• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1309-1314
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• 2003

If an agent has a learning ability using previous knowledge, then it is expected that the agent can speed up learning by interacting with environment. In this paper, we present an improved reinforcement learning algorithm using domain knowledge which can be represented by problem-independent features and their classifiers. Here, neural networks are employed as knowledge classifiers. To show the validity of our proposed algorithm, computer simulations are illustrated, where navigation problem of a mobile robot and a micro aerial vehicle(MAV) are considered.

• The KSFM Journal of Fluid Machinery
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• v.16 no.3
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• pp.18-25
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• 2013

Recently the requirement of long-term mobile energy source for mobile robot or small-sized unmanned vehicle is highly increased, and the micro turbine generator(MTG) which is known to have high energy and power density is under development. MTG is designed to have air foil bearing and high speed rotor of which operating speed is 400,000rpm. In the development stage of high speed rotor and bearing, stability analysis for the full operational speed range is essential and the dynamic coefficients such as stiffness and damping coefficients of bearing depending on the rotational speed are required for that. Although perturbation method is usually used to identify the dynamic coefficients, it's not easy to give the perturbation to the high speed rotating rotor. In this study, we present the dynamic coefficients measurement system for air foil bearing which consists of electromagnets, gap sensors, high speed motor and controller. This measurement system can exert the sine sweep force to the rotor-bearing, measure the displacement of rotor and get FRF(Frequency response function) of rotor-bearing. The least square estimation method is applied to identify the dynamic coefficients of bearing from the measured frequency response at the different rpm and the identified dynamic coefficients for the wide rotational speed range are presented.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.10
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• pp.1025-1031
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• 2007

GPS is widely used for positioning applications and attitude of a vehicle can be found also with multiple antennas. However, extremely weak signal level prevents GPS from indoor operation. DR with accelerometers and gyros and landmark based localization method used for indoor applications increase complexity and cost. In this paper, a simple but very efficient ultrasound based attitude determination system which determines both position and attitude in WSN is given. The range between transmitter and receivers are measured using the arrival time difference between ultrasound and RF signal. The 3 dimensional positions can be found using more than 3 range measurements. Furthermore, if more than 2 transmitters are used, the attitude can be determined using the baseline vectors obtained by differencing transmitter and receiver positions. The prototype system is implemented to evaluate the performance of the proposed method. In addition, an error analysis shows the relation between the attitude error and basel me length, quality of measurement and orientation of a vehicle. The static and dynamic experiments performed by micro mobile robot shows accurate position with less than 1.5cm error and attitude with less than 1 degree error can be obtained continuously with 20cm baseline. It is expected that these results can be adapted without modification to indoor applications such as home cleaning robot and autonomous wheelchair maneuvering.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.142-159
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• 1996

Engineering of automated tools for the agro-food industries and the rural world activities have to pick up two challenges : to answer the immediate important problems related to the situation of these industries, and to imaging the tools that their professional will need next century. Creating or modifying automated tools in the next few will be made taking into account parameters either technical (environmental protection, health and safety), or social and economical (investment , employment). There will be a strong interaction with disciplines like ecology, medicine, ergonomy, psycho-sociology , etc. , The partners for such a research, tools manufactures and users, should have an early involvement in its content, in order to find rapidly the solution to the drastic problems they are meeting. On a longer term , during the next 20 years , there will be an important evolution of the rural space management and of the food processes. This will imply the emergence of new types of activities and know-how's , with lines of automated tools to be invented and developed , like : micro-system for organic localized tasks -mobile and adaptive equipments highly autonomous for natural space actions - device for perception , decision and control reproducing automatically the expert behaviors of human operators. Design of such automated tools need to overcome technological difficulties like the automation of the expert-decision process, or the management of complex design.