Tension Dependent Twisted String Actuator Modelling and Efficacy Benchmarking in Force and Impedance Control
Herneth, Christopher Cheng, Yi Ganguly, Amartya Haddadin, Sami
Herneth, Christopher
Cheng, Yi
Ganguly, Amartya
Haddadin, Sami
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Department
Robotics
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Type
Conference proceeding
Date
2025
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Language
English
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Abstract
This study presents a comprehensive experimental analysis of Twisted String Actuators (TSA), focused on enhancing contraction modelling accuracy and establishing a baseline for TSA tension and impedance control efficacy. A novel TSA string radius function is introduced, computing effective radii for multi-strand bundles based on axial actuator tension. The proposed model was validated in physical experiments, resulting in a reduction of maximal errors between measured and simulated actuator contraction trajectories from up to 60 % in established models to around 10% in our work. Additionally, the tension-dependent radius modification effectively reduced errors between the estimated and the measured bundle tension by an order of magnitude, marking an essential step towards TSA control independent of bundle tension measurements. TSA tension control was assessed based on four metrics: accu-racy, precision, impact stability, and bandwidth, following ISO 9283:1998 standards. The quality of tension control was found to be dependent on bundle tension, twisting angle and strand quantity, whereas impact stability was maintained in all config-urations. Joint impedance control with TSA was evaluated for perturbation stability and position control bandwidth, where the latter was enhanced with increasing joint stiffness. The presented analysis informs designers about the capabilities of TSAs in different configurations, and their respective suitability for desired applications.
Citation
C. Herneth, Y. Cheng, A. Ganguly and S. Haddadin, "Tension Dependent Twisted String Actuator Modelling and Efficacy Benchmarking in Force and Impedance Control," 2025 IEEE International Conference on Robotics and Automation (ICRA), Atlanta, GA, USA, 2025, pp. 5075-5081, doi: 10.1109/ICRA55743.2025.11127389.
Source
International Conference on Robotics and Automation (ICRA)
Conference
2025 IEEE International Conference on Robotics and Automation (ICRA)
Keywords
Actuators, Computational Modeling, Stability Criteria, Measurement Uncertainty, Position Control, Bandwidth, Trajectory, Impedance, Robotics and Automation, Standards
Subjects
Source
2025 IEEE International Conference on Robotics and Automation (ICRA)
Publisher
IEEE