John Bares

Dante II: Technical Description, Results, and Lessons Learned

Dante II is a unique walking robot that provides important insight into high-mobility robotic locomotion and remote robotic exploration. Dante II’s uniqueness stems from its combined legged and rappelling mobility system, its scanning-laser rangefinder, and its multilevel control scheme. In 1994 Dante II was deployed and successfully tested in a remote Alaskan volcano, as a demonstration of the fieldworthiness of these technologies. For more than five days the robot explored alone in the volcano crater using a combination of supervised autonomous control and teleoperated control. Human operators were located 120 km distant during the mission. This article first describes in detail the robot, support systems, control techniques, and user interfaces. We then describe results from the battery of field tests leading up to and including the volcanic mission. Finally, we put forth important lessons which comprise the legacy of this project. We show that framewalkers are appropriate for rappelling in severe terrain, though tether systems have limitations. We also discuss the importance of future “autonomous” systems to realize when they require human support rather than relying on humans for constant oversight.

Ambler: an autonomous rover for planetary exploration

The authors are building a prototype legged rover, called the Ambler (loosely an acronym for autonomous mobile exploration robot) and testing it on full-scale, rugged terrain of the sort that might be encountered on the Martian surface. They present an overview of their research program, focusing on locomotion, perception, planning, and control. They summarize some of the most important goals and requirements of a rover design and describe how locomotion, perception, and planning systems can satisfy these requirements. Since the program is relatively young (one year old at the time of writing) they identify issues and approaches and describe work in progress rather than report results. It is expected that many of the technologies developed will be applicable to other planetary bodies and to terrestrial concerns such as hazardous waste assessment and remediation, ocean floor exploration, and mining.<<ETX>>

A robotic excavator for autonomous truck loading

Excavators are used for the rapid removal of soil and other materials in mines, quarries, and construction sites. The automation of these machines offers promise for increasing productivity and improving safety. To date, most research in this area has focussed on selected parts of the problem. In this paper, we present a system that completely automates the truck loading task. The excavator uses two scanning laser rangefinders to recognize and localize the truck, measure the soil face, and detect obstacles. The excavators software decides where to dig in the soil, where to dump in the truck, and how to quickly move between these points while detecting and stopping for obstacles. The system was fully implemented and was demonstrated to load trucks as fast as human operators.

Configuration of Autonomous Walkers for Extreme Terrain

Robots that can competently, efficiently, and autonomously operate in extreme terrain do not exist. Although walking locomotion offers unique advantages, existing walking mech anisms are not suited to the comprehensive requirements of extreme terrain autonomy. This work synthesizes and ana lyzes candidate walker configurations, implements and tests a walker of unprecedented capability and design, and devel ops insights regarding walker configuration and the class of orthogonal-legged walking robots. Three orthogonal-legged walker configurations are described and compared in a variety of terrain situations. Two of the configurations-circulating and weaving-are unique, as they place recovering feet ahead of supporting feet and are specifically notable for their long stride. The third uses a traditional follow-the-leader gait. The Ambler is a fully operable autonomous walking robot built in part to further investigate the benefits of the orthogonal leg and circulating gait configuration. The orthogonal leg appears to be well suited to autonomous walking in extreme terrain. A circulating walkers advantages—as demonstrated by the Am bler-notwithstanding, a follow-the-leader orthogonal-legged walker appears to have superior overall mobility and stability (the crucial capabilities in extreme terrain).

Walking robot with a circulating gait

The Ambler walking robot has been developed specifically for autonomous exploration of planetary and lunar surfaces. The Ambler, which maintains its body on a level trajectory while walking, has unique orthogonal legs that are stacked under the body instead of the traditional animal-like arrangement of legs around the body. The resulting stacked configuration leads to a novel circulating gait that promises to improve mobility in terrains of extreme roughness. The Amblers level body motion, orthogonal legs, and circulating gait greatly simplify physical control, terrain model construction, and motion planning-all of which are traditional impediments to autonomous travel across rough terrain.<<ETX>>

Tethering system design for Dante II

Dante II is a tethered mobile robot designed for volcano exploration. It has 6 pantographic legs, and is a rappelling robot that uses a tether to support itself on steep terrain, just as a mountaineer uses a climbing rope. The tether is connected to a generator and satellite communication station located at the volcanos rim. The satellite station relays data to and from remotely located operators. This paper describes the issues faced in the design of the tethering system of Dante II, and the approach used to address these issues.

A Semi-Autonomous Robot for Stripping Paint from Large Vessels

The National Robotics Engineering Consortium and UltraStrip Systems Inc. have developed a highly flexible and productive robot to strip paint from large ships and other large ferro-magnetic structures based on the patents obtained by UltraStrip Systems, Inc. (US patents: 6,425,340; 5,849,099; 5,628,271). Removal of corrosion and coatings from large vessels has become a serious economic and environmental problem, and current practices are becoming infeasible. The M2000 robot removes paint from ships using ultrahigh pressure water jets and recovers the water and debris in an environmentally sound way. The addition of simple, easy-to-use, cruise control features to the robot has permitted significant increases in productivity, safety, and stripping quality.

Behavior-based gait execution for the Dante II walking robot

The Dante project is developing walking robots to explore inside volcanic craters. These robots face many challenges including generating a walking gait in rough, obstacle-filled terrain. For the walking robot Dante II, we implemented a gait controller to address this situation. Our approach is embodied in a network of asynchronous processes that establish a fundamental gait cycle while maintaining body posture, and reacting to bumps and slips. We describe our implementation, and its relation to similar behavioral approaches, and discuss Dante IIs performance during testing and on its descent into Mount Spurr.

Ambler: a six-legged planetary rover

The goal of the planetary rover project is to prototype an autonomous mobile robot for planetary exploration. The authors have constructed a six-legged walking robot, called the Ambler, that features orthogonal legs, an overlapping gait, and a scanning laser rangefinder to model terrain. To enable the Ambler to walk over rugged terrain, they have combined perception, planning, and real-time control into a comprehensive robotic system.<<ETX>>

Locomotion configuration of a robust rappelling robot

Robotic rappelling is an intriguing concept for exploration of planetary craters and their Earth analogs, volcanoes. Integrating a tensioned tether to a framewalking robot enables a new statically-stable locomotive capability appropriate for rappelling on steep and rugged terrains. Rappelling with a tether-assisted framewalker also allows efficient execution of multi-level control. These ideas are manifested in the locomotion configuration of Dante II. The appropriateness of the Dante II configuration for rappelling was evaluated during a variety of tests and its 1994 exploration of the active volcano of Mount Spurr in Alaska.