Recently, electric vertical takeoff and landing (eVTOL) aircraft has attracted attention and are being developed worldwide. For social implementation, eVTOLs need to be continuously provided with high-speed, high-capacity communications, as applications such as dynamic map updates are required to ensure sufficient safety. Additionally, the use of cellular phone networks is currently being considered for eVTOLs, as is the case with Unmanned Aerial Vehicles (UAVs). As such, eVTOLs travelling in free space - the airspace above - are significantly affected by interference from their surroundings. However, existing handover methods only affect a single eVTOL, so it is necessary to develop a handover method that takes into account the impact of interference on the surrounding mobility. Therefore, this study proposes a handover method that considers the impact of interference on eVTOLs traveling over the surrounding area to maximize the total communication capacity of the entire eVTOL group. Results show that the proposed model improves the total communication capacity of the eVTOL group.

In this paper, the development of a two-degrees-of-freedom (DOF) human-powered robot using regenerative clutches and constant-force springs is described. A regenerative clutch can control a transmitted torque precisely and it includes a regenerative brake and a differential gear mechanism. The single-clutch human-powered joint-drive mechanism developed in this study is a system that can output forward and reverse torques and, to control the joint angle, performs servo control of the joint with one regenerative clutch by offsetting the torque using a constant-force spring. A crank-speed-sensitive spring-locking system has also been developed to implement a safe emergency stop function when the operator stops supplying power. The two-DOF human-powered robot using our systems realized planar trajectory tracking, suggesting that the position control of the end point of a multi-DOF human-powered robot is possible.

In this paper, a development of a single DOF joint drive mechanism using regenerative servo clutches is described. The regenerative servo clutch is a kind of a clutch developed by the authors which consists of a regenerative brake and a differential gear mechanism, and it can control the transmitted torque by controlling the regenerative brake torque. The joint drive mechanism developed in this study is the system which can perform the servo control of the angle of the output shaft using the externally provided constant-speed power directly, by controlling the transmitted torque by using the two regenerative servo clutches for normal and reverse rotation. Through the experimental results, the effectiveness of the developed mechanism and controller was confirmed.

This paper discusses the design and implementation of a three dimensional magnetic tweezer system to achieve measurement of mechanical properties of living cells by touching a magnetically levitated micro probe to specimen cells. The system consists of a three dimensional magnetic tweezer, an inverted optical microscope for 3D probe position measurement, and control/interface software. For reducing assembly error in the magnetic tweezer and accurate adjustment of the gap distance between sextuple magnetic poles that are sharpen-tipped permalloy rods having a driving coil on each, a pole positioning mechanism was implemented in the magnetic tweezer. Finally, two experiments were performed on the fabricated prototype: trajectory tracking in which a magnetic particle of 4.5μm diameter floating in medium was steered to follow target trajectories, and homogeneity evaluation that compared force generation from each magnetic pole.

When hyper redundant robots are used in complex and unpredictable environments such as human living space, they should deal with various contact conditions between surrounding objects. Robots thus should plan and optimize not only applying force to the object but also its distribution among contact area. This paper defines the ability to optimize stiffness distribution of a number of contact points as "flexibility" and proposes elastic closed-loop mechanism which has a serial chain of revolute joints with torsion coil springs as a lightweight and supple hyper redundant mechanism. Output stiffness is formulated based on the minimization of potential energy, the balancing of internal force and the velocity constraint to construct a closed-loop mechanism. Joint input to obtain both the desired stiffness distribution and desired output position simultaneously is derived from partial derivative of the output stiffness and compensation by a learning control scheme. Motion control experiments with a 10R elastic closed-loop robot demonstrate the effectiveness of the proposed control scheme.

This paper describes a new method to utilize redundancy of hyper redundant robots. In order to use redundancy effectively, the contribution of all actuators for the achievement of the target motions and capability for unpredictable target motions in the future should be considered. From this point of view, two evaluation indices, the movability index of each joint and the assistability index for the target motions are proposed. These indices are formulated with the angle and amplitude distribution of the column vectors of Jacobian matrices of each joint, including the end-effector. Then joint input to optimize these indices simultaneously are derived based on the improved gradient projection method. Motion control simulations and experiments with a planar 10R serial manipulator revealed the effectiveness of the proposed method.

Robot audition by its own ears (microphones) is essential for natural human-robot communication and interface. Since a microphone is embedded in the head of a robot, the head-related transfer function (HRTF) plays an important role in sound source localization and extraction. Usually, from binaural input, the interaural phase difference (IPD) and interaural intensity difference (IID) are calculated, and then the direction is determined by using IPD and IID with HRTF. The problem of HRTF-based sound source localization is that a HRTF should be measured for each robot in an anechoic chamber, because it depends on the shape of robot's head; HRTF should be interpolated to manipulate a moving talker, because it is available only for discrete azimuth and elevation. To cope with these problems of HRTF, we proposed the auditory epipolar geometry as a continuous function of IPD and IID to dispense with HRTF and have developed a real-time multiple-talker tracking system. This auditory epipolar geometry, however, does not give a good approximation to IID of all range and IPD of peripheral areas. In this paper, the scattering theory in physics is employed to take into consideration the diffraction of sounds around robot's head for better approximation of IID and IPD. The resulting system shows that it is efficient for localization and extraction of sound at higher frequency and from side directions.