We present a high-level language for programming modular robotic systems, based on locally distri... more We present a high-level language for programming modular robotic systems, based on locally distributed predicates (LDP), which are distributed conditions that hold for a connected subensemble of the robotic system. An LDP program is a collection of LDPs with associated actions which are triggered on any subensemble that matches the predicate. The result is a reactive programming language which efficiently and concisely supports ensemble-level programming. We demonstrate the utility of LDP by implementing three common, but diverse, modular robotic tasks.
One of the primary impediments to building ensembles of modular robots is the complexity and numb... more One of the primary impediments to building ensembles of modular robots is the complexity and number of mechanical mechanisms used to construct the individual modules. As part of the Claytronics project-which aims to build very large ensembles of modular robots-we investigate how to simplify each module by eliminating moving parts and reducing the number of mechanical mechanisms on each robot by using force-at-a-distance actuators. Additionally, we are also investigating the feasibility of using these unary actuators to improve docking performance, implement intermodule adhesion, power transfer, communication, and sensing.
AbstractThis paper presents a novel application of modu-lar robotic technology. Many researchers... more AbstractThis paper presents a novel application of modu-lar robotic technology. Many researchers expect manufacturing technology will allow robot modules to be built at smaller and smaller scales, but movement and actuation are increasingly difficult as dimensions shrink. We ...
Internal localization, the problem of estimating relative pose for each module (part) of a modula... more Internal localization, the problem of estimating relative pose for each module (part) of a modular robot is a prerequisite for many shape control, locomotion, and actuation algorithms. In this paper, we propose a robust hierarchical approach that uses normalized cut to identify dense subregions with small mutual localization error, then progressively merges those subregions to localize the entire ensemble. Our method works well in both 2D and 3D, and requires neither exact measurements nor rigid inter-module connectors. Most of the computations in our method can be effectively distributed. The result is a robust algorithm that scales to large, non-homogeneous ensembles. We evaluate our algorithm in accurate 2D and 3D simulations of scenarios with up to 10,000 modules.
Because of the timing, complexity, and asynchronicity challenges common in modular robot software... more Because of the timing, complexity, and asynchronicity challenges common in modular robot software we have recently begun to explore new programming models for modular robot ensembles. In this paper we apply two of those models to a metamodule-based shape planning algorithm and comment on the differences between the two approaches. Our results suggest that declarative programming can provide several advantages over more traditional imperative approaches, and that the differences between declarative programming styles can themselves contribute leverage to different parts of the problem domain.
A simple and robust inter-module latch is possibly the most important component of a modular robo... more A simple and robust inter-module latch is possibly the most important component of a modular robotic system. This paper describes a latch based on electric fields and capacitive coupling. Our design provides not only significant adhesion forces, but can also be used for inter-module power transmission and communication. The key insight presented in this paper, and the factor that enables electrostatic adhesion to be effective at the macroscale, is the use of electric field attraction to generate frictional shear forces rather than electric field attraction alone. A second important insight is that a specific degree of flexibility in the electrodes is essential to maximize their mutual coupling and the resulting forceselectrodes which are too flexible or too rigid will perform less well. To evaluate the effectiveness of our latch we incorporate it into a cubic module 28cm on a side. The result is a latch which requires almost zero static power and yet can hold 0.6N/cm 2 of latch area.
Most current sensor network research explores the use of extremely simple sensors on small device... more Most current sensor network research explores the use of extremely simple sensors on small devices called motes and focuses on overcoming the compute and power constraints of these devices. In contrast, our research explores the challenges of multimedia sensors and is motivated by the fact that multimedia devices, such as cameras, are rapidly becoming inexpensive, yet their use in a sensor network presents a number of unique challenges. For example, the data rates involved with multimedia sensors are orders of magnitude greater than those for sensor motes and this data cannot easily be processed by traditional sensor network techniques that focus on scalar data. In addition, the richness of the data generated by multimedia sensors makes them useful for a wide variety of applications. This paper presents an overview of IRISNET, a sensor network architecture that enables the creation of a planetary-scale infrastructure of multimedia sensors that can be shared by a large number of applications. To ensure the efficient collection of sensor readings, IRISNET enables the application-specific processing of sensor feeds on the significant computation resources that are typically attached to multimedia sensors. IRISNET enables the storage of sensor readings close to their source by providing a convenient and extensible distributed XML database infrastructure. Finally, IRISNET provides a number of multimedia processing primitives that enable the effective processing of sensor feeds in-network and at-sensor.
