Safety-critical bilateral teleoperation for omnidirectional aerial manipulation using force-sensorless haptic feedback

📃 Abstract: This paper presents a safety-critical bilateral teleoperation framework for omnidirectional aerial manipulators that integrates visual and force-sensorless haptic wrench feedback. Unlike existing approaches that either rely on onboard force/torque sensors or use model-dependent wrench estimates, which may become unreliable under model uncertainties or induce unintended feedback during free-flight, our method implements a hierarchical safety filter based on control barrier functions to avoid such limitations. The safety filter, being the key contribution, explicitly accounts for tracking errors arising from physical interaction between the aerial manipulator and its surroundings while enforcing thrust limits, a factor overlooked despite its critical importance for flight safety. This safety filter adjusts the command from the operator to ensure safe and stable aerial manipulation and evade motor saturation. The adjustment made by the filter is mapped to haptic feedback, which is intuitive to the operator and conveys information on physical interaction and impending motor saturation. By actual experiments with a hexarotor-based omnidirectional aerial manipulator, we demonstrate that the proposed method avoids haptic feedback during free-flight, provides directionally consistent feedback under physical interaction, and can be operated for diverse manipulative tasks. Moreover, an ablation study further shows that the saturation filter improves interaction stability by explicitly preventing motor saturation and informing the operator of corrective actions.

✊ Motivation: Addressing key limitations in bilateral teleoperation for omnidirectional aerial physical interaction (APhI):
❗ Existing haptic-feedback approaches often require onboard force/torque (FT) sensors or model-dependent wrench estimation, which can become unreliable under model uncertainties and generate unintended feedback even during free-flight
❗ Motor thrust limits are critical for flight safety during physical interaction, yet they are rarely considered in existing bilateral teleoperation frameworks

💡 Main contributions:

✔️ Force-sensorless bilateral teleoperation framework for omnidirectional aerial manipulation, integrating both visual and haptic feedback without requiring FT sensors on either the aerial manipulator or the master device
✔️ Two-stage hierarchical CBF-based safety filter that modifies the operator’s command according to tracking errors caused by physical interaction and motor thrust constraints
✔️ Interaction filter that limits position and attitude tracking errors and converts the resulting command adjustment into intuitive, directionally consistent haptic feedback, without explicitly estimating the interaction wrench
✔️ Saturation filter that explicitly enforces individual motor thrust limits and prevents motor saturation by minimally modifying the desired motion command
✔️ Filter corrections mapped directly to haptic wrench feedback, allowing the operator to perceive both physical interaction and impending motor saturation together with the direction of the required corrective action
✔️ No unintended haptic feedback during free-flight, unlike a momentum-based wrench-estimation baseline that exhibits estimation drift and consequently generates undesired motion commands
✔️ Real-world validation on a hexarotor-based omnidirectional aerial manipulator through cart pulling, plug pulling, push-and-slide, and pick-and-place experiments, demonstrating directionally coherent feedback and applicability to both static and dynamic physical interaction tasks
✔️ Ablation study validating the saturation filter, showing that explicitly preventing motor saturation suppresses destabilizing motion and simultaneously provides haptic cues that guide the operator away from unsafe commands

Bibtex

@INPROCEEDINGS{kim2026safety,
  author={Kim, Yubin and Lee, Jinwoo and Lee, Yongjun and Kim, H. Jin and Byun, Jeonghyun},
  booktitle={2026 IEEE/RSJ International Conference on Intelligent Robots & Systems (IROS)}, 
  title={Safety-critical bilateral teleoperation for omnidirectional aerial manipulation using force-sensorless haptic feedback}, 
  year={2026},
  volume={},
  number={},
  pages={},
  keywords={},
  doi={}}