Preparation of Fiberlike Silicon Nitride from Diatomaceous Earth

Fiberlike Si₃N₄ was prepared by the carbothermal reduction of diatomaceous earth in a flow of nitrogen and ammonia. Diatomaceous earth, which is an inexpensive raw material, is composed of 82.5 wt% SiO₂, 5.69 wt% Al₂O₃, and a very small amount of metal oxides (K₂O, CaO, and Fe₂O₃). Two types of fiberlike Si₃N₄ were obtained, short needlelike fiber and woollike fiber with Fe droplets at 1350°C.     

Psychological evaluations of robot motions

Human arm motions were simulated using both computer graphics and an industrial robot under various velocity patterns, and evaluated to examine which factors are essential for human-likeness. The results are summarized as follows. First, the velocity peak position in the normalized movement time of the motion is important for the emotion of human-likeness. Second, the maximum value of the velocity affects the human impression of the motion. There exists an appropriate maximum value which best gives a subject the impression of human-likeness. Finally, the emotion of human-likeness is related to that of agreeableness. These results are almost the same for both a simulated motion on CRT and a robot motion.

Relevance to industry

In the future, robots will play important roles by assisting or cooperating with humans in various industrial fields. In such cases, a robot's motion must be well designed taking into account human perception. The results of the research will become an important guide for the design of a robot's motion.     

Experience-Based Iterative Learning Controllers for Robotic Systems

An experience based iterative learning controller is proposed for a general class of robotic systems. Experience of the iterative learning controller is stored in the memory in terms of input output data and later used for the prediction of the initial control input for a new desired trajectory. It is proved in this paper that using this approach we can reduce the number of iterations to achieve a certain user defined tracking accuracy. This approach is very general and applicable to all kinds of existing iterative learning control schemes. Numerical illustrations showed the effectiveness of the proposed method.     

Alternative approach to Zakian's IMN approximant in numerical initial-value problems

Zakian's algorithm is applicable for numerical initial-value problems even if the system is stiff. In the letter the algorithm is derived directly in the time domain from the Padé approximant; originally it was given by the use of the Laplace transformation.     

An equation error method for the design of digital controllers

The purpose of the proposed equation error technique is to design a digital controller such that the response of the resulting closed-loop system matches approximately a specified response. The technique is based on the minimization of the equation error in closed loop. The necessary and sufficient condition for minimizing the equation error is given, and is used in the design method     

Ride quality evaluation of an actively-controlled stretcher for an ambulance

This study considers the subjective evaluation of ride quality during ambulance transportation using an actively-controlled stretcher (ACS). The ride quality of a conventional stretcher and an assistant driver's seat is also compared. Braking during ambulance transportation generates negative foot-to-head acceleration in patients and causes blood pressure to rise in the patient's head. The ACS absorbs the foot-to-head acceleration by changing the angle of the stretcher, thus reducing the blood pressure variation. However, the ride quality of the ACS should be investigated further because the movement of the ACS may cause motion sickness and nausea. Experiments of ambulance transportation, including rapid acceleration and deceleration, are performed to evaluate the effect of differences in posture of the transported subject on the ride quality; the semantic differential method and factor analysis are used in the investigations. Subjects are transported using a conventional stretcher with head forward, a conventional stretcher with head backward, the ACS, and an assistant driver's seat for comparison with transportation using a stretcher. Experimental results show that the ACS gives the most comfortable transportation when using a stretcher. Moreover, the reduction of the negative foot-to-head acceleration at frequencies below 0.2 Hz and the small variation of the foot-to-head acceleration result in more comfortable transportation. Conventional transportation with the head forward causes the worst transportation, although the characteristics of the vibration of the conventional stretcher seem to be superior to that of the ACS.     

A Learning Control for a Class of Linear Time Varying Systems Using Double Differential of Error

In this paper, a new iterative learning control based on the double differential of the error is proposed for the linear time varying system having relative degree greater than one. The convergence criterion of the proposed method is proved. Furthermore, it is shown by simulations that convergence of error can be increased considerably by using our proposed controller as compared to the iterative learning controller using error or single differential of the error for the modification of the control input without increasing the learning gain.     

Performance Competitions as Research Infrastructure: Large Scale Comparative Studies of Multi-Agent Teams

Performance competitions (events that pit many different programs against each other on a standardized task) provide a way for a research community to promote research progress towards challenging goals. In this paper, we argue that for maximum research benefit, any such competition must involve comparative studies under closely controlled, varying conditions. We demonstrate the critical role of comparative studies in the context of one well-known and growing performance competition: the annual Robotic Soccer World Cup (RoboCup) Championship. Specifically, over the past three years, we have carried out annual large-scale comparative evaluations—distinct from the competition itself—of the multi-agent teams taking part in the largest RoboCup league. Our study, which involved 30 different teams of agents produced by dozens of different research groups, focused on robustness. We show that (i) multi-agent teams exhibit a clear performance-robustness tradeoff; (ii) teams tend to over-specialize, so that they cannot handle beneficial changes we make to their operating environment; and (iii) teams improve in performance more than in robustness from one year to the next, despite the emphasis by RoboCup organizers on robustness as a key challenge. These results demonstrate the potential of large-scale comparative studies for producing important results otherwise difficult to discover, and are significant both in the lessons they raise for designers of multi-agent teams, and in understanding the place of performance competitions within the multi-agent research infrastructure.     

Automatic classification of ambulatory movements and evaluation of energy consumptions utilizing accelerometers and a barometer

This paper describes a method to evaluate daily physical activity by means of a portable device that determines the type of physical activity based on accelerometers and a barometer. Energy consumption of a given type of physical activity was calculated according to relative metabolic ratio (RMR) of each physical activity type that reflects exercise intensity of activities. Special attention was paid to classification algorithms for activity typing that identify detailed ambulatory movements considering vertical movements, such as stair/slope climbing or use of elevators. A portable measurement device with accelerometers and a barometer, and a Kalman filter was designed to detect the features of vertical movements. Furthermore, walking speed was calculated by an equation which estimates the walking speed as a function of signal energy of vertical body acceleration during walking. To confirm the usefulness of the method, preliminary experiments were performed with healthy young and elderly subjects. The portable device was attached to the waist. A standard accelerometer based calorie counter was also attached for comparison. Experimental results showed that the proposed method feasibly classified the type of ambulatory physical activities; level walking, stair going up and down and elevator use. It was suggested that the consideration of vertical movements made a significant improvement in the estimation of energy consumptions, and the proposed method provides better estimation of physical activity compared to the conventional calorie counter.