Millions of people walk and handle household tasks without giving any thought to balance or the use of their legs in these activities. Life is entirely different for those with impaired balance resulting from neurotrauma, such as stroke or traumatic brain injury or those adjusting to life with a prosthetic lower limb. Robotics research at Notre Dame is being applied to improve the quality of life for potentially tens of thousands of people whose ability to walk or maintain balance has been diminished.
James Schmiedeler, associate professor of aerospace and mechanical engineering, and the Locomotion and Biomechanics Lab at ND study a variety of topics, many related to the theme of understanding human balance and gait. Researchers study human balance and locomotion then apply what is learned to the study of robotics; in turn, the knowledge that is gained through the study of robotics is applied to the understanding of human walking and balance.
Balance is a foundational skill that plays a significant role in daily life. Regaining balance can reduce the risk of falling and the complications resulting from fall injuries. Restoring balance affects quality of life, enabling the individual to safely resume activities like preparing meals or getting in and out of a car easily. The group has developed a tool called the WeHab system that can be used in hospitals and clinics to assist in balance rehabilitation. The device uses relatively inexpensive gaming components and a tablet or laptop, coupled with visual feedback to help patients regain balance capabilities. Local hospitals are using the WeHab system and in future the software is expected to be available to anyone open source, extending the range of potential users.
In recent years, the number of individuals who have experienced the loss of a lower limb has increased, largely as a result of disease or military service. Not only is balance an issue for this group of individuals, but a correctly chosen and properly aligned prosthesis is critical for comfort and support. An optimal fit depends upon the skill of the individual prosthetist; by providing a tool to improve the ability of any prosthetist to correctly select components and align the prosthesis, a much greater number of individuals can benefit from a well-chosen and well-fitted device and an improved quality of life. The robotics team at ND has intensively studied human walking, then taken the control strategies used in creating a biped robot and successfully translated them into a highly accurate mathematical model capable of predicting human gait.
The predictive model is inspired by studies of the motion of the foot and ankle, and it predicts the individual’s step length and power when supplied with the person’s height, weight, and walking speed. For the user of a prosthesis, this means that a doctor or prosthetist can adjust the device to deliberately attain an expected gait for the user — adjustments and alignments can be more accurate and more easily modified, ultimately providing a more comfortable fit. Gait adjustments are expected: as children grow or adults age, the gait will need to change; the optimal pace may be increased to encourage strength building or reduced to accommodate other health issues that occur. Proper comfort and strength means the user is more likely to use the device and walk further and more often, a simple increase in exercise that can enhance cardiovascular health.
The wide array of projects underway in the Locomotion and Biomechanics Lab illustrates a balance between theory and experimentation; work in the robotics lab is neither purely theoretical nor purely experimental. The theories are developed in order to enable exciting experiments, and the experiments are grounded in solid theory; in turn people can benefit significantly from application of the tangible project outcomes.
Whether or not we fully realize it, our lives are greatly influenced by advancements that take place on the scale of micrometers and nanometers—at the level of ions and neutral particles in microplasmas, specifically low-temperature plasmas. For example, the energy-efficient compact fluorescent (CFL) light bulb is a plasma device used in most households, and plasma-based materials processing has been essential to computer chips in the consumer electronics industry. Plasma research and engineering has the potential to address challenging energy problems, offer new water purification methods, create new nanomaterials for specialized applications, and convert captured waste heat directly into electricity; greatly improving quality of life. These topics are just a sample of the range of diverse research actively under way in the Small Scale Transport (SST) Research Lab at Notre Dame, directed by David Go, assistant professor of aerospace and mechanical engineering.
Go and his group study the transport of energy, fluids, and charge at scales from millimeters all the way down to nanometers with his research ranging from understanding basic phenomena to technology development for a wide variety of applications. While projects include microfluidics and sprays for chemical analysis, as well as energy and heat transfer topics, plasma science and engineering is central to the various paths the research follows. Go views his plasma research as “attempting to understand the generation and fate of electrons and ions in novel plasma systems in order to optimize these systems for targeted applications.”
Researchers in the SST Lab push the boundaries of what is currently known about low-temperature plasmas, seeking new insights and a deeper understanding of what is taking place at the physiochemical level. They aim to understand how electrons are produced and what happens to them. This knowledge will provide clues regarding how to control the electron processes for specific applications.
Microplasmas, a specific class of low-temperature plasmas operated at micrometer scales, are unique because they can operate at atmospheric pressure. Thus, microplasmas are able to interact with liquids, plastics, tissues, and other surfaces that cannot be put into a vacuum. Studying the fundamental science, particularly how microplasma electrons interface with liquids, adds to the body of knowledge and creates opportunities for new applications. Some of these emerging applications include purifying water, treating open wounds, sterilizing surfaces, and biosensing. Currently, Go and his team are focusing on how electrons from the microplasma can be used to drive electrochemical reactions in liquids in work that involves synthesizing and patterning nanoparticles for use in biological sensing and other applications.
