Microfluidic and pneumatic logic systems are valuable for applications such as lab-on-a-chip devices, soft robotics, and factory automation. These systems are particularly advantageous when metal or electronic components are impractical or when there are constraints on the control system volume or weight. This paper introduces a novel individual membrane valve that functions as a set-reset latch and can reduce the number of valves required for some pneumatic or microfluidic logic systems. An application of pneumatic logic systems in soft robotics is the access to multiple tethered pneumatic elements through a reduced number of pneumatic lines. To this end, this paper proposes two pneumatic logic systems capable of selecting among multiple distributed sets of pneumatic elements and operating the elements of the set simultaneously and independently through the different pneumatic lines. The selection is achieved via a sequence of pressure pulses applied on the same lines used afterwards for operation. Two prototypes of these pneumatic logic systems were built and successfully demonstrated, consisting primarily of set-reset membrane valves and powered by binary high/low pressure sources. The first prototype features a hierarchical network with four lines and five sets of three pneumatic elements each; the second prototype features a non-hierarchical network with five lines and twelve sets of four pneumatic elements each.

Time division multiple access (TDMA) based on a pulse-coupled oscillator (PCO) model is promising for avoiding collisions in wireless communication networks. In this scheme, to keep the convergent states of node phases in the network, nodes must mutually communicate continuously. Convergent states are broken when the continuous communication is inhibited by, e.g., sleeping. Then a converging process must be conducted again. As described in this paper, we introduce a conservative sleep and wake-up control method that preserves the convergent states of node phases for energy savings. Its effectiveness is evaluated based on an order parameter of desynchronization through simulation. We also assess effects of network configuration change and clock variation.

Mobile robots of various types have been proposed for infrastructure inspection and disaster investigation. For such mobile robot applications, accessing the areas is of primary importance for missions. Therefore, various locomotive mechanisms have been studied. We introduce a novel mobile robot system, named DIR-3, combining a crawler robot and a microdrone. By rotating its arm back and forth, DIR-3, a very simple, lightweight crawler robot with a single 360-degree rotatable U-shaped arm, can climb up/down an 18 cm high step, 1.5 times its height.Furthermore, to inspect high places, which is considered difficult for conventional mobile robots, a drone mooring system for mobile robots is presented. The tethered microdrone of DIR-3 can be controlled freely as a flying camera by switching operating modes on the graphic user interface. The drone mooring system has a unique tension-controlled winding mechanism that enables stable landing on DIR-3 from any location in the air, in addition to measurement and estimation of relative positions of the drone. We evaluated the landing capability, position estimation accuracy, and following control of the drone using the winding mechanism. Results show the feasibility of the proposed system for inspection of cracks in a 5 m high concrete wall.

This paper describes a P2P wireless network framework with numerous nodes that can communicate with their neighbors in a stable condition with no collisions of transmissions. Under the network convergence state, every node transmits periodically in order with a cycle shared in the network. To realize that situation, we apply a pulse-coupled oscillator technique to shift the timing of transmission of each node to avoid overlapping with neighboring nodes' transmissions. Additionally, we propose an algorithm to find the suboptimal transmission cycle, preferred small for faster communication, depending on the number of nodes and the network topology based on a class of chromatic number problem in graph theory. We developed a multi-thread simulation platform for multiple node communications to verify the algorithm. Results demonstrate its feasibility both with simulations and with real devices by implementing the method onto an omnidirectional infrared communication device and an RF long-distance communication device.

MimicTile is a novel variable stiffness deformable user interface for mobile devices that implements two key features. The first feature is an input interface that accepts a variety of deformation-based gestures, providing a user with several ways of interacting with a small mobile device. The other feature is the ability to provide information to the user through haptic feedback by varying the stiffness of the interface. The features are suitable for enhancing mobile applications. They were implemented using only shape memory alloy (SMA) wires as the actuator. SMA wire is extremely flexible, making it ideal for deformable user interfaces. In MimicTile, SMA wires act as both actuators and external input sensors. The actuator function works by altering stiffness based on user input. This study also discusses ideas for further development of deformable user interfaces.

A spherical mobile robot has been developed with a 1-DOF mechanism that can generate two motions, translational and rotational, using only one motor. The basic concept is to attach vinyl strips to the sphere at regular intervals and to change the driving modes of the motor to produce the desired motion. For example, placing the motor in vibration mode causes the trajectory of the contact point between the sphere and ground to follow a specified closed path, such as an elliptical path, which makes the sphere rotate against the ground. Testing of this concept using a self-developed simulator confirmed that rotational motion is generated by the interactions between the surface attachments and the ground. On the basis of these results, a prototype spherical mobile robot was developed, and testing confirmed that switching the motor driving mode generated two different motions.

We introduce a unique shaped crawler robot aimed for high-step climbing that is considered the most necessary ability in urban search and rescue operations. The crawler robot is composed of two triangular-shaped crawler devices connected by a center shaft, a straight crawler device and a two-link mechanism connecting the shaft and the straight crawler. The robot is very compact and light weight compared to other rescue robots. It has eight D.O.F. in total, four of which are for crawlers and the others are for shifting the shape of the robot. We confirmed that the proposed robot can get over 36 cm high-step one-and-a-half times as high as its original height. We also implemented a height-independent climbing motion algorithm based on statics and geometrical analysis in climbing process. Various hardware experiments showed a capability of the developed robot and feasibility of the proposed climbing motion algorithm.

In this research, we developed a sphere-shaped mobile robot that can generate multiple behaviors by using only one motor. The robot can generate the translational motion and the rotational motion by controlling the motion of the motor. The motor itself acts as an eccentric weight during motions. To generate emergent behaviors, many protrusions are mounted on the surface of the spherical body. The emergent behaviors occur by an interaction between the external world and these protrusions when the sphere is vibrating, and the robot can move in a random walk manner.

