Cooperation or Collaboration? on a Human-Inspired Impedance Strategy in a Human-Robot Co-Manipulation Task
Lorenzo Vianello, Waldez Gomes, Alexis Aubry, Pauline Maurice, Serena Ivaldi
AI summary
Problem
It remains unclear whether robots should adopt fixed leader-follower roles or adaptive collaborative behaviors during physical co-manipulation, and how human-human interaction findings translate to human-robot dyads.
Approach
Fifteen participants performed a precise pipe-extraction task with a Franka robot under four conditions: fixed leader, fixed follower, mirrored adaptive stiffness, and reciprocal adaptive stiffness based on real-time EMG.
Key results
- Collaborative conditions yielded fewer task errors than cooperative ones
- Reciprocal impedance adjustment outperformed mirrored stiffness adaptation
- Human arm stiffness increased during collaboration, mirroring human-human dyad behavior
- Participants preferred collaborative robot behaviors over fixed-role cooperation
Why it matters
These findings guide the design of intuitive, high-performance collaborative robots for industrial and rehabilitation settings where physical task sharing is required.
Abstract
Robotic manipulators have the capability to en- gage in physical interaction with human operators, sharing not only the same workspace but also offering physical assistance to alleviate the human physical workload. In this study, we explore whether a robot should act as a collaborator or a cooperator in a co-manipulation task with a human partner, and investigate different collaboration strategies. In a previous study, we addressed the same question for a human–human dyad and found that collaboration is preferable to make fewer errors at the expense of increased arm stiffness for the humans. In our current investigation, a human physically interacts with a Franka robot in various co-manipulation conditions. In the cooperation conditions, the robot is either a leader or a follower, exhibiting fixed impedance strategies. In the collaborative conditions, the robot exhibits either reciprocal or mirrored adaptive impedance strategies that vary according to an online EMG-based function of the human arm stiffness. Our findings indicate that, for co-manipulation tasks, a robot collaborator is preferable to a robot cooperator (leader or follower), similarly to human dyads. However, unlike the behavior observed within human dyads, the reciprocal strategy for impedance adjustment appears to be the most effective for human–robot collaboration.