1,491 research outputs found
Revisiting the Minimum Constraint Removal Problem in Mobile Robotics
The minimum constraint removal problem seeks to find the minimum number of
constraints, i.e., obstacles, that need to be removed to connect a start to a
goal location with a collision-free path. This problem is NP-hard and has been
studied in robotics, wireless sensing, and computational geometry. This work
contributes to the existing literature by presenting and discussing two
results. The first result shows that the minimum constraint removal is NP-hard
for simply connected obstacles where each obstacle intersects a constant number
of other obstacles. The second result demonstrates that for simply
connected obstacles in the plane, instances of the minimum constraint removal
problem with minimum removable obstacles lower than can be solved in
polynomial time. This result is also empirically validated using several
instances of randomly sampled axis-parallel rectangles.Comment: Accepted for presentation at the 18th international conference on
Intelligent Autonomous System 202
A Certified-Complete Bimanual Manipulation Planner
Planning motions for two robot arms to move an object collaboratively is a
difficult problem, mainly because of the closed-chain constraint, which arises
whenever two robot hands simultaneously grasp a single rigid object. In this
paper, we propose a manipulation planning algorithm to bring an object from an
initial stable placement (position and orientation of the object on the support
surface) towards a goal stable placement. The key specificity of our algorithm
is that it is certified-complete: for a given object and a given environment,
we provide a certificate that the algorithm will find a solution to any
bimanual manipulation query in that environment whenever one exists. Moreover,
the certificate is constructive: at run-time, it can be used to quickly find a
solution to a given query. The algorithm is tested in software and hardware on
a number of large pieces of furniture.Comment: 12 pages, 7 figures, 1 tabl
Minimum Constraint Removal Problem for Line Segments is NP-hard
In the minimum constraint removal (), there is no feasible path to move
from the starting point towards the goal and, the minimum constraints should be
removed in order to find a collision-free path. It has been proved that
problem is when constraints have arbitrary shapes or even they are in
shape of convex polygons. However, it has a simple linear solution when
constraints are lines and the problem is open for other cases yet. In this
paper, using a reduction from Subset Sum problem, in three steps, we show that
the problem is NP-hard for both weighted and unweighted line segments
Soft Subdivision Motion Planning for Complex Planar Robots
The design and implementation of theoretically-sound robot motion planning algorithms is challenging. Within the framework of resolution-exact algorithms, it is possible to exploit soft predicates for collision detection. The design of soft predicates is a balancing act between easily implementable predicates and their accuracy/effectivity.
In this paper, we focus on the class of planar polygonal rigid robots with arbitrarily complex geometry. We exploit the remarkable decomposability property of soft collision-detection predicates of such robots. We introduce a general technique to produce such a decomposition. If the robot is an m-gon, the complexity of this approach scales linearly in m. This contrasts with the O(m^3) complexity known for exact planners. It follows that we can now routinely produce soft predicates for any rigid polygonal robot. This results in resolution-exact planners for such robots within the general Soft Subdivision Search (SSS) framework. This is a significant advancement in the theory of sound and complete planners for planar robots.
We implemented such decomposed predicates in our open-source Core Library. The experiments show that our algorithms are effective, perform in real time on non-trivial environments, and can outperform many sampling-based methods
Computational Tradeoff in Minimum Obstacle Displacement Planning for Robot Navigation
In this paper, we look into the minimum obstacle displacement (MOD) planning
problem from a mobile robot motion planning perspective. This problem finds an
optimal path to goal by displacing movable obstacles when no path exists due to
collision with obstacles. However this problem is computationally expensive and
grows exponentially in the size of number of movable obstacles. This work looks
into approximate solutions that are computationally less intensive and differ
from the optimal solution by a factor of the optimal cost.Comment: Accepted for presentation at the 2023 IEEE International Conference
on Robotics and Automation (ICRA
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