Roadmap-based path planning is a well-established method for multi-robot systems, where the free space of the environment is represented as a roadmap graph. The Voronoi diagram is known for its efficiency in creating roadmaps for single-robot systems due to its ability to generate paths with high clearance from obstacles. However, the design of the Voronoi diagram does not allow for redundant paths, as only one path is obtained between each pair of obstacles. In contrast, multi-robot path planning requires multiple path options for efficient solutions. Therefore, we propose redundant Voronoi roadmap graph, which incorporates multiple paths computed from the Voronoi diagram. In this approach, we introduce imaginary obstacles to modify the costmap and obtain a roadmap with more paths. Our proposed roadmap retains the high clearance feature of the Voronoi diagram and is suitable for multi-robot systems due to the availability of alternative route options. We demonstrate that our method can generate roadmaps in various simulated environments with different levels of redundancy. Additionally, we verify the efficiency of our proposed roadmap graph through graph analysis and multi-robot path planning experiments. Comparative analysis shows that the use of the proposed roadmap increases the success rate and solution quality compared to the roadmap obtained directly from the conventional Voronoi diagram.

Localization is crucial for various automation systems to provide awareness of the robot's position and orientation. Additionally, a localization system that offers portability, flexibility, and low computational and economic costs is required by a variety of robotics applications. However, no existing system can offer all the aforementioned features suitable for motion capture tasks involving ground swarm robots. In this study, we propose MoCArU, a novel Motion Capture system based on odometry and ArUco, robustly recognized through image data with low computational cost. We have evaluated the system's performance by comparing it with the ground truth trajectory and adopting different numbers of cameras. The results show that MoCArU can achieve a root mean square error of 0.1345±0.0065 m using ten cameras. Our findings add to previous knowledge by presenting a robust and cost-effective alternative to existing localization methods. Here, we show that MoCArU's use of lightweight camera stands and wireless communication ensures ease of installation, portability, and low computational cost, making it suitable for tracking swarm ground robot systems. We anticipate this system to be used in various applications, such as robot position control, navigation, and obstacle avoidance control. Overall, MoCArU provides a reliable and cost-effective solution for the real-time localization of robots, so its wider applicability in various environments is a significant advantage in robotics. An open-source implementation of MoCArU, as well as its related details, is open for public use at https://www.rm.is.tohoku.ac.jp/MoCArU.

There is an increasing demand for robots that can be substituted for humans in various tasks. Mobile robots are being introduced in factories, stores, and public facilities for carrying goods and cleaning. In factories and stores, desks and shelves are arranged such that the work and movement of personnel are reduced. The surrounding furniture is also set to ensure that a single task can be performed in the same place. It is essential to study the intelligence of robots using information from such layouts, wherein human labor and movements are optimized. However, There is no method of map construction or location estimation that uses the characteristics of furniture arrangements that facilitate human work in a work space. Therefore, this study proposes a method for object mapping using layouts in crowded workspaces. Graphically represent the characteristics of furniture placement that make it easy for people to work in a workspace. The links in the graph represent the connections between the objects in the layout property. The nodes are the objects, and the weights of the links represent the strength of the layout properties. This graph is optimized by GraphSLAM to construct a map that considers the arrangement's characteristics. Using the graph structure improves the map's accuracy while allowing for relative changes in placement. The results show a 50.44% improvement in accuracy in a space with 18 desks, followed by two variations of similar desk layouts. The same improvement in accuracy was also observed when the relative positioning of objects changed significantly in each variation, such as a change to the left or right on the same side.

We propose a novel toroidal origami monotrack capable of smooth-skin driving and bending for closed-skin-drive robots. Monotracks are a promising solution for achieving high mobility in unstructured environments. Toroidal-drive mechanisms enable whole skin drive; however, conventional methods experience unexpected wrinkling and buckles that lead to a large resistance. In this study, we propose an origami bellows structure with multiple rollers that can maintain the skin tension and deal with the cause of large friction between the skin and the body. The origami structure design method is presented, and the bending angle range and required drive force were derived through a theoretical analysis. The validity of the effectiveness of the concept was verified through prototype testing.

Machines tend to use powerful actuators and large gearboxes to bear large loads, which are inconvenient in terms of responsiveness as they affect the duration of operations. Thus, to compensate the force to grasp an object, we propose a clamping mechanism implementing the internally-balanced magnetic unit (IB Magnet) as a force amplifier, which is a mechanism able to switch attached and detached states of a permanent magnet with an external force considerably smaller than its original attractive force. To realize the bi-parting constitution of fingers, a new compensation method using conical coil springs was designed to provide both precision and miniaturization. Relative to the constitution with a single motored screw, the prototype gripper for proof of concept successfully amplified the grasping force at most to 292.2% assisted by the magnetic attraction, while keeping the increase in power consumption of a DC motor only by 11.8%, making the force-energy efficiency 2.6 times larger. Thus, it was verified that the proposed gripper enables the use of actuators and current supplies that require less power.

