Keyword: cable driven mechanisms
Tensegrity mechanisms are mechanical systems composed of rigid struts maintained in compression by tensioned springs. Thanks to this very particular structure, these mechanisms exhibit several advantages for various applications, ranging from mobile robots to manipulators.
Using integrated manufacturing processes with soft constituent materials, a new paradigm of soft, smart surgical devices can be realized to drastically reduce complication risks and enable safer procedures. We have designed, prototyped, and tested a ‘soft’, atraumatic, deployable surgical grasper that can be used during robolaparoscopic surgery to provide a safe, compliant intermediary between delicate organs and the sharp, rigid robotic forceps that are used to grasp and manipulate these organs on an ad-hoc basis. Multi-jointed, conformable fingers with embedded pressure sensors can conform to complicated geometry, thereby distributing forces and providing an inherently safe means of manipulating and retracting anatomy.
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.