The real-time control of planetary rovers through behavior modification

It is not yet clear of what type, and how much, intelligence is needed for a planetary rover to function semi-autonomously on a planetary surface. Current designs assume an advanced AI system that maintains a detailed map of its journeys and the surroundings, and that carefully calculates and tests every move in advance. To achieve these abilities, and because of the limitations of space-qualified electronics, the supporting rover is quite sizable, massing a large fraction of a ton, and requiring technology advances in everything from power to ground operations. An alternative approach is to use a behavior driven control scheme. Recent research has shown that many complex tasks may be achieved by programming a robot with a set of behaviors and activation or deactivating a subset of those behaviors as required by the specific situation in which the robot finds itself. Behavior control requires much less computation than is required by tradition AI planning techniques. The reduced computation requirements allows the entire rover to be scaled down as appropriate (only down-link communications and payload do not scale under these circumstances). The missions that can be handled by the real-time control and operation of a set of small, semi-autonomous, interacting, behavior-controlled planetary rovers are discussed

Path planning for planetary rover using extended elevation map

This paper describes a path planning method for planetary rovers to search for paths on planetary surfaces. The planetary rover is required to travel safely over a long distance for many days over unfamiliar terrain. Hence it is very important how planetary rovers process sensory information in order to understand the planetary environment and to make decisions based on that information. As a new data structure for informational mapping, an extended elevation map (EEM) has been introduced, which includes the effect of the size of the rover. The proposed path planning can be conducted in such a way as if the rover were a point while the size of the rover is automatically taken into account. The validity of the proposed methods is verified by computer simulations

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

Abstract — 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 contin-uous driving. This capability can maximize range and num-ber 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 ro-bust rover position estimation based on odometry and angu-lar rate sensing, efficient stereo vision elevation maps based on grids, and fast reaction and planning for obstacle detec-tion and obstacle avoidance based on a simple IF-THEN ex-pert system with fuzzy reasoning. To quickly design and im-plement these techniques, graphical programming has been used to build a fully autonomous piloting system using jus

Revisión de las arquitecturas de control distribuido

El documento se organiza de la siguiente forma. En el capítulo 2 se definen las arquitecturas de control y se contextualizan las arquitecturas revisadas. En el capítulo 3 se revisan las arquitecturas domóticas, inicialmente se repasan las características de los sistemas domóticos, para a continuación revisar ocho arquitecturas. En el capítulo 4 se sigue un esquema similar al capítulo anterior pero con las arquitecturas de navegación de robots. Finalmente se exponen algunas conclusiones acerca de las arquitecturas expuestas, así como la propuesta de características de optimización de arquitecturas y posibles líneas de investigación en el campo de las arquitecturas de control.Una de las claves en el control de sistemas es la arquitectura escogida para implementar dicho control. La elección de la arquitectura o el diseño de la misma determinarán, en gran medida el rendimiento que el control proporcionará al usuario. Existe una gran cantidad de arquitecturas de control en todos los ámbitos que éste cubre. Por ello parece conveniente realizar una revisión y exposición de las mismas, ya que de ésta manera se dispondrá de información suficiente para poder diseñar una arquitectura con las características más adecuadas a las funciones requeridas. En el presente documento se realiza una revisión exhaustiva de diferentes arquitecturas en dos de los ámbitos del control: la domótica y la navegación de robots. Estos dos ámbitos, que a primera vista parecen lejanos están, en parte, relacionados ya que cubren todos los ámbitos de las necesidades de control temporal, desde los bajos requerimientos de la domótica hasta las necesidades de tiempo real estricto de la navegación reactiva de robots. En el documento se hace especial hincapié en las características que las arquitecturas de control deben tener, ya que seleccionar correctamente las características de los requerimientos del sistema a controlar permitirá seleccionar o diseñar correctamente la arquitectura de un sistema.Posadas Yagüe, JL.; Poza Luján, JL. (2009). Revisión de las arquitecturas de control distribuido. http://hdl.handle.net/10251/640

Semantic correlation of behavior for the interoperability of heterogeneous simulations

A desirable goal of military simulation training is to provide large scale or joint exercises to train personnel at higher echelons. To help meet this goal, many of the lower echelon combatants must consist of computer generated forces with some of these echelons composed of units from different simulations. The object of the research described is to correlate the behaviors of entities in different simulations so that they can interoperate with one another to support simulation training. Specific source behaviors can be translated to a form in terms of general behaviors which can then be correlated to any desired specific destination simulation behavior without prior knowledge of the pairing. The correlation, however, does not result in 100% effectiveness because most simulations have different semantics and were designed for different training needs. An ontology of general behaviors and behavior parameters, a database of source behaviors written in terms of these general behaviors with a database of destination behaviors. This comparison is based upon the similarity of sub-behaviors and the behavior parameters. Source behaviors/parameters may be deemed similar based upon their sub-behaviors or sub-parameters and their relationship (more specific or more general) to destination behaviors/parameters. As an additional constraint for correlation, a conversion path from all required destination parameters to a source parameter must be found in order for the behavior to be correlated and thus executed. The length of this conversion path often determines the similarity for behavior parameters, both source and destination. This research has shown, through a set of experiments, that heuristic metrics, in conjunction with a corresponding behavior and parameter ontology, are sufficient for the correlation of heterogeneous simulation behavior. These metrics successfully correlated known pairings provided by experts and provided reasonable correlations for behaviors that have no corresponding destination behavior. For different simulations, these metrics serve as a foundation for more complex methods of behavior correlation

