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Most articulated robots comprise multiple joints and links that control the position and posture of the end effector. The kinematic pair arrangement determines characteristics such as output force. The link configurations can be classified as serial link and parallel link mechanisms. A typical parallel link mechanism is the spherical parallel mechanism (SPM), designed to ensure that the end effector has only rotational degrees of freedom. However, the kinematic pair arrangement has not been sufficiently examined in two degrees of freedom (2-DOF) SPMs. Herein, we present a basic design method for the proposed 2-DOF SPM curved biaxial swing mechanism, with inputs comprising arc sliders. The swinging area of the passive link was small, and infinite rotation around a certain axis was achieved without collision or transfer to a singular posture. Using the kinematics of this mechanism, we clarified the linear roll output and non-linear pitch output. Moreover, we fabricated a prototype and measured its basic drive characteristics. The results revealed that the output performance was greatly dependent on the rotation angle, high movable range in the roll axis, and low movable range in the pitch axis.

Grippers can be attached to objects in a rigid mode, and they are therefore used in various applications, for example granular jamming gripper. This paper introduces a cutting-edge radial layer jamming mechanism with is tunable stiffness, which is critical for the development of grippers. The layer jamming mechanism generates friction between the layers of multi cylindrical walls by pulling wire. This paper describes the principles of three types of proposed tendon-driven jamming mechanism, in addition to their prototypes of string configuration and the experiments conducted on the holding torques of their joints. Due to the string configuration, the surface and three-dimensional (3D) shape. This mechanism can be implemented in various applications., 7 pages, 11 figures

This study proposes a methodology to deliver contact information on construction robots to the remote operator by transmitting measured collision vibrations, which are often beyond the human-perceivable range. We focus on the human capacity to discriminate the envelope of high-frequency vibrations as an essential cue to perceive contact materials and collision conditions. The proposed method preserves the envelope shapes with amplitude-modulated waves with a single carrier frequency in the human sensitive range. In the preliminary experiments, a miniature shovel digging experiment confirmed that the proposed method improves the discriminability of the contact materials and sliding velocities. A psychophysical experiment also showed that the participants could discriminate the envelope differences irrespective of the carrier frequency. The proposed method was applied to the tactile transmission system for a construction robot developed in the ImPACT program. A vibration sensor was attached on the robot arm, and the vibrotactile feedback was applied to the operator's wrist. Performance evaluations under a delicate teleoperated task (insertion of a bar into bricks) showed that the peak force was reduced by the proposed method significantly for two out of the three participants. The results show that our proposal could improve the maneuverability of teleoperation.

Generation of stable and realistic haptic feedback during mid-air gesture interactions have recently garnered significant research interest. However, the limitations of the sensing technologies such as unstable tracking, range limitations, nonuniform sampling duration, self occlusions, and motion recognition faults significantly distort motion based haptic feedback to a large extent. In this paper, we propose and implement a hidden Markov model (HMM)-based motion synthesis method to generate stable concurrent and terminal vibrotactile feedback. The system tracks human gestures during interaction and recreates smooth, synchronized motion data from detected HMM states. Four gestures—tapping, three-fingered zooming, vertical dragging, and horizontal dragging—were used in the study to evaluate the performance of the motion synthesis methodology. The reference motion curves and corresponding primitive motion elements to be synthesized for each gesture were obtained from multiple subjects at different interaction speeds by using a stable motion tracking sensor. Both objective and subjective evaluations were conducted to evaluate the performance of the motion synthesis model in controlling both concurrent and terminal vibrotactile feedback. Objective evaluation shows that synthesized motion data had a high correlation for shape and end-timings with the reference motion data compared to measured and moving average filtered data. The mean $$R^{2}$$ values for synthesized motion data was always greater than 0.7 even under unstable tracking conditions. The experimental results of subjective evaluation from nine subjects showed significant improvement in perceived synchronization of vibrotactile feedback based on synthesized motion.

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.

Humans perceive and discriminate high-frequency tactile vibrations based on the intensity and envelope of the stimuli. However, no studies have investigated exactly how the envelope and intensity each affect the ability to discriminate. The objectives of this paper are to identify the boundary at which the envelope begins not to strongly affect the ability to discriminate vibrations and to investigate the effects of the carrier frequency and intensity on the discrimination ability. The results of our testing showed that the ability to discriminate was dependent on the envelope frequency and that the ability to discriminate sinusoidal and amplitude-modulated (AM) vibrations in which the envelope frequency ranged from 12 to 50 Hz was higher than that required to discriminate sinusoidal and AM vibrations in which the envelope frequency was above 80 Hz. When the envelope frequency of an AM vibration was 125 Hz, the ability to discriminate sinusoidal and AM vibrations was found to be low and no significant difference was noted in comparison to discriminating AM vibrations with the same envelope frequency. These results suggest that the boundary for envelope perception was at an envelope frequency of around 80-125 Hz at low intensities and that the carrier frequency had little effect on the discrimination, although the discrimination ability tended to increase as the intensity increased.

