A General Friction Model of Discrete Interactions for Tendon Actuated Dexterous Manipulators

Gao, Anzhu; Zou, Yuan; Wang, Zhidong; Liu, Hao

doi:10.1115/1.4036719

Cited by 30 publications

(10 citation statements)

References 19 publications

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“…It would be advantageous to account for the effects of stiction/friction and slack within the model, as this would improve the repeatability of the continuum robot control as the desired tip position will most commonly be reached from an undeformed backbone position. The friction occurring between the tendons and the routing holes could be modeled as Coulomb/dry friction, and will effect the moment applied to the backbone tip Yuan et al (2019) , Gao et al (2017) . However, there will also be cases where decreasing the tension to the desired value is required and so reduction of the inherent tendon friction of the continuum robot should also be pursued.…”

Section: Discussionmentioning

confidence: 99%

An Integrated Kinematic Modeling and Experimental Approach for an Active Endoscope

2021

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Continuum robots are a type of robotic device that are characterized by their flexibility and dexterity, thus making them ideal for an active endoscope. Instead of articulated joints they have flexible backbones that can be manipulated remotely, usually through tendons secured onto structures attached to the backbone. This structure makes them lightweight and ideal to be miniaturized for endoscopic applications. However, their flexibility poses technical challenges in the modeling and control of these devices, especially when closed-loop control is needed, as is the case in medical applications. There are two main approaches in the modeling of continuum robots, the first is to theoretically model the behavior of the backbone and the interaction with the tendons, while the second is to collect experimental observations and retrospectively apply a model that can approximate their apparent behavior. Both approaches are affected by the complexity of continuum robots through either model accuracy/computational time (theoretical method) or missing complex system interactions and lacking expandability (experimental method). In this work, theoretical and experimental descriptions of an endoscopic continuum robot are merged. A simplified yet representative mathematical model of a continuum robot is developed, in which the backbone model is based on Cosserat rod theory and is coupled to the tendon tensions. A robust numerical technique is formulated that has low computational costs. A bespoke experimental facility with precise automated motion of the backbone via the precise control of tendon tension, leads to a robust and detailed description of the system behavior provided through a contactless sensor. The resulting facility achieves a real-world mean positioning error of 3.95% of the backbone length for the examined range of tendon tensions which performs favourably to existing approaches. Moreover, it incorporates hysteresis behavior that could not be predicted by the theoretical modeling alone, reinforcing the benefits of the hybrid approach. The proposed workflow is theoretically grounded and experimentally validated allowing precise prediction of the continuum robot behavior, adhering to realistic observations. Based on this accurate estimation and the fact it is geometrically agnostic enables the proposed model to be scaled for various robotic endoscopes.

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Section: Discussionmentioning

confidence: 99%

An Integrated Kinematic Modeling and Experimental Approach for an Active Endoscope

2021

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“…However, in cases where friction cannot be ignored, an additional frictional force acting perpendicular to the disk needs to be included in the force balance equations. There are various tension propagation models ( Jung et al, 2011 ; Kato et al, 2016 ; Gao et al, 2017 ; Yuan et al, 2019 ) that can be adapted for use in such situations.…”

Section: Static Modellingmentioning

confidence: 99%

“…Consequently, the model uses variable curvature representation. We consider each subsegment as a rod experiencing tip forces and moments due to tendon interaction at each disk’s location, as done in Gao et al (2017) . Doing so allows us to model the behaviour of the partially constrained tendon path resulting from the use of spacer disks.…”

Section: Comparison Of Tdcr Models and Guidelinesmentioning

confidence: 99%

How to Model Tendon-Driven Continuum Robots and Benchmark Modelling Performance

et al. 2021

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Tendon actuation is one of the most prominent actuation principles for continuum robots. To date, a wide variety of modelling approaches has been derived to describe the deformations of tendon-driven continuum robots. Motivated by the need for a comprehensive overview of existing methodologies, this work summarizes and outlines state-of-the-art modelling approaches. In particular, the most relevant models are classified based on backbone representations and kinematic as well as static assumptions. Numerical case studies are conducted to compare the performance of representative modelling approaches from the current state-of-the-art, considering varying robot parameters and scenarios. The approaches show different performances in terms of accuracy and computation time. Guidelines for the selection of the most suitable approach for given designs of tendon-driven continuum robots and applications are deduced from these results.

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“…For the free bending configuration, the sliding status can be determined using the calibration method 20,46 by comparing the current cable profile along the whole continuum manipulator with its previous one; while for the loaded bending configuration, the sliding status can be determined by comparing the current cable location with the previous cable location, where the sticking status is ignored. Details can be found in the algorithms of appendixes.…”

Section: Friction Model and Tension Propagationmentioning

confidence: 99%

Laser-Profiled Continuum Robot with Integrated Tension Sensing for Simultaneous Shape and Tip Force Estimation

et al. 2020

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The development of miniaturised continuum robots has a wide range of applications in minimally invasive endoluminal interventions. In order to navigate inside tortuous lumens without impinging on the vessel wall and causing tissue damage or the risk of perforation, it is necessary to have simultaneous shape sensing of the continuum robot and its tip contact force sensing with the surrounding environment. Miniaturisation and size constraint of the device have precluded the use of conventional sensing hardware and embodiment schemes. In this paper, we propose the use of optical fibres for both actuation and tension/shape/force-sensing. It uses a model-based method with structural compensation, allowing direct measurement of the cable tension near the base of the manipulator without increasing the dimensions. It further structurally filters out disturbances from the flexible shaft. In addition, a model is built by considering segment differences, cable interactions/cross talks and external forces. The proposed model-based method can simultaneously estimate the shape of the manipulator and external force applied onto the robot tip. Detailed modelling and validation results demonstrate the accuracy and reliability of the proposed method for the miniaturised continuum robot for endoluminal intervention.

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A General Friction Model of Discrete Interactions for Tendon Actuated Dexterous Manipulators

Cited by 30 publications

References 19 publications

An Integrated Kinematic Modeling and Experimental Approach for an Active Endoscope

An Integrated Kinematic Modeling and Experimental Approach for an Active Endoscope

How to Model Tendon-Driven Continuum Robots and Benchmark Modelling Performance

Laser-Profiled Continuum Robot with Integrated Tension Sensing for Simultaneous Shape and Tip Force Estimation

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