A continuum manipulator for continuously variable stiffness and its stiffness control formulation

Zhao, Bin; Zeng, Lingqi; Wu, Zhonghao; Xu, Kai

doi:10.1016/j.mechmachtheory.2019.103746

Cited by 45 publications

(11 citation statements)

References 20 publications

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“…Units locking [41] \ \ \ 3.2 0.6N (47.5%) \ 13 mm 1 (\) \ FE Cable tension [43] \ AE180°7.87% (R) Approximately 2.5 2.5N (7.7%) \ 15.9 mm 1 (1) ϕ9.86 mm FE Tube insertion [44] 2.72%(F) AE180°\ 10.83 \ 2s(R!F) 7.4 mm 0 \ SPS 3s(F!R) Granular jamming [49] 3.75%(F) AE90°\…”

Section: Structurebased Methodsmentioning

confidence: 99%

“…Their prototypes typically require an energy exchanger, resulting in larger joint diameters, poor biocompatibility, and high leakage risks. The other solution for stiffness adjustment is structure-based technologies, including unit-locking mechanisms, [41,42] antagonistic arrangements, [43][44][45][46][47][48] jamming-based methods, [49][50][51][52][53] etc. The unit-locking mechanisms commonly adjust the stiffness by reorganizing the mechanical engagement among internal discrete structural units.…”

Section: Introductionmentioning

confidence: 99%

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A Novel Distal Hybrid Pneumatic/Cable‐Driven Continuum Joint with Variable Stiffness Capacity for Flexible Gastrointestinal Endoscopy

Luo

Song

Zhang

et al. 2023

Advanced Intelligent Systems

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The robot‐assisted flexible access surgery represented by the emerging robot‐assisted flexible endoscopy (FE) and natural orifice transluminal endoscopic surgery demands flexible and continuum manipulators instead of the rigid and straight instruments in the traditional minimally invasive surgery (MIS). These flexible manipulators are required to advance through the tortuous and narrow anatomic paths via natural orifices for dexterous diagnostic examination and therapeutic operations. Therefore, developing flexible endoscopic manipulators with the capacity of snake‐like movements for flexible access and variable stiffness regulation for operations to address these flexible access surgical difficulties is demanding but remains challenging. To address such challenges, herein, it is proposed that a novel distal continuum joint based on the hybrid pneumatic and cable‐driven approach achieves variable stiffness capacity, excellent bending characteristics in both flexible and rigid states, satisfactory motion consistency and shape‐locking ability during the rigid‐flexible transition, and relatively high loading capacity for flexible gastrointestinal endoscopic robots. Characterization experiments validate these performances, and phantom and ex vivo experiments have been performed to demonstrate the feasibility and effectiveness for FE. The presented method demonstrates an effective and practical approach to enabling continuum robots with both flexible access and tunable stiffness capacity and supports a convenient extension for MIS applications.

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Section: Structurebased Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Novel Distal Hybrid Pneumatic/Cable‐Driven Continuum Joint with Variable Stiffness Capacity for Flexible Gastrointestinal Endoscopy

Luo

Song

Zhang

et al. 2023

Advanced Intelligent Systems

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“…Continuum robots are suitable for running in non-structural environments and can perform better in human interaction scenes, which can be applied in many fields such as disaster relief [16], minimally inva-sive surgery [17][18][19][20][21], space inspection [22,23], and nuclear fusion vessel maintenance [24]. According to the structural characteristics, continuum robots can be divided into single-backbone continuum robots [25,26], multi-backbone continuum robots [27][28][29][30], and concentric-tube continuum robots [31,32]. Their motion forms are mostly manifested in spatial extension and contraction, and bending in all directions [33][34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Design and kinematic of a dexterous bioinspired elephant trunk robot with variable diameter

et al. 2022

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How to further improve the dexterity of continuum robots so that they can quickly change their structural size like flexible biological organs is a key challenge in the field of robotics. To tackle this dexterity challenge, this paper proposes a soft-rigid coupled bioinspired elephant trunk robot with variable diameter, which is enabled by combining a soft motion mechanism with a novel rigid variable-diameter mechanism (double pyramid deployable mechanism). The integration of these two mechanisms has produced three significant beneficial effects: i) The coexistence of multi-degree-of-freedom motion capability and variable size function greatly improves the dexterity of the elephant trunk robot. ii) The motion refinement can be improved by structural amplification, making up for the low resolution of soft actuators. iii) Its stiffness can be increased by enlarging its diameter, while its reachable workspace can be increased by decreasing its diameter. Thus, the elephant trunk robot can optimize its performance when facing different tasks by opening and closing the rigid variable-diameter mechanism. Further, we established a kinematic model of the elephant trunk robot by the structure discretization method and the principle of mechanism equivalence, and experimentally verified its reasonableness. The demonstration experiments show that the elephant trunk robot has good flexibility. This work provides a new variable diameter configuration for continuum robots, and presents a method of how to analyze the kinematics of continuum mechanisms using rigid mechanism theory.

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“…Regarding the variable stiffness mechanism, there are mainly three ways to change the stiffness. First, changing the mechanical structure 15 adjusts the stiffness, which depends on the mechanical motion, mostly using variable pivot point levers to adjust the stiffness, utilising the end of the cantilever beam to adjust the stiffness, 16 etc. Second, exploiting the nonlinear characteristics of the force‐deformation ratio adjusts the stiffness, which means some nonlinear force‐deformation ratio elastic components can be introduced.…”

Section: Introductionmentioning

confidence: 99%

Design and simulation verification of clamping instrument with active variable stiffness for pelvic fracture reduction

CHEN

Lei

CAI

et al. 2022

Robotics Computer Surgery

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Background: During the robot-assisted pelvic fracture reduction process, the clamping instrument are subjected to the large reduction force from the robot, resulting in inevitable great stress concentration and deformation of the bone pins, affecting the fracture reduction accuracy. Method:A compact and easily-to-adjust clamping instrument with active variable stiffness is designed. The relationship between the component's elongation and the clamping instrument's deformation and stiffness is derived and calculated.Furthermore, the finite element model of the fixed and the variable stiffness clamping instruments connecting with the injured pelvic musculoskeletal tissue is developed, respectively.Results: Applying the same reduction force, the deformation of the clamping instrument with variable stiffness is reduced, especially in the elongated state.Moreover, the new clamping instrument meets the strength requirements and makes a better stress distribution. Conclusion:The clamping instrument can achieve stiffness adjustment during the reduction process and will be used for improving the surgery accuracy.

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A continuum manipulator for continuously variable stiffness and its stiffness control formulation

Cited by 45 publications

References 20 publications

A Novel Distal Hybrid Pneumatic/Cable‐Driven Continuum Joint with Variable Stiffness Capacity for Flexible Gastrointestinal Endoscopy

A Novel Distal Hybrid Pneumatic/Cable‐Driven Continuum Joint with Variable Stiffness Capacity for Flexible Gastrointestinal Endoscopy

Design and kinematic of a dexterous bioinspired elephant trunk robot with variable diameter

Design and simulation verification of clamping instrument with active variable stiffness for pelvic fracture reduction

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