A novel mobile robot design is introduced. To realize high maneuverability such as getting over high steps or no deadlocks when it overturned, a rotational symmetrical structure and a center of gravity shifting mechanism are proposed. The robot is composed of triangle-shaped and straight crawlers connected by two links. The triangle-shaped crawlers can rotate about the axis bar by 360 degrees freely. The robot can get over steps by hanging one of the edges of the triangle-shaped crawlers on an obstacle and rotating the crawlers. In the video, the robot can surmount a 32 cm step which is higher than the robot. The robot system must be useful for information gathering tasks by integrating a sensor network technology into the robot system.

A modular robot has a distributed mechanical composition which can make various configurations and also make locomotion in a wide variety of configurations. Modular robots are thought to be useful in extreme or unknown environments by adaptively changing their shape and locomotion patterns. As for locomotion, two types can be used; one is whole-body fixed-configuration locomotion and the other is locomotion by self-reconfiguration. In this paper we deal with the former type of locomotion which is realized by coordinated joint actuation. So far, proposed control methods for whole-body locomotion by modular robots have been based on predefined locomotion sequences. However, locomotion based on predefined sequences cannot adapt to changing terrain conditions such as uphill, downhill, slippery and sticky grounds. To solve such problems, we propose a distributed control mechanism using a CPG controller which enables adaptive locomotion by modular robots. Besides the real-time CPG control we introduce a decentralized control mechanism for detecting the situation that the robot is stuck and initiating transformation to another shape for recovering the situation. The results of various hardware experiments by 4-legged structure prove the feasibility of the method for adaptive locomotion and transformation by our M-TRAN II modules.

A method for behavior planning is presented for a modular robot that applies a randomized planner to coherent structure of the robot. To cope with difficulty in planning of many degrees of freedom (DOFs) of a modular robot, coherent structure is introduced in terms of control system and robot configuration. As the control system, a simple phase synchronization mechanism is introduced that can control the robot with many DOFs with reduced number of parameters. Together with symmetrical configuration, this control system generates various dynamic motions. In order to plan the behaviors of the modular robot determined by the parameters of the control system, we adopt a randomized planner called rapidly exploring random trees (RRTs). This can benefit from a number of advantages of RRT planner, including simple implementation, uniform search, and applicability to a dynamic system with differential constraints. By exploring parameter space of the coherent control system, behaviors including dynamic motions can be planned. We have applied the proposed planner to M-TRAN modular robot to demonstrate the effectiveness of the proposed method through preliminary simulation results.

Locomotion, one of the most basic robotic functions, has been widely studied for several types of robots. As for self-reconfigurable modular robots, there are two types of locomotion; one type is realized as a series of self-reconfiguration and the other is realized as a whole body motion such as walking and crawling. Even for the latter type of locomotion, designing control method is more difficult than ordinary robots. This is because the module configuration includes many degrees of freedom and there are a wide variety of possible configurations. We propose an offline method to generate a locomotion pattern automatically for a modular robot in an arbitrary module configuration, which utilizes a neural oscillator as a controller of the joint motor and evolutionary computation method for optimization of the neural oscillator network, which determines the performance of locomotion. We confirm the validity of the method by software simulation and hardware experiments.

We have been developing a self-reconfigurable modular robotic system (M-TRAN) which can make various 3-D configurations and motions. In the second prototype (M-TRAN II), various improvements are integrated in order to realize complicated reconfigurations and versatile whole body motions. Those are a reliable connection/detachment mechanism, on-board multi-computers, high speed inter-module communication system, low power consumption, precise motor control, etc. Programing environments are also integrated to design self-reconfiguration processes, to verify motions in dynamics simulation, and to realize distributed control on the hardware. Hardware design, developed software and experiments are presented in this paper.

We have developed a modular robotic system (M-TRAN), which can change its configuration by itself. By using many DOFs of mechanism and self-reconfiguration capability, it can realize several types of motion, and can make various configurations. We have made two models of the system (M-TRAN I & II). In M-TRAN II, various improvements are integrated such as onboard multi-computers, reliable inter-module communication system, low power consumption, precise motor control, etc. Its hardware design, basic experiments and examples of motion are presented in this paper.

We have proposed a self-reconfigurable robotic module, which has a very simple structure. The system is capable of not only building a static structure, but also generating a dynamic robotic motion. We have also developed a simulator for the motion planning. In this paper, we present details of the mechanical and electrical designs of the developed module and its control system architecture. Experiments using ten modules demonstrate the robotic configuration change, crawling locomotion and three types of quadruped locomotion.

This paper addresses motion planning of a homogeneous modular robotic system. The modules have self-reconfiguration capability so that a group of the modules can construct a robotic structure. Motion planning for self-reconfiguration is a kind of computationally difficult problem because of many combinatorial possibilities of modular configuration and the restricted degrees of freedom of the module; only two rotation axes per module. We will show a motion planning method for a class of multimodule structures. It is based on global planning and local motion scheme selection that is effective to solve the complicated planning problem.

In this paper we describe the hardware design of a novel self-reconfigurable robotic system. We have classified previous studies on self-reconfigurable robotic systems into "lattice type" composed of spatially symmetric modules and "string type" like snake robots. The proposed system has both the advantages of simple operation of self-reconfiguration of the former and motion generation ability of the latter. Its simple structure and reliable operation allows us to construct large 3D self-reconfigurable structure which functions as a robotic system such as a legged walking machine. We have examined its basic mechanical functions and verified its reliable operation of self-reconfiguration.