Edward Tunstel

Planetary Rover Developments Supporting Mars Exploration, Sample Return and Future Human-Robotic Colonization

We overview our recent research on planetary mobility. Products of this effort include the Field Integrated Design & Operations rover (FIDO), Sample Return Rover (SRR), reconfigurable rover units that function as an All Terrain Explorer (ATE), and a multi-Robot Work Crew of closely cooperating rovers (RWC). FIDO rover is an advanced technology prototype; its design and field testing support NASAs development of long range, in situ Mars surface science missions. Complementing this, SRR implements autonomous visual recognition, navigation, rendezvous, and manipulation functions enabling small object pick-up, handling, and precision terminal docking to a Mars ascent vehicle for future Mars Sample Return. ATE implements on-board reconfiguration of rover geometry and control for adaptive response to adverse and changing terrain, e.g., traversal of steep, sandy slopes. RWC implements coordinated control of two rovers under closed loop kinematics and force constraints, e.g., transport of large payloads, as would occur in robotic colonies at future Mars outposts. RWC is based in a new extensible architecture for decentralized control of, and collective state estimation by multiple heterogeneous robotic platforms—CAMPOUT; we overview the key architectural features. We have conducted experiments with all these new rover system concepts over variable natural terrain. For each of the above developments, we summarize our approach, some of our key experimental results to date, and our future directions of planned development.

Rover autonomy for long range navigation and science data acquisition on planetary surfaces

This paper describes recent work undertaken at the Jet Propulsion Laboratory in Pasadena, CA in the area of increased rover autonomy for planetary surface operations. The primary vehicle for this work is the Field Integrated, Design and Operations (FIDO) rover. The FIDO rover is an advanced technology prototype that is a terrestrial analog of the Mars Exploration Rovers (MER) being sent to Mars in 2003. We address the autonomy issue through improved integration of rover based sensing and higher level onboard planning capabilities. The sensors. include an inertial navigation unit (INU) with 3D gyros and accelerometers, a sun sensor, mast and body mounted imagery, and wheel encoders. Multisensor fusion using an Extended Kalman Filter (EKF) approach coupled with pattern recognition and tracking algorithms has enabled the autonomy that is necessary for maximizing science data return while minimizing the number of ground loop interactions. These algorithms are coupled with a long range navigation algorithm called ROAMAN (Road Map Navigation) for an integrated approach to rover autonomy. We also report the results of algorithm validation studies in remote field trials at Black Rock Summit in Central Nevada, Californias Mojave Desert, and the Arroyo Seco at JPL.

Behavior Hierarchy for Autonomous Mobile Robots: Fuzzy-Behavior Modulation and Evolution

ABSTRACTRealization of autonomous behavior in mobile robots, using fuzzy logic control, requires formulation of rules which are collectively responsible for necessary levels of intelligence. Such a collection of rules can be conveniently decomposed and efficiently implemented as a hierarchy of fuzzy-behaviors. This article describes how this can be done using a behavior-based architecture. A behavior hierarchy and mechanisms of control decision-making are described. In addition, an approach to behavior coordination is described with emphasis on evolution of fuzzy coordination rules using the genetic programming (GP) paradigm. Both conventional GP and steady-state GP are applied to evolve a fuzzy-behavior for sensor-based goal-seeking. The usefulness of the behavior hierarchy, and partial design by GP, is evident in performance results of simulated autonomous navigation.

