Explicit communication is often valued for its directness in presenting information but requires attention during exchange, resulting in cognitive interruptions. On the other hand, implicit communication contributes to tacit and smooth interaction, making it more suitable for teaming, but requires inference for interpretation. This paper studies a novel type of implicit visual communication (IVC) using shadows via visual projection with augmented reality, referred to as active shadowing (ASD). Prior IVC methods, such as legible motion, are often used to influence the perception of robot behavior to make it more understandable. They often require changing the physical robot behavior, resulting in suboptimality. In our work, we investigate how ASD can be used to achieve similar effects without losing optimality. Our evaluations with user studies demonstrates that ASD can effectively creates ''illusions'' that maintain optimal physical behavior without compromising its understandability. We also show that ASD can be more informative than other explicit communication methods, and examine the conditions under which ASD becomes less effective.

翻译：显式通信因其在呈现信息时的直接性而常受重视，但需要在交换过程中保持注意，从而导致认知中断。另一方面，隐式通信有助于实现默契且流畅的交互，使其更适用于团队协作，但需要推理才能进行解读。本文研究一种利用增强现实视觉投影通过阴影实现的新型隐式视觉通信（IVC），称为主动阴影投射（ASD）。先前的IVC方法，例如可读运动，常被用来影响对机器人行为的感知，使其更易于理解。这些方法通常需要改变机器人的物理行为，从而导致次优性。在我们的工作中，我们研究了如何利用ASD在不损失最优性的情况下实现类似效果。我们通过用户研究进行的评估表明，ASD能够有效地创造"错觉"，在保持最优物理行为的同时不损害其可理解性。我们还表明，ASD可以比其他显式通信方法提供更多信息，并考察了ASD效果减弱的条件。