To detach a permanent magnet using a control force much smaller than its original attractive force, the internally-balanced magnetic unit (IB Magnet) was invented. It has been applied to magnetic devices such as wall-climbing robots, ceiling-dangling drones, and modular swarm robots. In contrast to its significant reduction rate with regard to the control force, the IB Magnet has two major problems in its nonlinear spring, which serves the purpose of cancelling out the internal force on the magnet. These problems include the complicated design procedure and the trade-off relationship between balancing the precision and the volume of the mechanism. This paper proposes a principle for a new balancing method for the IB Magnet. This method uses a like-pole pair of magnets as a magnetic spring, whose repulsive force should equal the attractive force of an unlike-pole pair. To verify the proposed principle, a prototype of the IB Magnet was designed using a magnetic spring and verified through experiments such that its reduction rate is comparable to those of conventional IB Magnets. Moreover, a robotic clamp was developed as an application example that contains the proposed IB Magnets as its internal mechanism.

We introduced the disturbance degree of ground and proposed an evaluation method to measure the mobile performance of a crawler on soft ground during direction switching. First, we developed a planar omnidirectional crawler, which had a configuration with two left and right unit crawlers for performing turning motion, as the target for evaluation. Second, by utilizing the proposed disturbance degree of ground evaluation method, we investigated how the turning and translational motions of the crawler mechanism affected soft ground by measuring the flow of sand on a horizontal surface. It was quantitatively shown that translational motion switched the travel direction with lesser disturbance to the road surface compared to turning motion. We confirmed that ground disturbance could be evaluated during direction switching using the proposed method.

Long flexible continuum robots have a high potential for search and rescue operations that explore deep layered debris. A general problem of these robots is in the control of the head motion because their thin bodies limit the space available to mount multiple actuators. This paper develops a biaxial active nozzle which can rotate the air jet direction along a roll and pitch axis in order to control the direction of reaction force and the head motion of a long flexible robot. A major challenge is how to change the air jet direction without a large resistance to the flow, which reduces the reaction force induced by the air jet. We propose a nozzle whose outlet is connected with a flexible air tube. The direction of the air jet is controlled by the smooth shape deformation of the tube. The nozzle should be compact enough to be installed on a thin robot, although the shape deformation of the tube may cause buckling. The flexible tube is modeled and simulated by a multiple link model used to derive the geometric parameters of the nozzle so that the nozzle is compact and the tube does not buckle. Based on the derived parameters, the biaxial active nozzle was developed. A basic performance experiment shows that the nozzle can change the reaction force direction by deforming the tube shape, while the magnitude of the reaction force is almost constant. We integrated the proposed nozzle with a conventional Active Scope Camera (ASC). The range where the robot can look around in a vertical exploration was significantly improved, which was three times larger than the previous ASC whose head was controlled by pneumatic actuators. The rubble field test demonstrates that the integrated ASC could move over rubble (maximum height of 200 mm) and steer the course.

The transmission of high-frequency collision vibration can effectively deliver tactile characteristics in teleoperation of remote robots and the virtual environment. However, high-frequency vibrations also introduces audible noise. To address this issue, we modulated the frequency and amplitude of collision vibration to keep the perceptually similar while reducing the sound of the vibrations. Our experimental results showed that the sound pressure level of the collision vibrations (f = 675 Hz and 1012 Hz) is higher than the perceptual similar collision vibrations (f = 300 Hz and 450 Hz). These results suggest that our modulation method is able to reduce the sound level of the collision vibrations while maintaining the perceptual similarity.

This paper presents a blind multichannel speech enhancement method that can deal with the time-varying layout of microphones and sound sources. Since nonnegative tensor factorization (NTF) separates a multichannel magnitude (or power) spectrogram into source spectrograms without phase information, it is robust against the time-varying mixing system. This method, however, requires prior information such as the spectral bases (templates) of each source spectrogram in advance. To solve this problem, we develop a Bayesian model called robust NTF (Bayesian RNTF) that decomposes a multichannel magnitude spectrogram into target speech and noise spectrograms based on their sparseness and low rankness. Bayesian RNTF is applied to the challenging task of speech enhancement for a microphone array distributed on a hose-shaped rescue robot. When the robot searches for victims under collapsed buildings, the layout of the microphones changes over time and some of them often fail to capture target speech. Our method robustly works under such situations, thanks to its characteristic of time-varying mixing system. Experiments using a 3-m hose-shaped rescue robot with eight microphones show that the proposed method outperforms conventional blind methods in enhancement performance by the signal-to-noise ratio of 1.03 dB.

Unnoticed collisions compromise the success of remote exploratory tasks with mobile robots. We propose a vibrotactile stimulation method to represent frontal collisions that is based on the way people perceive impacts on a bar held with both hands. We observed that to estimate the impact point in a bimanual impact localization task people relied on amplitude and duration differences of the impact vibrations delivered to their hands. Then, to apply these results, we obtained a psychophysical function that relates impact points and vibration parameters. Finally, we used a differential drive mobile robot equipped with a high speed tactile sensor on the front bumper to evaluate our method in a simplified teleoperation task. We observed that participants required less time to complete the task when vibrotactile feedback was available.

This study proposes a self-locking-type expansion mechanism for in-pipe robots. Previously, we proposed a highspeed locomotion mechanism using pneumatic hollow-shaft actuators; however, this mechanism lacked holding force and could not pass through a bent pipe. The proposed mechanism generates a large holding force and can easily pass through a bent pipe by invoking a self-locking phenomenon. We conceptualize and design the novel expansion mechanism and introduce its associated mathematical model to formulate the holding force and mechanism design. The characteristics and capabilities of the mechanism are elucidated by experiments. From the experimental results, we optimize the applied pressure and the design of the mechanism. The proposed mechanism generates a maximum holding force of 69.7 N, which is 5.2 times higher than that of the previous mechanism, and drastically improves the robot's bent-pipe-passing capability. Finally, the performance of this mechanism is confirmed in a simulated pipe test. In this trial, a robot equipped with the proposed mechanism smoothly and steadily moves through complex pipe configurations, including the vertical and bent pipes.

