Instability results from purely rotational stiffness for general tensegrity structure with rigid bodies

2022 ◽  
Vol 167 ◽  
pp. 104485
Author(s):  
Bingxing Chen ◽  
Hongzhou Jiang
Keyword(s):  
Rigid Bodies ◽  
Rotational Stiffness ◽  
Tensegrity Structure

Robotic Tensegrity Structure with a Mechanism Mimicking Human Shoulder Motion

2021 ◽  
pp. 1-20
Author(s):  
Lengxue Li ◽  
Sunhong Kim ◽  
Junho Park ◽  
Youngjin Choi ◽  
Qiang Lu ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Tensegrity Structure ◽  
Steel Wires ◽  
Class 1 ◽  
Ligamentous Structure ◽  
Rotating Shafts ◽  
Shoulder Motion ◽  
Human Injury ◽  
Made In

Abstract This paper proposes a three degrees-of-freedom tensegrity structure with a mechanism inspired by the ligamentous structure of the shoulder. The proposed mechanism simulates the wide motion ranges of the human shoulder joint and is composed of three rigid bodies and sixteen steel wires with three mutually perpendicular rotating axes. Since it belongs to the class 1 tensegrity structure that the rigid bodies do not make any contact with each other, the joint has a certain amount of flexibility, which not only can help protect its mechanism from external impacts but also can prevent human injury that might happen when the mechanism and humans interact each other. Moreover, the proposed mechanism can be manufactured by using fewer materials than a fully rigid mechanism, and thus, it can be made in a lightweight fashion and reduce the inertial effects as well. Finally, to actuate the robotic shoulder, the cables connected to each motor are able to drive the rotating shafts of the joint mechanism.

Design and Analysis of a Hybrid Parallel Platform That Incorporates Tensegrity

2004 ◽  
Author(s):  
Matthew Marshall ◽  
Carl D. Crane
Keyword(s):  
Energy Level ◽  
Potential Energy ◽  
Rigid Bodies ◽  
Total Potential Energy ◽  
Tensegrity Structure ◽  
Total Potential ◽  
Parallel Platform

A new hybrid parallel platform device that is based on tensegrity is introduced in this paper. A tensegrity structure is one that is comprised of members that are either in tension (ties) or compression (struts). The device studied in this paper replaces the ‘upper’ and ‘lower’ set of ties of a 3-strut tensesgrity system with rigid bodies. Further, the three struts are replaced by three leg connectors whose lengths can be changed via prismatic actuators. The three remaining ties are replaced by the series combination of a spring and a non-compliant tie where the length of the non-compliant tie can be controlled. An analysis is presented that shows how the connector leg lengths and non-compliant tie lengths can be determined so as to position and orient the upper platform at a desired pose and at a desired total potential energy level. It is the control of the potential energy in the system that makes this new hybrid parallel-platform unique.

Analysis of Three Degree of Freedom 6×6 Tensegrity Platform

2006 ◽  
Author(s):  
Antoin Baker ◽  
Carl D. Crane
Keyword(s):  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Constant Length ◽  
Six Degrees Of Freedom ◽  
Tensegrity Structure ◽  
Tension And Compression ◽  
Three Degree Of Freedom ◽  
Primary Contribution

The mechanism studied in this paper is a three degree of freedom 6×6 tensegrity structure. A tensegrity structure is one that balances internal (pre-stressed) forces of tension and compression. These structures have the unique property of stabilizing themselves if subjected to certain types of disturbances. The structure analyzed in this paper consists of two rigid bodies (platforms) connected by a total of six members. Three of the members are noncompliant constant-length struts and the other three members consist of springs. For typical parallel mechanisms, if the bottom platform is connected to the ground and the top platform is connected to the base by six compliant leg connectors, the top platform will have six degrees of freedom relative to the bottom platform. However, because three of the six members connecting the two platforms are noncompliant constant-length struts, the top platform has only three degrees of freedom. The primary contribution of this paper is the analysis of the three degree of freedom tensegrity platform. Specifically, given the location of the connector points on the base and top platforms, the lengths of the three noncompliant constant-length struts, and the desired location of a point embedded in the top platform measured with respect to a coordinate system attached to the base, all possible orientations of the top platform are determined.

The Dynamics of Coupled Planar Rigid Bodies. Part 2. Bifurcations, Periodic Solutions, and Chaos

1988 ◽  
Author(s):  
Y.-G. Oh ◽  
N. Sreenath ◽  
P. S. Krishnaprasad ◽  
J. E. Marsden
Keyword(s):  
Periodic Solutions ◽  
Rigid Bodies

Multiple Impacts in Rigid Bodies

2010 ◽  
Vol 14 (14) ◽  
pp. 1-14
Author(s):  
Mohamed Gharib ◽  
Yildirim Hurmuzlu
Keyword(s):  
Rigid Bodies ◽  
Multiple Impacts

Virtual Work & d’Alembert’s Principle

2018 ◽  
Author(s):  
Peter Mann
Keyword(s):  
Euler Equations ◽  
Virtual Work ◽  
Lagrange Equation ◽  
Classical Mechanics ◽  
Rigid Bodies ◽  
Gibbs Function ◽  
Constraint Force ◽  
Appell Equations ◽  
Jourdain's Principle ◽  
D'alembert's Principle

This chapter discusses virtual work, returning to the Newtonian framework to derive the central Lagrange equation, using d’Alembert’s principle. It starts off with a discussion of generalised force, applied force and constraint force. Holonomic constraints and non-holonomic constraint equations are then investigated. The corresponding principles of Gauss (Gauss’s least constraint) and Jourdain are also documented and compared to d’Alembert’s approach before being generalised into the Mangeron–Deleanu principle. Kane’s equations are derived from Jourdain’s principle. The chapter closes with a detailed covering of the Gibbs–Appell equations as the most general equations in classical mechanics. Their reduction to Hamilton’s principle is examined and they are used to derive the Euler equations for rigid bodies. The chapter also discusses Hertz’s least curvature, the Gibbs function and Euler equations.

Introductory Rotational Dynamics

2018 ◽  
Author(s):  
Peter Mann
Keyword(s):  
Angular Momentum ◽  
Angular Displacement ◽  
Rigid Bodies ◽  
Rotational Dynamics ◽  
Circular Motion ◽  
Uniform Rotation ◽  
Chemical Systems ◽  
Inertial Frames ◽  
Rotating Frames ◽  
Special Case

This chapter discusses the importance of circular motion and rotations, whose applications to chemical systems are plentiful. Circular motion is the book’s first example of a special case of motion using the laws developed in previous chapters. The chapter begins with the basic definitions of circular motion; as uniform rotation around a principle axis is much easier to consider, it is the focus of this chapter and is used to develop some key ideas. The chapter discusses angular displacement, angular velocity, angular momentum, torque, rigid bodies, orbital and spin momenta, inertia tensors and non-inertial frames and explores fictitious forces as well as transformations in rotating frames.

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