Masaaki Kumagai

Development of motion capture system using rotating magnetic field and differential magnetic field

There are several types of motion capture system for virtual reality. The authors propose a new type of motion capture system that uses rotating magnetic field for angular position detection and differential magnetic field for linear position detection. The detection is based on calculation of correlation that makes accuracy of measurement and tolerance to noise high enough, and it is also based on frequency multiplex method that enables 6-axis measurement simultaneously. The experiments were carried out and results showed efficiently good performance for virtual reality.

Sensor-based walking of human type biped robot that has 14 degree of freedoms

Walking robots are useful for uneven terrain where wheel or crawler is not suitable. The biped robot is a kind of walking robot which can be used in human-live environments. There are many research works on biped robots. Most of them use complex dynamic models of robots or prepared joint angle trajectories. In this paper, we propose a control method for human type biped robot which does not need complex dynamic model of the robot and prepared walking pattern. This control method is a combination of simple actions based on information obtained by many sensors. We show the experimental results which indicate ability of this method, here.

Vision based walking of human type biped robot on undulating ground

Walking robots are useful for uneven terrain where wheels or crawlers are unsuitable. The biped robot is a kind of walking robot that we can use under human-live environments. There are many research works on biped robots. The biped robots need ability to adapt itself to uneven or non-horizontal plane if we want to use them in our environment although the robots walked on flat horizontal plane or fixed inclined plane in most of these works. In this paper, we propose a control method for walking of biped robots on undulating ground. This method contains grade estimation of ground using stereo vision and walk of robot on slope. Experimental results that indicate ability of this method are also shown.

Sharpening directivity of ultrasonic range sensor using multiple transmitters by different amplitude and pulse width method

It is necessary to increase detectable length of ultrasonic range sensor for autonomous land vehicles. This means that we must radiate the powerful ultrasonic waves whose directivity is sharp. However sound waves have the characteristic that small attenuation in propagation and sharp directivity are incompatible with each other. In order to decrease attenuation rate for distance, the authors used multiple ultrasonic transmitters whose frequency is 40 kHz although their directivities are not sharp. We tried to sharpen the directivity by using plural transmitters and by exciting multiple transmitters whose individual outputs are different from each other. This paper describes how to get sharp directivity by ultrasonic transmitters array and its design method. The effectiveness is confirmed by simulations and experiments.

Development of a motion capture system that uses alternating field

Proposes a type of motion capture system that can detect attitude and position with high accuracy and high response-speed. Attitude and position of a target in an alternating field are calculated from an induced signal in a pair of three pickup coils. In this paper, principles of detection, methods for practical use, and a prototype system implemented on digital processing circuits are described in detail.

Conceptual design of a moving ring reactor: KARIN-I

A 650-MW(electric) deuterium-tritium fusion reactor, KARIN-I, has ten moving plasma rings, which are produced by relativistic electron beam injection, heated by a major radius compression, and transported into a linear cylindrical burning section by annularly flowing liquid lithium outside the silicon carbide first wall. The liquid lithium not only stabilizes the tilting motion of the rings but also works as the tritium breeder and the main coolant. Energy from the ash-accumulated rings is efficiently recovered at the exit during the major radius expansion. The linear alignment of reactor components ensures easy assembly and disassembly, and also provides for easy maintenance. These features of the reactor result in a net electric output power of 650 MW(electric) with overall plant efficiency of 30%.