Sign In

Legible and Proactive Robot Planning for Safe and Cooperative Human-Robot Interactions

Core Concepts
Robots can achieve safe, fluent, and prosocial interactions with humans by planning legible and proactive motions that leverage the inherent cooperativeness of humans in collision avoidance.
The paper presents a robot trajectory planning framework that encourages legible and proactive behaviors to enable safe and cooperative human-robot interactions. Key elements of the approach include: Markup factor: Introduces a markup term in the cost function to incentivize the robot to take nontrivial actions earlier rather than later, revealing its intent to avoid obstacles/humans earlier in the interaction. Inconvenience budget: Constrains the amount of "inconvenience" the robot can experience, ensuring no agent sacrifices too much of its own performance to benefit others, preventing the frozen robot problem. Collision avoidance slack: Treats collision avoidance as a soft constraint, allowing some constraint violations later in the planning horizon to be penalized less. This helps maintain feasibility despite the robot's model of human behavior not matching exactly. The proposed planner is evaluated against several baseline methods in simulation, demonstrating that it leads to safer, more fluent, and more prosocial interactions compared to other approaches. The real-time feasibility of the method is also shown through human-in-the-loop experiments.
The robot's trajectory length is shorter compared to the ideal trajectory without any obstacles. The robot's total acceleration is lower compared to other methods, indicating smoother motion. The minimum distance between the robot and human is maintained above the collision radius, despite using less stringent safety measures compared to other approaches.
"Humans have a remarkable ability to fluently engage in joint collision avoidance in crowded navigation tasks despite the complexities and uncertainties inherent in human behavior." "Our main hypothesis is that if the robot is able to indicate early to interacting humans its intent to avoid collision (e.g., pass to the right), then this will (i) provide the humans sufficient warning to adjust their plans to avoid collisions, (ii) remove ambiguity in how the joint collision avoidance maneuver should occur, and (iii) result in prosocial interactions where everyone equitably compromises their performance to benefit the group."

Deeper Inquiries

How can the proposed approach be extended to handle more complex human behaviors, such as intentional deception or adversarial actions?

To address more complex human behaviors like intentional deception or adversarial actions, the proposed approach can incorporate advanced modeling techniques and game theory concepts. By integrating models that can predict deceptive behaviors or adversarial strategies, the robot planner can adapt its trajectory planning to anticipate and respond to such actions. This may involve developing algorithms that can recognize patterns indicative of deception or adversarial intent in human behavior and adjust the robot's actions accordingly. Game-theoretic frameworks can be employed to analyze strategic interactions between the robot and humans, considering the possibility of deceptive or adversarial behaviors. By incorporating these elements into the planning framework, the robot can proactively navigate in environments where human intentions may not be straightforward.

What are the potential limitations of the inconvenience budget constraint, and how could it be further refined to better capture the nuances of human-robot interactions?

While the inconvenience budget constraint is effective in promoting equitable interactions and preventing excessive sacrifices in performance, it may have limitations in capturing the full complexity of human-robot interactions. One potential limitation is the subjective nature of defining inconvenience, as different individuals may perceive inconvenience differently. To address this, the inconvenience budget constraint could be refined by incorporating personalized models of human preferences and comfort levels. By considering individual differences in how humans perceive inconvenience, the constraint can be tailored to each specific interaction, leading to more nuanced and adaptive robot behaviors. Additionally, integrating real-time feedback mechanisms that adjust the inconvenience budget based on the human's responses during the interaction can enhance the constraint's effectiveness in capturing the nuances of human-robot interactions.

Given the focus on legibility and proactivity, how might this approach be adapted to scenarios where the robot needs to maintain a degree of unpredictability, such as in security or surveillance applications?

In scenarios where maintaining a degree of unpredictability is crucial, such as in security or surveillance applications, the approach focusing on legibility and proactivity can be adapted by introducing controlled variability in the robot's behaviors. Instead of aiming for complete predictability, the robot can exhibit intentional variability in its trajectories while still conveying its intent clearly to humans. This controlled variability can be achieved by introducing stochastic elements or randomized decision-making processes into the trajectory planning algorithm. By incorporating probabilistic elements in the robot's actions, it can maintain a level of unpredictability while ensuring legibility and proactivity in its interactions. Furthermore, the approach can be enhanced by dynamically adjusting the level of unpredictability based on the specific requirements of the security or surveillance task, allowing the robot to balance between unpredictability and effective communication of its intentions.