A Novel Modular Cable-Driven Soft Robotic Arm with Multi-Segment Reconfigurability

Moeen Ul Islam; Cheng Ouyang; Xinda Qi; Azlan Zahid; Xiaobo Tan; Dong Chen

cs.ROMar 2, 2026

A Novel Modular Cable-Driven Soft Robotic Arm with Multi-Segment Reconfigurability

Authors: Moeen Ul Islam, Cheng Ouyang, Xinda Qi, Azlan Zahid, Xiaobo Tan, Dong Chen

Organizations: Department of Agricultural and Biological Engineering, Mississippi State University, MS, USA · Department of Electrical and Computer Engineering, Michigan State University, MI, USA · Texas A&M AgriLife Research and Extension Center in Dallas, Texas A&M University, TX, USA

Abstract

This paper presents a novel, modular, cable-driven soft robotic arm featuring multi-segment reconfigurability. The proposed architecture enables a stackable system with independent segment control, allowing scalable adaptation to diverse structural and application requirements. The system is fabricated from soft silicone material and incorporates embedded tendon-routing channels with a protective dual-helical tendon structure. Experimental results showed that modular stacking substantially expanded the reachable workspace: relative to the single-segment arm, the three-segment configuration achieved up to a 13-fold increase in planar workspace area and a 38.9-fold increase in workspace volume. Furthermore, this study investigated the effect of silicone stiffness on actuator performance. The results revealed a clear trade-off between compliance and stiffness: softer silicone improved bending flexibility, while stiffer silicone improved structural rigidity and load-bearing stability. These results highlight the potential of stiffness tuning to balance compliance and strength for configuring scalable, reconfigurable soft robotic arms.

Figures & tables

Fig. 1 : Fabrication process of the silicone-based, cable-driven soft robotic arm: (a) internal assembly components, (b) silicone molding process, and (c) final cured segment.

Panel of Figure 2 — Fig. 2 : Modular design and assembly of the soft robotic arm. (a) Exploded and assembled views of the actuation module. (b)–(d) Progressive assembly of one-, two-, and three-segment configurations.

Fig. 3 : Controller of the modular soft robotic arm: (a) control board for a single-segment system and (b) complete setup for three-segment actuation.

Fig. 4 : Experimental setup with soft robotic arm, tracking markers, motion capture cameras, and RGB camera.

Fig. 5 : Workspace evaluation of the modular soft robotic arm showing (a) single-, (b) two-, and (c) three-segment configurations. Each subplot presents the workspace envelope and corresponding maximum radial reach ( $R_{\max}$ ).

Configuration	$R_{\max}$ (mm)	Planar Area (mm 2 )	Workspace Volume (mm 3 )
One segment	51.3	8.26 $\times$ 10 3	4.94 $\times$ 10 5
Two segments	136.3	5.84 $\times$ 10 4	1.12 $\times$ 10 7
Three segments	184.4	1.07 $\times$ 10 5	1.92 $\times$ 10 7

TABLE I : Workspace evaluation of single- and multi-segment configurations.

Fig. 6 : Effect of payload on (a) bending angle, (b) tendon tension, and (c) vertical displacement across silicone stiffness levels.

Fig. 7 : Bending curvature and deformation of the modular soft robotic arm under varying payloads for different silicone stiffness levels. While Ecoflex-00-10 and Ecoflex-00-30 achieve higher bending angles, Ecoflex-00-50 exhibits greater linear displacement along the Z-axis, highlighting a clear trade-off between angular flexibility and vertical load-bearing deformation.

Fig. 8 : Effect of segment stacking on (a) bending angle and tendon tension and (b) vertical (Z-axis) displacement.

Soft Robotics

Soft robotics studies robots with compliant bodies and actuators that deform to move, sense, and interact with uncertain environments.

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VSL-Skin: Individually Addressable Phase-Change Voxel Skin for Variable-Stiffness and Virtual Joints Bridging Soft and Rigid Robots

Zihan Oliver Zeng, Jiajun An, Preston Luk, Upinder Kaur

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Robotics Soft Robotics

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Soft robots are compliant but often cannot support loads or hold their shape, while rigid robots provide structural strength but are less adaptable. Existing variable-stiffness systems usually operate at the scale of whole segments or patches, which limits precise control over stiffness distribution and virtual joint placement. This paper presents the Variable Stiffness Lattice Skin (VSL-Skin), the first system to enable individually addressable voxel-level morphological control with centimeter-scale precision. The system provides three main capabilities: nearly two orders of magnitude stiffness modulation across axial (15-1200 N/mm), shear (45-850 N/mm), bending (810^2 - 310^4 N/deg), and torsional modes with centimeter-scale spatial control; the first demonstrated 30% axial compression in phase-change systems while maintaining structural integrity; and autonomous component-level self-repair through thermal cycling, which eliminates fatigue accumulation and enables programmable sacrificial joints for predictable failure management. Selective voxel activation creates six canonical virtual joint types with programmable compliance while preserving structural integrity in non-activated regions. The platform incorporates closed-form design models and finite element analysis for predictive synthesis of stiffness patterns and joint placement. Experimental validation demonstrates 30% axial contraction, thermal switching in 75-second cycles, and cut-to-fit integration that preserves addressability after trimming. The row-column architecture enables platform-agnostic deployment across diverse robotic systems without specialized infrastructure. This framework establishes morphological intelligence as an engineerable system property and advances autonomous reconfigurable robotics.

Abstract

Soft Robotics

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