• 제어로봇시스템학회논문지
• /
• 제20권10호
• /
• pp.1057-1062
• /
• 2014

This paper proposes a tip-over detection method for a mobile robot using a support inscribed circle defined as an inscribed circle of a support polygon. A support polygon defined by the contact points between the robot and the terrain is often used to analyze the tip-over. For a robot moving on uneven terrain, if the intersection between the extended line of gravity from the robot's COG and the terrain is inside the support polygon, tip-over will not occur. On the contrary, if the intersection is outside, tip-over will occur. The terrain is detected by using an RGB-D sensor. The terrain is locally modeled as a plane, and thus the normal vector can be obtained at each point on the terrain. The support polygon and the terrain's normal vector are used to detect tip-over. However, tip-over cannot be detected in advance since the support polygon is determined depending on the orientation of the robot. Thus, the support polygon is approximated as its inscribed circle to detect the tip-over regardless of the robot's orientation. To verify the effectiveness of the proposed method, the experiments are carried out using a 4-wheeled robot, ERP-42, with the Xtion RGB-D sensor.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제49권5호
• /
• pp.257-263
• /
• 2000

One of the basic assumptions in the static gait design for a walking robot is that the weight of leg should be negligible compared to that of body, so that the total gravity center is not affected by swing of a leg. Based on the ideal assumption of zero leg-weight, conventional static gait has been simply designed for the gravity center of body to be inside the support polygon, consisting of each support leg's tip position. In case that the weight of leg is relatively heavy, however, while the gravity center of body is kept inside the support polygon, the total gravity center of walking robot can be out of the polygon due to weight of a swinging leg, which causes instability in walking. Thus, it is necessary in the static gait design of a real robot a compensation scheme for the fluctuation in the gravity center. In this paper, a body impedance control is proposed to obtain the total gravity center based on foot forces measured from load cells of a real walking robot and to adjust its position to track the pre-designed trajectory of the corresponding ideal robot's body center. Therefore, the walking stability is secured even in case that the weight of leg has serious influence on the total gravity center of robot.

• 한국기계가공학회지
• /
• 제14권3호
• /
• pp.112-123
• /
• 2015

There are many systems for cutting plates or pipes into a desired shape. A typical system is a plasma cutter. It uses plasma, which means that an effective design of the table supporting the workpiece is an important issue in order to ensure a long operational career. Conventional roller-support worktables have a short lifespan due to scratches from the plasma, and it is also difficult to maintain the roller balance. By using a bolt-fastening method, deformation and failure of the final product can occur due to the stress concentration at bolting points. To escape these issues, a polygon support and bracket fastening method was designed. Due to polygons having a number of support surfaces, when one surface has been damaged, it is possible to reuse the support by utilizing a different surface. The bracket-fastening method can extend the worktable lifetime and increase productivity by reducing stress concentration. In this paper, the polygon support/bracket-fastening method is compared with existing technologies. Consequently, performance benchmarks are verified through a structure analysis and experimentation.

• 대한임베디드공학회논문지
• /
• 제3권2호
• /
• pp.119-125
• /
• 2008

This paper presents the polygon-based Q-leaning and Cascade Support Vector Machine algorithm for object search with multiple robots. We organized an experimental environment with ten mobile robots, twenty five obstacles, and an object, and then we sent the robots to a hallway, where some obstacles were lying about, to search for a hidden object. In experiment, we used four different control methods: a random search, a fusion model with Distance-based action making (DBAM) and Area-based action making (ABAM) process to determine the next action of the robots, and hexagon-based Q-learning and dodecagon-based Q-learning and Cascade SVM to enhance the fusion model with DBAM and ABAM process.

• 한국CDE학회논문집
• /
• 제2권3호
• /
• pp.195-210
• /
• 1997

In Rapid Prototyping process, the time required to build multiple prototype parts can be reduced by packing several parts optimally in a work volume. Interactive arrangement of the multiple parts is a tedious process and does not guarantee the optimal placement of all the parts. In this case, packing is a kind of 3-D nesting problem because parts are represented by STL files with 3-D information. 3-D nesting is well known to be a problem requiring an intense computation and an efficient algorithm to solve the problem is still under investigation. This paper proposes that packing 3-D parts can be simplified into a 2-D irregular polygon nesting problem by using the characteristic of rapid prototyping process that the process uses 2-dimensional slicing data of the parts and that slice of the STL parts are composed of polygons. Our algorithm uses no-fit-polygon (NFP) to place each slice without overlapping other slices in the same z-level. The allowable position of one part at a fixed orientation for given parts already packed can be determined by obtaining the union of all NFP's that are obtained from each slice of the part. Genetic algorithm is used to determine the order of parts to be placed and orientations of each part for the optimal packing. Optimal orientation of a part is determined while rotating it about the axis normal to the slice by finite angles and flipping upside down. This algorithm can be applied to any rapid prototyping process that does not need support structures.

