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Peng et al. Soft Sci. 2025, 5, 38 Soft Science
DOI: 10.20517/ss.2025.31

Research Article Open Access

Load-adaptive shape sensing and control of a

tendon-driven continuum robot actuated by SMA
springs

1,*
2
1
1
Yuxuan Peng , Jing Bian , Jingjing Ji , Junfeng Li , YongAn Huang 2,*
1
School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China.
2
State Key Laboratory of Intelligent Manufacturing Equipment and Technology, Huazhong University of Science and Technology,
Wuhan 430074, Hubei, China.
* Correspondence to: Assoc. Prof. Junfeng Li, School of Mechanical and Electronic Engineering, Wuhan University of Technology,
Luoshi Road 122, Wuhan 430070, Hubei, China. E-mail: jflichina@whut.edu.cn; Prof. YongAn Huang, State Key Laboratory of
Intelligent Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan
430074, Hubei, China. E-mail: yahuang@hust.edu.cn
How to cite this article: Peng, Y.; Bian, J.; Ji, J.; Li, J.; Huang, Y. Load-adaptive shape sensing and control of a tendon-driven
continuum robot actuated by SMA springs. Soft Sci. 2025, 5, 38. https://dx.doi.org/10.20517/ss.2025.31

Received: 16 Jun 2025 First Decision: 16 Jul 2025 Revised: 28 Jul 2025 Accepted: 4 Aug 2025 Published: 18 Aug 2025
Academic Editor: Carlo Massaroni Copy Editor: Pei-Yun Wang Production Editor: Pei-Yun Wang

Abstract
In this paper, a load-adaptive continuum robot with accurate shape sensing and control capabilities through tendon
tension modulation is presented. First, three shape memory alloy (SMA) springs actuate the bioinspired continuum
robot to achieve 3D deformation. Second, the bending shape can be accurately estimated in real time using the
tensions of the SMA springs based on the forward kinematics of a modified Cosserat model that considers friction
between the tendons and disks. For a desired position, the required tensions of the SMA springs can be obtained
using the inverse kinematics of the proposed model. Finally, a closed-loop control method is implemented to test
the continuum robot’s shape control performance. Experiments demonstrate that the robot exhibits accurate
tracking results for different complex trajectories, both with and without an external load at the end effector, based
on the proposed model’s forward and inverse kinematics. In conclusion, SMA actuation combined with tension
feedback control enables accurate load-bearing capacity, shape sensing, and position tracking, representing a
promising approach for developing future design guidelines for continuum robots.

Keywords: Continuum robots, shape sensing, Cosserat rod theory, load-adaptive

INTRODUCTION
Many slender organs and animals, such as a monkey’s tail, snakes, and an elephant’s trunk, as shown in

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