Modular Self-Reconfigurable Robot Systems [Grand Challenges of Robotics]

151

115

Most animals exhibit significant neurological and morphological change throughout their lifetime. No robots to date, however, grow new morphological structure while behaving. This is due to technological limitations but also because it is unclear that morphological change provides a benefit to the acquisition of robust behavior in machines. Here I show that in evolving populations of simulated robots, if robots grow from anguilliform into legged robots during their lifetime in the early stages of evolution, and the anguilliform body plan is gradually lost during later stages of evolution, gaits are evolved for the final, legged form of the robot more rapidly-and the evolved gaits are more robust-compared to evolving populations of legged robots that do not transition through the anguilliform body plan. This suggests that morphological change, as well as the evolution of development, are two important processes that improve the automatic generation of robust behaviors for machines. It also provides an experimental platform for investigating the relationship between the evolution of development and robust behavior in biological organisms.evolutionary computation | robotics | evolutionary robotics | biomechanics | locomotion U sing robots to study adaptive behavior is of interest as a basic intellectual pursuit, but it may also lead to machines that assist or replace humans in unstructured or outdoor environments. To date, however, limited success has been achieved in realizing machines that continually perform simple yet robust behaviors in unstructured environments. It is contended here that this is due to overemphasis on the proximate mechanisms (1) of adaptive behavior-copying specific morphological and neuromorphological detail from organisms of interest into robots (2) in the hopes of replicating their behavior-and too little emphasis on the ultimate mechanisms of behavior-replicating the ontogenetic processes and selection pressures that gave rise to the behavior initially.To demonstrate the value of incorporating the evolution of development (3) into robotics, here I show that the automated discovery of robot behaviors can be accelerated if their body plans progress from an infant to an adult form over their lifetime (Fig. 1B)-and this ontogenetic change itself changes over successive generations of robots ( Fig. 1 D and F) such that later robots exhibit only the adult form during their lifetime (Fig. 1H)-than if robots maintain the adult form throughout behavior optimization. Moreover, robots evolved with this evolution-of-development method were found to be more robust to environmental perturbation than robots evolved without it because the former robots' ancestors assumed a range of body plans and thus had to maintain the behavior over a wider range of sensor-motor relationships.

Section: Discussionmentioning

confidence: 99%

Morphological change in machines accelerates the evolution of robust behavior

Bongard

2011

151

115

“…An extensive review of the achievements and challenges in modular self-reconfiguring machines is given by ref. 13. Much of this prior work considers unit-modules on the order of 5 -10 cm in size, whereas our work involves 1 cm modules.…”

mentioning

confidence: 99%

Programmable matter by folding

Hawkes

Benbernou

et al. 2010

577

474

Programmable matter is a material whose properties can be programmed to achieve specific shapes or stiffnesses upon command. This concept requires constituent elements to interact and rearrange intelligently in order to meet the goal. This paper considers achieving programmable sheets that can form themselves in different shapes autonomously by folding. Past approaches to creating transforming machines have been limited by the small feature sizes, the large number of components, and the associated complexity of communication among the units. We seek to mitigate these difficulties through the unique concept of self-folding origami with universal crease patterns. This approach exploits a single sheet composed of interconnected triangular sections. The sheet is able to fold into a set of predetermined shapes using embedded actuation. To implement this self-folding origami concept, we have developed a scalable end-to-end planning and fabrication process. Given a set of desired objects, the system computes an optimized design for a single sheet and multiple controllers to achieve each of the desired objects. The material, called programmable matter by folding, is an example of a system capable of achieving multiple shapes for multiple functions.reconfigurable robotics | self-assembly | multifunctional materials | computational origami E very day, scientists and engineers design new devices to solve a current problem. Each device has a unique function and thus has a unique form. The geometry of a cup is designed to hold liquid and is therefore different from that of a knife which is meant to cut. Even if both are made of the same material (e.g., metal, ceramic, or plastic), neither can perform both tasks. Is this redundancy in material, yet limitation in tasks entirely necessary? Is it possible to create a programmable material that can reshape for multiple tasks?Programmable matter is a material whose properties can be programmed to achieve specific shapes or stiffnesses upon command. In this paper we consider the theory and design of programmable matter material that can assume multiple desired shapes on demand.We have developed a unique concept of self-folding origami with universal crease patterns that decreases the complexity in individual elements and is scalable in the number and size of elements. Instead of relying on many individual subunits, which may be complex and difficult to orient correctly, we utilize a single sheet with repeated triangular tiles connected by flexible creases. This sheet can fold with a certain crease pattern to create multiple three-dimensional shapes, depending on which creases fold, in which direction, and in which order. We build on a large body of prior work in self-reconfiguring robotics to realize machines with changing shapes. Self-reconfiguring robots are modular systems whose bodies consist of multiple modules that can communicate and move relative to each other to form different shapes. These shapes support the different locomotive, manipulative, or sensing needs of the robo...

“…T he cooperative behavior of flocks, schools, and swarms has received much attention by biologists (1, 2), mathematicians (3,4), and roboticists (5,6). Ants are particularly well known for their ability to work together to complete complex tasks such as foraging, nest construction, and food cultivation (7).…”

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confidence: 99%

Fire ants self-assemble into waterproof rafts to survive floods

Mlot

Tovey²,

Hu³

2011

239

Why does a single fire ant Solenopsis invicta struggle in water, whereas a group can float effortlessly for days? We use time-lapse photography to investigate how fire ants S. invicta link their bodies together to build waterproof rafts. Although water repellency in nature has been previously viewed as a static material property of plant leaves and insect cuticles, we here demonstrate a selfassembled hydrophobic surface. We find that ants can considerably enhance their water repellency by linking their bodies together, a process analogous to the weaving of a waterproof fabric. We present a model for the rate of raft construction based on observations of ant trajectories atop the raft. Central to the construction process is the trapping of ants at the raft edge by their neighbors, suggesting that some "cooperative" behaviors may rely upon coercion.cooperative animal behavior | surface tension | adhesive | emergent | differential equation