Showing papers by "Larry Matthies published in 2020"

Mars Extant Life: What's Next? Conference Report.

Abstract: On November 5–8, 2019, the “Mars Extant Life: What's Next?” conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines relate...

Extended Navigation Capabilities for a Future Mars Science Helicopter Concept

Abstract: This paper introduces an autonomous navigation system suitable for supporting a future Mars Science Helicopter concept. This mission concept requires low-drift localization to reach science targets far apart from each other on the surface of Mars. Our modular state estimator achieves this through range, solar and Visual-Inertial Odometry (VIO). We propose a novel range update model to constrain visual-inertial scale drift in the absence of motion excitation using a single-point static laser range finder, that is designed to work over unknown terrain topography. We also develop a sun sensor measurement model to constrain VIO yaw drift. Solar VIO performance is evaluated in a simulation environment in a Monte Carlo analysis. Range-VIO is demonstrated in flight in real time on 1 core of a Qualcomm Snapdragon 820 processor, which is the successor of the NASA's Mars Helicopter flight processor.

Online Photometric Calibration of Automatic Gain Thermal Infrared Cameras

Abstract: Thermal infrared cameras are increasingly being used in various applications such as robot vision, industrial inspection and medical imaging, thanks to their improved resolution and portability. However, the performance of traditional computer vision techniques developed for electro-optical imagery does not directly translate to the thermal domain due to two major reasons: these algorithms require photometric assumptions to hold, and methods for photometric calibration of RGB cameras cannot be applied to thermal-infrared cameras due to difference in data acquisition and sensor phenomenology. In this paper, we take a step in this direction, and introduce a novel algorithm for online photometric calibration of thermal-infrared cameras. Our proposed method does not require any specific driver/hardware support and hence can be applied to any commercial off-the-shelf thermal IR camera. We present this in the context of visual odometry and SLAM algorithms, and demonstrate the efficacy of our proposed system through extensive experiments for both standard benchmark datasets, and real-world field tests with a thermal-infrared camera in natural outdoor environments.

Terrain Relative Navigation for Guided Descent on Titan

Abstract: Titan's dense atmosphere, low gravity, and high winds at high altitudes create descent times of >90 minutes with standard entry/descent/landing (EDL) architectures and result in large unguided landing ellipses, with 99% values of ~110x110 km and 149x72 km in recent Titan lander proposals. Enabling precision landing on Titan could increase science return for the types of missions proposed to date and make additional types of landing sites accessible, opening up new possibilities for science investigations. Precision landing on Titan has unique challenges, because the hazy atmosphere makes it difficult to see the surface and because it requires guided descent with divert ranges that are one to two orders of magnitude larger than needed for other target bodies, i.e. up to on the order of 100 km. It is conceivable that such a divert capability could be provided economically by a parafoil or other steerable aerodynamic decelerator deployed several 10s of km above the surface. The long descent times lead to large inertial navigation errors, hence a need for terrain relative navigation (TRN). This would require a TRN capability that can operate at such altitudes, despite challenges of seeing the surface sufficiently clearly and of depending on map products that are two orders of magnitude lower in spatial resolution than those for Mars and airless bodies. This paper addressed the TRN problem for Titan guided descent, assuming parafoil deployment at an altitude around 40 km. We define a notional sensor suite including an inertial measurement unit (IMU), a radar altimeter, and two descent cameras, with spectral responses in the visible/near infrared (VNIR) (~0.5 to 1 um) and short wave infrared (SWIR) (~2.0 to 2.1 um), Due to the low resolution of current Titan map products, we define two altitude regimes (above and below ~ 20 km) that need different navigation techniques. Map matching is applicable in the upper regime, but challenging or infeasible in the lower one. Feature tracking with decent imagery is desirable in the lower regime, but challenging in the upper one. We derive image contrast requirements for TRN from prior literature and create models of achievable image contrast by radiative transfer modeling; this shows that the requirements should be achievable for a SWIR descent camera in the upper regime, and that a VNIR descent camera is preferable in the lower regime. We then develop algorithms for map matching and feature tracking with descent images and test these with synthetic images created from Cassini/Huygens data sets and our radiative transfer model. We also introduce new possibilities for TRN based on the potential to discriminate some specific types of terrain onboard in descent imagery, such as lake vs adjacent ground and dune vs interdune. We use sensor measurement noise models in simulations of state estimation with an extended Kalman filter that includes coordinates of a set of tracked features in the state vector. Case studies were done for two notional landing sites, one in a site with only dry ground and one in a Titan lake district. In both cases, the filter error model shows 3σ position error at touchdown on the order of 2 km. More work is needed to validate these results with higher fidelity camera models and larger data sets, but this is very promising.

Integrated Simulation and State Estimation for Precision Landing on Titan

Abstract: This paper reports on a study of the application of a ram-air parafoil to Entry, Descent, and Landing (EDL) on Titan. A comprehensive simulation was constructed to enable simulation of EDL state estimation performance from 10 minutes before entry (E-10 min) to touchdown on the surface of Titan. EDL performance is characterized assuming an entry phase starting at E-10 min followed by a parafoil guided phase for descent and landing to enable precise landing on a predetermined target. Guided descent during the parafoil phase is achieved using the parafoil steering capability while state estimation is accomplished using vision-based Terrain Relative Navigation (TRN). The simulation is used in this study to conduct Monte Carlo analysis of TRN state estimation for a full entry phase sequence followed by a straight line flight path descent and landing.