Keyword: actuators and transmissions
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.
Our prior work has shown that the Smart Composite Microstructures (SCM) process can be applied to produce folded millirobots that do not compromise on performance. The next frontier of this research is to bring these robots outside, into unknown and hazardous environments where needs for protection and sensing will be determined by task. To make this translation we present rapid, and low-cost manufacturing methods for more robust SCM structures, protective exoskeletons that aid locomotion, anisotropic claws that double traction, integrated tactile sensing arrays, and print-in-place strain gauges. These new structures protect SCM millirobots and add to their capabilities in ways that broaden their applicability to real-world situations.
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.