Modelling to Analyze the Vertical Oscillation of RHex with Flexible Body

Author(s):  
Minh Khong ◽  
Van-Luc Ngo
2020 ◽  
Vol 6 (1) ◽  
pp. e000963
Author(s):  
Sheeba Davis ◽  
Aaron Fox ◽  
Jason Bonacci ◽  
Fiddy Davis

Grounded running predominantly differs from traditional aerial running by having alternating single and double stance with no flight phase. Approximately, 16% of runners in an open marathon and 33% of recreational runners in a 5 km running event adopted a grounded running technique. Grounded running typically occurs at a speed range of 2–3 m·s−1, is characterised by a larger duty factor, reduced vertical leg stiffness, lower vertical oscillation of the centre of mass (COM) and greater impact attenuation than aerial running. Grounded running typically induces an acute increase in metabolic cost, likely due to the larger duty factor. The increased duty factor may translate to a more stable locomotion. The reduced vertical oscillation of COM, attenuated impact shock, and potential for improved postural stability may make grounded running a preferred form of physical exercise in people new to running or with low loading capacities (eg, novice overweight/obese, elderly runners, rehabilitating athletes). Grounded running as a less impactful, but metabolically more challenging form, could benefit these runners to optimise their cardio-metabolic health, while at the same time minimise running-related injury risk. This review discusses the mechanical demands and energetics of grounded running along with recommendations and suggestions to implement this technique in practice.


A layer of water in a cylindrical tank is known to be capable of sustaining standing solitary waves within a certain parametric domain when the tank is excited under vertical oscillation. A new mode of forced waves is discovered to exist in a different parametric domain for rectangular tanks with the wave sloshing across the short side of the tank and with its profile modulated by one or more hyperbolic-tangent, or kink-wave-like envelopes. A theoretical explanation for the kink wave properties is provided. Experiments were performed to confirm their existence.


2018 ◽  
Vol 108 (10) ◽  
pp. 703-707
Author(s):  
D. Kupzik ◽  
S. Coutandin ◽  
J. Fleischer

Die steigende Variantenvielfalt im Automobilbau durch neue Modelle und elektrische Derivate motiviert ein Umdenken im Karosserierohbau. In „SmartBodySynergy“ (SBS) wird ein flexibler Karosserierohbau in Werkstattfertigung entwickelt. Für dessen Umsetzung sind flexible Fügezellen notwendig. In diesem Artikel wird der Einsatz einer vorrichtungsfreien, kamerageregelten Bauteilpositionierung für den Einsatz in varianten- sowie vorgangsflexiblen Fügezellen untersucht und eine Demonstratorzelle vorgestellt.   The increasing diversity of variants in the automotive industry through new models and electrical derivatives motivates a rethinking of body shop construction. In „SmartBodySynergy“ (SBS), a flexible body shop is being developed in workshop production. For its implementation, flexible joining cells are necessary. This article examines the use of device-free, camera-controlled component positioning for use in variant- and process-flexible joining cells and introduces a demonstrator cell.


2020 ◽  
Vol 2020 (0) ◽  
pp. 513
Author(s):  
Masato TAKEUCHI ◽  
Kensuke HARA ◽  
Hiroshi YAMAURA

Author(s):  
Martin M. Tong

Numerical solution of the dynamics equations of a flexible multibody system as represented by Hamilton’s canonical equations requires that its generalized velocities q˙ be solved from the generalized momenta p. The relation between them is p = J(q)q˙, where J is the system mass matrix and q is the generalized coordinates. This paper presents the dynamics equations for a generic flexible multibody system as represented by p˙ and gives emphasis to a systematic way of constructing the matrix J for solving q˙. The mass matrix is shown to be separable into four submatrices Jrr, Jrf, Jfr and Jff relating the joint momenta and flexible body mementa to the joint coordinate rates and the flexible body deformation coordinate rates. Explicit formulas are given for these submatrices. The equations of motion presented here lend insight to the structure of the flexible multibody dynamics equations. They are also a versatile alternative to the acceleration-based dynamics equations for modeling mechanical systems.


2018 ◽  
Vol 860 (2) ◽  
pp. 113 ◽  
Author(s):  
Q. M. Zhang ◽  
H. S. Ji
Keyword(s):  

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