Disaster response robots for searching in a narrow area have limited space to mount tactile sensors, but the operators require sensory feedback to recognize contact situations with the surrounding environment. This study proposes a new approach to transmitting contact information of a remote-operated snake-like robot called Active Scope Camera (ASC) to the operator using simple configurations for the sensing and display methods. For the sensing side, we develop a contact estimation method with a limited number of tactile sensors. We establish the method to localize the contact position and the magnitude by sensing multiple propagated vibrations based on experiments and formulations. Preliminary experiments show that the developed method estimates a collision angle with high probability (93.8% at the worst condition) at several collisional situations. For the display side, we combine visual and vibrotactile feedback to provide the operator both directional and temporal cues to perceive contact events. The proposed visualization method uses colored bars, peripherally superposed on the video image, to show the estimated contact location and magnitude. A single DoF vibrotactile feedback is used for a joystick interface to control the head movement of the ASC. The effect of vibrotactile feedback on the response time to contact events is evaluated. Finally, we investigate the performance of the operation by identifying the contact behavior at simulated scenarios. Experimental results show that collision times per operation time is decreased by the developed feedback system compared with a simple video-based operation.

Tethered robots often experience entangling of their cables with obstacles in uncertain disaster environments. This paper proposes a spherical tether handling device that unfastens a robot's tether during surveys by releasing the tether and carrying it aside. By using a differential mechanism, the device drives shells and rollers that hold the tether. On flat surfaces, the device moves forward by driving the shells. When the device climbs over steps, the rollers are driven by the differential mechanism to pull the tether automatically. After prototyping the device, we confirm the surmountability of the proposed device against steps. The results show that the device can climb a height 90.9% of its diameter. We also demonstrate a scenario to handle the tether and untangle multiple tangles in an environment with several obstacles.

3D posture estimation for a hose-shaped robot is critical in rescue activities due to complex physical environments. Conventional sound-based posture estimation assumes rather flat physical environments and focuses only on 2D, resulting in poor performance in real world environments with rubble. This paper presents novel 3D posture estimation by exploiting microphones and accelerometers. The idea of our method is to compensate the lack of posture information obtained by sound-based time-difference-of arrival (TDOA) with the tilt information obtained from accelerometers. This compensation is formulated as a nonlinear state-space model and solved by the unscented Kalman filter. Experiments are conducted by using a 3m hose-shaped robot with eight units of a microphone and an accelerometer and seven units of a loudspeaker and a vibration motor deployed in a simple 3D structure. Experimental results demonstrate that our method reduces the errors of initial states to about 20 cm in the 3D space. If the initial errors of initial states are less than 20 %, our method can estimate the correct 3D posture in real-time.

The purpose of this study is to establish a quantitative method that can evaluate the motor function of human lower limbs in dynamic situations. As an index of motor function, we focus on the mechanical impedance characteristics of the lower limbs. By controlling these characteristics, humans can improve motion stability and adapt their movement to disturbances in the environment. In this paper, we propose a method that can estimate the impedance characteristics of the lower limbs of a human subject applying torque perturbations during a pedaling exercise. To improve the accuracy of the proposed estimation method, the effects of inertia and gravity in the measurement data were considered by representing the lower limbs by a multi-link model. Experiments were performed in two participants to estimate the stiffness and viscosity at different phases of the periodic movement. The distributions of these parameters showed symmetric properties for both legs in a pedaling cycle-a tendency that was observed in both participants. This agreement suggests that our method could extract a component of human motor control strategy that adjust mechanical impedances during pedaling exercises.

This study proposes a high-speed locomotion mechanism for a pipe-inspection robot. As a result of the narrow and complex structures of pipeline networks, it is difficult for robots to move quickly within the pipes. The new pneumatic mechanism proposed here realizes high-speed locomotion along with advantageous features for pipe inspection including a small diameter, flexibility, and low weight. First, we present the design concept of the novel locomotion mechanism using pneumatic flexible hollow-shaft actuators, which was previously developed by the authors. The prototype constructed to realize this concept and the associated mathematical model are then introduced. Second, the basic characteristics of the proposed mechanism are evaluated in terms of the holding force (generated by an expansion mechanism against the pipe wall) and the impellent force that induces forward motion in the robot. Finally, the in-pipe movement performance is confirmed. The experimental results show that the designed robot can be propelled inside a 53-mm-diameter pipe at a maximum speed of 250 mm/s, which is exceedingly faster than conventional designs.

A novel gait phase detection method that can extract the timing of foot contact conditions (Heel Strike and Toe Off) by a single piezo film sensor attached on each leg is proposed. We focused on the occurrence of high-frequency vibrations (> 100 Hz) in the beginning and the end of stance phases during gait. After the features of vibration waveforms during gait were confirmed, we proposed the phase detection method. The optimal parameters were investigated to detect the phases robustly despite the walking speed and the shoe types. Experimental results showed that the detected ground contact events had high accuracy of timing. Finally, we confirmed the feasibility with the prototype wearable device in usual environments.

