The effectiveness of transmitting force by using undulation is well known, but it takes time for the whip to flex and then sequentially transmit force. An example of using undulation is a whip whose tip movement exceeds the speed of sound. The whip-like motion principle requires that the user firmly plant the feet on the ground – a position that may lead to physical damage. Experts note that the load on different parts of the body is lowered by using the entire body appropriately. Using the term “nanba” symbolically to indicate body movement that does not use twisting, undulation, or the firm planting of the feet and that exerts minimal load on the joints, we investigate movement of a bipedal robot based on state transitions that utilize instability. Speed and robustness result when a state (posture) is created instantaneously so that no blockage by the body occurs and transitions from state to state are made in a single step.

The movement of live cat righting itself in midair, is investigated analytically and experimentally. The objective of the author is to develop a robot that lands upright on its feet like a cat. Interestingly, explanations in physics and dynamics textbooks that dealing with feline the self-righting remain contradictory and ambiguous. This is analyzed based on the law of conservation of angular momentum using a cat model. A robotic cat was then developed to turn in mid air. The robot righted itself completely after performing a 180° turn in the air.

According to the aged society in Japan, the expectation is high for the development of the human support robot or devices in daily life and in medical treatment and welfare. The human centered design and the universal design are very important concept for creating the useful human support devices. Human centric and universal designs are the designs of products and environments to be usable by all people, to the greatest extent possible, without the need for adaptation or specialized design. This special issue provides current researches and developments of human centric, universal and interactive design for robotics and mechatronics. Also, this special issue covers a broad range of research topics, such as human centric design, universal and interactive design, human machine interaction, transport system, housing environment system, rehabilitation devices, multi modal interface, evaluation of the usability, sensor/actuator technologies for assistive system, robotics and mechatronics to support elderly persons.

We thank the authors for their fine contributions and the reviewers for their generous time and effort. In closing, we thank the Editorial Board of the Journal of Robotics and Mechatronics for helping make this issue possible.

The semi-active assist mechanism proposed as a soft, flexible power assist device consists of an elastomer and actuator. Assist force is controlled by the actuator. in previous study, skill assist using periodical input control (PIC) had a motion-correction effect in motion for a single frequency. However, there is a problem by energy control in periodical input control for motion with multiple frequency components. In this study, we propose expanded PIC for motion with multiple frequency components. We verified the effect of skill-assist considering multiple frequency components of human motion.

This paper presents a novel arm-training system, known as the image-projecting desktop arm trainer (IDAT), which is aimed at hand-eye coordination training. The projector displays an exercise image on a desktop in front of a seated patient, and the scanning range finder measures the behavior of the patient as he/she performs the exercise. IDAT is non-invasive and does not constrain the patient. Its efficiency is based on the voluntary movements of the patient, although it offers neither the physical assistance nor tactile feedback of some conventional systems. Three kinds of training content have been developed: “mole-hitting,” “balloon-bursting,” and “fish-catching.” These games were designed for training hand-eye coordination in different directions. A patient and/or medical professional can set a suitable training level, that is, the training time, speed of movement of the objects, and number of objects to appear at any one time, based on the patient’s condition and ability. A questionnaire survey was carried out to evaluate IDAT-3, and the results showed that it was highly acclaimed in terms of user-friendliness, fun, and usefulness.

To meet the higher requirements of human-machine interface technology, a robot with human-following capability, a classic but significant problem, is discussed in this paper. We first propose a human detection method that uses only a single laser range scanner to detect the waist of the target person. Second, owing to the limited speed of a robot and the potential risk of obstructions, a new human-following algorithm is proposed. The speed and acceleration of a robot are adaptive to the human-walking speed and the distance between the human and robot. Finally, the performance of the proposed control system is successfully verified through a set of experimental results obtained using a two-wheel mobile robot working in a real environment under different scenarios.

Visually impaired persons may find it difficult to take part in a chorus or other singing group because they cannot see the beat indicated by conductor’s hand movements. This paper provides a chorus support system for visually impaired persons using depth image sensor. This consists of an electric music baton with an acceleration sensor, a radio module, haptic interface devices with vibration motors, a depth image sensor, and a PC. The electric music baton transmits the signal indicating the conductor’s motion to visually impaired players based on sensor acceleration. Since the conductor must give individual instruction to player, we use a depth image sensor to indicate the direction in which the conductor’s baton points. This direction is estimated based on the conductor’s posture. We also attempted to develop a chorus support system without using the electric music baton. The beat is obtained by the maximum velocity position of the conductor’s hand motion using a depth image sensor. The effectiveness of our system is clarified by several experimental results.

For a robot that uses two arms to lift and transfer a care receiver from a bed to a wheelchair, we report a method of estimating the positioning of the care receiver. The maneuver for such a task involves a high DOF, and the robot is capable of executing the maneuver much like a human being. The care receiver may experience pain or become unstable when being carried, however, depending on the positioning of contact between the robot’s arms and the care receiver. For this reason, nursing care robots must be able to recognize the positioning of contact with the care receiver and either modify it or alert the operator if it is unsuitable. We use the information obtained by tactile sensors on the robot’s arms when making contact with the care receiver to estimate the latter’s positioning. By dividing a care receiver’s position on a bed into nine zones and applying machine learning to tactile sensor data and positioning, it is possible to estimate positioning highly accurately.

