Perceived safety in human-cobot interaction for fixed-path and real-time motion planning algorithms

Area of Science:

• Human-Robot Interaction
• Robotics
• Control Systems

Background:

• Collaborative robots (cobots) are increasingly used in human-robot workspaces.
• Ensuring human safety and maximizing productivity are key challenges in cobot deployment.
• Perception of cobot behavior by humans influences acceptance and collaboration effectiveness.

Purpose of the Study:

• To investigate human subjects' perceptions of different motion planning algorithms for cobots.
• To evaluate the impact of real-time trajectory planning versus fixed paths on perceived safety and productivity.
• To assess the effect of heart rate-based speed adjustments on perceived safety and productivity.

Main Methods:

• 48 human subjects interacted with a cobot under four different motion planning conditions.
• Algorithms varied in path planning (fixed vs. real-time nonlinear model predictive control) and speed modulation (heart rate-based vs. no modulation).
• Human safety was ensured using speed and separation monitoring principles.

Main Results:

• Fixed path planning, compared to real-time planning, potentially reduced productivity but increased perceived safety, especially without heart rate modulation.
• Reducing cobot speed based on heart rate measurements decreased productivity without improving perceived safety.
• Perceived safety was positively influenced by habituation over the experimental period.
• Previous human experience with robots did not significantly affect perceived safety.

Conclusions:

• Real-time motion planning may enhance cobot productivity but requires careful consideration of perceived safety.
• Heart rate-based speed reduction is not an effective strategy for improving perceived safety in cobot operations.
• Habituation plays a significant role in shaping human perception of cobot safety during interaction.