Bio-inspired robot design for legged locomotion...Fig. 2: Stickybot, a bio-inspired robot capable of...
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Bio-inspired robot design for legged locomotion Sangbae Kim, Massachusetts Institute of Technology Cambridge, Massachusetts 02139 email: [email protected], web: http://web.mit.edu/sangbae/www/research.html Design goal problem definition Biology work with biologists Robotics implementations of principles Analysis test and analyze results refinement Principles from biological observation Fig. 1: A design process for bio-inspired robots I. LEARNING FROM BIOLOGY Mobile robot designers are increasingly searching for in- spirations and design cues from biological models. Although animals are great model for mobile robots, the process of implementation is often ambiguous. The direct implementation of biological features and morphology often becomes ineffec- tive and misleads engineers due to various reasons. Firstly, engineers investigate animals to achieve a few particular functions whereas features of animals may serve for multiple functions or often remains unknown. Biological system are believed to evolves for many functions. Animals need to adapt to various natural environments, reproduce themselves, eat, digest, and grow. When it comes to robotics platforms, the requirements are much simpler and based on the applications. Secondly, difference between engineering building blocks and biological mechanisms prevent engineers from direct replica- tion. Biological systems grows whereas mechanical systems are manufactured. Control system, actuators, structures, energy sources and mechanical properties in biological systems differ from artificial counterparts in a great extent. II. DESIGN PROCESS For effective implementation of ideas, a design process is introduced. The design process begins with seeking a function from biological systems. Often locomotive functions of animals become target function that engineers seek to achieve. Next step undergoes extensive observation of related behaviors in collaboration with biologists. Conversations with biologists are invaluable for identifying a range of animal examples and for pointers to the literature concerning their morphology and operation. Although the animal examples are generally impressive, it is important to remember that nature does not produce optimal solutions in any formal sense. Rather, nature works on the principle of what is “good enough” Fig. 2: Stickybot, a bio-inspired robot capable of climbing smooth surfaces. Inset: detail of toes curling to facilitate detachment to afford a competitive advantage. Through comparative anal- ysis and careful abstraction, hypothesizing principles follows. Sometimes, comparing homologous features among several species helps to remove bias from the interpretation. Through cautious observation and reasoning, we can extract hypotheses about the principles that govern the animals’ behavior and performance. The principles includes design principles behind detail features, simplified model of certain behaviors, and physical principles of a phenomenon. Hypothesized principles can be verified by biologists and engineering tools such as simulations and experiments. The next step is, selectively, to implement the principles in a robot. Since mechanical components differ from biological organisms, the principles need to be adapted in an artificial design space. The under- lying functional principles need to be extracted from biology, digested by the designer and reincarnated. Modification of the principles through subsequent experimentations and analysis will ultimately provide refinement of the principles, and will accordingly improve the final design.
Transcript of Bio-inspired robot design for legged locomotion...Fig. 2: Stickybot, a bio-inspired robot capable of...
Bio-inspired robot design for legged locomotion
Sangbae Kim,Massachusetts Institute of Technology
Cambridge, Massachusetts 02139email: [email protected], web: http://web.mit.edu/sangbae/www/research.html
Design goal problem definition
Biology work with biologists
Robotics implementations of principles
Analysis test and analyze results
refinement
Principles from biological observation
Fig. 1: A design process for bio-inspired robots
I. LEARNING FROM BIOLOGY
Mobile robot designers are increasingly searching for in-spirations and design cues from biological models. Althoughanimals are great model for mobile robots, the process ofimplementation is often ambiguous. The direct implementationof biological features and morphology often becomes ineffec-tive and misleads engineers due to various reasons. Firstly,engineers investigate animals to achieve a few particularfunctions whereas features of animals may serve for multiplefunctions or often remains unknown. Biological system arebelieved to evolves for many functions. Animals need to adaptto various natural environments, reproduce themselves, eat,digest, and grow. When it comes to robotics platforms, therequirements are much simpler and based on the applications.Secondly, difference between engineering building blocks andbiological mechanisms prevent engineers from direct replica-tion. Biological systems grows whereas mechanical systemsare manufactured. Control system, actuators, structures, energysources and mechanical properties in biological systems differfrom artificial counterparts in a great extent.