Mars Exploration Rover surface operations: driving opportunity at Meridiani Planum

Since landing on the Meridiani Planum region of Mars in January 2004, the Mars exploration rover (MER) vehicle named Opportunity has been sending back pictures taken from several different craters that would provide evidence that the region did indeed have a watery past. This paper details the experience of driving Opportunity through this alien landscape during its first 400 days on Mars, from the point of view of the other rover planners, the people who tell the rover where to drive and how to use its robotic arm

A rule-based fuzzy traversability index for mobile robot navigation

This paper presents a rule-based fuzzy traversability index that quantifies the ease-of-traversal of a terrain by a mobile robot based on real-time measurements of terrain characteristics retrieved from imagery data. These characteristics include, but are not limited to slope, roughness, hardness, and discontinuity. The proposed representation of terrain traversability incorporates an intuitive, linguistic approach for expressing terrain characteristics that is robust with respect to imprecision and uncertainty in the terrain measurements. The terrain assessment method is tested and validated with a set of real-world imagery data. These tests demonstrate the capability of the terrain classification algorithm for perceiving hazards associated with terrain traversal.

Fuzzy behavior hierarchies for multi-robot control

Hierarchical approaches and methodologies are commonly used for control system design and synthesis. Well‐known model‐based techniques are often applied to solve problems of complex and large‐scale control systems. The general philosophy of decomposing control problems into modular and more manageable subsystem control problems applies equally to the growing domain of intelligent and autonomous systems. However, for this class of systems, new techniques for subsystem coordination and overall system control are often required. This article presents an approach to hierarchical control design and synthesis for the case where the collection of subsystems is comprised of fuzzy logic controllers and fuzzy knowledge‐based decision systems. The approach is used to implement hierarchical behavior‐based controllers for autonomous navigation of one or more mobile robots. Theoretical details of the approach are presented, followed by discussions of practical design and implementation issues. Example implementations realized on various physical mobile robots are described to demonstrate how the techniques may be applied in practical applications involving homogeneous and heterogeneous robot teams.

Enhancing fuzzy robot navigation systems by mimicking human visual perception of natural terrain traversability

The paper presents a technique for learning to assess terrain traversability for outdoor mobile robot navigation using human-embedded logic and real-time perception of terrain features extracted from image data. The methodology utilizes a fuzzy logic framework and vision algorithms for analysis of the terrain. The terrain assessment and learning methodology is tested and validated with a set of real world image data acquired by an onboard vision system.

Computational Aspects of Cognition and Consciousness in Intelligent Devices

We review computational intelligence methods of sensory perception and cognitive functions in animals, humans, and artificial devices. Top-down symbolic methods and bottom-up sub-symbolic approaches are described. In recent years, computational intelligence, cognitive science and neuroscience have achieved a level of maturity that allows integration of top-down and bottom-up approaches in modeling the brain. Continuous adaptation and teaming is a key component of computationally intelligent devices, which is achieved using dynamic models of cognition and consciousness. Human cognition performs a granulation of the seemingly homogeneous temporal sequences of perceptual experiences into meaningful and comprehensible chunks of concepts and complex behavioral sehemas. They are accessed during action selection and conscious decision making as part of the intentional cognitive cycle. Implementations in computational and robotic environments are demonstrated.

Ethology as an Inspiration for Adaptive Behavior Synthesis in Autonomous Planetary Rovers

A navigation and control approach that supports adaptive behavior in rovers is presented. It is motivated by ethological models that suggest hierarchical organizations of behavior. The methodology employs fuzzy logic as a means to emulate animal behavior control mechanisms such as behavior activation levels, multi-behavior modulation, and threshold activation. The paper describes how these concepts can be tailored for autonomous navigation to provide a suitable framework for situated adaptation in rover control algorithms. In addition, an interesting characteristic of observed behavioral interactions achieved by an implementation of the approach is discussed, which is analogous to phenomena observed in measurements of animal brain activity during transitions between distinct behaviors.

FIDO rover field trials as rehearsal for the NASA 2003 Mars Exploration Rovers mission

This paper describes recent extended field trials performed using the FIDO (Field Integrated Design & Operations) rover, an advanced NASA technology development platform and research prototype for the next planned rover mission to Mars. Realistic physical simulation of the NASA 2003 Mars Exploration Rovers mission was achieved through collaborative efforts of roboticists, planetary scientists, and mission operations personnel. An overview of the objectives, approach, and results is reported.