# Lazy Rearrangement Planning in Confined Spaces

arXiv: https://arxiv.org/abs/2203.10379 · HTML: https://mlsanity.com/paper/2203.10379/

## Key facts

- Cited by 2 papers in the map (data through 14 Oct 2026).
- Builds on 10 of its 26 references that are in the map.
- First posted on arXiv 19 Mar 2022.

## Builds on (most cited first, 10 of 10)

- [Generalized Lazy Search for Robot Motion Planning: Interleaving Search and Edge Evaluation via Event-based Toggles](https://mlsanity.com/paper/1904.02795/) (2019)
- [Lazy Receding Horizon A* for Efficient Path Planning in Graphs with Expensive-to-Evaluate Edges](https://mlsanity.com/paper/1803.04998/) (2018)
- [Probabilistic completeness of RRT for geometric and kinodynamic planning with forward propagation](https://mlsanity.com/paper/1809.07051/) (2018)
- [Uniform Object Rearrangement: From Complete Monotone Primitives to Efficient Non-Monotone Informed Search](https://mlsanity.com/paper/2101.12241/) (2021)
- [Persistent Homology for Effective Non-Prehensile Manipulation](https://mlsanity.com/paper/2202.02937/) (2022)
- [Efficient and High-quality Prehensile Rearrangement in Cluttered and Confined Spaces](https://mlsanity.com/paper/2110.02814/) (2021)
- [Non-Prehensile Manipulation in Clutter with Human-In-The-Loop](https://mlsanity.com/paper/1904.03748/) (2019)
- [Coordination of two robotic manipulators for object retrieval in clutter](https://mlsanity.com/paper/2109.15220/) (2021)
- [Scalable and Probabilistically Complete Planning for Robotic Spatial Extrusion](https://mlsanity.com/paper/2002.02360/) (2020)
- [Lazy Lifelong Planning for Efficient Replanning in Graphs with Expensive Edge Evaluation](https://mlsanity.com/paper/2105.12076/) (2021)

## Built on by (most cited first, 2 of 2)

- [ORLA*: Mobile Manipulator-Based Object Rearrangement with Lazy A Star](https://mlsanity.com/paper/2309.13707/) (2023)
- [Planning for Manipulation among Movable Objects: Deciding Which Objects Go Where, in What Order, and How](https://mlsanity.com/paper/2303.13385/) (2023)

## Abstract (arXiv)

Object rearrangement is important for many applications but remains challenging, especially in confined spaces, such as shelves, where objects cannot be accessed from above and they block reachability to each other. Such constraints require many motion planning and collision checking calls, which are computationally expensive. In addition, the arrangement space grows exponentially with the number of objects. To address these issues, this work introduces a lazy evaluation framework with a local monotone solver and a global planner. Monotone instances are those that can be solved by moving each object at most once. A key insight is that reachability constraints at the grasps for objects' starts and goals can quickly reveal dependencies between objects without having to execute expensive motion planning queries. Given that, the local solver builds lazily a search tree that respects these reachability constraints without verifying that the arm paths are collision free. It only collision checks when a promising solution is found. If a monotone solution is not found, the non-monotone planner loads the lazy search tree and explores ways to move objects to intermediate locations from where monotone solutions to the goal can be found. Results show that the proposed framework can solve difficult instances in confined spaces with up to 16 objects, which state-of-the-art methods fail to solve. It also solves problems faster than alternatives, when the alternatives find a solution. It also achieves high-quality solutions, i.e., only 1.8 additional actions on average are needed for non-monotone instances.