论文标题
狭窄的空间中的懒惰重排计划
Lazy Rearrangement Planning in Confined Spaces
论文作者
论文摘要
对象重新安排对于许多应用很重要,但仍然具有挑战性,尤其是在诸如货架之类的狭窄空间中,那里无法从上方访问对象,并且它们彼此之间可以阻止可达性。这样的限制需要许多运动计划和碰撞检查呼叫,这在计算上昂贵。此外,布置空间随物体数量呈指数增长。为了解决这些问题,这项工作介绍了一个懒惰的评估框架,并使用本地单调求解器和全球规划师。单调实例是可以通过最多一次移动每个对象来解决的实例。一个关键的见解是,对象的启动,在grasps上的可及性约束可以迅速揭示对象之间的依赖关系,而不必执行昂贵的运动计划查询。鉴于此,本地求解器懒洋洋地建立了一个尊重这些可达性约束的搜索树,而无需验证手臂路径是否无碰撞。它仅在找到有前途的解决方案时进行碰撞检查。如果找不到单调解决方案,则非单调计划器将加载懒惰的搜索树,并探索将对象转移到中间位置的方法,从单调解决方案可以找到目标。结果表明,所提出的框架可以解决具有多达16个对象的限制空间中的困难实例,而最先进的方法无法解决。当替代方案找到解决方案时,它还比替代方案更快地解决问题。它还可以实现高质量的解决方案,即,非单调实例平均只需要1.8个额外的动作。
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.