Geometric Recursive Dynamic Modelling and Simulation of Soft Robotic Systems

A new method of multibody system dynamics, named discrete time transfer matrix method of multibody system (MS-DT-TMM) is developed and widely used in engineering field in recent years. When using this method for the problems of multibody system dynamics, the global dynamics equations of the system are not needed and the orders of involved system matrices are always small. The advance in MS-DT-TMM in recent years has been studied in this paper as following: 1 Discrete time transfer matrix method of rigid-flexible multibody system is developed to study rigid-flexible multibody system dynamics. 2 Mixed method of MS-DT-TMM and finite element method is developed to study rigid-flexible multibody system dynamics. 3 Mixed method of MS-DT-TMM and multibody system dynamics method is developed to study rigid-flexible multibody system dynamics. 4 Riccati discrete time transfer matrix method of multibody system is developed to increase the computation speed and the computation stability. 5 Discrete time transfer matrix method of controlled multibody system is developed to study dynamics of controlled multibody system. Several corresponding numerical examples are done to validate these proposed methods. All this implies that the proposed methods provide a powerful tool for the study of multibody system dynamics.

Multibody systems in planar motion are modelled as two or more rigid components that are connected and can move relative to each other. The dynamics of such multibody systems in planar motion in a central gravitational force field is analysed. The equations of motion of the system include the equations for the orbital motion of the bodies, the orientation (attitude) of the assembly, and the relative orientation (shape) of the bodies with respect to each other. Dynamic coupling between these degrees of freedom gives rise to complex dynamical systems that are usually not integrable. Relative equilibria, corresponding to circular orbits of the multibody system, are obtained. The free dynamics has a symmetry due to a cyclic coordinate. Routh reduction is carried out to eliminate this coordinate and obtain the reduced dynamics. The stability of the relative equilibria is analysed using the Routh stability criterion when it is applicable; an expansion of the Hamiltonian in normal form is used otherwise. We apply the general results to a multibody system consisting of two hinged planar bodies, each modelled as a rigid massless link with a point mass at one end with their other ends connected by a hinge joint. We obtain the relative equilibria of this model, and carry out a stability analysis for the relative equilibria. Numerical simulations using a symplectic integrator are carried out for perturbations to these relative equilibria, to confirm their stability properties.

In large, rigid multibody dynamics problems with friction and contact, encountered for instance in granular flows, one can witness distinctly different system-level dynamics. This contribution concentrates on the case of fluid-like behavior of large multibody dynamics systems such as granular materials, when the system experiences large strains. The results reported herein draw on computer simulation; on the one hand, we solve the Newton-Euler equations of motion, which govern the evolution of multibody dynamics system featuring frictional contact. On the other hand, we solve the Navier-Stokes equations which describe the time evolution of fluids. To demonstrate the similarities and differences between the multibody and fluid dynamics we consider three problems modeled and solved using different methods; (i) a compressibility test; (ii) the classical dam break problem, and (iii) the dam break simulation with an obstacle. These experiments provide insights into conditions under which on can expect similar characteristics from multibody and fluid dynamics systems governed by manifestly different equations of motion and solved by vastly different numerical solution methods. The models and simulation platform used are publicly available and part of an open source code called Chrono. Both the multibody and fluid dynamics simulations are carried out using GPU computing.

Data standardization is still an open research field in multibody system (MBS) dynamics, and the lack of a standard neutral data format to encode information about MBS models (topology, geometry, rigid and flexible body data, applied forces, type of analysis, …) hinders the exchange and share of models between users of MBS software. Therefore, the MBS research community should start to address the interoperability needs in this field as soon as possible. This article presents some foundations for that task: the requirements for a neutral data format are presented, the current interoperability state in MBS dynamics is evaluated, and two data modeling technologies (STEP and XML) are compared in order to develop a robust yet easy-to-use neutral data format for multibody systems. An XML-based prototype implementation of such a format is proposed, demonstrating the excellent aptitudes of XML for this task. Finally, guidelines for future standardization of multibody system data are given. In conclusion, both STEP and XML should be combined in the future to solve the interoperability problems in multibody system dynamics in an effective way.

The principle of virtual work is used to derive the Euler-Lagrange equations of motion in order to describe the dynamics of multibody android systems. The constrained variational equations are in fact differential-algebraic equations of high index and are cast as ordinary differential equations through differentiation of the constraint equations. The integration routine LSODAR and the fourth-order Runge-Kutta method are used to compute the generalized coordinates, their time derivatives and the body forces of two android models. The graphs of the constraint forces reveal the whiplash effect on the neck and that the stiffness of both multibody systems is due to large magnitude impulsive forces experienced by many bodies simultaneously.

This text is a classical and complete book on rigid multibody dynamics. Some of the topics covered include: various angular orientation descriptions, including Euler angles, Bryan angles, and Euler-Rodrigues parameters; quaternion algebra; virtual power; graph theory; and vibration analysis of chains of bodies. The textbook is an excellent reference, containing valuable material for graduate students and researchers. The chapters have an average of six example and problem sets, for which solutions are provided. Aside from the lack of problems, the book can easily be used as a text for a graduate course on the dynamics of rigid multibody systems.

