We present the first free-floating autonomous underwater construction system capable of using active ballasting to transport cement building blocks efficiently. It is the first free-floating autonomous construction robot to use a paired set of resources: compressed air for buoyancy and a battery for thrusters. In construction trials, our system built structures of up to 12 components and weighing up to 100Kg (75Kg in water). Our system achieves this performance by combining a novel one-degree-of-freedom manipulator, a novel two-component cement block construction system that corrects errors in placement, and a simple active ballasting system combined with compliant placement and grasp behaviors. The passive error correcting components of the system minimize the required complexity in sensing and control. We also explore the problem of buoyancy allocation for building structures at scale by defining a convex program which allocates buoyancy to minimize the predicted energy cost for transporting blocks.

翻译：我们提出了首个能够利用主动压载系统高效运输水泥建筑构件的自由漂浮式自主水下建造系统。该系统是首个采用配对资源（用于浮力的压缩空气和用于推进器的电池）的自由漂浮式自主建造机器人。在建造试验中，我们的系统成功构建了由多达12个构件组成、总重量达100公斤（水中重量75公斤）的结构。该系统通过结合新型单自由度机械臂、可修正放置误差的两构件水泥块建造系统，以及将主动压载系统与柔性放置和抓取行为相结合的方式实现了这一性能。系统中的被动误差修正组件最大程度地降低了传感与控制所需的复杂性。我们还通过定义凸优化程序来分配浮力以最小化运输构件的预测能耗，从而探索了大规模建造结构时的浮力分配问题。