• Journal of the Korean Society for Precision Engineering
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• 제26권6호
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• pp.74-80
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• 2009

Path tracking of unmanned vehicle is a basis of autonomous driving and navigation. For the path tracking, it is very important to find the exact position of a vehicle. GPS is used to get the position of vehicle and a direction sensor and a velocity sensor is used to compensate the position error of GPS. To detect path lines in a road image, the bird's eye view transform is employed, which makes it easy to design a lateral control algorithm simply than from the perspective view of image. Because the driving speed of vehicle should be decreased at a curved lane and crossroads, so we suggest the speed control algorithm used GPS and image data. The control algorithm is simulated and experimented from the basis of expert driver's knowledge data. In the experiments, the results show that bird's eye view transform are good for the steering control and a speed control algorithm also shows a stability in real driving.

• The Journal of Korea Robotics Society
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• 제18권3호
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• pp.251-259
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• 2023

In the path traveling of differential-drive robots, the steering controller plays an important role in determining the path-following performance. When a robot with a pure-pursuit algorithm is used to continuously drive a right-angled driving path in an unstructured environment without turning in place, the robot cannot accurately follow the right-angled path and stops driving due to the ground and motor load caused by turning. In the case of pure-pursuit, only the current robot position and the steering angle to the current target path point are generated, and the steering component does not reflect the speed plan, which requires improvement for precise path following. In this study, we propose a driving algorithm for differentially driven robots that enables precise path following by planning the driving speed using the radius of curvature and fusing the planned speed with the steering angle of the existing pure-pursuit controller, similar to the Model Predict Control control that reflects speed planning. When speed planning is applied, the robot slows down before entering a right-angle path and returns to the input speed when leaving the right-angle path. The pure-pursuit controller then fuses the steering angle calculated at each path point with the accelerated and decelerated velocity to achieve more precise following of the orthogonal path.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2072-2077
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• 2003

Animal-like robots are serving an important role as a linkage between biology and engineering. So, in this paper, we aim to develop a biomimetic microrobot that mimics the locomotion mechanism of a gastropod. This microrobot has 3 DOF (x, y translation and rotation), and has small size, unlimited traveling range, high resolution and low cost. Its movement can be made using propagation wave that is generated by the controllable sinusoidal voltage source and piezoelectric effects. This soft motion that can be generated by propagation wave and piezoelectric mechanism would be useful for the motion on the slippery surface. So we modeled the propagation wave mechanism including piezoelectric effect and friction on the contact surface, and could know the velocity of the microrobot is dependent on the driving frequency, input voltage peak, propagation wavelength and surface friction coefficient. With these results we design the microrobot, and accomplish its fabrication and experimentation. The development of this microrobot shall be aimed to design an autonomous moving actuator like animal. Also it can be used from micromanipulation system technology to biology and medicine.

• IEMEK Journal of Embedded Systems and Applications
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• 제13권1호
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• pp.33-43
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• 2018

In this paper, we describe an sound tracking mobile robot suitable for areas where GPS is not available. Sound sensors are attached to four sides of the robot in order to locate the person in a danger, and the robot is supposed to move to the yelling person. The traveling distance of the mobile robot is calculated by the encoder attached to the wheel of the mobile robot. The moving direction of the mobile robot is measured by a gyro sensor on the robot. When the person in danger pushes a button of the mobile robot, the mobile robot transmits the trajectory data to a designated server.

• Journal of Power System Engineering
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• 제10권3호
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• pp.88-96
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• 2006

While the crane system operate in port, one of main objective is to transport containers to the goal position as soon as possible. Because this is one of the biggest problem in terms of productivity of port, the container crane is operated by an expert operator until now. However recently an automatic control system with high performance is required to improve the performance of the crane system and to make high productivity. Therefore we developed an optimal controller based on Humoral Immune Algorithm with PID controller. The proposed system has a real time structure and can improve the performance such as anti-sway problem. Some computer simulations are implemented to assess the characteristics of the proposed controller.