The high current that can be produced by controlling the discharge of electrons from a surface into a microplasma is also being used by researchers to develop new electron-driven devices. One of the specific applications being explored involves using microplasmas to enhance the conversion of heat directly into electricity by way of thermionic energy conversion, a process that addresses energy issues on the ground and in space technology. Heat from the sun, nuclear energy, or waste heat from power plants is used to heat materials that “emit” electrons into a microplasma where it increases conversion efficiency. In another application Go’s group is studying, electrons injected into a plasma can enhance catalytic reactions; in particular, microplasmas are being used in converting natural gas (methane) into hydrogen for use in fuel cells and other energy applications.
Many more innovative topics are explored in the SST research lab as well. According to Go, he and his group “ask interesting questions then go and find or develop the tools to answer those questions, which ultimately will lead to new discoveries and new technologies.”
A recent donation to the University of Notre Dame’s Airborne Aero-Optics Laboratory (AAOL) is about to give laser-directed energy and free-space communication a transonic boost: researching at the speed of sound.
A Falcon 10 aircraft, donated by Philadelphia-area businessman Matthew McDevitt, will enable the University to continue its groundbreaking aerospace research and development that will advance technology for weapons systems and communications. The results could pave the way to high-field-of-regard, point-to-point airborne laser propagation for directed energy and communications as fast and robust as fiber-optic Internet connectivity. In other words, high-flying research at Notre Dame is not only helping to refine the U.S.’s weapons systems, but it could lead to a television show streaming just as fast on a commercial flight as it does in a living room.
Since the mid-1990s, aerospace engineering research has found its home at Notre Dame through the Institute for Flow Physics and Control’s Aero-Optics Group, directed by Eric Jumper, professor of aerospace and mechanical engineering. With support from the High Energy Laser-Joint Technology Office (HEL-JTO), Notre Dame faculty and researchers have been working with the Air Force Institute of Technology’s Center for Directed Energy (CDE) and MZA Associates Corp. to conduct studies focused on directed energy, specifically laser interactions with turbulence, or aero-optics.
The AAOL — one of the research programs within the Aero-Optics Group — has taken the lasers to the skies, studying the effects of turbulence on a laser directed from one aircraft to a turret installed on a tandem-flying aircraft about 50 meters away flying at transonic speeds.
“Planes have difficulty using lasers because even a tiny amount of turbulence can effectively turn a laser into a really expensive flashlight,” said Jumper. “Supported by funding from the HEL-JTO, we have developed aero-optic wave front beam-control architectures that overcome aircraft vibration and mitigate the effects of turbulence, which could enable such technologies as free-space communication.”
Beyond the obvious improvements to directed energy applications, the research will also lead to more than just in-flight streaming entertainment for bored airplane passengers. If brought to market, point-to-point airborne laser communications could improve transmissions between aircraft systems and other aircraft, satellites or ground stations and create a foundation for video feeds from unmanned flights over battlefields or disaster areas.
AAOL’s research has been conducted in wind tunnel labs on Notre Dame’s campus to simulate flight conditions, and in 2010 the team successfully completed laser-based testing in-flight on two leased Cessna Citations outfitted as sophisticated airborne aero-optics laboratories. The following series of in-flight tests helped ensure the performance of the aero-optic system developed at the University, but testing was required at higher Mach speeds — and the need for a Falcon 10 arose.
“To really continue our research, we needed to realize higher levels than we could achieve in wind tunnel studies and with previous aircraft,” said Jumper. “With a Falcon 10, we can conduct research at Mach numbers above Mach 0.8, providing an authentic environment that produces more accurate results than a simulated set-up.”
Growing up in a Catholic family and attending 12 years of Catholic school, McDevitt, who previously owned the aircraft for private use with his family, learned about the University’s need for a fast-flying jet and generously donated the aircraft. Since the donation, the Falcon 10 has been transformed into a high-speed, high-altitude flying lab, outfitted with the laser-tracking turret and additional aero-optic technology. And, with an engine protection program donated from longtime Notre Dame research partner and South Bend neighbor Honeywell Aerospace, the Falcon 10’s engines will be maintained at no cost to the University for six years.
“This dedicated plane allows the AAOL team to set up, troubleshoot and conduct complex experiments, which was not available when we leased aircraft one week at a time,” said Jumper. “This is about a $1.25 million gift, and without it we would certainly have a less robust program.”
During a recent visit to Notre Dame, McDevitt got a first-hand look at the aircraft since it was converted to a state-of-the-art component of AAOL’s aerospace research.
By Amanda Kinnucan, Notre Dame Communications