entrance to national conferences. Through facility tours, technical discussions from industry personnel and AIAA sponsored design competitions the student members gain valuable relationships with and insight into their scientific field, their industrial community, and their engineering family.

AIAA Facebook: https://www.facebook.com/OUAIAA/

DBF Crimson Skies is the University of Oklahoma Design/Build/Fly competition team. They design, fabricate, and test an R/C aircraft for the AIAA hosted Design Build Fly Competition.

DBF Crimson Skies Facebook: https://www.facebook.com/DBFCrimsonSkies/

 

 

 

Dr. Hays and Students Place First in the American Radio Relay League RTTY Rookie Roundup

Aerospace engineering sophomore Jarrod Manning, data science masters student Jorge Garcia, and Dr. Hays placed first in ARRL’s (American Radio Relay League) RTTY rookie roundup competition on August 18th.

The students used the national weather center’s tri-band yagi antenna to make 50 contacts using RTTY (Baudot FSK digital mode). Contacts came from widely varying distances as close as Norman, and as far abroad as Belgium. The competition encourages new amateur radio operators that have earned their license within the previous three years to engage in antenna, propagation, and digital mode studies. ARRL is the primary amateur radio organization in the United States and sponsors many similar competitions throughout the year.

Dr. Song’s Research is Promoted in the Press

Dr. Song’s research on developing a smart AC system has received lots of promotion in the media. On August 19, it was promoted in an article by The Journal Record.

The article speaks about Dr. Song and Dr. Tang, an assistant professor from the School of Electrical and Computer Engineering, and their research with making smart thermostats. Dr. Song and Dr. Tang are working on ways to create a cheaper way to cool homes.

Students can read the article for free on the OU Libraries website. Once on the OU Library home page, students can go to databases and e-references, find The Journal Report and then search “OU researchers developing smart AC system that could lower bills by 40%” in the search bar. A full text will be available in the results.

Non-students can click here to visit The Journal Record website where the article is located.

Following the article in the Journal Record, KFOR also promoted Dr. Song’s research. Click here to view the article.