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Fluid injection has promising potential as a novel actuation approach for robots to enable the rapid switching of large forces. We have proposed a nozzle unit with multiple active rotating nozzles for controlling the magnitude and direction of the net force simultaneously. However, a new fundamental challenge arises when multiple nozzle units are connected to a long flexible robot, hence addressing the need to expand the injection range caused by twisting. The proposed nozzle unit can drastically expand the injection range using a passive rotation mechanism to automatically follow the intended injection direction. Concretely, the nozzle unit consists of the passive joint to rotate and two active rotating nozzles to realize the net force. If the unit emits the jets inwardly, the nozzle posture converges to the direction of net force without any additional control. By modeling the proposed nozzle unit, we theoretically validate the global stability of the proposed unit and derive sufficient conditions for geometric parameters. Moreover, we demonstrate that some geometrical parameters could modify the responsiveness of the posture. The developed nozzle unit experimentally verifies that the nozzle unit can direct the net force direction in the range of 180 degrees from the upward to the downward direction. In addition, we observe the step responses of the posture for several gains and confirm that responsiveness could be tuned by geometrical parameters. The results of the experiments agree well with the model trends.

Several ground-based robots have been developed to support dangerous fire extinguishing activities; however, in such cases, it is difficult to access the fire sources directly. The concept of a hos...

Flexible continuum robots exhibit a strong potential for approaching narrow and intricate spaces. However, such long flexible bodies often experience oscillations, making them unstable. To enhance their performance in order to realize rapid and precise movements, unnecessary vibrations should be suppressed. The authors have proposed a new type of continuum robot, aimed for firefighting; this robot, Dragon Firefighter (DFF), can fly using water jets. The DFF suffers from the same problem of body oscillation. In particular, a more challenging issue for the DFF is the use of limited number of actuators owing to the constraints of weight and water flow. Discrete locations of the actuators on the long body of a robot can generate uncontrollable resonant modes. This letter proposes a mechanical approach to suppress the oscillation passively without actuation control. The proposed mechanism is composed of wires threaded along the body and connected to rotary dampers to restrict the deformation of the body. First, a numerical model to simulate the oscillation and damping behavior was reported. A basic experiment with a 1-m-long flexible tube shows that the damping mechanism suppresses the vibration appropriately, which also corresponds well with the simulation. Second, a stability analysis of the simulation of the flying motion shows that the passive damping mechanism can improve the stability, with the convergence time becoming approximately 2.4 times shorter than that in the case without the mechanism. Finally, we apply the damping mechanism to a 3.6-m-long flying robot. The demonstration shows that the robot can float stably and that the damping mechanism works correctly.

Disaster response, especially fire-fighting and rescue, is highly risky for firefighters engaged in action. As a result, many robots intended for fire-fighting have been proposed. However, it is difficult for them to directly access fire sources because their mobility is limited. Specifically, existing robots are large and heavy. Therefore, we propose a novel hose-type robot, which can fly directly into the fire source via a water jet. First, to control the reaction force for stable flying, we developed a nozzle module. By combining two nozzles whose outlet direction can be controlled, the resultant reaction force can be controlled. Finally, we developed a robot with a nozzle module and conducted an experiment. The experiment demonstrates that a robot with a length of approximately 2 m can fly stably in the air by leveraging the water jet. In addition, the head direction can also be controlled.

[abstFig src='/00290001/19.jpg' width='300' text='Human-voice enhancement system for a hose-shaped robot' ] This paper presents the design and implementation of a two-stage human-voice enhancement system for a hose-shaped rescue robot. When a microphone-equipped hose-shaped robot is used to search for a victim under a collapsed building, human-voice enhancement is crucial because the sound captured by a microphone array is contaminated by the ego-noise of the robot. For achieving both low latency and high quality, our system combines online and offline human-voice enhancement, providingan overview first and then details on demand. The online enhancement is used for searching for a victim in real time, while the offline one facilitates scrutiny by listening to highly enhanced human voices. Our online enhancement is based on an online robust principal component analysis, and our offline enhancement is based on an independent low-rank matrix analysis. The two enhancement methods are integrated with Robot Operating System (ROS). Experimental results showed that both the online and offline enhancement methods outperformed conventional methods.

We herein propose the method for developing an “aerial hose type robot” called the “Dragon Firefighter (DFF)” that can fly along with the water jet. We focus on realizing a novel concept through which obstacles can be avoided and fire spots can be accessed from a distance, thereby enabling direct firefighting, and evaluating fire suppression ability from a close distance of fire source for practical useage. Using robotics, we aim to extinguish the fire from a distance, simultaneously guaranteeing firefighters' safety. We were able to realize stable floating of a hose of length 2.8 m (total length of 3.6 m), which is twice that of a conventional one, overcoming the height gap of approximately 1.5 m and the size of frontage $\mathbf{1.0} \times \mathbf{2.5}\ \mathbf{m}$ . We demonstrated a fire extinguishing, however the ability of fire extinguishing about DFF was unknown. Hence, we conducted a mist spray experiment from a close distance to validate the cooling effect of water. Considering the aerial nature of our robot, we concluded that a mist spray from its nozzle module will be more effective for extinguishing fires. Finally, we presented the consideration of firefighting tactics using the proposed DFF for practical implementation.

