We are developing a radio wave sensing technology focusing on antenna impedance. Since this sensing method uses physical phenomena different from conventional sensing technology, it may be able to complement conventional sensors. In the studies, we investigated a sensing method that covers a range of less than several tens of centimeters by measuring the complex voltage reflectance and confirmed its validity by FDTD analysis. However, the sensor circuit for this method had not yet been developed. In this paper, a prototype sensing circuit corresponding to the proposed sensing method was fabricated and evaluated.

International Telecommunications Research Institute International (ATR) and Kyoto University (Kyoto Univ.) have jointly promoted a wireless COE (Center of Excellence) program with the support of the Ministry of Internal Affairs and Communications since 2019. The objectives of the program are to create technologies related to resilient radio resource utilization and to accelerate the development of SMEs, start-ups and young talents to lead the wireless technology of the future. In order to achieve the objectives, we have mainly conducted three activities: the concurrent promotion of R&D projects, the construction and operation of open wireless R&D facilities, and the assignment of mentors and their R&D support. Through three-year promotion of the activities with mutual collaboration, we got outcomes and lessons learned. In this paper, we report the overall picture of the program and current status we got through the activities so far.

We propose a new “wire-free robotic system” applicable to an articulated robot that realizes both control and power lines wirelessly at the same time in the joints. The wire-free robotic system consists of a wireless communication system, a wireless power transfer system, and a robot operation system. Control lines are realized by wireless communication in the 60 GHz band with selection-based transmission site diversity. Power lines are realized by wireless power transfer of the magnetic resonance method with load-independence. We developed a prototype robot and verified the communication quality and the operation. It is confirmed that the prototype robot can achieve more than 99% of packet delivery ratio in almost all operating areas. It is also confirmed that the prototype can be controlled and powered wirelessly.

In this paper, transmission performance for wireless harness systems is evaluated using propagation models which include pathloss and power delay profile in an automobile engine compartment. In the wireless harness system in vehicles, it is assumed that an electronic control unit has a wireless access point (AP) and each sensor has a wireless station terminal (ST). First, pathloss and power delay profile models are analyzed using measured propagation data of the scattering parameter in the Toyota Prius's engine room which size is 0.9 × 1.2 × 0.6 m on condition that the vehicle's engine is turned off. Second, performance results of channel capacity and throughput, where on-off keying based signals are transmitted between the AP and each ST, are evaluated using analyzed propagation models. Simulation results confirm that high channel capacity and throughput performance are satisfied when transmit power is less than 0 dBm in 2-3 GHz on condition that positions of AP's antennas are fixed, positions of STs are uniformly set in the engine space, and wireless channels are quasi-static.

This paper proposes a measurement scheme of power delay profiles using IEEE 802.11g based wireless packets at 2.4 GHz band. In the proposed scheme, at first, a signal analyzer which can save the received Ich and Qch signal receive the OFDM based packets from wireless access point to mobile terminal. Secondly, positions of long preambles in the received IQ data are detected in the cross correlation process using a long preamble signal which is known between a transmitter and a receiver. Thirdly, the power delay profile is calculated by averaging of channel impulse responses which are estimated from received long preamble signals. Computer simulations confirm that the proposed scheme can be expected to achieve almost the same performance with PN sequence based measurement scheme.

Tactile sensors for slip detection are essential for implementing human-like gripping in a robot hand. In previous studies, we proposed flexible, thin and lightweight slip detection sensors utilizing the characteristics of pressure-sensitive conductive rubber. This was achieved by using the high-frequency vibration component generated in the process of slipping of the gripped object in order to distinguish between slipping of the object and changes in the normal force. In this paper, we design a slip detection sensor for a multi-fingered robot hand and examine the influence of noise caused by the operation of such a hand. Finally, we describe an experiment focusing on the adjustment of the gripping force of a multi-fingered robot hand equipped with the developed sensors.

This paper proposes a control framework for a two-armed and two-wheeled mobile robot that can coordinate all the joint forces to achieve diverse motion objectives such as position, velocity, acceleration, force and impedance at any part of the body. The framework comprises two components: 1) Generalized Inverse Dynamics (GID) that determines joint forces satisfying multiple objectives considering task priorities and various constraints and 2) the Idealized Joint Unit (IJU) that generates accurate torque with assigned apparent inertia and viscosity. GID treats the robot as a single manipulator with multiple branches using a joint model with 2-DOF motion subspace equivalent to two opposing wheels. A 21-DOF mobile robot equipped with IJUs is set up and GID is applied to it. The result shows that GID works well in the examples of physical human-robot interaction and object manipulation where motion objectives are attained coordinating the whole body while keeping passivity due to the redundancy and the assigned impedance property.

In this paper we propose a new robust force and position control method for property-unknown objects grasping. The proposed control method is capable of selecting the force control or position control, and smooth and quick switching according to the amount of the external force. The proposed method was applied to adaptive grasping by three-fingered hand which has 12 DOF, and the experimental results revealed that the smooth collision process and the stable grasping is realized even if the precise surface position, the mass and the stiffness are unknown. In addition a new algorithm determines the grasp force according to the "slip" measured with the tactile sensor and the viscoelastic media on the fingertip. This algorithm works at starting and stationary state, so the friction and mass unknown object grasping is realized by the effectual force.

A novel method of model order selection and separation of spectral structures is proposed for practical signals which are composed of multiple structured spectra. The input time sequence signal is considered to have multiple spectral structure, i.e. a main spectral structure and a residual spectral structure. The main structure is determined by the signal dominant power spectral component of the input signal and the residual structure is defined by the residual power spectral component after the dominant power spectral component is removed from the whole spectral structure. The method first estimates the dominant spectrum of the main structure using the AR (autoregressive) model with order p(AR (p)) and then estimates the spectrum of the residual structure using the AR model with order q(AR (q)). By computer simulation, the method is proved to give a good solution to the problem of reliable spectral estimation.>