II. DESIGN PROCESS
For effective implementation of ideas, a design processis introduced. The design process begins with seeking afunction from biological systems. Often locomotive functionsof animals become target function that engineers seek toachieve. Next step undergoes extensive observation of relatedbehaviors in collaboration with biologists. Conversations withbiologists are invaluable for identifying a range of animalexamples and for pointers to the literature concerning theirmorphology and operation. Although the animal examplesare generally impressive, it is important to remember thatnature does not produce optimal solutions in any formal sense.Rather, nature works on the principle of what is “good enough”
Fig. 2: Stickybot, a bio-inspired robot capable of climbingsmooth surfaces. Inset: detail of toes curling to facilitatedetachment
to afford a competitive advantage. Through comparative anal-ysis and careful abstraction, hypothesizing principles follows.Sometimes, comparing homologous features among severalspecies helps to remove bias from the interpretation. Throughcautious observation and reasoning, we can extract hypothesesabout the principles that govern the animals’ behavior andperformance. The principles includes design principles behinddetail features, simplified model of certain behaviors, andphysical principles of a phenomenon. Hypothesized principlescan be verified by biologists and engineering tools such assimulations and experiments. The next step is, selectively,to implement the principles in a robot. Since mechanicalcomponents differ from biological organisms, the principlesneed to be adapted in an artificial design space. The under-lying functional principles need to be extracted from biology,digested by the designer and reincarnated. Modification of theprinciples through subsequent experimentations and analysiswill ultimately provide refinement of the principles, and willaccordingly improve the final design.
SLIP model Biomechanical study Sprawl robots
Fig. 3: Bio-inspired robot design based on principles frombiological study.
Fig. 4: iSprawl is a small (0.3 Kg) autonomous, bio-inspiredhexapod that runs at 15 body-lengths/second(2.3 m/s).
III. BIO-INSPIRED ROBOTS
Introduction of three successful bio-inspired robots exem-plify the process: a) iSprawl is a cockroach-inspired hexapodwith compliant, under-actuated legs and runs at 15 body-lengths per second, b)Spinybot is a hexapod that uses itstoes with microspines to climb rough surfaces, includingstucco, concrete and brick walls. Stickybot is a gecko-inspiredquadruped that climbs smooth vertical surfaces using theworlds first directional adhesive, directional polymeric stalks(DPS) inspired by the directional setae and lamellae of thegecko. The design principles of Stickybot include hierarchicalcompliance, directional adhesion, and distributed force control.
IV. FUTURE WORK
The future research direction of the biomimetic robotics labincludes obtaining principles behind highly dynamic behaviorsof the animals and implementing on robotic platforms. Exten-sive study on biological runners such as dogs and cheetahswill inspire the morphologic design of the galloping robotcapable of the fast traverse on rough and unstructured terrains.Figure 5 shows a potential concept platform that enablesresearch on hyper dynamic robotics. This new field of studywill focus on qudrupeds’ behavior such as jumping, highspeed running with gallop gait, and energy efficient runningwith trotting gait. Agile mobility of the robotic platformrequires high acceleration capability with dynamic stability,jumping over large obstacles, and landing with the flexible
Flexible spine
Multi-material fabrication
Directional adhesion
Multi-body dynamic modeling- Morphology design
Cable driven power transmission
sensor
Serial compliance
Polymeric sensors
Magnetoactive polymeric Impedance control unit
Hierarchical control architecture
Fig. 5: A schematics of new quadruped running roboticplatforms. This platform will be capable of basic locomotivefunctions for hyper dynamic robotic research.
body articulation. These highly dynamic behaviors involvemulti-body dynamics of the dynamic control with tunablemechanical impedance. Based on the mechanical propertiesof actuators, the actuator allocation and actuation scheme canbe optimized in order to achieve maximum performance. Thefirst key thrusts include the development of high power densityactuators with impedance control in pursuit of optimized forcecoordination of multi-degree of freedom legs and effectiveenergy storage. Second research thrust seek to achieve a newcontrol architecture that allows discrete impulse control ofeach stride to transition from one state to another and maintaina certain steady state. The final research thrust focuses ondevelopment of manufacturing techniques that allows light-weight resilient structure capable of dynamic locomotion.
