## Theory and Experiments in Autonomous Sensor-Based Motion Planning with Applications for Flight Planetary Microrovers (1999)

Citations: | 16 - 3 self |

### BibTeX

@TECHREPORT{Laubach99theoryand,

author = {Sharon Lynn Laubach},

title = {Theory and Experiments in Autonomous Sensor-Based Motion Planning with Applications for Flight Planetary Microrovers},

institution = {},

year = {1999}

}

### OpenURL

### Abstract

With the success of Mars Pathfinder's Sojourner rover, a new era of planetary exploration has opened, with demand for highly capable mobile robots. These robots must be able to traverse long distances over rough, unknown terrain autonomously, under severe resource constraints. Much prior work in mobile robot path planning has been based on assumptions that are not truly applicable to navigation through planetary terrains. Based on the author's firsthand experience with the Mars Pathfinder mission, this work reviews issues which are critical for successful autonomous navigation of planetary rovers. No current methodology addresses all of these constraints. We next develop the sensor-based "Wedgebug" motionplanning algorithm. This algorithm is complete, correct, requires minimal memory for storage of its world model, and uses only on-board sensors, which are guided by the algorithm to e#ciently sense only the data needed for motion planning, while avoiding unnecessary robot motion. The p...

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Citation Context ...m developed by Kamon, Rimon, and Rivlin [23] in 1995, whose name in turn acknowledges the globally-convergent, reactive nature of the “Bug” algorithms first developed by Lumelsky and Stepanov in 1=-=987 [40]-=-. These algorithms, and their exact relation to Wedgebug, are discussed in more detail in Section 1.2. The related RoverBug algorithm, also developed in this thesis, is the implementation of the Wedge... |

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Citation Context ...o create maps or channels for robot navigation (see Fig. 1.1(a)). Examples of roadmap algorithms include the visibility and reduced visibility (also known as tangent) graphs [57],[36], Voronoi graphs =-=[58], and -=-Canny’s silhouette method [7]. Each of these schemes constructs a set of one-dimensional curves which encapsulate the topology of the free space, and serve as a system of “freeways,” complete wi... |

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Citation Context ...tchy information may exist—are greatly facilitated by robots which are able to not only sense their environs, but to react accordingly as they navigate toward their goal. Sensor-based motion plannin=-=g [9], as-=- a field, arose to address this issue. The basic sensor-based “find-goal” problem is formulated as follows: the robot is situateds2 in unknown terrain, usually with an associated coordinate frame.... |

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Citation Context ...s Brooks’ subsumption architecture [5] or the track arbitration schemes developed at CMU [26],[78], as well as the “Go To Waypoint” algorithm employed by the Sojourner rover [54] and the Rocky7 =-=rover [82]-=- (see Table 1.1), share the useful property of being able to be made sensorbased much more easily than the classical planners, and can be applied to unknown terrains. These planners dispense with the ... |

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Citation Context ...mplemented on a HMMWV, and shares the ACCN system’s susceptibility to dead-ends (i.e., the algorithm is not complete). • RANGER, developed in Singh and Kelly (1995) [74] and Kelly and Stentz (1997=-=,8) [24], -=-[25]. This system, implemented on both a HMMWV and CMU’s prototype lunar rover RATLER, also arbitrates between inputs from hazard avoidance and goal-seeking behaviours. It optimises the behaviour of... |

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Citation Context ...ourtesy JPL) †† 3% of the ground in the MPF site was covered by rocks >20 cm tall, on average. The maximum concentration was 20%, in the “Rock Garden” [14],[16]. The predicted coverage was rou=-=ghly 8% [15]; fo-=-r comparison, VL1 had 4% coverage, and VL2 11% [85], [86]. ‡‡ The batteries, used during the mission primarily for nighttime operation and for ondemand power boosts during traverses, lasted 56 sol... |

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Citation Context ...y when paired with a goal-seeking behaviour. Examples include: • Gat’s implementation of his ATLANTIS architecture (1991) [12], utilises as10 heuristic planner based on Slack’s “navigation tem=-=plates” [75] for-=- obstacle avoidance and goal seeking, as well as a version of Barraquand and Latombe’s non-holonomic planner [4] to recover from cul-de-sacs. The planner was implemented on JPL’s Robby, a large pr... |

