Issue: February 2015

Development and Validation of a Dynamic Model of Magneto-Active Elastomer Actuation of the Origami Waterbomb Base
February 2015

Origami, which was once a purely artistic field, has recently become a source of novel engineering ideas and products. Many of the everyday objects we use could benefit from being capable of folding into a more compact state for storage. Several examples of recent origami-inspired designs include a foldable space solar array, disposable medical forceps, and inexpensive, customizable robots. Engineers are particularly interested in self-folding origami, where a sheet of material folds itself into a number of shapes in response to electricity, temperature, or a magnetic field. To assist in the creation such self-folding sheets, it is important to simulate how they might fold and behave using computer software, which can be referred to as a dynamic model. In this work a magnetically-activated, self-folding dynamic model is created of the origami waterbomb base, a fundamental origami model. The accuracy of the developed dynamic model is then verified against an experiment which was performed for this purpose. The model is shown to predict the experimental results reasonably well, demonstrating the potential use of the dynamic model as a design tool for future origami-inspired products.


A Cable Based Active Variable Stiffness Module With Decoupled Tension
February 2015

The ability to modulate the physical energetic interactions of a robot with external entities (such as humans, other robots or even the environment) is very important in many application arenas such as cooperative payload transport, haptics, and dynamic walking, etc.. A common approach to handle the modulation of these energetic interactions is to selectively introduce compliance to accommodate the stiffness (or more generally the impedance) mismatch at the physical-interaction interface, i.e. variable stiffness. Variable stiffness modules add significant robustness to mechanical systems during forceful interactions with uncertain environments. Most existing variable stiffness modules tend to be bulky – by virtue of their use of solid components – making them less suitable for mobile applications. In recent times, pretensioned cable-based variable-stiffness modules have been proposed to reduce weight. While passive, these modules depend on significant internal tension to provide the desired stiffness – as a consequence, their stiffness modulation capability tends to be limited. In this paper, we present design, analysis and testing of a cable-based active variable-stiffness module which can achieve large stiffness modulation range with low tension.


Design and Analysis of a Novel Articulated Drive Mechanism for Multifunctional NOTES Robot
February 2015

Our research involves the development of robotic tools for minimally invasive surgery. Through this work, we are bringing the field of robotics and the practice of medical care one step closer together, with the long-term goal of improving healthcare and the human condition. Our paper describes the design of a snake-like linkage as part of a more comprehensive surgical robot system and presents a model for its motion. We show through modeling and experiments how the linkage system operates and how the components of the surgical system interact to achieve functionality relevant to minimally invasive surgical tasks.


The Role of the Orthogonal Helicoid in the Generation of the Tooth Flanks of Involute-Gear Pairs With Skew Axes
February 2015

Camus’s theorem provides a universal approach to the synthesis of conjugate profiles when the relative motion program is assigned through the relative centrodes (pitch curves). The main point is to choose the most convenient auxiliary curve, in order to trace the pair of conjugate tooth profiles as trajectories of a point or envelope of a second curve attached to this auxiliary curve. Thus, Camus’ concept of auxiliary surface (AS) is extended to the case of involute gears with skew axes with the aim to provide a unified theory to synthesize any type of gears.


Design of Planar Multi-Degree-of-Freedom Morphing Mechanisms
February 2015

Morphing mechanisms represent a class of machines that can change their shapes to perform critical functions in a variety of fields. This paper considers morphing mechanisms composed of rigid links that can be designed to approximate different shapes defined by planar curves. Such mechanisms may have applications in morphing aircraft wings that increase flight efficiency and morphing dies for manufacturing complex plastic products faster and less expensively than is currently possible.