https://users.encs.concordia.ca/~ymzhang/publications/ARC32-2-98Zhang_pp.229-252.pdf

Bibliographical review on reconfigurable fault-tolerant control systems

Surveys the developments of the last 20 years in the area of vision for mobile robot navigation. Two major components of the paper deal with indoor navigation and outdoor navigation. For each component, we have further subdivided our treatment of the subject on the basis of structured and unstructured environments. For indoor robots in structured environments, we have dealt separately with the cases of geometrical and topological models of space. For unstructured environments, we have discussed the cases of navigation using optical flows, using methods from the appearance-based paradigm, and by recognition of specific objects in the environment.

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Vision for mobile robot navigation: a survey

Motion planning is one of the most important areas of robotics research. The complexity of the motion-planning problem has hindered the development of practical algorithms. This paper surveys the work on gross-motion planning, including motion planners for point robots, rigid robots, and manipulators in stationary, time-varying, constrained, and movable-object environments. The general issues in motion planning are explained. Recent approaches and their performances are briefly described, and possible future research directions are discussed.

Gross motion planning—a survey

We present serial and parallel algorithms for solving a system of equations that arises from the discretization of the Hamilton-Jacobi equation associated to a trajectory optimization problem of the following type. A vehicle starts at a prespecified point x/sub o/ and follows a unit speed trajectory x(t) inside a region in /spl Rscr//sup m/ until an unspecified time T that the region is exited. A trajectory minimizing a cost function of the form /spl int//sub 0//sup T/ r(x(t))dt+q(x(T)) is sought. The discretized Hamilton-Jacobi equation corresponding to this problem is usually solved using iterative methods. Nevertheless, assuming that the function r is positive, we are able to exploit the problem structure and develop one-pass algorithms for the discretized problem. The first algorithm resembles Dijkstra's shortest path algorithm and runs in time O(n log n), where n is the number of grid points. The second algorithm uses a somewhat different discretization and borrows some ideas from a variation of Dial's shortest path algorithm (1969) that we develop here; it runs in time O(n), which is the best possible, under some fairly mild assumptions. Finally, we show that the latter algorithm can be efficiently parallelized: for two-dimensional problems and with p processors, its running time becomes O(n/p), provided that p=O(/spl radic/n/log n). >

/pdf/efficient-algorithms-for-globally-optimal-trajectories-15ino6dhzd.pdf

Efficient algorithms for globally optimal trajectories

The issues involved in integrating multiple sensors into the operation of a system are presented in the context of the type of information these sensors can uniquely provide. A survey is provided of the variety of approaches to the problem of multisensor integration and fusion that have appeared in the literature in recent years ranging from general paradigms, frameworks, and methods for integrating and fusing multisensory information to existing multisensor systems used in different areas of application. General multisensor fusion methods, sensor selection strategies, and world models are examined, along with approaches to the integration and fusion of information from combinations of different types of sensors. Short descriptions of the role of multisensor integration and fusion in the operation of a number of existing mobile robots are provided, together with proposed high-level multisensory representations suitable for mobile robot navigation and control. Existing multisensor systems for industrial and other applications are considered. >

Multisensor integration and fusion in intelligent systems

A description is given of the first cross-country map and sensor-based autonomous operation of a robotic vehicle. Experiments on the autonomous land vehicle (ALV) in natural terrain were performed. An overview of the software architecture is provided, and details of the perception and planning techniques are presented. Two key experiments in which the vehicle avoided known and unknown obstacles in its path are described. >

Autonomous cross-country navigation with the ALV

This paper describes a highly distributed fault-tolerant control system capable of compensating for deficiencies in system-level performance even when the cause of a fault cannot be explicitly identified. Developed for an autonomous underwater vehicle that must remain operational for several weeks without human intervention, this system must be capable of dealing with events that cannot be anticipated at design time. A unique aspect of this system is that it handles such events by attempting to “do whatever works” if it is unable to diagnose and correct specific faults. The software architecture used in this approach is applicable to a wide range of complex autonomous control applications.

Do whatever works: A robust approach to fault-tolerant autonomous control

A reasoning system to support the planning and control requirements of an autonomous land vehicle is described. This system is designed specifically to handle diverse terrain with maximal speed, efficacy, and versatility. the hierarchical architecture for this system is presented along with the detailed algorithms, heuristics, and planning methodologies for the component modules. the architecture is structured such that lower-level modules perform tasks requiring greatest immediacy, while higher-level modules perform tasks involving greater assimilation of sensor data, making use of large amounts of a priori knowledge. In describing the component modules of this system, specific techniques for mission planning, map-based route planning, local terrain navigation, and reflexive vehicle control are presented. These techniques have been demonstrated both in a detailed realtime simulation and on a small indoor robotic vehicle.

Planning and reasoning for autonomous vehicle control

An algorithm for planning paths through a digital terrain map has been developed for guiding an autonomous land vehicle A grid representation of the terrain allows finding optimal paths when considering terrain data such as elevation, mobility, cultural features, and military threats A solution to the digitization bias of a grid representation is presented

Planning Strategic Paths Through Variable Terrain Data

A system and method for rapidly obtaining information about the suitability of terrain to meet concealment or visibility objectives, such as might be needed for military planning or for determining placement of relay antennas in a cellular communication system, is disclosed. The disclosed system precomputes heuristic visibility fields for a geographic area, then uses the precomputed heuristic visibility fields to rapidly determine points on a map that will provide the desired characteristics of exposure or concealment in response to a query.

David M. Keirsey

Papers

Autonomous cross-country navigation with the ALV

Do whatever works: A robust approach to fault-tolerant autonomous control

Planning and reasoning for autonomous vehicle control

Planning Strategic Paths Through Variable Terrain Data

System and method for rapid determination of visibility-based terrain properties over broad regions