• Journal of Multimedia Information System
• /
• 제6권1호
• /
• pp.23-30
• /
• 2019

A communications profile is a system that acquires information from communication links to an ambulance or other vehicle moving on a road and compiles a database based on this information. The equipment (six sets of HDTVs, fish-eye camera, satellite antenna with tracking system, and receiving power from the satellite beacon of the N-star) mounted on the roof of the vehicle, image data were obtained at Yokohama Japan. From these data, the polygon of the building was actually produced and has arranged on the map of the Geographical Survey Institute of a 50 m-mesh. The optical study (relationship between visibility rate and elevation angle) were performed on actual data taken by fish-eye lens, and simulated data by 3D-Map with polygons. There was no big difference. This 3D map system then predicts the communication links that will be available at a given location. For line-of-sight communication, optical analysis allows approximation if the frequency is sufficiently high. For non-line-of-sight communication, previously obtained electric power data can be used as reference information for approximation in certain cases when combined with predicted values calculated based on a 3D map. 3D maps are more effective than 2D maps for landing emergency medical helicopters on public roadways in the event of a disaster. Using advanced imaging technologies, we have produced a semi-automatic creation of a high-precision 3D map at Yokohama Yamashita Park and vicinity and assessed its effectiveness on telecommunications and ambulatory merits.

• ETRI Journal
• /
• 제44권2호
• /
• pp.286-299
• /
• 2022

Human activity recognition in real time is a challenging task. Recently, a plethora of studies has been proposed using deep learning architectures. The implementation of these architectures requires the high computing power of the machine and a massive database. However, handcrafted features-based machine learning models need less computing power and very accurate where features are effectively extracted. In this study, we propose a handcrafted model based on three-dimensional sequential skeleton data. The human body skeleton movement over a frame is computed through joint positions in a frame. The joints of these skeletal frames are projected into two-dimensional space, forming a "movement polygon." These polygons are further transformed into a one-dimensional space by computing amplitudes at different angles from the centroid of polygons. The feature vector is formed by the sampling of these amplitudes at different angles. The performance of the algorithm is evaluated using a support vector machine on four public datasets: MSR Action3D, Berkeley MHAD, TST Fall Detection, and NTU-RGB+D, and the highest accuracies achieved on these datasets are 94.13%, 93.34%, 95.7%, and 86.8%, respectively. These accuracies are compared with similar state-of-the-art and show superior performance.

• 한국BIM학회 논문집
• /
• 제13권3호
• /
• pp.30-38
• /
• 2023

Building Information Models(BIM) provides rich geometric and attribute information throughout the entire life cycle of a building and infrastructure object, while Geographic Information System(GIS) enables the detail analysis of urban issues based on the geo-spatial information in support of decision-making. The Integration of BIM and GIS data makes it possible to create a digital twin of the land in order to effectively manage smart cities. In the perspective of integrating BIM data into GIS systems, this study performs literature reviews on georeferencing techniques and identifies limitations in carrying out the georeferencing process using attribute information associated with absolute coordinates probided by Industry Foundation Classes(IFC) as a BIM standard. To address these limitations, an automated georeferencing process is proposed as a pilot study to position a IFC model with the Local Coordinate System(LCS) in GIS environments with the Reference Coordinate System(RCS). An evaluation of the proposed approach over a BIM model demonstrates that the proposed method is expected to be a great help for automatically georeferencing complex BIM models in a GIS environment, and thus provides benefits for efficient and reliable BIM and GIS integration in practice.

• Nuclear Engineering and Technology
• /
• 제44권5호
• /
• pp.507-522
• /
• 2012

When decommissioning a nuclear power plant, it is difficult to make an appropriate plan to ensure sufficient space for temporary placement and conveyance operations of dismantling targets. This paper describes a system to support temporary placement and conveyance operations using augmented reality (AR). The system employs a laser range scanner to measure the three-dimensional (3D) information of the environment and a dismantling target to produce 3D surface polygon models. Then, the operator simulates temporary placement and conveyance operations using the system by manipulating the obtained 3D model of the dismantling target in the work field. Referring to the obtained 3D model of the environment, a possible collision between the dismantling target and the environment is detectable. Using AR, the collision position is presented intuitively. After field workers evaluated this system, the authors concluded that the system is feasible and acceptable to verify whether spaces for passage and temporary storage are sufficient for temporary placement and conveyance operations. For practical use in the future, some new functions must be added to improve the system. For example, it must be possible for multiple workers to use the system simultaneously by sharing the view of dismantling work.

• 제어로봇시스템학회논문지
• /
• 제15권6호
• /
• pp.626-633
• /
• 2009

A motion planning algorithm is presented in this paper for a commercialized quadruped walking of robot pet. Stable walking is the basic requirement for a commercial-purpose legged robot. In order to secure the walking stability, modified body sway to the centroid of support polygon is addressed. By representation of walking motion with respect to the world coordinate system rather than body coordinate, it is possible to design the several gaits in unified fashion. The initial gait posture is introduced to maximize the stride and to achieve fast walking. The proposed walking motion planning is verified through computer simulation and experiments.