Cruciate-Ligament-Inspired Compliant Joints: Application to 3D-Printed Continuum Surgical Robots

The anterior cruciate ligament (ACL) is one of the most prone to injury in the human body. Due to its insufficient vascularization and low regenerative capacity, surgery is often required when it is ruptured. Most of the current tissue engineering (TE) strategies are based on scaffolds produced with fibers due to the natural ligament’s fibrous structure. In the present work, composite filaments based on poly(L-lactic acid) (PLA) reinforced with graphite nanoplatelets (PLA+EG) as received, chemically functionalized (PLA+f-EG), or functionalized and decorated with silver nanoparticles [PLA+((f-EG)+Ag)] were produced by melt mixing, ensuring good filler dispersion. These filaments were produced with diameters of 0.25 mm and 1.75 mm for textile-engineered and 3D-printed ligament scaffolds, respectively. The resulting composite filaments are thermally stable, and the incorporation of graphite increases the stiffness of the composites and decreases the electrical resistivity, as compared to PLA. None of the filaments suffered significant degradation after 27 days. The composite filaments were processed into 3D scaffolds with finely controlled dimensions and porosity by textile-engineered and additive fabrication techniques, demonstrating their potential for ligament TE applications.

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A Fully 3D-Printed Steerable Instrument for Minimally Invasive Surgery

Materials ◽

10.3390/ma14247910 ◽

2021 ◽

Vol 14 (24) ◽

pp. 7910

Author(s):

Costanza Culmone ◽

Kirsten Lussenburg ◽

Joost Alkemade ◽

Gerwin Smit ◽

Aimée Sakes ◽

...

Keyword(s):

Additive Manufacturing ◽

Surgical Instruments ◽

Drastic Reduction ◽

New Approach ◽

Single Procedure ◽

Compliant Joints ◽

Hand Control ◽

Final Design ◽

Grasping Force ◽

3D Printed

In the field of medical instruments, additive manufacturing allows for a drastic reduction in the number of components while improving the functionalities of the final design. In addition, modifications for users’ needs or specific procedures become possible by enabling the production of single customized items. In this work, we present the design of a new fully 3D-printed handheld steerable instrument for laparoscopic surgery, which was mechanically actuated using cables. The pistol-grip handle is based on ergonomic principles and allows for single-hand control of both grasping and omnidirectional steering, while compliant joints and snap-fit connectors enable fast assembly and minimal part count. Additive manufacturing allows for personalization of the handle to each surgeon’s needs by adjusting specific dimensions in the CAD model, which increases the user’s comfort during surgery. Testing showed that the forces on the instrument handle required for steering and grasping were below 15 N, while the grasping force efficiency was calculated to be 10–30%. The instrument combines the advantages of additive manufacturing with regard to personalization and simplified assembly, illustrating a new approach to the design of advanced surgical instruments where the customization for a single procedure or user’s need is a central aspect.

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A Continuously Tunable Stiffness Arm With Cable-Driven Mechanisms for Safe Physical Human-Robot Interaction

Volume 10: 44th Mechanisms and Robotics Conference (MR) ◽

10.1115/detc2020-22035 ◽

2020 ◽

Author(s):

Yu She ◽

Zhaoyuan Gu ◽

Siyang Song ◽

Hai-Jun Su ◽

Junmin Wang

Keyword(s):

Variable Stiffness ◽

Human Robot Interaction ◽

Robotic Arm ◽

Robot Arm ◽

Robot Interaction ◽

Safety Issues ◽

Compliant Joints ◽

Mechanical Compliance ◽

3D Printed ◽

Tunable Stiffness

Abstract In this paper, we present a continuously tunable stiffness arm for safe physical human-robot interactions. Compliant joints and compliant links are two typical solutions to address safety issues for physical human-robot interaction via introducing mechanical compliance to robotic systems. While extensive studies explore variable stiffness joints/actuators, variable stiffness links for safe physical human-robot interactions are much less studied. This paper details the design and modeling of a compliant robotic arm whose stiffness can be continuously tuned via cable-driven mechanisms actuated by a single servo motor. Specifically, a 3D printed compliant robotic arm is prototyped and tested by static experiments, and an analytical model of the variable stiffness arm is derived and validated by testing. The results show that the lateral stiffness of the robot arm can achieve a variety of 221.26% given a morphing angle of 90°. The study demonstrates that the compliant link design could be a promising approach to address safety concerns for safe physical human-robot interactions.

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Design, Modeling, and Manufacturing of a Variable Lateral Stiffness Arm via Shape Morphing Mechanisms

Journal of Mechanisms and Robotics ◽

10.1115/1.4050379 ◽

2021 ◽

pp. 1-15

Author(s):

Yu She ◽

Zhaoyuan Gu ◽

Siyang Song ◽

Hai-Jun Su ◽

Junmin Wang

Keyword(s):

Variable Stiffness ◽

Robotic Arm ◽

Lateral Stiffness ◽

Robot Arm ◽

Safety Issues ◽

Shape Morphing ◽

Compliant Joints ◽

Mechanical Compliance ◽

3D Printed ◽

Tunable Stiffness

Abstract In this paper, we present a continuously tunable stiffness arm for safe physical human-robot interactions. Compliant joints and compliant links are two typical solutions to address safety issues for physical human-robot interactions via introducing mechanical compliance to robotic systems. While extensive studies explore variable stiffness joints/actuators, variable stiffness links for safe physical human-robot interactions are much less studied. This paper details the design and modeling of a compliant robotic arm whose stiffness can be continuously tuned via cable-driven mechanisms actuated by a single servo motor. Specifically, a 3D printed compliant robotic arm is prototyped and tested by static experiments, and an analytical model of the variable stiffness arm is derived and validated by testing. The results show that the lateral stiffness of the robot arm can achieve a variety of 221.26 % given a morphing angle of 90°. The variable stiffness arm design developed in this study could be a promising approach to address safety concerns for safe physical human-robot interactions.

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