Remote robotic explorations for collapsed buildings in a severe disaster are demanded. However, rescue robots cannot approach the rubble due to safety risks. This study proposes a remote vertical exploration system for collapsed buildings with a robotic inspection system hoisted by a crane. An Active Scope Camera (ASC) has many advantages for the vertical exploration such as a light and flexible continuum body to produce distributed driving forces. The purpose of this paper is to confirm the feasibility of the vertical exploration system with the ASC. The vertical explorations have proper problems related to contact and hanging conditions of the scope cable. We developed a new ASC that has a two-step bending mechanism to produce larger head movement in multi-DOF. We also evaluated the performances of the prototype when the contact areas were small. Finally, we conducted a remote vertical exploration experiments at the simulated collapsed building in 6 m height. The robot could explore in six different pathways by changing head directions and running the rubbles within seven trials. The experimental results showed that the proposed system has high potential to get inserted in the deep area in the rubble.

The overlapping of vibrations that are in different phases and in close proximity to each other produces a tactile image that is more localized than one produced by pin vibrators. The mechanism behind the former is still unclear; it may be attributed to the fact that the resultant vibration is highly localized and of a high frequency, making the tactile sensations more perceptible by the human hand. In this study, a finite element (FE) model of a human finger is analyzed to investigate the reason for the difference in the sizes of tactile images produced under different mechanical conditions. In the dynamic analysis, we observed the spatial distribution of the strain energy density (SED) in the model and estimated the perceptual area of the mechanical stimuli. To determine the perceptual area, the threshold SED for perceiving the vibratory stimuli was determined by analyzing the FE finger model on a flat vibratory surface. In the deformation analysis results, we observed that the spatial distribution of SED was more localized by the overlapped vibrations than in a pin vibrator. Moreover, spectral analysis revealed that a higher-frequency vibration was generated locally between the two vibrations. A psychophysical experiment was conducted to determine the effect of the high frequency component on detection thresholds.

A novel flexible pneumatic linear actuator is proposed in this paper. The proposed actuator realizes high-speed reciprocating motion by the moving part which has multiple rollers moves smoothly along the flexible hollow shaft. An effective application of this actuator is its use in endoscope robots and tether robots because cables of cameras or sensors can be passed inside the actuator by using the hollow structure. First, we discuss the physical model of the actuator pressurized in the resting state, and we provide an analysis of the generated force of the actuator. The model relates the generated force to the relevant design parameters such as the applied pressure, the material of the pressure chamber, the size of the moving part, etc. Second, we describe the measurement experiment of the generated force, and we show the validity of our model by comparing the experimental results with the analysis results. Third, we present the motion evaluation using a prototype of the actuator. We found that the maximum velocity of the moving parts is 9 m/s and that the moving parts can move smoothly even if the actuator is curved. Finally, we present the drive mechanism that uses the actuator, as an application example.

This paper presents an initial data that could show a possible contribution of mechanoreceptor activity to the perception of forces applied on grasped objects. Here, we obtained detailed psychophysical characteristics of perceived force-magnitude in multiple degrees of freedom (MDOF) using multi-point suction pressure stimuli. To obtain such data, we developed a multi-point stimulation method that can represent MDOF perceived force on a tool. We characterized the perceived force response of human subjects to suction pressure stimuli through psychophysical experiments. Moreover, we analyzed the strain energy density (SED) on the finger pads considering the force applied through finite element simulation. The results of the psychophysical experiments showed that multi-point stimulation method is effective for evoking MDOF perceived force on a tool. Interestingly, we found that the results of the finite element analysis agree with those of the psychophysical data. Therefore, we have verified that it is possible to use multi-point suction pressure stimulation for representing perceived force on objects held in a hand. In addition, a preliminary insight into the role of SED for perceiving force on tools is provided.

Active Scope Camera (ASC) using a linear inchworm drive, which can run on various road surfaces assumed in disaster sites, have been developed as a snake-like rescue robot. However, it is difficult for the linear inchworm drive to run in crooked narrow pathways, because its rigid body actuator reduces the flexibility of the scope camera and becomes immovable when the scope camera is curved. There are many crooked narrow pathways inside collapsed houses and under rubble. ASC's search range could be vastly expanded if ASC can run in such environments. In this paper, we developed a flexible linear actuator, which has the bellows structure and the hollow structure, for ASC in order to solve these problems. The actuator was able to generate large force more than 6 N from 60 kPa of applied pressure even if it was curved at 200 mm bending radius. Moreover, we developed a flexible linear inchworm drive using this actuator. The flexible linear inchworm drive keeps the running characteristics on the various road surfaces of the conventional linear inchworm drive. The minimum width of 80 deg crooked pathway that the flexible linear inchworm drive could run through was 60 mm, which was one-thirds narrower than that of the conventional inchworm drive.

In this paper, an estimation method using the flexible multi-body dynamics model, inertial/magnetic sensor system, and probabilistic state estimation is proposed for estimating the shape of a flexible cable. Sensors mounted on flexible cables, such as endoscopes, are often picked up noise, and their size and number are restricted. The proposed method can estimate motion using the flexible dynamics model if there are few sensors. In addition, this method is robust against noise because it can integrate some types of sensor information by probabilistic state estimation. The proposed method uses the Absolute Nodal Coordinate Formulation (ANCF) as a flexible dynamics model and the Unscented Kalman Filter (UKF) for probabilistic state estimation. It can model a greatly deformed cable at any point using ANCF, and it can fit nonlinear motion and achieve high versatility about models because of UKF. In the second half of this paper, experiments using Active Scope Camera (ASC) are conducted to evaluate the proposed method. The ASC is a snake-like rescue robot, and its sensor system picks up strong noise. In the experiments, the proposed method estimates three types of motion, and it shows the effectiveness if the number of sensors decreases.

