Continuum Robot Stiffness Under External Loads and Prescribed Tendon Displacements

Oliver-Butler, Kaitlin; Till, John; Rucker, D. Caleb

doi:10.1109/tro.2018.2885923

Cited by 130 publications

(52 citation statements)

References 30 publications

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“…To evaluate the physical realism of the tendon robot dynamic model, a robot was constructed from a spring steel backbone with acrylic spacer disks and a single Kevlar tendon, shown in Figure 15. The tendon displacement is controlled by a geared servo motor (Dynamixel MX-28-AT), which is a prescribed-displacement actuation setup as recently studied by Oliver-Butler et al (2019). A step input (shown in Figure 15) is applied to pull the robot upward, then after a steady state is reached, another step input is applied to return to the original tendon displacement as shown in Figure 15.…”

Section: Cable-driven Robotsmentioning

confidence: 99%

Real-time dynamics of soft and continuum robots based on Cosserat rod models

Till

Aloi

Rucker

2019

The International Journal of Robotics Research

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255

185

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The dynamic equations of many continuum and soft robot designs can be succinctly formulated as a set of partial differential equations (PDEs) based on classical Cosserat rod theory, which includes bending, torsion, shear, and extension. In this work we present a numerical approach for forward dynamics simulation of Cosserat-based robot models in real time. The approach implicitly discretizes the time derivatives in the PDEs and then solves the resulting ordinary differential equation (ODE) boundary value problem (BVP) in arc length at each timestep. We show that this strategy can encompass a wide variety of robot models and numerical schemes in both time and space, with minimal symbolic manipulation required. Computational efficiency is gained owing to the stability of implicit methods at large timesteps, and implementation is relatively simple, which we demonstrate by providing a short MATLAB-coded example. We investigate and quantify the tradeoffs associated with several numerical subroutines, and we validate accuracy compared with dynamic rod data gathered with a high-speed camera system. To demonstrate the method’s application to continuum and soft robots, we derive several Cosserat-based dynamic models for robots using various actuation schemes (extensible rods, tendons, and fluidic chambers) and apply our approach to achieve real-time simulation in each case, with additional experimental validation on a tendon robot. Results show that these models capture several important phenomena, such as stability transitions and the effect of a compressible working fluid.

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Section: Cable-driven Robotsmentioning

confidence: 99%

Real-time dynamics of soft and continuum robots based on Cosserat rod models

Till

Aloi

Rucker

2019

The International Journal of Robotics Research

Self Cite

255

185

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“…The CC model requires the tendon forces to be converted to the resulting tendon displacements for it to be solved. To do this conversion, the robot shape is computed with the VC model and the corresponding tendon length is deduced from the path followed by the tendons along the backbone ( Oliver-Butler et al, 2019 ). The length of tendon k is written as

…”

Section: Methodsmentioning

confidence: 99%

“…While in theory, the tendons can be employed using many different routing paths along the backbone, e.g. helical ( Starke et al, 2017 ) or converging ( Oliver-Butler et al, 2019 ) paths, we focus on generalising models for straight tendon routing throughout this work as the most common routing method employed. For each segment, any number of tendons can be employed and routed along the robot’s backbone, while at least two are needed to allow for bending in one degree of freedom (planar bending) and three for bending in two degrees of freedom (spatial bending), respectively.…”

Section: Mechanical Structure Of Tdcrmentioning

confidence: 99%

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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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“…we describe the rope path. There are studies of bending motion by using ropes [12] [13]. In these studies, ropes are placed along the arm using rope guides, and the bending moment is generated by winding up the rope attached the tip position of arm.…”

Section: A Designmentioning

confidence: 99%

Tendon-driven Elastic Telescopic Arm -Integration of Linear Motion and Bending Motion-

Ogawa

Fujioka

Nabae

et al. 2020

2020 IEEE/SICE International Symposium on System Integration (SII)

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The telescopic structure has a high extension-tocontraction ratio and is suitable for using a long manipulator that reduces the size of the structure because it is lightweight and small in diameter. There is a problem that conventional telescopic structures are only used in an open environment because it can not avoid obstacles on the axis of extension. In this paper, we propose a linear mechanism that can extend and contract one node at a time by a linear movement mechanism using a slide screw, and clarify its effectiveness by experiments. In addition, we control the tip position of the arm by the rope winding length and discuss the accuracy quantitatively. In addition, by integrating the linear mechanism and the bending mechanism, we achieved the linear motion while avoiding obstacles on the axis of extension.

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Continuum Robot Stiffness Under External Loads and Prescribed Tendon Displacements

Cited by 130 publications

References 30 publications

Real-time dynamics of soft and continuum robots based on Cosserat rod models

Real-time dynamics of soft and continuum robots based on Cosserat rod models

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

Tendon-driven Elastic Telescopic Arm -Integration of Linear Motion and Bending Motion-

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