The capture of a target spacecraft by a chaser is an on-orbit docking operation that requires an accurate, reliable, and robust object recognition algorithm. Vision-based guided spacecraft relative motion during close-proximity maneuvers has been consecutively applied using dynamic modeling as a spacecraft on-orbit service system. This research constructs a vision-based pose estimation model that performs image processing via a deep convolutional neural network. The pose estimation model was constructed by repurposing a modified pretrained GoogLeNet model with the available Unreal Engine 4 rendered dataset of the Soyuz spacecraft. In the implementation, the convolutional neural network learns from the data samples to create correlations between the images and the spacecraft’s six degrees-of-freedom parameters. The experiment has compared an exponential-based loss function and a weighted Euclidean-based loss function. Using the weighted Euclidean-based loss function, the implemented pose estimation model achieved moderately high performance with a position accuracy of 92.53 percent and an error of 1.2 m. The in-attitude prediction accuracy can reach 87.93 percent, and the errors in the three Euler angles do not exceed 7.6 degrees. This research can contribute to spacecraft detection and tracking problems. Although the finished vision-based model is specific to the environment of synthetic dataset, the model could be trained further to address actual docking operations in the future.
In one, docking is defined as “when one incoming spacecraft rendezvous with another spacecraft and flies a controlled collision trajectory in such a manner to align and mesh the interface mechanisms”, and defined docking as an on-orbital service to connect two free-flying man-made space objects. The service should be supported by an accurate, reliable, and robust positioning and orientation (pose) estimation system. Therefore, pose estimation is an essential process in an on-orbit spacecraft docking operation. The position estimation can be obtained by the most well-known cooperative measurement, a Global Positioning System (GPS), while the spacecraft attitude can be measured by an installed Inertial Measurement Unit (IMU). However, these methods are not applicable to non-cooperative targets. Many studies and missions have been performed by focusing on mutually cooperative satellites. However, the demand for non-cooperative satellites may increase in the future. Therefore, determining the attitude of non-cooperative spacecrafts is a challenging technological research problem that can improve spacecraft docking operations. One traditional method, which is based on spacecraft control principles, is to estimate the position and attitude of a spacecraft using the equations of motion, which are a function of time. However, the prediction using a spacecraft equation of motion needs support from the sensor fusion to achieve the highest accuracy of the state estimation algorithm. For non-cooperative spacecraft, a vision-based pose estimator is currently developing for space application with a faster and more powerful computational resource.
คณะวิศวกรรมศาสตร์
The production process of the food rancidity indicator label consists of three main steps: 1) preparation of the indicator solution, 2) preparation of the cellulose solution, and 3) formation of the sheet. The indicator solution includes bromothymol blue and methyl red, which act as indicators. The cellulose solution consists of hydroxypropyl methylcellulose, carboxymethyl cellulose, sodium hydroxide, polyethylene glycol 400, and the indicator solution. For the sheet formation, the cellulose solution was mixed with natural latex to increase flexibility and impart hydrophobic properties. After drying, the invention appears as a thin, dark blue label. When exposed to volatile compounds from rancid food, the label changes color from dark blue to green, and then to yellow, corresponding to the increasing amount of volatile compounds from the rancid food.
คณะวิศวกรรมศาสตร์
Given the fact that the equity market contributes a significant amount to Thai economy and increasing participants and interest by Thai companies, these facts inspire and motivate us to establish a study to analyze whether the stock market can indeed be an active booster of company performances and characteristics of companies which will be beneficial from being in the stock market. These results can support higher listing interest from companies, provide actionable ideas to companies aiming to improve their performance in the competitive arena, and suggest improvements for the stock market to further establish a stronger capital market penetration and foundation in Thailand. The main hypothesis driving this project is to examine whether “aging in the market” contributes to measurable improvements in a company’s performance. Specifically, we seek to understand if the presence of Thai companies in the Stock Exchange of Thailand correlates with enhanced operational outcomes, thereby providing insights into the true benefits of public listing on long-term performance.
คณะเทคโนโลยีสารสนเทศ
Currently, the issue of developmental writing disabilities in children is a matter of great importance for school-age children. Diagnosing whether a child has developmental writing disabilities relies on writing skill assessments, which are administered to those seeking diagnosis and evaluated by medical professionals or experts. However, there are still limitations in the diagnostic process, which depends heavily on expert physicians, leading to a high demand for human resources. To address this, we have developed a method for scoring writing skill assessments using image processing technology, based on existing scoring criteria. Currently, three criteria are used for scoring: writing position, article format, and copying speed. We have also created a web application to make the system more accessible and easier to use.