An active scope camera (ASC) is a special type of videoscope for search and rescue operations; the ASC has a self-propelled mechanism with a ciliary vibration drive. From an analysis of the problems encountered with the conventional ASC during applications to practical disaster environments, we propose a new tube-type ASC with enhanced mobility and practical functionality for rescue activities. We designed a smart structure to mount vibration motors on a long tubular cable without any rigid projections. A suitable tubular cable material was also selected experimentally to propagate the vibration efficiently. We integrated several practical functions such as a head bending structure, an auditory communication system, and a gravity indicator for the head orientation. We conducted several fundamental performance experiments. Finally, the enhanced performance of the tube-type ASC for practical use was demonstrated at a training site for first responders.

Previous surface shape presenting methods had difficulties in generating high-density tactile information owing to blurriness in tactile images caused by lateral skin deformations. In this study, a new surface shape presenting method is proposed, and it employs overlapping small-amplitude vibrations instead of a single vibration. This method represents the mechanism of stationary boundary contacts (SBCs), a vibrotactile sensitivity enhancement method proposed in a previous research. A series of psychophysical experiments showed that the vibrations overlapping method can significantly enhance the human vibrotactile sensitivity and lead to the production of sharp tactile images. Moreover, the stimuli intensity can be controlled not only by changing the vibration amplitudes but also by changing the phase deviations between vibrations; this enables the presentation of various surface shape patterns that cannot be presented by using the previous SBC method alone.

An experimental study was done to examine the relationship between vibrotactile amplitude displacement and softness sensation. Merkel Disk behavior relative to softness sensation was studied under psychophysical experimentation of human participants. Restrictions are carefully applied on contact area spreading so that vibration will be the only factor that would induce a sensation. A vibrotactile device was excited at constant frequency and its amplitude is adjusted at different levels to alter the amount of skin displacement. Volunteers participated in a two-alternative force choice experiment were ask to compare the perceived softness difference between voice coil and silicone rubber. Statistical analysis on the responses of participants showed a decline of spring constant. It was interesting to note, that even though contact area was significantly restrained participants were still able to discriminate softness sensation form vibrotactile stimulation. Such observation possibly shows that illusion of contact area spread rate can be reproduced by vibrotactile stimulation.

Perception of minute force through tactile feedback from a tool is an important aspect for humans to maintain dexterity during manipulation of embedded objects invisible to the naked eye, such as repairing tissues in minimally invasive surgery. Different pressure levels at finger contacts could be responsible factors concerning the perception of forces on a tool. In this paper, an experimental study was done to verify if pressure stimulation to the thumb and index fingers on a precision grip position could alter the perception of force. We requested participants to perform a psychophysical experiment by holding a grounded pen-type interface having a single degree of freedom which induces pressure sensation using air suction. Perceived force was observed to increase when pressure was applied increasingly. Experimental results suggested that vacuum pressure can be used as a complementary tactile stimulus for inducing force sensation. This study had confirmed that negative pressure stimulus can be used to augment force perception.

Tactile sensations experienced by humans, such as roughness and softness, require not only high-frequency (200 Hz) but also lower-frequency vibrations (< 50 Hz). However, such low frequencies are difficult to achieve with small actuators that can be integrated into mobile devices. Therefore, it is necessary to develop methods for enhancing human vibrotactile sensitivity. We focused on a phenomenon whereby simultaneous contact with vibratory and stationary surfaces enhances human vibrotactile sensitivity, which we call stationary-boundary-contact (SBC) enhancement. SBC produces a line sensation along the gap between the vibratory and stationary surfaces. In this study, we determined the detection thresholds for SBC-enhanced sensitivity under several conditions. Psychophysical experiments showed that the detection thresholds of SBC were reduced by more than three times at low frequencies as compared to those under normal conditions. We then investigated the mechanism behind SBC enhancement by using a finite element model for the skin. Static and dynamic deformation analyses indicated that the dynamic impact of skin against the edge of a stationary surface contributes to an increase in the vibration frequency of the skin. This hypothesis was also supported by the psychophysical experiment, which showed that an edge-rounded stationary surface had less effect on sensitivity enhancement. Finally, we investigated possible SBC arrangements for practical applications on the basis of line sensation.

Remote transmission of high quality sense of touch requires the representation of multiple tactile properties and compensation of communication delay. We developed a real-time remote transmission system that can deliver multiple tactile properties using a master-slave robot system. First, we assessed what type of tactile properties should be transmitted and how to connect them in real time. Three tactile properties - roughness, friction, and softness - were transmitted on the basis of the real-time estimated physical properties of three main wavelengths, a kinetic friction coefficient, and spring constants, respectively. Tactile stimulations were generated in synchronization with hand exploration at the master side by using local tactile generation models to compensate for communication time delay. The transmission of multiple tactile properties was achieved by the integration and enhancement of our previously reported methods for vibrotactile displays and tactile sensors. A discrimination experiment using different materials showed the feasibility of the total system involving the three tactile properties.

