This paper mathematically conceives a novel walking support device that leverages passive dynamics and coupling effects. In this model, a passive human walker is flexibly connected to an active humanoid, where the coupling effect induces a stable walking gait of the human. To understand the key mechanism of such indirect gait regulation, different actuation modes are designed for the humanoid and compared via phase-plane analysis of the steady-state gaits. Moreover, stability analysis is conducted via Poincaré map. The results show that it is difficult to enhance the human walker's stability when coupled to a humanoid robot using additional sensory information, compared to using a humanoid robot actuated with a predetermined force that employs no state feedback. The present mathematical model and our theoretical findings contribute to analysis and control design for locomotion systems with robot-human or inter-robots cooperation.

Undulation is the most common gait generated by legless creatures, which enables their robust and efficient locomotion in various environments. Such advantages inspired the control design of many kinds of locomotion robots. Despite their technical details, most of them realize the undulation gait via tracking predetermined trajectories called serpenoid curves, which are a group of sinusoidal waveforms with specified phase differences. This technique, however, sounds quite redundant in terms of sensing and control. Here, we investigate the research question: whether the sinusoidal waveform is necessary to be encoded in the control signal to make the whole body an “S-shape”? We use a 4-link rigid body dynamics model as a simple example, by which numerical simulations are conducted. Together with theoretical analysis, we show that undulation gait emerges naturally based on embodied position controller and filter, where binary actuation torques are required only. Our results not only discover locomotion mechanisms for significantly reducing the sensing and control requirement of generating artificial undulation gait, but also provide additional understandings for biological systems from the mechanical engineering point of view.

Biological observations on tetrapods locomotion deduce that anti-phase synchronization (APS) between fore and rear parts is beneficial for achieving a high-speed walking. On the other hand, theoretical analysis and experimental studies on quadruped robots suggest that a flexible spine potentially improves the gait efficiency and adaptability via smoothing the ground collisions. However, these two mechanisms have never been placed together by a comprehensive investigation in terms of their synergetic effect. Namely, an advanced principle is still lacking in combining the APS and the spine flexibility for quadruped walking robots. To address this issue, we construct a mathematical model for a quadruped dynamic walker under different spine conditions. First, the APS effect is generated via entrainment-based control method under a rigid spine condition. Then, flexible spines realized by three kinds of springs are compared with the rigid one via theoretical analysis. The results suggest that the APS mechanism and the flexible spine can be synergized via an appropriate deformation control. The theoretical findings not only uncover locomotion control mechanisms for quadruped walking robots, but also provide additional understandings of tetrapods dynamic walking from a mechanical engineering point of view.

This paper presents an advanced locomotion method that produces non-slipping motion in digestive organs and the abdominal cavity. New movement principle of the robot, which has a soft and deformable body that can move through a confined space is proposed. The mechanism of a toy water snake is applied to this principle. Magnetic particles inside the water balloon are affected by the external magnetic field and push the inner side of a balloon to the direction of a magnetic field. We construct an experimental model to verify the proposed principle, the sliding movement is measured using the model. Confirmatory experiments of movement are conducted in the two sheets that imitated internal organs.

This paper presents a new type of magnetic fluid and the rotational drive with simple magnetic field. We have proposed a driving principle and developed the verification models and the generator of magnetic field. It became clear that our proposed driving principle results from collision of the magnetic particles to the outer cover, deformation of the whole form of magnetic particles and movement of the center of gravity. We have succeeded to drive a rolling model by simple magnetic field control.

This paper reports the pneumatic PDMS micro hand as an end-effector of robot and miniaturized parallel link robot (guide robot) for manipulating a tiny and delicate object. Micro finger structure for the micro hand consists of bonded two films having different stiffness. Balloon structures are designed between the two films. Swelling of the balloon structure by applied pressure generates bending motion of the micro finger. This combination of the micro hand is based on the human being's finger and/or hand. The guide robot has several design specifications such as multi degrees of freedom joint as a human, small size, highly accurate directional control and water/ sterilization proof. Micro manipulation robot system is developed by assembling the micro finger with two or three degree of freedom, the guide robot and VR (virtual reality) interface device. The hybrid motion and the manipulation of a single egg (phi1 mm) of fish and a hair (phi100 mum) in macro world is successfully realized

We propose a safety-optimizing method for safety strategies of human-care robots using our danger evaluation method. First, various safety evaluation methods are discussed, and an optimizing method of safety design is proposed. Second, we make a comparative study of two general safety control methods, and then a method of optimizing robot control is proposed. These proposed methods enable us to optimally distribute cost among several safety strategies, and to derive suitable approaching motion of a multi-link manipulator to a human. The validity and effectiveness of these methods are demonstrated by numerical analysis. As a result, the design and control to increase safety are successfully obtained.

Proposes a safety evaluation method for use in various kinds of control strategies for human-care robots. In the case of a careless collision between a robot and a human, impact force and impact stress are chosen as evaluation measures, and a danger-index is defined to quantitatively evaluate the effectiveness of each safety strategy used for control. As in a previous paper on safety design, this proposed method allows us to assess the contribution of each safety control strategy to the overall safety performance of a human-care robot. In addition, a new type of 3D robot simulation system for danger-evaluation is constructed on PC. The system simplifies to evaluate danger about both design and control of various kind of human-care robots to quantify the effectiveness of various safety strategies.

This paper proposes the world's first general evaluation method of safety for human-care and medical robots. The safety values chosen are impact force and impact stress. The danger index and safety index are defined to make quantitative evaluation of the effectiveness of each safety strategy. Moreover, this proposed method enables us to know the contribution of each safety strategy to the overall safety performance of human-care robots. As a result, design optimization of safe robots is discussed successfully.

We have proposed a new concept for an active endoscope with hyper redundancy. This medical tool called "Hyper Endoscope" for minimally invasive surgery is driven by miniature cybernetic actuators. A dynamic model of the cybernetic actuator, taking into account its piezoelectric effect, is proposed and its detailed performance analyzed. Based on the result, a new technique to minimize the number of lead wires is proposed and verified experimentally. The frequency modulation velocity control with two lead wires as an analog control method has been perfected.