Moderator: Alex Slocum, PhD, Pappalardo Professor of Mechanical Engineering MacVicar Faculty Fellow, MIT, slocum@mit.edu
Bio-Inspired Robot Design
with Compliant Mechanism Fabrication
Sangbae Kim, PhD, Post-doctorate fellow, Micro-robotics
Laboratory, Harvard University, sangbae@mit.edu
Mobile robot designers are increasingly searching for inspiration and design cues from biological models. Biomechanical studies on running animals underscore the importance of the passive properties of muscles, tendons, and other elements of the musculoskeletal system. These elements play significant roles in self-stabilization and elastic energy storage, resulting in smoother and more efficient performance in natural environments. Through abstraction and simplification of biological inspiration, fundamental design principles are embodied in a number of bio-inspired robots. To demonstrate this process, the core design features of three legged robots are described, focusing on compliant under-actuated mechanism made by multi-material manufacturing process called shape deposition manufacturing. The first bio-inspired robot is iSprawl, a cockroach-inspired hexapod with compliant, under-actuated legs. Its passive hip joints and a light and flexible push-pull cable transmission allow it to run at 15 body-lengths per second. The second robot is Spinybot, a hexapod that uses its toes with microspines to climb rough surfaces, including stucco, concrete and brick walls. The last robot is Stickybot, a gecko-inspired quadruped that climbs smooth vertical surfaces using directional dry adhesion. Stickybot contains several types of under-actuated mechanisms in its body, legs and toes. At the smallest length scale, the undersides of the toes are covered with a unique material called directional polymeric stalk (DPS), inspired by the directional setae and lamellae of the gecko. The future direction of Sangbae Kim's research involves several design principles toward bio-inspired robots and a novel manufacturing technology that enables hybrid structures combining multiple materials, including multi-grade elastomeric/solid materials, liquid, and gas with embedded sensors and actuators.
Fluidic Logic_-
Merging Chemistry and Computation with Microfluidics
Manu Prakesh, PhD, Elected Junior Fellow (Physics),
Harvard Society of Fellows; Visiting Scholar, MIT, manup@mit.edu
Starting from genetic blueprints, biological materials turn into complex, multi-compartmental "living" things with algorithmic precision. One fundamental difference between biological and physical materials is their inherent computational ability. Though we have long understood that "Information representation is invariably physical", we are only now beginning to exploit this insight to shape, program and manipulate matter in engineered systems. Manu Prakesh will introduce a paradigm in computation where bits can simultaneously transport and manipulate both materials and information, similar to how integrated circuits allow us to control the flow of electrons. He will describe an entirely new digital logic family which implements universal Boolean logic in an all-fluidic system, exploiting purely hydrodynamic nonlinearities in low-Reynolds number two-phase flow. Such a physical implementation thus provides a flow control mechanism for sub-nanoliter droplets operating at KHz frequencies with no moving parts. A "lego-set" like toolbox comprising of microfluidic circuits including AND/OR/NOT gates, flip-flops, counters, ring-oscillators and synchronizers will be introduced. These show the nonlinearity, gain, bistability, synchronization, cascadability, feedback and programmability required for scalable universal computation and all-fluidic control. This platform technology represents initial steps towards modular design of sub-nanoliter droplet reactors with applications in high throughput screening for novel materials, combinatorial chemistry and implanted devices.
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