Accepted Manuscripts

Cai Jianguo, Liu Yangqing, Ma Ruijun, Feng Jian and Zhou Ya
J. Mechanisms Robotics   doi: 10.1115/1.4036738
Rigid origami is seen as a fundamental model in many self-folding machines. A key issue in designing origami is the rigid/non-rigid foldability. The kinematic and foldability of Kresling origami, which is based on an origami pattern of the vertex with six creases, are studied in this paper. The movement of the single-vertex is firstly discussed. Based on the quaternion method, the loop-closure equation of the vertex with six creases is obtained. Then the multi-transformable behavior of the single vertex is investigated. Furthermore, the rigid foldability of origami patterns with multi-vertex are investigated with an improved dual quaternion method, which is based on studying the folding angle and the coordinates of all vertices. It can be found that the Kresling cylinder is not rigidly foldable.
TOPICS: Kinematics, Machinery, Design, Cylinders
Technical Brief  
Kazi M. Hossain, Carl A. Nelson and Prithviraj Dasgupta
J. Mechanisms Robotics   doi: 10.1115/1.4036740
Modular robotics is a popular topic for robotic applications and design. The reason behind this popularity is the ability to use and re-use the same robot modules for accomplishing different tasks through reconfiguration. The robots are capable of self-reconfiguration based on the requirements of the task and environmental constraints. It is possible to have a large number of configuration combinations for the same set of modules. Therefore, it is important to identify unique configurations from among the full set of possible configurations and establish a kinematic strategy for each before reconfiguring the robots into a new shape. This becomes more difficult for robot units having more than one connection type and more degrees of freedom. For example, ModRED II modules have two types of connections and four degrees of freedom per module. In this paper, the set of configurations is enumerated, and determination of configuration isomorphism is accomplished for ModRED II modules using graph theory. Kinematic equations are then derived for unique configurations. The kinematic method is then demonstrated for certain example configurations using ModRED II modules.
TOPICS: Kinematics, Robots, Degrees of freedom, Robotics, Shapes, Design, Equations of motion
Xingwei Zhao, Haitao Liu, Huafeng Ding and Lu Qian
J. Mechanisms Robotics   doi: 10.1115/1.4036718
This paper presents a novel approach for the force/motion transmissibility analysis of 3 degree of freedom planar multi-loop mechanisms by drawing on the duality of twist space and wrench space. By making a comparison study on the velocity model of planar parallel mechanisms and that of planar multi-loop mechanisms, it is concluded that the velocity model of a planar multi-loop mechanism can be expressed as the form of a planar parallel mechanism. Thereby, a set of dimensionally homogeneous transmission indices are proposed which can be employed for precisely representing the closeness to different types of singularities as well as for dimensional optimization. A 3-RRR parallel mechanism and a 3-DOF planar multi-loop mechanism for face-shovel excavation are taken as examples to demonstrate the validity and effectiveness of the proposed method.
TOPICS: Degrees of freedom, Optimization, Parallel mechanisms
Anzhu Gao, Yun Zou, Zhidong Wang and Hao Liu
J. Mechanisms Robotics   doi: 10.1115/1.4036719
Continuum robots present the great dexterity and compliance as dexterous manipulators to accomplish complex positioning tasks in confined anatomy during minimally invasive surgery. Tendon actuation is one of the most popular approaches, which is to insert the tendon to eccentrically go through and interact with the flexible backbone to accomplish compliant bends. However, hysteresis of tip trajectory of tendon actuated dexterous manipulators has been observed during the loading and unloading procedure, which is mainly caused by the hindered friction at discrete interactions between the actuation tendon and conduits. This paper aims to propose a general friction model to describe the interactions and friction profile at the multiple discrete contact points for tendon actuated dexterous manipulators under the history dependent tendon tension. The friction model was integrated into the beam theory to describe the hysteresis and loading history dependent behavior by solving the profiles of tendon force, normal force and friction force, as well as the deflection of the dexterous manipulator. Experiments were carried out to validate the effectiveness of the proposed friction model. Results indicate that the friction model can successfully describe the discrete interaction and predict the deflection of dexterous manipulator subject to the different tendon loading histories. Furthermore, we also discuss the effects of discrete friction to the tendon force propagation and the loading history dependent behavior.
TOPICS: Friction, Manipulators, Tendons, Deflection, Euler-Bernoulli beam theory, Anatomy, Tension, Robots, Trajectories (Physics), Surgery

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