Task-space model-based control of pneumatic soft actuators

Task-space model-based control of pneumatic soft actuators

|Authors: Nithin S. Kumar, Joshua Gaston, D. Caleb Rucker, Eric J. Barth

|Venue: arXiv preprint | Year: 2026

|arXiv: 2608.27186v1

Abstract

Soft actuators enable dexterous and compliant interaction, but closed-loop task-space control remains challenging due to strong nonlinearities, distributed deformation, and uncertainty in their dynamics. This paper presents a real-time dynamic-model-based task-space feedback and estimation framework based on a non-minimal coordinate discrete elastic rod model formulated in absolute coordinates with holonomic constraints. The resulting structure preserves distributed mechanics while maintaining computational efficiency through sparse system matrices, enabling real-time control with up to 10 discretized rods. A quasi-static feedforward inverse model is combined with a task-space PI controller and a dynamic observer that fuses measurement residuals as virtual forces, enabling full-state estimation from sparse sensing. The approach is experimentally validated on three planar pneumatic soft actuators with varying geometries. Across five tasks, including drawing the digits 0-9 across the workspace (3-18 mm/s tip speed), tracking periodic motion (up to 37 cm/s), cross-platform generalization, reduced sensing conditions, and real-time user-defined references, our method achieves 1.5-2.3 mm root mean square error (RMSE) for precision motions and 5.5-12.4 mm RMSE at 1-2 Hz. Results demonstrate that structured, non-minimal dynamic models can enable real-time, high-precision, moderate-bandwidth task-space control of planar soft pneumatic actuators in free space.

Key Contributions

• Soft actuators enable dexterous and compliant interaction, but closed-loop task-space control rem…
• This paper presents a real-time dynamic-model-based task-space feedback and estimation framework …
• The resulting structure preserves distributed mechanics while maintaining computational efficienc…
• A quasi-static feedforward inverse model is combined with a task-space PI controller and a dynami…
• The approach is experimentally validated on three planar pneumatic soft actuators with varying ge…

Topics

• manipulation
• control

Code & Data

No code repository linked in paper metadata.

BibTeX

@article{Kumar2026_260827186v1,
  title     = {Task-space model-based control of pneumatic soft actuators},
  author    = {Nithin S. Kumar and Joshua Gaston and D. Caleb Rucker and Eric J. Barth},
  year      = {2026},
  eprint    = {2608.27186v1},
  archivePrefix = {arXiv},
  primaryClass  = {cs.RO},
  url       = {https://arxiv.org/abs/2608.27186v1}
}