This video captures human-robot interaction which occurred during an evaluation of a novel, snake-like search and rescue robot assisting with victim management. Most of the observations confirmed previous findings- That a 2:1 H-R ratio ratio is appropriate, Team coordination is enhanced by shared visual perception, and Poor interfaces continue to lead to incomplete coverage. However, the victims responded to the robot in two surprising ways: grabbing the robot and being concerned about its appearance.

In this study, a tactile-roughness transmission system applicable to master-slave systems with a communication time delay is developed. The master-side system constructs a local model of target objects placed in the slave-side environment. Tactile feedbacks presented to an operator at the master side are produced by combining the physical properties of target objects in the local model and the kinetic information of the operator. The time delay between the operator's motion and the tactile feedback is cancelled because the stimuli are synchronized with the exploratory motions. The proposed system is applied to the transmission of tactile-roughness. The tactile stimuli presented to the operator are vibratory stimuli whose amplitude and frequency are controlled. These stimuli are locally synthesized by combining the surface wavelength of target objects and the operator's hand velocity. Using the developed tactile-roughness transmission system, an experiment for transmitting the perceived roughness of grating scales was conducted. As a result, the roughness perceived by the operators was found to highly correlate with the roughness of the scales in the slave-side environment with a coefficient of 0.83.

We propose a new framework for a self-propelled flexible cable in which the freedom of lateral motion with sliding movements is increased on the basis of simple shape information.We developed a large-scale prototype of the flexible cable that has a ciliary drive mechanism and precise shape sensors to investigate our concept.We developed a kinetic model for the prototype by employing the nonlinear driving force model and the lateral friction model for representing slippages. Further, we proposed a sliding motion control method that focus on the shape and length of the straight element. We applied the method to control the running direction. The experimental results and dynamic simulations demonstrated the effectiveness of sliding motion for controlling the running direction.

The tactile display for handheld devices requires compact hardware and useful applications. To satisfy these points, we have proposed the concept of `virtual active touch' that implements virtual exploration with a cursor on a screen through a pointing-stick-type tactile interface. The objective of this study is to present three-dimensional shapes on a two-dimensional screen without force feedback devices. It is possible to present three-dimensional shapes such as a bump using a lateral force. In order to represent human perception of geometric surface shape, instead of the lateral force, we use the cutaneous sensation of friction that occurs when a human finger strokes object surfaces. First, we confirmed that the virtual active touch interface could present cutaneous sense of friction. Second, we evaluated the perception of surface height in the context of bumped shape induced by the friction display. The experimental results agreed with our expectation that faster and longer increases in friction sensation were perceived as higher bumped shapes.

Today there are many tactile sensors in the world. Though there is few sensor whose characteristics are similar to cutaneous sensation of human. If we want to measure the tactile information of human we have to use human-like tactile sensor. Here we have developed a reflection-type tactile sensor by using imaging device. This sensor employs a simple total reflection characteristic, so it has many degrees of freedom of selecting sensing units, and designing layer structures. This paper describes the design of the sensing unit and the structure of layers which has similar characteristics of human. First we compare the temporal frequency of the proposed sensor and human skin. Second we estimate the required spatial density of sensing units by simulation. Then we compare the total ability of proposed reflection-type sensor and cutaneous sensation of human.

Haptic interaction with handheld devices is limited by space and size constraints that inhibit free hand exploration. We developed a compact haptic interface called Vib-Touch, which is operated by fingertip via a pointing-stick input device containing a tactile feedback. A cursor on the screen could perform virtual exploration as a substitute for the finger movement. We call this technology virtual active touch. We also propose a tactile stimulation method to represent not only tactile sensations, but the whole touch experience, including kinesthetic senses and a sense of shapes perceived by a fingertip. This study reports on the first prototype of the vib-touch interface for handheld devices. We confirmed that the prototype could provide friction sensation and geometric shape information using the proposed friction display method.

Tactile display is a technology that gives an artificial sense of touch to operators of information terminals or master-slave systems. The generation of tactile stimuli in response to the hand movements of the operators is associated with active touch and is considered to be one of the effective display methods, however which inevitably causes delayed tactile feedbacks from tactile displays. The knowledge of the detection threshold of system latency between the hand movements and the stimuli is helpful in designing the tactile displays. In this study, the identification of the thresholds through psychophysical experiments of 13 participants revealed two types of thresholds. One was the time-delay at which the participants observed the existence of latency. The other was the minimal time-delay that could affect the subjective feelings of the operators while they were not conscious of the latency. The means of the thresholds were 41 ms and 59 ms, respectively. The participants reported that the time-delay stimuli caused various changes in their subjective feelings. The empirical results suggest that the two types of thresholds depend on different sensory processes. This paper also proposes a design policy for tactile display systems in terms of system latency.