Soft robots have attracted much attention in recent years owing to their high adaptability. Long articulated soft robots enable diverse operations, and tip-extending robots that navigate their environment through growth are highly effective in robotic search applications. Because the robot membrane extends from the tip, these robots can lengthen without friction from the environment. However, the flexibility of the membrane inhibits tip retraction. Two methods have been proposed to resolve this issue; increasing the pressure of the internal fluid to reinforce rigidity, and mounting an actuator at the tip. The disadvantage of the former is that the increase is limited by the membrane pressure resistance, while the second method adds to the robot complexity. In this paper, we present a tip-retraction mechanism without bending motion that takes advantage of the friction from the external environment. Water is used as the internal fluid to increase ground pressure with the environment. We explore the failure pattern of the retraction motion and propose plausible solutions by using hydrostatic skeleton robot. Additionally, we develop a prototype robot that successfully retracts by using the proposed methodology. Our solution can contribute to the advancement of mechanical design in the soft robotics field with applications to soft snakes and manipulators., 8 pages, 10 figures

In this paper, we propose a flexible pneumatic robot that can move in narrow pipes and across open spaces. The development of such robots is necessary to access the insides of Fukushima Daiichi Nuclear Power Plant’s pressure containment and reactor pressure vessels via pipes and to then move around inside and investigate damage to them. The novel flexible pneumatic robot proposed here realizes both in-pipe and open-space locomotion by integrating expansion-type pneumatic hollow-shaft actuators and a pneumatic rotary steering mechanism. We first present the propulsion and steering concept of the proposed robot before detailing its design and the developed prototype. Further, we present the experimental evaluation of the characteristics and performances of the steering and propulsion mechanisms. We found that each expansion-type pneumatic hollow-shaft actuator can generate a maximum traction force of 11 N, whereas the steering mechanism generates a maximum steering force of 0.55 N. Finally, we conducted a trial to confirm the locomotion performance of the robot both in pipes and across open space. The results show that the robot can smoothly touch down into open space from high-lying pipes and subsequently move around across open spaces toward a given coordinate.

[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.

A human can judge the hardness of an object based on the damped natural vibration caused by tapping the surface of the object using a fingertip. In this study, we investigated the influence of the dynamic characteristics of vibrations on the hardness perceived by tapping. Subjectively reported hardness values were related to the dynamic stiffness of several objects. The dynamic stiffness, which characterizes the impulsive response of an object, was acquired across the 40-1,000 Hz frequency range for cuboids of 14 types of materials by administering a hammering test. We performed two psychophysical experiments-a ranking task and a magnitude-estimation tasks-wherein participants rated the perceived hardness of each block by tapping it with a finger. We found that the perceptual effect of dynamic stiffness depends on the frequency. Its effect displayed a peak around 300 Hz and decreased or disappeared at higher frequencies, at which human perceptual capabilities are limited. The acquired results help design hardness experienced by products.

A mechanism that allows a robotic arm to quickly grip various forms of objects at disaster sites will enhance the mobility of rescue robots by keeping their bodies stable and maintaining manipulability for target objects, such as debris. Such a mechanism requires the ability to quickly and omnidirectionally change arm postures toward the target and hold it in a stable manner. Continuum robots are expected to provide this functionality. Conventional continuum robots realize the function of changing arm postures and grasping objects by controlling pneumatic actuators with multiple air chambers arranged in parallel. However, conventional robots cannot be applied to potential disaster sites filled with flammable gases, gasoline, or high radiation levels because they require electronic components (e.g., solenoid valves, and sensors) to control air pressures. This study proposes a unique approach to realize reflexive omnidirectional bending motion using only mechanical components without any electrical devices. The proposed system realizes a reflexive motion to bend the arm in the target’s direction by detecting a contact location using a mechanical reactive system. The proposed simple mechanism has the advantages of high durability and easy implementation. This paper aims to confirm the proposed concept by prototyping a drive mechanism coupled with contact detection and bending motion using mechanical port valves. We report the design concept and development of this prototype. The fundamental characteristics and feasibility of the proposed mechanism are experimentally confirmed. First, a prototype is developed using a mathematical model. Its performance in the bending and omnidirectional motions is evaluated. The results show that the model has a margin of −4.9% error in the bending angle and −7.4% error in the central curvature compared with the experimental values. We also confirm that using a higher pressure could realize a smaller radius of curvature and reduce an unnecessary twisting motion. We also tested a second prototype to confirm the grasping motion and force by changing the applied pressures. The influence of the bending direction was then evaluated. We confirm that a higher pressure generated a larger grasping force. The prototype can omnidirectionally produce approximately the same forces although the generated forces depend on the number of air chambers excited by the contact pads. Subsequently, we experimentally confirm the influence of gravity. The test shows that the effect of own weight greatly influences the posture after the object is in contact. This effect should not be ignored. Furthermore, the curve became sufficiently large when its contact pad is pressed. This result experimentally proved that self-holding is possible. The experimental results show the potential of the proposed mechanism.

