3D printed soft actuator with built-in force sensing and bending
A Monolithic Force-Proprioception Soft Acutuator Enabled by Single-Material 3D printing
Robotics
Summary
Soft robots need to bend and sense forces to work safely and accurately. The authors created a soft bending actuator that can both move and feel how much force it is applying using just one material and one 3D printing step. They used a special conductive plastic that changes electrical resistance when stretched to sense how the actuator bends and the force it exerts. Their device bends up to 40 degrees, pushes with 12.5 newtons of force, and detects forces up to 45 newtons reliably. They also built a two-finger gripper using this actuator that can grasp objects while sensing the force applied.
What this means in practice
- •For roboticists: Build soft robot grippers that sense how much force they use while bending, enhancing delicate manipulation.
- •For 3d printing engineers: Produce integrated soft actuators and sensors in one printing step using conductive TPU without assembly or multiple materials.
- •For prosthetics developers: Design prosthetic fingers with built-in self-sensing soft actuators to measure grip force without extra sensors.$Commercial implications: Enables compact, integrated prosthetic components with sensing and actuation from single-material 3D prints for better device cost and reliability.
Authors
Nan Huang, Lele Liu, Junfeng Lu, Yipan Zhu, Jiansheng Dai, Sicong Liu
Abstract
Pneumatic proprioceptive actuators integrate actuation and sensing for soft robots that attract interest due to functional potential. Existing approaches often suffer from assembly errors or stress concentrations caused by heterogeneous materials. In this work, we propose the Monolithic Force-Proprioception Soft (MFPS) design and fabrication method that integrates an Asymmetric Origami Bending (AOB) chamber and a Force-Proprioception Soft (FPS) sensor with single material through one-step Fused Deposition Modeling (FDM) fabrication. Based on the resistance response to strain of conductive thermoplastic polyurethane (TPU), we design and analyze the structure of the FPS sensor, and conduct parametric analysis on the sensing characteristics. The FDM fabrication parameters of the MFPS actuator are analyzed, followed by actuator fabrication and characterization of the actuation and proprioception performance. Experimental results show that the MFPS actuator achieves a bending angle of 40°, an output force of 12.5 N, and a resistance change of 26.9% as the applied external force increased from 0 to 45 N. A two-finger force-proprioception gripper is developed based on the MFPS actuator. The grasping and force-proprioception capabilities are experimentally validated, proving that the MFPS design method provides a new approach for the development of self-sensing actuators.