Fully-Printable Soft Actuator with Variable Stiffness by Phase Transition and Hydraulic Regulations

Actuators

Manivannan Sivaperuman Kalairaj¹  Catherine Jiayi Cai¹  Zion Tsz Ho Tse²  Tingchen Liao³  Hongliang Ren³ 

[1] Department of Biomedical Engineering, National University of Singapore, Singapore 117575, Singapore;Department of Electronic Engineering, University of York, Heslington, York YO10 5DD, UK;NUSRI Suzhou, Suzhou 215123, China;

关键词: shape memory polymers;    hydraulic actuators;    valves;    soft actuators;    variable stiffness;    soft gripper;   

DOI  :  10.3390/act10100269

来源: DOAJ

【 摘 要 】

Actuators with variable stiffness have vast potential in the field of compliant robotics. Morphological shape changes in the actuators are possible, while they retain their structural strength. They can shift between a rigid load-carrying state and a soft flexible state in a short transition period. This work presents a hydraulically actuated soft actuator fabricated by a fully 3D printing of shape memory polymer (SMP). The actuator shows a stiffness of 519 mN/mm at 20 ${}^{\circ }$C and 45 mN/mm at 50 ${}^{\circ }$C at the same pressure (0.2 MPa). This actuator demonstrates a high stiffness variation of 474 mN/mm (10 times the baseline stiffness) for a temperature change of 30 ${}^{\circ }$C and a large variation (≈1150%) in average stiffness. A combined variation of both temperature (20–50 ${}^{\circ }$C) and pressure (0–0.2 MPa) displays a stiffness variation of 501 mN/mm. The pressure variation (0–0.2 MPa) in the actuator also shows a large variation in the output force (1.46 N) at 50 ${}^{\circ }$C compared to the output force variation (0.16 N) at 20 ${}^{\circ }$C. The pressure variation is further utilized for bending the actuator. Varying the pressure (0–0.2 MPa) at 20 ${}^{\circ }$C displayed no bending in the actuator. In contrast, the same variation of pressure at 50 ${}^{\circ }$C displayed a bending angle of 80${}^{\circ }$. A combined variation of both temperature (20–50 ${}^{\circ }$C) and pressure (0–0.2 MPa) shows the ability to bend 80${}^{\circ }$. At the same time, an additional weight (300 g) suspended to the actuator could increase its bending capability to 160${}^{\circ }$. We demonstrated a soft robotic gripper varying its stiffness to carry various objects.

【 授权许可】

Unknown