Massless Cable for Real‐time Simulation

Servin, Martin; Lacoursière, Claude

doi:10.1111/j.1467-8659.2007.01014.x

Cited by 20 publications

(17 citation statements)

References 11 publications

(17 reference statements)

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“…We introduce stretch and bend viscoelasticity based on conventional material. As was shown in [18] and [19] …”

Section: B the N-body Wire Constraintmentioning

confidence: 50%

“…The present model can easily be extended to include also constraints and elasticity for wire torsion [19]. If desired, the material parameters may be set arbitrarily stiff or soft to simulate unnatural materials as well.…”

Section: B the N-body Wire Constraintmentioning

confidence: 99%

“…The drawback of that approach is the lack of a stable and fast contact method to combine it with. Another attempt to remedy the high mass ratio instability is the quasistatic massless cable model presented in [19] which is a many-body constraint-carrying no mass elements at allthat constrains the motion of the rigid bodies in the system to preserve the total length between the wire endpoints and via an arbitrary number of intermediate eye nodes that, in effect, allow the bodies to slide along the wire. This approach was extended in [20] to include wire oscillations superimposed on the quasistatic wire and contacts modeled as pulleys with fixed positions.…”

Section: A Related Workmentioning

confidence: 99%

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Hybrid, Multiresolution Wires with Massless Frictional Contacts

Servin

Lacoursière

Nordfelth

et al. 2011

IEEE Trans. Visual. Comput. Graphics

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Abstract-We describe a method for the visual interactive simulation of wires contacting with rigid multibodies. The physical model used is a hybrid combining lumped elements and massless quasistatic representations. The latter is based on a kinematic constraint preserving the total length of the wire along a segmented path which can involve multiple bodies simultaneously and dry frictional contact nodes used for roping, lassoing and fastening. These nodes provide stick and slide friction along edges of the contacting geometries. The lumped element resolution is adapted dynamically based on local stability criteria, becoming coarser as the tension increases, and up to the purely kinematic representation. Kinematic segments and contact nodes are added and deleted and propagated based on contact geometries and dry friction configurations. The method gives dramatic increase on both performance and robustness because it quickly decimates superfluous nodes without loosing stability, yet adapts to complex configurations with many contacts and high curvature, keeping a fixed, large integration time step. Numerical results demonstrating the performance and stability of the adaptive multiresolution scheme are presented along with an array of representative simulation examples illustrating the versatility of the frictional contact model.

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“…We introduce stretch and bend viscoelasticity based on conventional material. As was shown in [18] and [19] …”

Section: B the N-body Wire Constraintmentioning

confidence: 50%

Section: B the N-body Wire Constraintmentioning

confidence: 99%

Section: A Related Workmentioning

confidence: 99%

See 1 more Smart Citation

Hybrid, Multiresolution Wires with Massless Frictional Contacts

Servin

Lacoursière

Nordfelth

et al. 2011

IEEE Trans. Visual. Comput. Graphics

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“…We currently have an experimental implementation of a massless cable based on work by Servin et al [33], [34]. The above data will help us ensure realistic dynamics, and we will conduct additional tests for the contact dynamics, both on individual cables and on complete robots.…”

Section: Discussionmentioning

confidence: 96%

Towards bridging the reality gap between tensegrity simulation and robotic hardware

Mirletz

Park

Quinn

et al. 2015

2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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Using a new hardware implementation of our designs for tunably compliant spine-like tensegrity robots, we show that the NASA Tensegrity Robotics Toolkit can effectively generate and predict desirable locomotion strategies for these many degree of freedom systems. Tensegrity, which provides structural integrity through a tension network, shows promise as a design strategy for more compliant robots capable of interaction with rugged environments, such as a tensegrity interplanetary probe prototype surviving multi-story drops. Due to the complexity of tensegrity structures, modeling through physics simulation and machine learning improves our ability to design and evaluate new structures and their controllers in a dynamic environment. The kinematics of our simulator, the open source NASA Tensegrity Robotics Toolkit, have been previously validated within 1.3% error on position through motion capture of the six strut robot ReCTeR. This paper provides additional validation of the dynamics through the direct comparison of the simulator to forces experienced by the latest version of the Tetraspine robot. These results give us confidence in our strategy of using tensegrity to impart future robotic systems with properties similar to biological systems such as increased flexibility, power, and mobility in extreme terrains.

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“…Therefore, they used a smaller spring coefficient or reduced the integration time step. To overcome the stiffness problem, Servin and Lacoursière (2007) chose the discrete Euler-Lagrange (DEL) equation, which is known to be stable despite a large spring coefficient.…”

Section: Related Studiesmentioning

confidence: 99%