Mark W. Maimone

Developing Nomad for Robotic Exploration of the Atacama Desert

Recent years have seen renewed attention to planetary exploration, and robotics is recognized as essential to many upcoming missions. In this article we describe the ongoing efforts of the Nomad project to develop robots for planetary and terrestrial exploration. The project is developing, demonstrating, and evaluating systems capable of long-distance, long-duration missions. In 1997 this work has resulted in the Atacama Desert Trek, in which a mobile robot named Nomad, explored the Atacama Desert of northern Chile. Nomads 45-day objective was to travel 200 km across the rugged, barren landscape. We then will describe the technologies for Nomads transforming chassis, high data-rate communication, safeguarded teleoperation and autonomy, panoramic imaging and visualization, and remote science. We then focus on issues of long-distance, long-duration exploration and describe the events and results of the Atacama Desert Trek.

Miro: visual specification of security

Miro is a set of languages and tools that support the visual specification of file system security. Two visual languages are presented: the instance language, which allows specification of file system access, and the constraint language, which allows specification of security policies. Miro visual languages and tools are used to specify security configurations. A visual language is one whose entities are graphical, such as boxes and arrows, specifying means stating independently of any implementation the desired properties of a system. Security means file system protection: ensuring that files are protected from unauthorized access and granting privileges to some users, but not others. Tools implemented and examples of how these languages can be applied to real security specification problems are described. >

Modeling foreshortening in stereo vision using local spatial frequency

Many aspects of the real world continue to plague stereo matching systems. One of these is perspective foreshortening, an effect that occurs when a surface is viewed at a sharp angle. Because each stereo camera has a slightly different view, the image of the surface is more compressed and occupies a smaller area in one view. These effects cause problems because most stereo methods compare similarly sized regions (using the same-sized windows in both images), tacitly assuming that objects occupy the same extents in both images. Clearly this condition is violated by perspective foreshortening. We show how to overcome this problem using a local spatial frequency representation. A simple geometric analysis leads to an elegant solution in the frequency domain which, when applied to a Gabor filter-based stereo system, increases the systems maximum matchable surface angle from 30 degrees to over 75 degrees.

Miro semantics for security

The Miro project comprises designing and implementing a visual language for specifying properties of large software systems. The authors are designing the language in tandem with giving it a formal semantics. They present the semantics of the language as applied to the security domain.<<ETX>>

Evolution of a Prototype Lunar Rover: Addition of Laser-Based Hazard Detection, and Results from Field Trials in Lunar Analog Terrain

This paper presents the results of field trials of a prototype lunar rover traveling over natural terrain under safeguarded teleoperation control. Both the rover and the safeguarding approach have been used in previous work. The original contributions of this paper are the development and integration of a laser hazard detection system, and extensive field testing of the overall system. The laser system, which complements an existing stereo vision system, is based on a line-scanning laser ranger viewing the area 1 meter in front of the rover. The laser system has demonstrated excellent performance: zero misses and few false alarms operating at 4 Hz. The overall safeguarding system guided the rover 43 km over lunar analogue terrain with 0.8 failures per kilometer.