Research Topics

Draper’s vision-aided navigation (VAN) capabilities support anytime, anywhere, any threat navigation by leveraging visible-spectrum and/or LWIR cameras to produce position and velocity estimates whenever the Earth or moon’s surface is in view of a ground vehicle, aircraft, or spacecraft. Our VAN capabilities include relative positioning systems, like Vision-aided Inertial Odometry (VIO), which enables GPS-denied flight through obstacles at low altitudes, and absolute positioning systems like Terrain Relative Navigation (TRN), which enables precision lunar landing by recognizing landmarks on the surface of the moon. Advancements in this area are primarily related to improving robustness in challenging conditions, expanding availability to new scenarios, and enabling realistic performance simulations. Draper Scholar projects could potentially address the following challenges:

• Reducing sensitivity to changing lighting conditions and improving robustness to seasonal variations.
• Improving performance when there is very little terrain variability or features, such as due to environmental challenges or the use of long-wave IR imagery.
• Expanding TRN to navigate at very low altitudes for user-wearable devices and surface vehicles on Earth or planetary bodies such as the Moon and Mars.
• Improving performance when multiple vehicles are operating together as a team.

Though there are many navigation techniques that can and do complement GPS in current operations, even the best of these techniques has limitations. Terrain registration, as a simple example, only works over feature-rich land, not over open water. Other approaches, such as signals of opportunity, rely on the presence of RF signals. Thus far, no “silver bullet” complementary PNT approaches exist. Instead, navigation systems synthesize multiple navigation techniques together to generate a coherent navigation update. For example, the navigation system may combine inputs from sensors already on the platform – inertial, radar and imaging systems – and new sensors installed solely for complementary PNT. Open research questions include:

• How can information from various APNT sources be combined optimally in scenarios that do not conform to textbook linear Gaussian assumptions?
• How can the information added by various sensors be quantified?
• What are the most computationally efficient and modular algorithms for combining information from multiple APNT sources?
• How can knowledge and inference about navigation challenges inform higher-level mission planning?

The ability to measure celestial objects across different spectral regions, using advanced imaging processing techniques, utilizing ultrasensitive detection techniques, and/or leveraging adaptive optics can enable significant increases in observational capacity and ultimately better positional accuracies. We seek to foster different modalities that can improve imaging of celestial objects (including those in Earth orbit). Some questions that we are interested in are:

• How can non-centrosymmetric optics be used to improve compact telescope designs (particularly by removing obscurants)?
• Can size-, weight-, and power-constrained focal plane arrays be built that examine multiple spectral regions? Can multiple focal plane arrays be used in highly limited form factors to increase spectral ranges?
• Are there novel methods for sensing and correcting incoming light through highly degrading environments or rapidly changing conditions?
• How can field of view be maximized while limiting or eliminating aberrations (spherical, chromatic, etc.)? Are there techniques, methods, or processes for achieving very high fields of view?
• Are there novel techniques for pointing optics in a very small form factor?
• Advanced, lightweight telescope concepts and designs
• Very high bandwidth camera and image processing throughput for examining wide fields of view and/or multiple, independent fields of view

Atomic and molecular systems provide a set of highly precise and accurate energy level transitions that can be used as stable frequency references for precision timing. Some questions we are seeking insight into are:

• How can we reduce the size of chip-scale atomic clocks? How can we improve their performance to remain stable for longer durations?
• Can we integrate clocks with atomic references at much higher frequencies than are used today in commercial devices (e.g., from gigahertz to terahertz) to improve timing accuracy and stability? Can we miniaturize and ruggedize these “optical clocks” so they can be ubiquitously adopted in fielded applications?
• How can we rapidly and accurately synchronize multiple independent clocks that are spatially separated?
• Beyond the commonly used systems, what other atomic or molecular gases have the potential to achieve very high timing precision? Can the ancillary support structures also be miniaturized and packaged?
• How can integrated photonics help produce smaller, cheaper, and more robust atomic clocks?

Contributions to the local magnetic field produced by either manmade or natural sources can support several APNT applications when measured by a portable magnetometer. For example, onboard measurements of the topography of earth’s magnetic field on a moving platform serve as a globally-available, unjammable reference to bound the error growth in inertial navigation systems – a key enabler for navigation in GPS-contested environments. In addition, oscillating magnetic fields from man-made sources can be used for improved situational awareness such as direction finding, communications, and subsurface imaging. Commercial magnetometers may already have the capability to perform these functions, but development of a novel magnetometer (either classical or quantum) with an improved sensor characteristic may directly enhance application performance. A Draper Scholar may contribute to:

• Fusion of magnetic and inertial sensor systems for magnetic-aided inertial navigation (MagNav)
• Analysis of systematic effects in magnetic maps for improved navigation
• Geophysical modeling of electromagnetic propagation for improved situational awareness
• Novel atomic magnetometer development emphasizing omni-directional measurements on size, weight, and power constrained platforms

Delivering the complete APNT solution requires comprehensive sensing across the operational domain. Draper develops technologies that detect, process, and produce sound and vibration signals to maintain PNT assurance. These deployable solutions provide the situational awareness and resilience required for systems to effectively navigate under a variety of conditions. Some research questions we are seeking answers to are:

• How can acoustic signals be fused with signals from other sensing modalities to enhance autonomous system navigation?
• How can we optimally collect and process acoustic signals from sensor arrays to localize and track events of interest (e.g., approaching drone)?
• How can we design algorithms that effectively detect when an acoustic event of interest has occurred and extract key information in the presence of noise?
• How can we design low-bandwidth acoustic communication systems to support navigation of autonomous systems?
• What novel and/or non-traditional acoustic sensors could be developed to extract key information from an environment and aid in navigation?

Draper's long history in gravimetry dates as far back as the Lunar Traverse Gravimeter, which operated on the Moon in 1972, and now encompasses precision gravity survey analysis, quantum gravimeter development, and gravity-aided navigation. We continue to develop fieldable yet highly precise quantum and MEMS hardware, as well as develop the system-level algorithms required to fully exploit the sensors for each application.  Current and future work aims to apply novel technologies to reduce sensor size, weight, and power, while also boosting system performance through sensor fusion. Draper scholars could assist in the following areas:

• Development and validation of novel algorithms to use Earth’s gravity anomalies for assured navigation in GPS-denied environments.
• Development and validation of novel algorithms to fuse Earth’s gravity anomalies with magnetic anomalies for assured navigation in GPS-denied environments.
• Development and validation of new methods to invert or otherwise process gravity measurements in order to infer an unknown mass distribution.
• Design, fabrication, and testing of ultra-stable MEMS accelerometers.