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Abstract Quadruped robots are regarded as a new trend in robotics due to their superior gait stability and robustness to disturbances. In recent years, many robotics researchers are making their best efforts to improve the locomotion speed, as well as the stability and robustness, of quadruped robots. The high-speed locomotion creates various challenges in the development of actuators, mechanical design, and control algorithms of the robot. In this paper, a linear actuation system for the high-speed locomotion of a quadruped robot is introduced. The proposed actuator is designed based on the principle of brushed direct-current electric motor systems. The mechanical and electrical properties of the actuation system, such as back-drivability, controllability, and response time, are verified by experimental results. A robotic leg, which is the rear leg of a cheetah-like robot, is designed with the proposed actuator, and is introduced briefly in this paper also.

Abstract Soil texture has an important influence on agriculture, affecting crop selection, movement of nutrients and water, soil electrical conductivity, and crop growth. Soil texture has traditionally been determined in the laboratory using pipette and hydrometer methods that require a considerable amount of time, labor, and expense. Recently, in-situ soil texture classification systems using optical diffuse reflectometry or mechanical resistance have been reported, especially for precision agriculture where more data is needed than in conventional agriculture. This paper is a part of overall research to develop a soil texture classification system using image processing. Application of image processing was motivated by simple traditional approaches such as visual inspection and the “hand-feel” method. In this paper, the potential of soil texture classification using RGB histograms was investigated. Seven sites representing major Korean paddy soil series were selected, 4-6 core samples up to a 50-cm depth were obtained from each site, and each sample was segmented by 5-cm intervals. For each segmented soil sample, four surface images were taken using a miniaturized CCD camera, and texture fractions were determined by the pipette method. Scatter plots showed linear patterns between silt content and histogram variables such as brightness, skewness, and mode - brightness. When 5% averaged silt content was linearly regressed with mode - brightness, R 2 , RMSEC, and RMSEP were 0.96, 2.2%, and 6.3%, respectively. When soils were classified using USDA criteria, the laboratory method and the in-situ image processing method produced the same results for 48% of the samples.

Abstract This paper addresses a stable vision system for indoor moving robot using encoder information. The proposed system uses encoder signals to calculate robot motion and rotates the camera in order to fix the target on the image frame during locomotion. Since the calculation of rotating angle of the camera is based on the integration of encoder data over time, this leads to the unbounded accumulation of error. To prevent the error accumulation, vision sensor signals are used periodically to compensate for the errors. The resulting standard deviations of the rotated camera angle error were 0.94°, 0.32° and 1.55° for rotation, translation and rotation-translation combined motion while the robot heading angles have standard deviations of 23.27°, 16.56° and 48.53°, respectively. However, the system shows performance degradation in slippery ground conditions. In our experiments the errors have trends to increase with the decrease of friction coefficient between the ground and the robot wheels. Future work should overcome this problem using additional sensors such as inertial measurement units (IMUs) that are able to detect the correct robot motion even in the case of slip disturbance.

Abstract The interest in a healthy and happy life for seniors has increased of late as the quality of life in old age has become a hot issue. Moreover, the interest in health has led industrial companies to concentrate on healthcare technology. Healthcare robot technology is one of the biggest issues in the robotics field, and many companies and institutes have sought to develop a healthcare robot technology. The healthcare robot must have certain abilities that would allow it to help a person mentally and/or physically. There is no common interface module, however, for healthcare robot platforms, and few robots that have healthcare abilities exist. Therefore, developing a common interface technology and applying the technology to robot platforms can pave the way for the development of a technology that could improve the physical and mental health of humans. This paper introduces the authors’ research on a common interface module and a healthcare service robot platform. First, a common interface module is one that can be used in common in the healthcare robot area. The research on a common interface module contains the following technologies: biosignal processing modules; voice signal processing modules, which could recognize voice commands; control modules for robot actuators; and a human-friendly design for a healthcare system. Lastly, the research on a healthcare service robot platform contains three types of robot platforms: ChairBot for relaxation, RideBot for exercising, and LifecareBot for human emotions. Each robot platform has common interface modules for healthcare services and can provide specialized intelligent services based on their own objectives. In conclusion, the intellectual healthcare robot is expected to promote a new field and to pave the way for a new product.

For obtaining the height information, a vertically damped inertial navigation system (INS) using the height reference of barometer measurements is conventionally instrumented. Since it requires delicate construction of INS system, in many cases, it has been costly. In this paper, a novel altitude estimation system is proposed by effectively combining the information of the GPS height and air data measurements such as ambient air pressure and temperature. Based on the fact that the barometer errors mainly consist of bias and scale factor errors, a filter to estimate the bias and scale factor using the GPS height is derived by means of multiple hypothesis Gaussian approximation filter technique. The estimated bias and scale factor is used to compensate the baro-altitude. Simulation results show that this method can construct a good altitude measurement system with relatively low cost.

Abstract ‘Seoul National University’ and ‘Daewoo Shipbuilding & Marine Engineering’ in Korea jointly developed a mobile welding robot, the ‘Rail Runner’ (RRX), which is able to freely move in both transverse and longitudinal directions, and perform welding tasks in double hull structures. Recently, RRX2, (the second version of RRX), was presented at ‘Robotics and Applications 2007'. In this paper, the design, manufacturing, and application of RRX3, the third version of RRX, is described. The moving mechanism of RRX, which is able to move freely in a double hull structure, has two functions. 1) To move in a longitudinal direction by driving wheels using longi. faces as ‘rails', and 2) To move in a transverse direction by sliding along supporting longi. faces using extension arms. The body of the RRX3 is composed of a 12-axis, 6-axis mobile platform that supports the RRX moving mechanism and a 6-axis welding robot to do the welding job. The main point in designing RRX3 is to make it capable of passing through a 600mm×800mm sized access hole, the entrance into an enclosed double hull structure. The full size of the manufactured RRX3 is 1825mm×495mm×569mm, and thus the RRX3 is able to pass through an access hole. The weight is 250kg with a 6-axis mobile platform, 6-axis welding robot, and mounted controller.

This paper provides a receding horizon control method for bilinear systems in the presence of input constraints. Periodically-invariant sets are derived for a bilinear system with respect to a series of time-varying state feedback gains. The dual-mode control strategy is adopted and the periodically-invariant sets are used as target invariant sets. The state feedback gains used to define the target invariant sets are also used to render degrees of freedom to steer the current state into the target set. The region of attraction for the proposed algorithm is enlarged significantly with an extension of the horizon of periodicity while the on-line computation remains easy to handle. Copyright © 2007 International Federation of Automatic Control All Rights Reserved.

Abstract In order to improve the task performance of service robots, interaction between humans and robots is critical. Existing models for service robots have been based on multiple scripts defining the actions required to carry out tasks. These models have attempted to resolve task decision-making problems through interaction with humans. In addition to interactions for the decision-making model, this paper proposes a system that manages physical actions interactively with humans. A managing model was established by considering major related issues and was implemented with a computer simulator.

Abstract This paper proposes a new effective behaviour-based reactive navigation methodology for autonomous mobile robot. Its main contribution is based on newly proposed egocentric 'homeostatic' approach by which behaviours are coordinated while taking advantages of both competitive and cooperative method. In order to accomplish autonomous navigation, direction and velocity are modulated automatically by single real value, ***'satisfaction level' without any central or additional module so that this method becomes simple, consistent, and flexible. The validities of the proposed methodology are shown by graphic simulation and experiments with wheeled mobile robot.