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In the investigation of contact safety assessment of collaborative work between robot systems and humans, the development of a sensor-equipped human dummy is a viable approach for obtaining the internal distribution of strain or stress. It is considered necessary to develop a dummy that faithfully replicates human mechanical characteristics. This paper presents the design and construction of a finger dummy that replicates the dimensions and mechanical characteristics of the human finger. Ultrasound technology is employed to gauge the soft tissue thickness, enabling determination of previously unknown phalanx dimensions. The research also delves into the investigation of the coefficient of friction and elastic property to approximate the human finger. Various surface treatment techniques are used to adjust the friction coefficient. Furthermore, the elasticity of the improved palm dummy samples is assessed based on the strain–stress relationship. These mechanical characteristics were effectively optimized through a meticulous comparison of the measurement results obtained from both the dummy samples and actual human fingers.

When mascot suits or plush fabrics are used to cover a human-friendly robot, frequent sterilization may be required, depending on the use of the robot. However, the effects of such sterilization are not sufficiently understood. In this study, variations in the strength and color values of plush fabrics were measured and quantitatively evaluated following 50 cycles of sterilization by ethylene oxide gas (EOG). The fabrics were composed of boa fabric, which is commonly used in mascot suits and plush dolls, and cloth reinforced with polyurethane foam. The tensile strength and the elongation were measured by the tensile strength test for clothes or clothing seams, in accordance with the standard JISL1096. In terms of appearance, red-green-blue (RGB) color values were obtained from photographs taken under the same light conditions to evaluate the color tone. A friction test was used to evaluate the tactile sensation. These results showed that EOG sterilization did not notably affect the properties of the fabrics; however, a single cycle of autoclave sterilization degraded the fabrics. Notably, the boa fabric shrunk and hardened. Thus, EOG sterilization, which does not feature elevated temperatures, may be an effective sterilization approach for these materials.

The teleoperation feature of a leader–follower robot is used to operate the robot in a working environment that is dangerous to the operator. This paper proposes a method for estimating the intended operation of the operator of the leader–follower robot and generating behaviors for the follower robot. By generating partially autonomous robot behavior, our proposed method decreases the burden on the operator and realizes a safe controller that is robust against misoperation or disturbances. Owing to the impact of misoperation on estimation and the potential for unintended movement of the follower robot, our proposed estimation method relies on historical values of intended operation. The proposed method was verified through simulation using real operation inputs to the leader system based on practical scenarios, including misoperation.

It is expected that human iPS cell-derived cardiomyocytes (hiPSC-CMs) can be used to treat serious heart diseases. However, the properties and functions of human adult cardiomyocytes and hiPSC-CMs, including cell maturation, differ. In this study, we focused on the temperature dependence of hiPSC-CMs by integrating the temperature regulation system into our sensor platform, which can directly and quantitatively measure their mechanical motion. We measured the beating frequency of hiPSC-CMs at different environmental temperatures and found that the beating frequency increased as the temperature increased. Although the rate at which the beating frequency increased with temperature varied, the temperature at which the beating stopped was relatively stable at approximately 20 °C. The stopping of beating at this temperature was stable, even in immature hiPSC-CMs, and was considered to be a primitive property of cardiomyocytes.

Electoadhesive (EA) gel can be applied to various mechatronics devices because it provides more degrees of freedom in mechanical design than other functional materials. While case studies have revealed much about these devices, the knowledge attained is still not integrated. We assembled new structured and controllable transmission and braking elements by fixing EA gel on plain and/or winding surfaces. This paper summarizes the characteristics of these devices from experimental findings on the initial pressure on the EA gel surface. The results showed that it is important for the initial pressure to be stable at approximately 0.5–1 kPa.

Abstract In the current study, we tested a prototype of an isokinetic exercise device for the lower limbs, named the ERIK. The ERIK enables a type of single-limb squat exercise with a translational load on the swing leg in a closed kinetic chain, putting load on the muscles of the stance leg in the standing position. This training applies load to the gluteal muscles, which is effective for avoiding excessive knee valgus moment, a major factor in anterior cruciate ligament injuries. To enhance the quality of the load, an electro-rheological (ER) fluid brake system is implemented in the ERIK. The ER brake can reversibly control resistive torque with a rapid response. This paper reports a prototype of the device with four training modes, verifying its performance through basic experiments. Although high resistance is created within a wide motion area and requires isokinetic training by controlling the velocity of the trainee’s legs, the ERIK has the advantage of a high level of safety because of its passive resistive function.

This paper describes the structural analysis of the programming operation of the tangible programming tool P-CUBE, which is a tangible block-type programming tool that was developed for use by beginners, including those with visual impairments. An experiment was conducted to compare P-CUBE and conventional programming software platforms, and it was demonstrated that P-CUBE encourages the development of beginners' understanding of the structure of a program. The differences between the programming operations of P-CUBE and the programming software are considered to be a factor causing differences in users' understanding of programming structures. The structures of the programming operations were analyzed using formal concept analysis, and differences between the logical frameworks in the operation of P-CUBE and a conventional software platform were demonstrated.

In virtual reality (VR) technology, force feedback/display devices are expected to enhance fine sensation and contribute to the user's immersive experience. This is particularly true for glove-type devices. Force display gloves, however, do not have a specific numerical value to indicate display accuracy. In this paper, we report the results of sensory testing and analysis with VR cylindrical objects using a passive-type force display glove. The size discrimination threshold for grasping was determined to be smaller than the nominal average error of the device; however, the threshold was larger than either the actual accuracy of the device or the threshold from an organoleptic test of a barehanded human. We have also identified the possible superimposition of the sensory accuracy errors of the operator with those of the glove. Despite this finding, we have determined that the device shows adequate accuracy for representing cylindrical objects during specific grasping tasks.