• Journal of the Korean Society of Industry Convergence
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• 제26권2_1호
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• pp.225-230
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• 2023

This research addresses sound command based human tracking problems for autonomous cleaning mobile robot in a networked AI space. To solve the problem, the difference among the traveling times of the sound command to each of three microphones has been used to calculate the distance and orientation of the sound from the cleaning mobile robot, which carries the microphone array. The cross-correlation between two signals has been applied for detecting the time difference between two signals, which provides reliable and precise value of the time difference compared to the conventional methods. To generate the tracking direction to the sound command, fuzzy rules are applied and the results are used to control the cleaning mobile robot in a real-time. Finally the experiment results show that the proposed algorithm works well, even though the mobile robot knows little about the environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제19권6호
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• pp.639-645
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• 2018

This paper is intended to develop a decision model that can be applied to autonomous vehicles and autonomous mobile vehicles. The developed module has an independent configuration for application in various driving environments and is based on a platform for organically operating them. Each module is studied for decision making on lane changes and for securing safety through reinforcement learning using a deep learning technique. The autonomous mobile moving body operating to change the driving state has a characteristic where the next operation of the mobile body can be determined only if the definition of the speed determination model (according to its functions) and the lane change decision are correctly preceded. Also, if all the moving bodies traveling on a general road are equipped with an autonomous driving function, it is difficult to consider the factors that may occur between each mobile unit from unexpected environmental changes. Considering these factors, we applied the decision model to the platform and studied the lane change decision system for implementation of the platform. We studied the decision model using a modular learning method to reduce system complexity, to reduce the learning time, and to consider model replacement.

• Journal of Biosystems Engineering
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• 제34권6호
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• pp.391-396
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• 2009

The percentage of those aged 60 and over is 43.5% among our country's 3,186 thousands farming population, so farm village is getting aging society rapidly. Moreover agricultural competitiveness has being weakened due to labor shortage by degradation in quality of labor configuration from elderly porson. For realisms easy workability, we developed a motor vehicle for agricultural activity. The vehicle has an automatic guidance system which could follows a track of magnetic tape on the floor for easy moving to given working position. We collected data from two guidance sensors, located on front and rear end of the vehicle and calculated displacement and angle deviation from the track. This traveling system was stably controlled with processing information deflection S, angle of deviation, D and angle velocity, Vt = $k_1D$ - $k_2S$ from two guidance sensors attached on front and rear of th motor vehicle. Also this system have been tested under various condition of $k_1$, $k_2$ for comparison on both stepped and turning routes. The results show that traveling performance is best at $k_1$=0.7, $k_2$=3.

• Journal of Platform Technology
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• 제11권2호
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• pp.26-38
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• 2023

This paper is a study on a transport robot capable of autonomously driving to a destination using a QR code in an indoor environment. The transport robot was designed and manufactured by attaching a lidar sensor so that the robot can maintain a certain distance during movement by detecting the distance between the camera for recognizing the QR code and the left and right walls. For the location information of the delivery robot, the QR code image was enlarged with Lanczos resampling interpolation, then binarized with Otsu Algorithm, and detection and analysis were performed using the Zbar library. The QR code recognition experiment was performed while changing the size of the QR code and the traveling speed of the transport robot while the camera position of the transport robot and the height of the QR code were fixed at 192cm. When the QR code size was 9cm × 9cm The recognition rate was 99.7% and almost 100% when the traveling speed of the transport robot was less than about 0.5m/s. Based on the QR code recognition rate, an experiment was conducted on the case where the destination is only going straight and the destination is going straight and turning in the absence of obstacles for autonomous driving to the destination. When the destination was only going straight, it was possible to reach the destination quickly because there was little need for position correction. However, when the destination included a turn, the time to arrive at the destination was relatively delayed due to the need for position correction. As a result of the experiment, it was found that the delivery robot arrived at the destination relatively accurately, although a slight positional error occurred while driving, and the applicability of the QR code-based destination self-driving delivery robot was confirmed.

• Korean Journal of Agricultural Science
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• 제45권1호
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• pp.120-127
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• 2018

The rural labor force has gradually been decreasing due to the decrement of the farm population and the increment of the aging population. To solve these problems, it is necessary to develop and study autonomous agricultural machinery. Therefore, analyzing the dynamic behavior of vehicles in an autonomous agricultural environment is important. Until now, most studies on agricultural machinery, especially on ground vehicle dynamics, have been done by field tests. However, these field test methods are time consuming and costly with seasonal restrictions. A research method that can replace existing field test methods by using simulations is needed. In this study, we did basic research analyzing the effect of the travelling speed of a tractor on tire slip using simulation software. A tractor simulation model was developed based on field conditions following a straight path. The simulation was done for three ranges of speed: 20 - 30 km/h (considered the normal travelling speed range), 6 - 8 km/h (considered the plow tillage speed range) and 2 - 4 km/h (considered the rotary tillage speed range). The results of the simulation show that the slip ratio and slip angle values tended to increase as the traveling speed range of the tractor decreased. From the simulation results, it can be concluded that at low tractor speeds, it becomes more difficult to control the vehicle path. In future research, simulations will be done with various work environments such as a curved path as well as with various friction coefficient conditions, and the simulation results will be experimentally verified by applying them to an agricultural tractor.