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.

In this paper, design of control system and power combination mechanism of a power assist system of the walking chair were discussed based on kinetostatic characteristics of human arm. The walking chair is a welfare walking machine which is an alternative vehicle of the wheelchair, and expected to be driven by user's cranking operation with assisting actuator. To efficiently utilize user's power as much as possible for long locomotion without giving much fatigue to the user while providing comfortable driving feeling to the user, the human arm characteristics were taken into consideration. Kinetostatic characteristics of human arm were experimentally investigated for its modeling. This model was applied to the design of mechanism and control system of the power assist system of the walking chair to provide a good driving feeling, and to reduce the fatigue and improve power efficiency

In this paper, we discuss the mechanism and control strategy of power assisting systems for the walking chair and then propose a new power assisting system. A power assisting system must reflect a human operator's intentions and control the assisting motors to generate required driving power. A power assisting system for the walking chair must provide a constant output velocity though human driving has variations of velocity. It must also provide a stable driving torque so that the user does not suffer any discomfort. Therefore, we proposed two types of mechanisms for power combination and compared them through experiments. Finally, we proposed a hybrid power assisting system based on the combination of two types of mechanisms, and experimentally investigated the system's effectiveness.

We propose an in-parallel actuate mechanism that can simultaneously realize fine positioning resolution and a large working space, and we discuss its infinitesimal displacement characteristics. Based on a kinematic synthesis of this mechanism, an experimental manipulator has been developed and we discuss the results of experiments regarding its fine positioning characteristics.

We have established a research collaboration project to develop a precise and high-speed arm applied to assembly process in electrical product and machine industries, supported by the International Robots and Factory Automation Foundation (IROFA). The paper addresses the background of the development, the required specification for the robot arm, and the brief introduction of the prototype arm.

A calculation method for symbol error probability is proposed for multilevel QAM systems. Carrier-to-noise ratio penalties are estimated by this method for seven typical impairment factors, including recovered carrier phase error, timing error, receive filter residual delay, etc. The validity of the method is verified by experiments on penalties caused by recovered carrier phase error and timing error. Based on the new method of analysis, signatures of a 64 QAM modem are estimated theoretically, using a pseudo-two-ray model of multipath fading. The dependence of signatures on the above-mentioned impairment factors is investigated in detail. A qualitative deduction of impairment factors from a measured signature is demonstrated. The measured signature agrees well with a calculated one in which reasonable values of the impairment factors are assumed.