A small tactile display that can be attached to a mobile terminal device or a handheld game controller will enhance user experience in virtual worlds. This paper proposes an ultrasonic vibrator which has a compact mechanism to produce vibratory stimulation on human skin using a pin array driven by a single piezoelectric actuator. Amplitude modulations of the ultrasonic vibration can generate tactile sensations even if a finger is fixed on the vibrator. To generate enough stimulation to deform the skin, resonance of the piezoelectric actuator was designed. We proposed a new mechanical design method to arrange arbitrary distributions of vibration for the pin array using the principle of a dynamic vibration absorber. Detailed designs were conducted by finite element analysis. We successfully designed a smart vibrator which had a size of 17 times 17 times 3.65 mm and a weight of about 4 g. The vibrator could mount on the joystick of the PlayStation2 controller. Trial experiments of tactile presentation showed that the prototype vibrator could generate vibratory feelings in the range of 30 - 50 Hz and 200 - 300 Hz. In addition, stimulation corresponding to joystick operation generated some rubbing-like sensation.

This Paper presents a hybrid tactile displaying method of realistic texture using ultrasonic vibrator and force display. The aim of this study is to display various realistic tactile senses by controlling multiple factors including roughness, softness and friction sense. First, a tactile displaying system was configured for displaying roughness, softness and friction sense simultaneously by compensating the interference among multiple parameters of ultrasonic vibration and force feedback on multiple tactile senses. Second, by conducting several sensory evaluation experiments, the proposed method for displaying softness and friction senses were verified. The relationship between each control parameter and the tactile senses were quantified as well. Then, material discrimination experiment was conducted. As a result, percentage of questions answered correctly was more than 87.5 in all materials. Finally, the tactile senses of real materials and artificial tactile senses were evaluated using adjectives. As a result, the correlation coefficients between real materials and hybrid artificial tactile senses were quite high at the evaluation items on roughness, softness and friction senses.

A practical active scope camera for urban search and rescue is developed using ciliary vibration drive mechanism. Optimization of design parameters such as material, a diameter, density and an inclination angle of cilia, and specifications and density of vibration motors is performed on the basis of experimental evaluation of test pieces and prototypes with changing surface materials. A prototype of a scope camera 8 m long crawls at a maximum speed of 47 mm/s, climbs slopes of 20 deg, surmounts obstacles 200 mm high, follows walls, and turns on floors. Experiments at Collapsed House Simulation Facility of International Rescue System Institute, Kobe Laboratory demonstrate its practical advantage in rubble piles.

Tactile telepresence has been expected to be technology which encourages operators of robotic systems to remotely maneuver objects or recognize materials being touched through robotic arms. In remote environments, temporal disparity in tactile sensations is caused by temporal latency between a touch motion of the operator and a tactile stimulus applied on him. A framework of tactile telepresence systems, which is suitable in remote environments, has been proposed in the present paper. In the framework, a tactile display locally generates the tactile stimulus in synchronization with the touch motion of the operator in order to cancel communication delay. The tactile stimulus is generated by combining the motion and tactile factors, which are sensed by a tactile sensor. The factors are characteristic parameters of objects and effect on tactile sensations. In the present paper, physical parameters of the objects are selected as the factors because the tactile stimuli can be computed using physical models involving the motions and the parameters. Based on the proposed framework, a roughness feeling telepresence system was implemented and successfully transferred a roughness factor to the operator.

A method is proposed to control human grasping force unconsciously by generating small distributed vibration stimuli on a finger based on a human reflex action against detection of partial slippage of contact. Human beings can increase grasping force before the grasped object slips off the fingers based on afferent signals from tactile receptors that detect the expansion of the partial slippage area. We assumed that vibration stimuli that have an appropriate frequency and distribution generate a virtual sensation of partial slippages and induce a reflective grasping force increase. Grasping experiments with minute distributed vibration stimuli using ICPF (ionic conducting polymer gel film) actuators were performed. Experiments results showed that the effective vibratory frequency was 30 Hz, which is the most sensitive range for Meissner's corpuscles that are closely related to detection of partial slippage. We also found that distribution of vibration stimuli were important to produce human grasping force increase

Carbon micro coil (CMC) tactile sensor, containing CMCs in elastic material, is considered to have LCR circuit. When the sensor is transformed by mechanical force, LCR circuit changes in the sensor. In consequence, the sensor is able to detect various kind of tactile information by measuring impedance. In this paper, we focused on LCR circuit formed by distribution of CMCs. By changing CMC weight percent, we made the sensors in which CMCs are in contact and not in contact. First, we analyzed static characteristics of CMC tactile sensor. When the sensor is under unloaded condition, we measured the relationship between frequency of alternating voltage and impedance. As the result, we found that electrical parameters change with CMC weight percent. When the sensor is under transformed condition, we measured relationship between strain and impedance. As the result, we found that impedance changes by deformation of CMC and change in distance between CMCs. Secondly, we analyzed dynamic characteristics of CMC tactile sensor. We measured relationship between mechanical frequency and impedance by exciting vibration on CMC tactile sensor

Proposed new actuation mechanism realizes active or semi-active mobility for flexible long cables such as fiberscopes and scope cameras. A ciliary vibration mechanism was developed using flexible ciliary tapes that can be attached easily to existing cables. Driving characteristics of the active cables were confirmed through experiments and numerical analyses. Finally, the actuation mechanism was applied for an advanced scope camera that can reduce friction with obstacles and avoid stuck or tangled cables