We demonstrate modular robot prototypes developed as part of the Claytronics Project . Among the ... more We demonstrate modular robot prototypes developed as part of the Claytronics Project . Among the novel features of these robots ("catoms") is their ability to reconfigure (move) relative to one another without moving parts. The absence of moving parts is central to one key aim of our work, namely, plausible manufacturability at smaller and smaller physical scales using high-volume, lowunit-cost techniques such as batch photolithography, multimaterial submicron 3D lithographic processing, and self assembly.
We describe a monocular robot vision system which accomplishes accurate 3-DOF dead-reckoning, clo... more We describe a monocular robot vision system which accomplishes accurate 3-DOF dead-reckoning, closedloop motion control, and precipice and obstacle detection, all in dynamic environments, using a single, consumer-grade webcam and typical laptop computer hardware. Simultaneous translation and rotation are accurately measured, and the camera need not be placed at the robot's center of rotation. The algorithm is straightforward to implement and robust to noisy measurements. The software is based on open source computer vision libraries and is itself open source. It has been tested in a wide variety of real-world environments and on several different mobile robot platforms.
Motion vision (visual odometry, the estimation of camera egomotion) is a well researched field, y... more Motion vision (visual odometry, the estimation of camera egomotion) is a well researched field, yet has seen relatively limited use despite strong evidence from biological systems that vision can be extremely valuable for navigation. The limited use of such vision techniques has been attributed to a lack of good algorithms and insufficient computer power, but both of those problems were resolved as long as a decade ago. A gap presently yawns between theory and practice, perhaps due to perceptions of robot vision as less reliable and more complex than other types of sensing. We present an experimental methodology for assessing the realworld precision and reliability of visual odometry techniques in both normal and extreme terrain. This paper evaluates the performance of a mobile robot equipped with a simple vision system in common outdoor and indoor environments, including grass, pavement, ice, and carpet. Our results show that motion vision algorithms can be robust and effective, and suggest a number of directions for further development.
power. Smaller, more numerous modules increase the adaptability of a given volume or mass of robo... more power. Smaller, more numerous modules increase the adaptability of a given volume or mass of robot, allowing the aggregate robot to take on a wider variety of configurations, but do so at a cost of reducing the power and complexity budget of each module. Fewer, larger modules can incorporate more powerful actuators and stronger hinges, but at a cost of overspecializing the resulting robot in favor of corresponding uses. In this paper we describe a technique for coordinating the efforts of many tiny modules to achieve forces and movements larger than those possible for individual modules. In a broad sense, our work aims to make actuator capacity and range at least partly fungible by algorithm design and ensemble topology, rather than being immutable properties of a particular module design. An important aspect of this technique is its ability to bend complex and large-scale structures and to realize the equivalent of large-scale joints. By enabling scalable joints, and the "muscles" that could actuate larger structures, our work makes it more likely that modular robot ensembles can successfully be scaled up in number and down in size.
We describe a novel shape formation algorithm for ensembles of 2-dimensional lattice-arrayed modu... more We describe a novel shape formation algorithm for ensembles of 2-dimensional lattice-arrayed modular robots, based on the manipulation of regularly shaped voids within the lattice ("holes"). The algorithm is massively parallel and fully distributed. Constructing a goal shape requires time proportional only to the complexity of the desired target geometry. Construction of the shape by the modules requires no global communication nor broadcast floods after distribution of the target shape. Results in simulation show 97.3% shape compliance in ensembles of approximately 60,000 modules, and we believe that the algorithm will generalize to 3D and scale to handle millions of modules.
Tightly-coupled multi-agent systems such as modular robots frequently exhibit properties of inter... more Tightly-coupled multi-agent systems such as modular robots frequently exhibit properties of interest that span multiple modules. These properties cannot easily be detected from any single module, though they might readily be detected by combining the knowledge of multiple modules. Testing for distributed conditions is especially important in debugging or verifying the correctness of software for modular robots.
This paper describes a novel approach to powering a radical type of microrobot. Our long-term aim... more This paper describes a novel approach to powering a radical type of microrobot. Our long-term aim is to enable the construction of ensembles of millions of coordinated nearspherical, submillimeter microrobots. Both the large number of potential simultaneous neighbors of each robot (12) and the difficulty of fine actuation at such small scales preclude the use of complex connectors previously developed in many modular robotics efforts. Instead, we propose to leverage multirobot cooperation to simplify the mechanics of modular robot docking.