Object transportation is a basic task for which mechanical systems provide support. Examples of the many types of mobile devices developed thus far are handcarts, unmanned autonomous vehicles, forklifts and turret trucks. Most such vehicles are based on wheeled mobile mechanisms, which would be difficult to use for moving objects in areas with high steps. A walking mobile mechanism, in contrast, enables steps to be ascended and descended, so it is expected that walking mechanisms could support object transportation in environments with stairs or steps. In this paper, we present a biped robot that supports object transportation involving stairs instead of human operators doing so. We start with the design of a biped robot with four actuators for one each for the hips and knees of each leg. Dynamics of the biped robot is then derived for simulation in which force applied by a human operator and a reaction from the ground are considered. A controller is presented for transporting objects up stairs having an unknown step height. Experimental results and photos confirm that the developed system successfully climbs the stairs of unknown height during human operation.

We propose a framework for forming the development of object delivery services provided through cooperation among heterogeneous robots and sensors. For this, we extended the previous framework based on 4W1H abstraction to develop informative and physical robotic services. The proposed framework abstracts information about sensors and robots as 4W data for users, objects and robots, robotic functions, and property data of robots and objects. We then develop physical services done one by one in combination with service information. We also describe the service application development platform based on the framework. Experimental results show that service applications can be efficiently developed by using the service application development platform.

We are developing an electronic baton system as an alternative haptic interface to facilitate music lessons for the visually impaired. This system incorporates an acceleration sensor in the baton, transmits data to a player via radio signals, and acts as a haptic interface by generating vibrations. In this paper, we experimentally evaluate responses to the stimulus of the visual and the tactile senses in order to verify that a haptic interface can substitute for vision in scenarios that involve real-time tasks, such as music lessons. In the first experiment, we verify that clue motions are important for both the visual and a tactile senses. Next, we test the new method of communicating strength. This method uses not vibration strength but oscillating time for vibrations of the haptic device. The results of the experiment confirm that the technique is effective.

In previous work, we proposed controlling power-assisted carts by using a motor torque limiter that achieves the desired load-reduction ratio even if torque saturates. We assumed, however, that the operator accelerates smoothly up to the target speed, so that when velocity is affected largely by the input force of walking, prediction error becomes large and the target load reduction ratio was not achieved. To solve this problem, we propose an improving the achievement rate of the target load reduction ratio in two steps, first, by predicting the number of steps toward target speed from initial input and, second, by switching the prediction model. We use cart input force and speed to predict operator acceleration patterns. Our proposal predicts operator needs and delivers the desired load-reduction ratio by predicting operation. Results show that the achievement rate of the target load-reduction ratio is improved by using our proposed control. In other words, applying our proposal improves the short available time of power-assisted carts.

We are developing a passive power assist supporter called Smart Suit Lite. Smart Suit Lite, a compact, lightweight device, uses the force of elastic belts both to support muscles and to stabilize the torso in a way similar to the corset. It is reported that the corset stabilizes posture, and decreases intradiscal pressure by applying pressure around the pelvis. The mechanism behind this remains to be fully elucidated, however, and has not been used actively for power assist devices. This study aims to construct a mechanical model of trunk stabilization generated by assistive devices. In this paper, we propose modeling based on basic experiments measuring motions under static conditions.

Decreasing fuel consumption and emissions in automobiles continues to be an active research problem. A promising technology is powertrain hybridization. Study in this area usually focuses on the development of optimal power management control methods. The equivalent consumption minimization strategy (ECMS) is a widely used real-time control method used for determining the optimal trajectory of the power split between the engine and motor. Reports also cover applying ECMS to find an optimal gear changing strategy, but results are not always satisfactory in fuel economy and drivability. One possible reason for this is that gearbox dynamics are slow, but ECMS is based on instant optimization and neglects this time delay. This paper proposes a simple prediction strategy for improving ECMS performance used with gear changing control. The proposed controller improves fuel efficiency and drivability without the need of adding extra sensors to the automobile. The proposed method’s simplicity makes it suitable for implementation.

The sushi robot (Fig. 1) developed in 1981 by Suzumo Machinery Co., Ltd., headquartered in Tokyo and founded in 1961, is the world’s first robot to form sushi rice balls (shari-tama). Hand-rolled sushi, a traditional Japanese dish invented during the Edo period (1603–1867), was originally expensive and served only on special occasions made by sushi chefs who had undergone long years of training.

The sushi robot broke the convention of requiring experienced sushi chefs by automating sushi making and enabling those who were comparatively unskilled to make sushi. It cut labor costs,^* which were higher than those for other types of food services, and helped make sushi more accessible to the general public. Sushi robots are now widely used, e.g., in supermarkets and conveyor-belt sushi restaurants, making it possible for anyone to serve sushi economically.

^* The average cost for the entire food-service industry is about 30%, compared to just 40–50% among conveyor-belt sushi restaurants [2].