To realize a telepresence system with tactile feedback and force feedback, real-time estimation of various tactile sensation must be conducted. Because several types of tactile sensation consist in touch and human tactile feeling has high time resolution. A man feels active touch extraordinary with time delayed transmission of tactile information. Our proposing human finger mimetic sensor covers three tactile factors, which are roughness, softness and friction of objects to touch. Current tactile telepresence systems represent just one tactile sensation in addition to kinesthetic information. For augmented reality, wider tactile factors must be sensed at a tactile sensor system and transferred to a tactile display system with small time delay. We realized quick estimation of vibrational frequencies of the sensor and softness of objects to regenerate touch feelings to human skin by tactile displays, which usually need time-consuming samples and make it hard to address tactile telepresence system. Quick estimation of vibrational frequency was conducted by emulating impulse emission of Meissner's corpuscles. Quick estimation of Young's modulus of objects was solved by computing strain distribution in a sensor

This paper discusses a novel approach in developing a texture sensor emulating the major features of a human finger. The aim of this study is to realize precise and quantitative texture sensing. Three physical properties, roughness, softness, and friction are known to constitute texture perception of humans. The sensor is designed to measure the three specific types of information by adopting the mechanism of human texture perception. First, four features of the human finger that were focused on in designing the novel sensor are introduced. Each feature is considered to play an important role in texture perception; the existence of nails and bone, the multiple layered structure of soft tissue, the distribution of mechanoreceptors, and the deployment of epidermal ridges. Next, detailed design of the texture sensor based on the design concept is explained, followed by evaluating experiments and analysis of the results. Finally, we conducted texture perceptive experiments of actual material using the developed sensor, thus achieving the information expected. Results show the potential of our approach.

This paper presents a useful tactile display method that can control multiple tactile sensations such as roughness, pressure, and friction sensations using simple vibratory stimulations. Our concepts are based on two points: frequency range selection for making selective stimulation on different tactile receptors types and timing control of the stimulation in response to hand movements. The selective stimulations were realized by selecting reactive frequencies of vibratory stimulation based on temporal response characteristics of tactile receptors. For representing roughness sensation, vibrating frequencies were modulated in response to hand velocity considered as a temporal coding perception of FA I type receptor. Two reactive frequencies were also selected for representing pressure sensation and friction sensation corresponding to SA I and FA II type receptors respectively. A wearable tactile display using ICPF (ionic conducting polymer gel film) actuators verified our proposed methods. Finally, we conducted a total texture feeling display combined with our methods for roughness, pressure, and friction sensations in a parameterized manner. Comparison with real clothes showed that some combinations of multiple tactile sensations could express texture feels of the expected materials.

This paper deals with the software architecture of a rescue robot, named FDNet. This architecture provides the rescue robot with intelligence and flexibility. When this architecture is used, the robot system is described using networks. These networks are composed by data and processing units. The data, referred to as "data", is a distributed component. The processing units, referred to as "relation", are a distributed and parallel-processing component, which can refer to any existing Data. We consider nodes that can formally connect to any other node, and relations that can be organized according to human's or any other network's pattern. This architecture was called FDNet (flat-distributed networks for rescue robots). We describe proposition of the architecture and its implementation for a robot. Then, we report some experimental results. We provide this architecture for any intelligent rescue system.

In order to display delicate touch feeling of surface of some materials, active touch of human hand movements should be considered. In this paper, a wearable stimulation device that can produce various distributed stimuli on human skin in response to hand movements was developed using ICPF (Ionic Conducting Polymer gel Film) actuators. Characteristics of touch feel of roughness were measured using vibratory stimulation. The results showed that the threshold amplitude under active touch were smaller than under passive touch. A stimulation method which generate selective stimuli to sense receptors in accordance with velocities and accelerations of hand motions was proposed. It was confirmed experimentally that some kinds of pattern of driving waves express touch feels in response to hand movements.

This study presents a tactile feel display of virtual reality for subtle fine touch of clothes. The device developed using soft high polymer gel actuators could express subtle differences of touch of clothes, especially rough materials such as a towel and denim. Considering the superiority of vision in the multimodal sensational perception, a virtual tactile feel display integrated with visual information which express more real touch of cloth was proposed. In order to evaluate the influence of visual information adding to the tactile feel quantitatively, a factor analysis was performed using adjective pair scales. Factor analysis applied to the real materials showed that the roughness factor is highly correlated with the visual sensation although the softness factor is relatively independent from image information. The same analysis applied to the artificial tactile feel showed more complex results. It was confirmed that vision could help the recognition of tactile feel only when the characteristics of the material was expressed well by visual information although could also mislead tactile perception when visual information was not appropriate. The superiority of visual information was also evaluated by applying wrong visual information different from the artificial tactile feels.

Molluskan robots perform their tasks by freely deforming their shape like slugs and amoebas on the basis of soft actuator materials. This paper presents a new actuator model, Fukuhara-Tadokoro model of a high polymer actuator, ICPF (or IPMC) as a fundamental of design, fabrication, control and application of future molluskan robotics. Ionic migration in actuator material causes electric unbalance of sulfo groups producing lateral strain in addition to volume change by water unbalance. Simulation results show internal state change according to the motion principle.

It is difficult for the conventional tactile displays to express fine touch as a surface of cloth. A mechanical device appropriate for minute distributed stimuli on human skin does not exist. This paper proposes a ciliary device using soft high polymer gel actuators (ICPF) as a solution to this problem. This new device can generate various distributed stimuli to human sense receptors. It was experimentally confirmed that, combinations of vibratory stimuli of high frequency and low frequency produced complex tactile feels. Comparison of the artificial tactile feels and cloth material samples demonstrated that this device developed could display subtle distinction in the touch of cloth.