Multiple robot systems are favored for object manipulation and transportation, especially for large objects. However, in more complex manipulation such as flipping, these systems encounter a new challenge, configuration disconnectivity of manipulators. Grasping objects by manipulators will impose closed-chain constraints on the system, which in turn limits the feasible motions of manipulators and further compromises the configuration connectivity. Multiple mobile manipulator systems show much more flexibility in object manipulation with the mobility of the mobile platform and have the potential to address the above problem. In this paper, a novel planning framework is proposed for complex flipping manipulation by incorporating platform motions and regrasping. Firstly, two types of trajectories, mobile manipulator planning and regrasping planning, are classified and can be assigned different priorities for different tasks. Secondly, corresponding planning methods are designed for each type of trajectory. Specifically, in mobile manipulator planning, the configuration of the platform is determined through optimization to ensure connectivity when the manipulator approaches configuration boundaries. In regrasping planning, closed-chain constraints are temporarily disregarded and the manipulation capabilities are prioritized to facilitate subsequent planning. Finally, the structure of the overall planning framework is provided. Experimental results demonstrate that the proposed planner efficiently plans the motions of the system to accomplish flipping manipulation. Additionally, a comprehensive experiment emphasizes the significance of our planner in extending the capabilities of multiple mobile manipulator systems in complex tasks.

翻译：多机器人系统在物体操作和运输中备受青睐，尤其适用于大型物体。然而，在更复杂的操作（如翻转）中，这些系统面临新的挑战——机械臂的配置不连通性。机械臂抓取物体会对系统施加闭环约束，进而限制机械臂的可行运动，并进一步破坏配置的连通性。多移动机械臂系统凭借移动平台的机动性，在物体操作中展现出更高的灵活性，并有望解决上述问题。本文提出了一种新颖的规划框架，通过融合平台运动与重新抓取策略来实现复杂翻转操作。首先，将轨迹分为两类：移动机械臂规划和重新抓取规划，并可根据不同任务分配不同的优先级。其次，针对每类轨迹设计了相应的规划方法。具体而言，在移动机械臂规划中，通过优化确定平台配置，以确保机械臂接近配置边界时的连通性；在重新抓取规划中，临时忽略闭环约束并优先考虑操作能力，以促进后续规划。最后，给出了整体规划框架的结构。实验结果表明，所提出的规划器能够高效规划系统运动以完成翻转操作。此外，一项综合性实验强调了该规划器在扩展多移动机械臂系统复杂任务能力方面的重要性。