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Citation Context ... a line, that line is tangent § to obstacles containing the segment’s endpoints (see Figure 3.2: The Tangent Graph. † The Tangent Graph can also be constructed for curved 2D obstacles, as detaile=-=d in [38]. ‡ i.e., a vertex-=- v of an obstacle O such that in a neighborhood N ∈ O of v, the segment {x|x = λx1 +(1−λ)x2;0≤λ≤1}∈O, ∀x1,x2 ∈N. § A line l is tangent to a C-obstacle CB at a vertex x iff in a neigh... |

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Citation Context ...d of the vehicle require significant computational resources, not available on the current batch of flightlike Mars microrovers. • Pagnot and Grandjean’s fast cross-country navigation approach (19=-=95) [60], whic-=-h computes a (typically trapezoidal) “trace” of possible rover trajectories (including uncertainty in sensing, motion control, and localisation) in each of 20 directions, incremented by 1 ◦ step... |

12 |
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Citation Context ...nted on a HMMWV, and shares the ACCN system’s susceptibility to dead-ends (i.e., the algorithm is not complete). • RANGER, developed in Singh and Kelly (1995) [74] and Kelly and Stentz (1997,8) [2=-=4], [25]. -=-This system, implemented on both a HMMWV and CMU’s prototype lunar rover RATLER, also arbitrates between inputs from hazard avoidance and goal-seeking behaviours. It optimises the behaviour of follo... |

12 |
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Citation Context ...ssume that the boundaries are continuous and rectifiable.) We assume that the reader has basic knowledge of real analysis, differential geometry, and of topology; good references for these topics are =-=[69], [6-=-8], [29] (for real analysis), [31] ∗ or rather basins of attraction, as will be shown later † Specifically, Kamon, Rimon, and Rivlin state that there are a finite number of local minima in the (as... |

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Citation Context ...radius. This system has also been implemented on a HMMWV, and shares the ACCN system’s susceptibility to dead-ends (i.e., the algorithm is not complete). • RANGER, developed in Singh and Kelly (19=-=95) [74] a-=-nd Kelly and Stentz (1997,8) [24], [25]. This system, implemented on both a HMMWV and CMU’s prototype lunar rover RATLER, also arbitrates between inputs from hazard avoidance and goal-seeking behavi... |

8 |
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Citation Context ...ented to the author’s knowledge, but have been demonstrated in simulation: • the similar extended elevation grid methods developed by Simeon and Dacre Wright (1992) [73] and by Kubota et al. (1995=-=,7) [33]-=-, [34]. Both of these methods use a grid search method to select a path, based upon simulated static placements of a given rover model on the terrain at each node. These methods assume full prior know... |

7 |
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Citation Context ...nally thought to be purely volcanic [62]. (courtesy JPL) †† 3% of the ground in the MPF site was covered by rocks >20 cm tall, on average. The maximum concentration was 20%, in the “Rock Garden�=-=�� [14],[16]. Th-=-e predicted coverage was roughly 8% [15]; for comparison, VL1 had 4% coverage, and VL2 11% [85], [86]. ‡‡ The batteries, used during the mission primarily for nighttime operation and for ondemand ... |

7 |
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Citation Context ...ary drivers for memory are the same as for CPU choice, plus cost (e.g., a single shielded PROM costs $30K) and volume [84].s30 Figure 2.12: Map of Sojourner’s traverse, from rover odometry, Sols 1-7=-=8 [87]. (c-=-ourtesy Rick Welch) flight-qualified electronics, will continue to constrain the computing capabilities— and therefore the complexity of on-board autonomy—of future rovers. Of note, in order to ma... |

7 |
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Citation Context ...ain classification) are planned along this path. • the breadth-first, parallel grid search method developed by Gennery (1998) [13]. This algorithm uses a parallel search method derived from Witkowsk=-=i [88]-=- on an extended elevation grid which includes information on slope and terrain roughness at each cell. At the end of the search, the total cost of the optimum path through each node in the local grid ... |