Terrain Aware Traverse Planning for Mars Rovers

NASA is proposing a Mars Sample Return mission, to be completed within one Martian year, that will require enhanced autonomy to perform its duties faster, safer, and more efficiently. With its main purpose being to retrieve samples possibly tens of kilometers away, it will need to drive beyond line-of-sight to get to its target more quickly than any rovers before. This research proposes a new methodology to support a sample return mission and is divided into three compo-nents: map preparation (map of traversability, i.e., ability of a terrain to sustain the traversal of a vehicle), path planning (pre-planning and replanning), and terrain analysis. The first component aims at creating a better knowledge of terrain traversability to support planning, by predicting rover slip and drive speed along the traverse using orbital data. By overlapping slope, rock abundance and terrain types at the same location, the expected drive velocity is obtained. By combining slope and thermal data, additional information about the experienced slip is derived, indicating whether it will be low (less than 30%) or medium to high (more than 30%). The second component involves planning the traverse for one Martian day (or sol) at a time, based on the map of expected drive speed. This research proposes to plan, offline, several paths traversable in one sol. Once online, the rover chooses the fastest option (the path cost being calculated using the distance divided by the expected velocity). During its drive, the rover monitors the terrain via analysis of its experienced wheel slip and actual speed. This information is then passed along the different pre-planned paths over a given distance (e.g., 25 m) and the map of traversability is locally updated given this new knowledge. When an update occurs, the rover calculates the new time of arrival of the various paths and replans its route if necessary. When tested in a simulation study on maps of the Columbia Hills, Mars, the rover successfully updates the map given new information drawn from a modified map used as ground truth for simulation purposes and replans its traverse when needed. The third component describes a method to assess the soil in-situ in case of dangerous terrain detected during the map update, or if the monitoring is not enough to confirm the traversability predicted by the map. The rover would deploy a shear vane instrument to compute intrinsic terrain parameters, information then propagated ahead of the rover to update the map and replan if necessary. Experiments in a laboratory setting as well as in the field showed promising results, the mounted shear vane giving values close to the expected terrain parameters of the tested soils

A layered control architecture for mobile robot navigation

A Thesis submitted to the University Research Degree Committee in fulfillment ofthe requirements for the degree of DOCTOR OF PHILOSOPHY in RoboticsThis thesis addresses the problem of how to control an autonomous mobile robot navigation in indoor environments, in the face of sensor noise, imprecise information, uncertainty and limited response time. The thesis argues that the effective control of autonomous mobile robots can be achieved by organising low level and higher level control activities into a layered architecture. The low level reactive control allows the robot to respond to contingencies quickly. The higher level control allows the robot to make longer term decisions and arranges appropriate sequences for a task execution. The thesis describes the design and implementation of a two layer control architecture, a task template based sequencing layer and a fuzzy behaviour based low level control layer. The sequencing layer works at the pace of the higher level of abstraction, interprets a task plan, mediates and monitors the controlling activities. While the low level performs fast computation in response to dynamic changes in the real world and carries out robust control under uncertainty. The organisation and fusion of fuzzy behaviours are described extensively for the construction of a low level control system. A learning methodology is also developed to systematically learn fuzzy behaviours and the behaviour selection network and therefore solve the difficulties in configuring the low level control layer. A two layer control system has been implemented and used to control a simulated mobile robot performing two tasks in simulated indoor environments. The effectiveness of the layered control and learning methodology is demonstrated through the traces of controlling activities at the two different levels. The results also show a general design methodology that the high level should be used to guide the robot's actions while the low level takes care of detailed control in the face of sensor noise and environment uncertainty in real time

Implementación de una arquitectura de control híbrida para robots autónomos

La robótica es un campo de la informática que se encuentra muy de moda actualmente. Aunque los medios de comunicación nos muestran unos avances realmente impresionantes, la verdad es que es un terreno en el que no se ha profundizado demasiado, y en el que es complicado solucionar problemas que aparentemente son muy básicos. Este proyecto aborda el tema de la navegación básica de robots móviles autónomos, en concreto de un robot Pioneer 3-DX. Se trata de diseñar e implementar una arquitectura haciendo uso del paradigma híbrido de la robótica, que une los paradigmas deliberativo y reactivo, para asentar las bases de un marco de trabajo que permita dotar de comportamientos inteligentes a estos robots móviles. El diseño de la arquitectura busca la creación de este marco, que sea lo más modular, extensible e independiente de las aplicaciones cliente, para poder incorporar nuevas funcionalidades y convertirse en un proyecto de investigación que se alargue y utilice en el futuro, no limitándose a resolver únicamente el problema planteado inicialmente. __________________________________________________________________________________________________________________Nowadays, one of the most famous and interesting fields in technological sciences is robotics. Mass media show incredible advances on this field. However, that doesn’t adjust to reality. This is a field which has not been deepened, and it’s very difficult to solve problems that they look relatively easy. This project deals with the problem of basic navigation in autonomous mobile robots, specifically a Pioneer 3-DX robot. The objective of the project is designing and developing a robot architecture, by using the hybrid paradigm in robotics. This architecture shall combine deliberative and reactive paradigms in order to establish a framework which allows providing mobile robots with intelligent behaviours. The hybrid architecture designed must create this framework, being as modular, extensible and client-application independent as possible, in order to provide new functionalities and become a researching project into the future, so it doesn’t just confine to solve the initial problem of basic navigation.Ingeniería en Informátic