In this paper we develop a theory of metamodules and an associated distributed asynchronous plann... more In this paper we develop a theory of metamodules and an associated distributed asynchronous planner which generalizes previous work on metamodules for lattice-based modular robotic systems. All extant modular robotic systems have some form of non-holonomic motion constraints. This has prompted many researchers to look to metamodules, i.e., groups of modules that act as a unit, as a way to reduce motion constraints and the complexity of planning. However, previous metamodule designs have been specific to a particular modular robot.
This paper describes an application that enables quick reconstruction of interconnected events, s... more This paper describes an application that enables quick reconstruction of interconnected events, sparsely captured by one or more surveillance cameras. Unlike related efforts, our approach does not require indexing, advance knowledge of potential search criteria, nor a solution to the generalized object-recognition problem. Instead, we strategically pair the intelligence and skill of a human investigator with the speed and flexibility of a parallel image search engine that exploits local storage and processing capabilities distributed across large collections of video recording devices. The result is a system for fast, interactive, brute-force video searching which is both effective and highly scalable.
ABSTRACT Imaging sensors are inherently high bandwidth devices, and ap-plications which store ima... more ABSTRACT Imaging sensors are inherently high bandwidth devices, and ap-plications which store image data often encounter disk or memory limits. Commonly, upon reaching such a limit, storage systems will cease sampling or overwrite existing data in an oldest-first fash- ...
We present a high-level language for programming modular robotic systems, based on locally distri... more We present a high-level language for programming modular robotic systems, based on locally distributed predicates (LDP), which are distributed conditions that hold for a connected subensemble of the robotic system. An LDP program is a collection of LDPs with associated actions which are triggered on any subensemble that matches the predicate. The result is a reactive programming language which efficiently and concisely supports ensemble-level programming. We demonstrate the utility of LDP by implementing three common, but diverse, modular robotic tasks.
One of the primary impediments to building ensembles of modular robots is the complexity and numb... more One of the primary impediments to building ensembles of modular robots is the complexity and number of mechanical mechanisms used to construct the individual modules. As part of the Claytronics project-which aims to build very large ensembles of modular robots-we investigate how to simplify each module by eliminating moving parts and reducing the number of mechanical mechanisms on each robot by using force-at-a-distance actuators. Additionally, we are also investigating the feasibility of using these unary actuators to improve docking performance, implement intermodule adhesion, power transfer, communication, and sensing.
We present a high-level language for programming modular robotic systems, based on locally distri... more We present a high-level language for programming modular robotic systems, based on locally distributed predicates (LDP), which are distributed conditions that hold for a connected subensemble of the robotic system. An LDP program is a collection of LDPs with associated actions which are triggered on any subensemble that matches the predicate. The result is a reactive programming language which efficiently and concisely supports ensemble-level programming. We demonstrate the utility of LDP by implementing three common, but diverse, modular robotic tasks.
One of the primary impediments to building ensembles of modular robots is the complexity and numb... more One of the primary impediments to building ensembles of modular robots is the complexity and number of mechanical mechanisms used to construct the individual modules. As part of the Claytronics project-which aims to build very large ensembles of modular robots-we investigate how to simplify each module by eliminating moving parts and reducing the number of mechanical mechanisms on each robot by using force-at-a-distance actuators. Additionally, we are also investigating the feasibility of using these unary actuators to improve docking performance, implement intermodule adhesion, power transfer, communication, and sensing.
AbstractThis paper presents a novel application of modu-lar robotic technology. Many researchers... more AbstractThis paper presents a novel application of modu-lar robotic technology. Many researchers expect manufacturing technology will allow robot modules to be built at smaller and smaller scales, but movement and actuation are increasingly difficult as dimensions shrink. We ...
Internal localization, the problem of estimating relative pose for each module (part) of a modula... more Internal localization, the problem of estimating relative pose for each module (part) of a modular robot is a prerequisite for many shape control, locomotion, and actuation algorithms. In this paper, we propose a robust hierarchical approach that uses normalized cut to identify dense subregions with small mutual localization error, then progressively merges those subregions to localize the entire ensemble. Our method works well in both 2D and 3D, and requires neither exact measurements nor rigid inter-module connectors. Most of the computations in our method can be effectively distributed. The result is a robust algorithm that scales to large, non-homogeneous ensembles. We evaluate our algorithm in accurate 2D and 3D simulations of scenarios with up to 10,000 modules.
Because of the timing, complexity, and asynchronicity challenges common in modular robot software... more Because of the timing, complexity, and asynchronicity challenges common in modular robot software we have recently begun to explore new programming models for modular robot ensembles. In this paper we apply two of those models to a metamodule-based shape planning algorithm and comment on the differences between the two approaches. Our results suggest that declarative programming can provide several advantages over more traditional imperative approaches, and that the differences between declarative programming styles can themselves contribute leverage to different parts of the problem domain.