This paper reports upon the design and evaluation of an inchworm drive based on frictional anisotropy for an Active Scope Camera (ASC), which is a snake-like rescue robot used in disaster-affected areas. The conventional ASC is mounted on a ciliary vibration drive and can search under rubble. It has been found, however, that there are some situations in which the vibration drive performs weakly, such as on soft or rough road surfaces. In this paper, the authors propose an inchworm drive with an ASC. The inchworm drive developed in this research shows a running performance that resolves some of the weak points of the vibration drive. The authors focus in particular on the evaluation of driving experiments that were conducted on a variety of surfaces that might be encountered while searching inside a collapsed building or under rubble.

Tactile transmission systems deliver tactile information such as texture roughness to operators of robotic systems. Such systems are typically composed of tactile sensors that sense the physical characteristics of textures and tactile displays that present tactile stimuli to operators. One problem associated with tactile transmission systems is that when the system has a bottleneck, it is difficult to identify whether the tactile sensor, tactile display, or perceptual ability of the user is the cause because they have different performance criteria. To solve this problem, this study established an evaluation method that uses the discriminability index as an evaluation criterion. The method lets tactile sensors, displays, and human tactile perception be assessed in terms of the ability to transmit physical quantities; the same criterion is used for all three possible causes so that their abilities can be directly compared. The developed method was applied to a tactile-roughness transmission system (Okamoto et al. 2009), and its tactile sensor was identified as the bottleneck of the system.

We develop Distributed Inclination Sensors (DISs) to measure the distributed inclination of track shoes, i.e., determining where a tracked vehicle clutches road bumps using the reflection-intensity inclination of track shoes due to dead weight. We confirmed in experiments that dead weight on a slope is a major factor in measurement error.

The active scope camera we proposed has active mobility using a ciliary vibration drive mechanism for long flexible cables. The physical details have yet to be clarified. We determined it based on detailed physical phenomena to design an optimal ciliary vibration drive. We discuss the reasons for design efficiency based on the analysis of dynamic models of ciliary parts, focusing on (1) the characteristic vibration of the cilia and (2) stick-slip contact. We constructed a pseudo linear spring model and a stick-slip friction model to evaluate these phenomena. We determined optimal driving vibration frequencies and the inclined angle of cilia through experiments and analysis. Qualitative comparisons with the dynamic models and the results of experiments indicated the effective physical factors of the activation mechanism. A prototype of the active scope camera showed good performance in practical rescue activities.

It is necessary to ascertain tactile texture recognition of humans in developing tactile devices that create or detect lifelike texture. Tactile texture has been researched in the field of psychophysics and neuroscience, but its function-structure relationship cannot be still uncertain by their method. In this paper, modeling of tactile texture recognition mechanism by numerical simulation system is discussed. The model is made of two parts ; reception part and perception part. Reception model is built by finite element model of human finger and filters emulating mechanoreceptors response properties. Perception model is built by feed forward type of neural network with 3 layers. This network is considered for configuration and module structure of primary somatosensory area. Finally, validity of the total model is confirmed by comparing output data of this model to the result of sensory evaluation.

Carbon Micro Coil (CMC) tactile sensor, containing CMCs in elastic component, is considered to have LCR circuit. When the sensor is transformed by mechanical force, LCR circuit changes. In consequence, the sensor is considered to be 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 that CMCs are in contact and not in contact. 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 thrust displacement and impedance. As the result, we found that impedance changes by deformation of CMC and change in distance between CMCs.

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 which 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 feeling 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 generates 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 feelings such as starting, stopping and sliding feel of hand motions.

Systematic biases have been found when matching haptic and visual locations. In this demo we can show two things; first we can show that these biases are similar when pointing at a visual target with the index finger or with a handle in a power grip. Second, we show that intermodal biases are not simply the result of a mismatch between the senses and that the transformations of the position information between modalities (and hands) are not simply reversible.

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.