Richard Petras

The CLARAty architecture for robotic autonomy

This paper presents an overview of a newly developed Coupled Layer Architecture for Robotic Autonomy (CLARAty), which is designed for improving the modularity of system software while more tightly coupling the interaction of autonomy and controls. First, we frame the problem by briefly reviewing previous work in the field and describing the impediments and constraints that been encountered. Then we describe why a fresh approach to the topic is warranted, and introduce our new two-tiered design as an evolutionary modification of the conventional three-level robotics architecture. The new design features a tight coupling of the planner and executive in one Decision Layer, which interacts with a separate Functional Layer at all levels of system granularity. The Functional Layer is an object-oriented software hierarchy that provides basic capabilities of system operation, resource prediction, state estimation, and status reporting. The Decision Layer utilizes these capabilities of the Functional Layer to achieve goals by expanding, ordering, initiating and terminating activities. Both declarative and procedural planning methods are used in this process. Current efforts are targeted at implementing an initial version of this architecture on our research Mars rover platforms, Rocky 7 and 8. In addition, we are working with the NASA robotics and autonomy communities to expand the scope and participation in this architecture, moving toward a flight implementation in the 2007 time-frame.

The Rocky 7 rover: a Mars sciencecraft prototype

This paper describes the design and implementation at the Jet Propulsion Laboratory of a small rover for future Mars missions requiring long traverses and rover-based science experiments. The small rover prototype, called Rocky 7, is capable of long traverses, autonomous navigation, and science instrument control. This rover carries three science instruments, and can be commanded from any computer platform from any location using the World Wide Web. In this paper we describe the mobility system, the sampling system, the sensor suite, navigation and control, onboard science instruments, and the ground command and control system. We also present key accomplishments of a recent field test of Rocky 7 in the Mojave Desert in California.

Toward developing reusable software components for robotic applications

We present an overview of the CLARAty architecture which aims at developing reusable software components for robotic systems. These components are to support autonomy software which plans and schedules robot activities. CLARAty modifies the conventional 3-level robotic architecture into a 2-layered design: the functional layer and the decision layer. The former provides a representation of the system components and an implementation of their functionalities. The latter is the decision-making engine that drives the former. It globally reasons about the goals, system resources, and system state. The functional layer is composed of a set of interrelated object-oriented hierarchies consisting of active and passive objects that represent the system abstraction levels. We present an overview of the design of the functional layer. It is decomposed into a set of reusable core components and a set of extended components that adapt the reusable set to different hardware implementations. The reusable components provide interface definitions and implementations of basic functionality, provide local executive capabilities, manage local resources, and support decision layer queries.

A prototype manipulation system for Mars rover science operations

This paper provides an overview of a new manipulation system developed for sampling and instrument placement from small autonomous mobile robots for Mars exploration. Selected out of the design space, two manipulators have been constructed and integrated into the Rocky 7 Mars rover prototype. This paper describes the design objectives and constraints for these manipulators, and presents the finished system and some results from its operation.

Fuzzy reactive piloting for continuous driving of long range autonomous planetary micro-rovers

A complete piloting control subsystem for a highly autonomous long range rover will be defined in order to identify the key control functions needed to achieve continuous driving. This capability can maximize range and number of interesting scientific sites visited during the limited life time of a planetary rover. To achieve continuous driving, a complete set of techniques have been employed: fuzzy based control, real-time artificial intelligence reasoning, fast and robust rover position estimation based on odometry and angular rate sensing, efficient stereo vision elevation maps based on grids, and fast reaction and planning for obstacle detection and obstacle avoidance based on a simple IF-THEN expert system with fuzzy reasoning. To quickly design and implement these techniques, graphical programming has been used to build a fully autonomous piloting system using just the techniques of classic control concepts of cyclic data processing and event driven reaction. Experimental results using the JPL rover Rocky 7 are given in order to validate the mentioned techniques for continuous driving.