A simple and robust inter-module latch is possibly the most important component of a modular robo... more A simple and robust inter-module latch is possibly the most important component of a modular robotic system. This paper describes a latch based on electric fields and capacitive coupling. Our design provides not only significant adhesion forces, but can also be used for inter-module power transmission and communication. The key insight presented in this paper, and the factor that enables electrostatic adhesion to be effective at the macroscale, is the use of electric field attraction to generate frictional shear forces rather than electric field attraction alone. A second important insight is that a specific degree of flexibility in the electrodes is essential to maximize their mutual coupling and the resulting forceselectrodes which are too flexible or too rigid will perform less well. To evaluate the effectiveness of our latch we incorporate it into a cubic module 28cm on a side. The result is a latch which requires almost zero static power and yet can hold 0.6N/cm 2 of latch area.
Most current sensor network research explores the use of extremely simple sensors on small device... more Most current sensor network research explores the use of extremely simple sensors on small devices called motes and focuses on overcoming the compute and power constraints of these devices. In contrast, our research explores the challenges of multimedia sensors and is motivated by the fact that multimedia devices, such as cameras, are rapidly becoming inexpensive, yet their use in a sensor network presents a number of unique challenges. For example, the data rates involved with multimedia sensors are orders of magnitude greater than those for sensor motes and this data cannot easily be processed by traditional sensor network techniques that focus on scalar data. In addition, the richness of the data generated by multimedia sensors makes them useful for a wide variety of applications. This paper presents an overview of IRISNET, a sensor network architecture that enables the creation of a planetary-scale infrastructure of multimedia sensors that can be shared by a large number of applications. To ensure the efficient collection of sensor readings, IRISNET enables the application-specific processing of sensor feeds on the significant computation resources that are typically attached to multimedia sensors. IRISNET enables the storage of sensor readings close to their source by providing a convenient and extensible distributed XML database infrastructure. Finally, IRISNET provides a number of multimedia processing primitives that enable the effective processing of sensor feeds in-network and at-sensor.
We demonstrate modular robot prototypes developed as part of the Claytronics Project . Among the ... more We demonstrate modular robot prototypes developed as part of the Claytronics Project . Among the novel features of these robots ("catoms") is their ability to reconfigure (move) relative to one another without moving parts. The absence of moving parts is central to one key aim of our work, namely, plausible manufacturability at smaller and smaller physical scales using high-volume, lowunit-cost techniques such as batch photolithography, multimaterial submicron 3D lithographic processing, and self assembly.
We describe a monocular robot vision system which accomplishes accurate 3-DOF dead-reckoning, clo... more We describe a monocular robot vision system which accomplishes accurate 3-DOF dead-reckoning, closedloop motion control, and precipice and obstacle detection, all in dynamic environments, using a single, consumer-grade webcam and typical laptop computer hardware. Simultaneous translation and rotation are accurately measured, and the camera need not be placed at the robot's center of rotation. The algorithm is straightforward to implement and robust to noisy measurements. The software is based on open source computer vision libraries and is itself open source. It has been tested in a wide variety of real-world environments and on several different mobile robot platforms.
Motion vision (visual odometry, the estimation of camera egomotion) is a well researched field, y... more Motion vision (visual odometry, the estimation of camera egomotion) is a well researched field, yet has seen relatively limited use despite strong evidence from biological systems that vision can be extremely valuable for navigation. The limited use of such vision techniques has been attributed to a lack of good algorithms and insufficient computer power, but both of those problems were resolved as long as a decade ago. A gap presently yawns between theory and practice, perhaps due to perceptions of robot vision as less reliable and more complex than other types of sensing. We present an experimental methodology for assessing the realworld precision and reliability of visual odometry techniques in both normal and extreme terrain. This paper evaluates the performance of a mobile robot equipped with a simple vision system in common outdoor and indoor environments, including grass, pavement, ice, and carpet. Our results show that motion vision algorithms can be robust and effective, and suggest a number of directions for further development.
power. Smaller, more numerous modules increase the adaptability of a given volume or mass of robo... more power. Smaller, more numerous modules increase the adaptability of a given volume or mass of robot, allowing the aggregate robot to take on a wider variety of configurations, but do so at a cost of reducing the power and complexity budget of each module. Fewer, larger modules can incorporate more powerful actuators and stronger hinges, but at a cost of overspecializing the resulting robot in favor of corresponding uses. In this paper we describe a technique for coordinating the efforts of many tiny modules to achieve forces and movements larger than those possible for individual modules. In a broad sense, our work aims to make actuator capacity and range at least partly fungible by algorithm design and ensemble topology, rather than being immutable properties of a particular module design. An important aspect of this technique is its ability to bend complex and large-scale structures and to realize the equivalent of large-scale joints. By enabling scalable joints, and the "muscles" that could actuate larger structures, our work makes it more likely that modular robot ensembles can successfully be scaled up in number and down in size.