It is an exceptional success when multibody dynamics researchers Multibody System Dynamics journal one of the most highly ranked journals in the last 10 years. In the inaugural issue, Professor Schiehlen wrote an interesting article explaining the roots and perspectives of multibody system dynamics. Professor Shabana also wrote an interesting article to review developments in flexible multibody dynamics. The application possibilities of multibody system dynamics have grown wider and deeper, with many application examples being introduced with multibody techniques in the past 10 years. In this paper, the development of multibody dynamics is briefly reviewed and several applications of multibody dynamics are described according to the author’s research results. Simulation examples are compared to physical experiments, which show reasonableness and accuracy of the multibody formulation applied to real problems. Computer simulations using the absolute nodal coordinate formulation (ANCF) were also compared to physical experiments; therefore, the validity of ANCF for large-displacement and large-deformation problems was shown. Physical experiments for large deformation problems include beam, plate, chain, and strip. Other research topics currently being carried out in the author’s laboratory are also briefly explained.

Generalized mass metric in Riemannian manifold plays a central role in dynamics and control of multibody system (MBS). In this work, two profitable aspects of multibody system dynamics studies, generalized mass metric in Riemannian geometry and recursive momentum formulation, are described. Firstly, we will derive an Adjoint-based expression of Riemannian metric and operator factorization of generalized mass tensor from a general-topology rigid MBS which comprises of a special Euclidian group SE(3) set. The specific expression can help to clearly understand what reasons lead to these components (Riemannian metric) of the generalized mass tensor and how they measure the curves of generalized velocity space. Meanwhile, the power algorithm of MBS is presented based on the Adjoint map of generalized velocity and generalized force. Next, from the generalized momentum definition depending on such Riemannian mass metric, recursive momentum equations of MBS dynamics are developed for progressively more complex systems: open-chains, topological trees, and closed-loop systems. In terms of the relation principle of impulse and momentum, a new method is proposed for describing conservative MBS form a given initial orientation and location to desired final ones without needing to solve motion process.

Dynamics and control of a spatial rigid-flexible multibody system with multiple cylindrical clearance joints

A systematic trend analysis of 3D printing techniques used in specific soft robotic elements

Distinguished from traditional robots made of rigid materials, soft robots have great potential in fields such as human–robot interaction and biomedical applications due to their mechanical pliability. Soft actuators are one of the most important components in soft robotics systems and can be activated by external stimuli such as heat, light, humidity, electric fields, or magnetic fields. Among them, magnetically responsive soft actuators composed of strong magnetic composite can achieve multi‐degree‐of‐freedom wireless remote control and reversible driving action, which have considerable application potential. In this perspective, we first discuss the properties and actuation mechanisms of the strong‐magnetic flexible composites. Then, the preparation method of magnetic actuators by strong‐magnetic flexible composites are briefly introduced. Next, various applications of magnetically responsive soft actuators, such as grasping, walking, swimming, and sensing control, are highlighted. Finally, current opportunities and challenges for stimulus‐responsive soft robots are discussed. This review provides scientists with the latest technological advances and information needed to design and develop the next generation of soft bionic robotic systems, and further demonstrates the future applications of these robots are vast and promising.

The Technical Committee on Multibody Systems and Nonlinear Dynamics (MSND-TC) of the ASME Design Engineering Division solicits nominations for the D'Alembert Award and the Lyapunov Award. These awards will be presented at the 6th ASME International Conference on Multibody Systems, Nonlinear Dynamics and Control, as part of the ASME 2007 International Design Engineering Technical Conferences to be held in Las Vegas, Nevada, September, 2007.The D'Alembert Award is established to recognize lifelong contributions to the field of multibody system dynamics.The Lyapunov Award is established to recognize lifelong contributions to the field of nonlinear dynamics.These awards recognize lifelong impact of research contributions, education and training of researchers and/or practitioners, and overall leadership in advancing the field. Nominations should include (1) a nomination letter describing the field of, and the impact of, the nominee, (2) a curriculum vitae, and (3) up to five letters of support. All nomination materials must be submitted in electronic (pdf) format.Submit nomination materials beforeJuly 1, 2006to either one of the Co-Chairs of the Awards Subcommittee.Professor Olivier A. BauchauCo-Chair MSND-TC AwardsSchool of Aerospace EngineeringGeorgia Institute of Technology270 Ferst Street, SST Building, Rm. 212Atlanta, GA 30332-0150Email: olivier.bauchau@ae.gatech.eduTel: (404) 894-0042Fax: (404) 894-2760Professor Noel C. PerkinsCo-Chair MSND-TC Awards SubcommitteeMechanical EngineeringUniversity of Michigan2350 Hayward St.Ann Arbor, MI 48109-2125Email: ncp@umich.eduTel: (734) 936-0403Fax: (734) 615-6647

Professor Dr. Kurt Magnus (1912–2003) would celebrate his 100th birthday on September 8, 2012. That is a reason to remember this internationally renowned scientist in the field of mechanics, particularly gyrodynamics and multibody system dynamics. By him, the science of gyrodynamics had once again a golden age in Germany. He established branches of mechanics, which we call today “multibody system dynamics” and “mechatronics.” Also, he was very well known as the editor-in-chief of the Ingenieur-Archiv (Archive of Applied Mechanics) from 1963 to 1980. In this contribution, his scientific career will be described and his outstanding research work will be acknowledged. From 1966 to 1980, Kurt Magnus was Full Professor of Mechanics at the Munich University of Technology. During this period, the research field of multibody system dynamics became more and more interesting. Therefore, he initiated and chaired the first IUTAM Symposium on Dynamics of Multibody Systems at Munich, August 29–September 3, 1977. Excellent lectures and intensive discussions showed the state-of-the-art and the further potential for research and application. This contribution will remember these early steps of multibody system dynamics.

Design optimization of dynamic flexible multibody systems using the discrete adjoint variable method

Finite-element based recursive formulation for real time dynamic simulation of flexible multibody systems