The Active Scope Camera has self-propelled mobility with a ciliary vibration drive mechanism for inspection tasks in narrow spaces but still lacks necessary mobility and sensing capabilities for search and rescue activities. The ImPACT-TRC program aims to improve the mobility of ASC drastically by applying a new air-jet actuation system to float ASC in the air and integrate multiple sensing systems, such as vision, auditory and tactile sensing functions, to enhance the searching ability. This paper reports an overview of the air-floating-type Active Scope Camera integrated with multiple sensory functions as a thin serpentine robot platform.

Snake-like robots are useful for exploring narrow spaces such as in collapsed buildings after a severe disaster. Two people are usually required for operating serpentine robot, one for pushing and twisting, and the other for controlling the tip. In this paper, we propose a way to control a snake robot with a single operator, by the use of robotic thruster. Further, a robotic thruster has the advantage of improving the estimation of tip position and shape, by measuring the inserted length of the cable. In this study, the focus is on “ hairy ” robots, so called because an Active Scope Camera (ASC) is covered by inclined cilia acting as a self-propelling mechanism. When operating a snake robot, the most difficult challenge is to insert it without damaging the cilia. First, opposed flexible rollers are proposed to push the robot whose cylindrical surfaces are covered by tensed flexible wires. The wires sandwich the robotic body between the hairs to avoid damage. Then, by using the rollers, a thruster is proposed which can push and twist the ASC, and measure both the inserted length and twisting angles. Basic performance experiments showed that the thruster could successfully push and twist an ASC of approximately 5 m. The accuracy of the inserted length and twisting angle were less than 10% and 45%, respectively. The thruster was able to push and twist the ASC on flat environments with obstacles, and in a three-dimensional rubble environment.

In this paper, we investigate effects of the flexibility of the body on locomotion of a quadruped robot using computer simulation with physical models. So far, many researchers have used legged robots whose bodies consist of one rigid body and examined dynamical properties, such as stability of gaits and energy efficiency. However, from the observation of animals, it has been suggested that flexibility of the body is important for dynamic locomotion. We used two types of simple physical models, with and without a springy joint in their body to evaluate the importance of the body flexibility on the bounding gait, where left and right legs simultaneously kick the ground. Our simulation results show that when we use the same mechanical energy for these two models, the maximum ground reaction force for the model with a body springy joint is smaller than that for the model without a body springy joint (rigid body) even when their locomotion speeds are identical. This suggests that the flexibility of the body can reduce the foot loading of the robot in the bounding gait.

Among quadrupedal gaits, the galloping gait has specific characteristics in terms of locomotor behavior. In particular, it shows a left-right asymmetry in gait parameters such as touchdown angle and the relative phase of limb movements. In addition, asymmetric gait parameters show a characteristic dependence on locomotion speed. There are two types of galloping gaits in quadruped animals: the transverse gallop, often observed in horses; and the rotary gallop, often observed in dogs and cheetahs. These two gaits have different footfall sequences. Although these specific characteristics in quadrupedal galloping gaits have been observed and described in detail, the underlying mechanisms remain unclear. In this paper, we use a simple physical model with a rigid body and four massless springs and incorporate the left-right asymmetry of touchdown angles. Our simulation results show that our model produces stable galloping gaits for certain combinations of model parameters and explains these specific characteristics observed in the quadrupedal galloping gait. The results are then evaluated in comparison with the measured data of quadruped animals and the gait mechanisms are clarified from the viewpoint of dynamics, such as the roles of the left-right touchdown angle difference in the generation of galloping gaits and energy transfer during one gait cycle to produce two different galloping gaits.

Walking animals produce adaptive interlimb coordination during locomotion in accordance with their situation. Interlimb coordination is generated through the dynamic interactions of the neural system, the musculoskeletal system, and the environment, although the underlying mechanisms remain unclear. Recently, investigations of the adaptation mechanisms of living beings have attracted attention, and bio-inspired control systems based on neurophysiological findings regarding sensorimotor interactions are being developed for legged robots. In this review, we introduce adaptive interlimb coordination for legged robots induced by various factors (locomotion speed, environmental situation, body properties, and task). In addition, we show characteristic properties of adaptive interlimb coordination, such as gait hysteresis and different time-scale adaptations. We also discuss the underlying mechanisms and control strategies to achieve adaptive interlimb coordination and the design principle for the control system of legged robots. peerReviewed