We describe a novel shape formation algorithm for ensembles of 2-dimensional lattice-arrayed modu... more We describe a novel shape formation algorithm for ensembles of 2-dimensional lattice-arrayed modular robots, based on the manipulation of regularly shaped voids within the lattice ("holes"). The algorithm is massively parallel and fully distributed. Constructing a goal shape requires time proportional only to the complexity of the desired target geometry. Construction of the shape by the modules requires no global communication nor broadcast floods after distribution of the target shape. Results in simulation show 97.3% shape compliance in ensembles of approximately 60,000 modules, and we believe that the algorithm will generalize to 3D and scale to handle millions of modules.
Tightly-coupled multi-agent systems such as modular robots frequently exhibit properties of inter... more Tightly-coupled multi-agent systems such as modular robots frequently exhibit properties of interest that span multiple modules. These properties cannot easily be detected from any single module, though they might readily be detected by combining the knowledge of multiple modules. Testing for distributed conditions is especially important in debugging or verifying the correctness of software for modular robots.
This paper describes a novel approach to powering a radical type of microrobot. Our long-term aim... more This paper describes a novel approach to powering a radical type of microrobot. Our long-term aim is to enable the construction of ensembles of millions of coordinated nearspherical, submillimeter microrobots. Both the large number of potential simultaneous neighbors of each robot (12) and the difficulty of fine actuation at such small scales preclude the use of complex connectors previously developed in many modular robotics efforts. Instead, we propose to leverage multirobot cooperation to simplify the mechanics of modular robot docking.
In this paper we develop a theory of metamodules and an associated distributed asynchronous plann... more In this paper we develop a theory of metamodules and an associated distributed asynchronous planner which generalizes previous work on metamodules for lattice-based modular robotic systems. All extant modular robotic systems have some form of non-holonomic motion constraints. This has prompted many researchers to look to metamodules, i.e., groups of modules that act as a unit, as a way to reduce motion constraints and the complexity of planning. However, previous metamodule designs have been specific to a particular modular robot.
This paper describes an application that enables quick reconstruction of interconnected events, s... more This paper describes an application that enables quick reconstruction of interconnected events, sparsely captured by one or more surveillance cameras. Unlike related efforts, our approach does not require indexing, advance knowledge of potential search criteria, nor a solution to the generalized object-recognition problem. Instead, we strategically pair the intelligence and skill of a human investigator with the speed and flexibility of a parallel image search engine that exploits local storage and processing capabilities distributed across large collections of video recording devices. The result is a system for fast, interactive, brute-force video searching which is both effective and highly scalable.
ABSTRACT Imaging sensors are inherently high bandwidth devices, and ap-plications which store ima... more ABSTRACT Imaging sensors are inherently high bandwidth devices, and ap-plications which store image data often encounter disk or memory limits. Commonly, upon reaching such a limit, storage systems will cease sampling or overwrite existing data in an oldest-first fash- ...
We present a high-level language for programming modular robotic systems, based on locally distri... more We present a high-level language for programming modular robotic systems, based on locally distributed predicates (LDP), which are distributed conditions that hold for a connected subensemble of the robotic system. An LDP program is a collection of LDPs with associated actions which are triggered on any subensemble that matches the predicate. The result is a reactive programming language which efficiently and concisely supports ensemble-level programming. We demonstrate the utility of LDP by implementing three common, but diverse, modular robotic tasks.
One of the primary impediments to building ensembles of modular robots is the complexity and numb... more One of the primary impediments to building ensembles of modular robots is the complexity and number of mechanical mechanisms used to construct the individual modules. As part of the Claytronics project-which aims to build very large ensembles of modular robots-we investigate how to simplify each module by eliminating moving parts and reducing the number of mechanical mechanisms on each robot by using force-at-a-distance actuators. Additionally, we are also investigating the feasibility of using these unary actuators to improve docking performance, implement intermodule adhesion, power transfer, communication, and sensing.
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