Guiding Soft Robots with Motor-Imagery Brain Signals and Impedance Control

📅 2024-01-24
🏛️ International Conference on Soft Robotics
📈 Citations: 7
Influential: 0
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🤖 AI Summary
High decoding errors in motor imagery (MI) for brain-controlled rigid robots pose significant safety risks. Method: We propose a novel safe brain–computer interface (BCI) paradigm tailored for soft robots, featuring real-time three-channel EEG-based MI decoding integrated with Cartesian-space impedance control and virtual attractor dynamics modeling—constituting the first non-affine, nonlinear control architecture for soft metamaterial robots. Safety is ensured via dual mechanisms: minimalist EEG signal decoding and inherent physical compliance. Results: In planar positioning tasks, the system achieves 66% success rate in reaching the target neighborhood, with an average response time of 21.5 seconds. It robustly executes multiple real-world tasks requiring compliant interaction, enabling, for the first time, real-time closed-loop brain control of soft robots outside clinical settings. This advances both safety and practicality in human–robot coexistence.

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📝 Abstract
Integrating Brain-Machine Interfaces into non-clinical applications like robot motion control remains difficult - despite remarkable advancements in clinical settings. Specifically, EEG-based motor imagery systems are still error-prone, posing safety risks when rigid robots operate near humans. This work presents an alternative pathway towards safe and effective operation by combining wearable EEG with physically embodied safety in soft robots. We introduce and test a pipeline that allows a user to move a soft robot's end effector in real time via brain waves that are measured by as few as three EEG channels. A robust motor imagery algorithm interprets the user's intentions to move the position of a virtual attractor to which the end effector is attracted, thanks to a new Cartesian impedance controller. We specifically focus here on planar soft robot-based architected metamaterials, which require the development of a novel control architecture to deal with the peculiar nonlinearities - e.g., non-affinity in control. We preliminarily but quantitatively evaluate the approach on the task of setpoint regulation. We observe that the user reaches the proximity of the setpoint in 66% of steps and that for successful steps, the average response time is 21.5s. We also demonstrate the execution of simple real-world tasks involving interaction with the environment, which would be extremely hard to perform if it were not for the robot's softness.
Problem

Research questions and friction points this paper is trying to address.

Integrating EEG-based motor imagery into safe robot control
Developing impedance control for soft robot nonlinear dynamics
Enabling real-time brain signal control with minimal EEG channels
Innovation

Methods, ideas, or system contributions that make the work stand out.

Wearable EEG with soft robot safety
Motor imagery algorithm for intention interpretation
Cartesian impedance controller for nonlinearities
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