Robot reflex control enables faster safer human-robot interactions
Sub-Millisecond Reflexes for Continuous Physical Human-Robot Interaction
Robotics
Summary
Robots that work closely with humans need to react very quickly to changes, like unexpected touches or limits in their movements, without stopping what they’re doing. Current robot control systems usually pause to change how they respond, causing delays and interruptions. The authors developed a new control system that can switch its behavior in less than a millisecond without stopping the robot. This makes robots safer and smoother, reducing jerky motions and speeding up task completion.
What this means in practice
- •For industrial robot integrators: Enable robotic arms to safely and rapidly adapt control during human collaboration without stopping task execution.
- •For robotics software developers: Implement sub-millisecond control mode switching in ROS 2-based robots to improve safety and smoothness in manipulation tasks.
Authors
Jon Škerlj, Sami Haddadin
Abstract
Continuous physical human-robot interaction requires robots to rapidly adapt their control behaviour without interrupting task execution. However, existing ROS 2 control architectures rely on stop-to-switch mechanisms that introduce substantial delays and interrupt execution. We present an open-source, sub-millisecond reflex engine based on an enhanced ROS 2-compatible multimode controller that enables deterministic switching between control modalities and integrates reflex behaviours for mitigating contact hazards and kinematic limit violations. Experiments on a Franka Robotics manipulator demonstrate switching delays below 0.1 ms, more than four orders of magnitude faster than conventional ros2_control, while maintaining continuous operation during safety-critical events. In a multi-stage manipulation task, the proposed framework reduced execution time by 3.5% and peak trajectory jerk by more than threefold. By eliminating runtime middleware overhead, controller transitions are implemented as lock-free pointer operations, enabling reflex-level responsiveness within an open-source robotics framework.