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
This study focuses on the use of ceramic tile powder as a cement replacement material in concrete at an appropriate ratio. The objective is to investigate the properties of replacing cement with tile powder and to determine the optimal mixing ratio of tile powder in cement mortar that can yield properties equivalent to or superior to conventional cement mortar. The experiment involved preparing cement mortar samples by replacing cement with two types of ceramic tile powder waste from tile manufacturing plants: waste tile powder and rectified tile powder. The mixing process was divided into two parts: Part 1 used a cement and tile powder ratio, while Part 2 used the results of the strength analysis from Part 1 to adjust the ratio accordingly. Various properties were tested, including specific gravity, normal consistency, setting time, tensile strength, and compressive strength. The results of the study revealed that replacing of cement with rectified tile powder provided the highest tensile and compressive strength, comparable to that of conventional cement mortar. Therefore, the use of ceramic tile powder as a replacement can enhance compressive strength while reducing cement usage, which has positive environmental implications by decreasing greenhouse gas emissions from cement production. Furthermore, this approach promotes the effective use of waste materials from the ceramic industry, contributing to the sustainability of the construction industry.
คณะวิทยาศาสตร์
A smartphone-based colorimetric sensor for quantitative detection of pyridoxine (Vitamin B6, VB-6) in functional drink samples has been realized by developing double layer hydrogel. Electrostatic interaction initiates the cross-linking and produces double layer hydrogel.
คณะครุศาสตร์อุตสาหกรรมและเทคโนโลยี
This project presents the development of a single-frequency GPS-based total electron content measurement tool. It applies theories related to total electron content in the ionospheric layer and the measurement of total electron content using GPS time delay to design the single-frequency GPS total electron content measurement tool. The tool consists of an antenna, a single-frequency GPS satellite receiver, a data processing unit for evaluating and calculating total electron content, and a display unit for showing total electron content data. The performance of the single-frequency GPS total electron content measurement tool is tested by comparing it with total electron content data obtained from the International Reference Ionosphere (IRI) model, which is a global reference model for electron content. The tool is also put to practical use. The results of the comparison and practical applications conclude that the single-frequency GPS-based total electron content measurement tool can be effectively utilized, with the difference from the IRI model being 50 TECU