Characterization of optical communication in a leader-follower unmanned underwater vehicle formation

As part of the research to development an optical communication design of a leader-follower formation between unmanned underwater vehicles (UUVs), this paper presents light field characterization and design configuration of the hardware required to allow the use of distance detection between UUVs. The study specifically is targeting communication between remotely operated vehicles (ROVs). As an initial step in this study, the light field produced from a light source mounted on the leader UUV was empirically characterized and modeled. Based on the light field measurements, a photo-detector array for the follower UUV was designed. Evaluation of the communication algorithms to monitor the UUV’s motion was conducted through underwater experiments in the Ocean Engineering Laboratory at the University of New Hampshire. The optimal spectral range was determined based on the calculation of the diffuse attenuation coefficients by using two different light sources and a spectrometer. The range between the leader and the follower vehicles for a specific water type was determined. In addition, the array design and the communication algorithms were modified according to the results from the light field

Pose Detection and control of multiple unmanned underwater vehicles using optical feedback

This paper proposes pose detection and control algorithms in order to control the relative pose between two Unmanned Underwater Vehicles (UUVs) using optical feedback. The leader UUV is configured to have a light source at its crest which acts as a guiding beacon for the follower UUV which has a detector array at its bow. Pose detection algorithms are developed based on a classifier, such as the Spectral Angle Mapper (SAM), and chosen image parameters. An archive look-up table is constructed for varying combinations of 5-degree-of-freedom (DOF) motion (i.e., translation along all three coordinate axes as well as pitch and yaw rotations). Leader and follower vehicles are simulated for a case in which the leader is directed to specific waypoints in horizontal plane and the follower is required to maintain a fixed distance from the leader UUV. Proportional-Derivative (PD) control (without loss of generality) is applied to maintain stability of the UUVs to show proof of concept. Preliminary results indicate that the follower UUV is able to maintain its fixed distance relative to the leader UUV to within a reasonable accuracy

Evaluation of Detector Array Designs for Optical Communication Between Unmanned Underwater Vehicle

The communication interface is essential for unmanned underwater vehicles (UUVs) to interact with each other or with a stationary target, such as docking station. In this paper, we investigate different optical array designs using a simulator. In addition to the hardware characteristics (e.g., sensitivity of the detectors and noise sources), the environmental conditions affecting the light field underwater were also taken into account. The simulator product is an image of the light field sensed by the detector array. The simulator product provides a signature that allows the UUV to track its position and orientation with respect to a light source. A variety of motion types (i.e., translation in the x, y, z directions including rotation about these axes) were analytically tested and evaluated for different array designs. The results from the simulator are to be validated against empirical measurements conducted in the water tank facilities in the Ocean Engineering Laboratory at the University of New Hampshire. Preliminary results suggest that unique image signatures can be obtained for the relative translational and rotational motion between two platforms

Simple guide to starting a research group

Conducting cutting-edge research and scholarship becomes more complicated with each passing year; forming a collaborative research group offers a way to navigate this increasing complexity. Yet many individuals whose work might benefit from the formation of a collaborative team may feel overwhelmed by the prospect of attempting to build and maintain a research group. We propose this simple guide for starting and maintaining such an enterprise

Simple Guide to Using Generative Artificial Intelligence Writing Tools in Research & Scholarship at UNH

While Artificial Intelligence (AI) technologies have existed for years, the recent arrival of widespread generative AI writing tools such as ChatGPT has provoked varied reactions in the scholarly community worldwide. Undoubtedly easy access to such tools may help to level the scholarly playing field for certain groups, particularly those with limited writing skills or proficiency with English as the primary language for written and oral communication of research and scholarship. There are, however, concerns about these tools, including, but not limited to, the accuracy, consistency, and bias of the information generated, appropriate acknowledgement of source material, and the tools’ lack of ability to reason or to understand meaning when generating output. This simple guide was developed to assist researchers and trainees to understand the fundamental issues with these technologies regarding research integrity

ACL-98-005 Comparison of the Sliding Observer to Several State Estimators Using a Rotational Inverted Pendulum

Because of the inherent characteristics of nonlinear systems, state estimation of these systems continues to pose difficult problems. The objective of this paper is to test the Sliding Mode Observer techniqe on a highly nonlinear non-minimum phase system. The chosen system is the rotaional inverted pendulum system of Misawa, Arrington, and Ledgerwood [7]. In addition, the observer technique is compared to that of other techniques: the Linear Kalman Filter, Thau's Method, the Adaptive Observer, the High Gain Observer, the Multistage Nonlinear Observer, and the Equivalent Control-Based Sliding Mode Observer. The bases of comparison is performance, robustness against disturbances and modeling errors, stability, and ease of application. 1 Introduction Due to its complex behavior, the test system was chosen to be the rotaional inverted pendulum (RIP) developed by Misawa et. al. [7] The RIP is a fourth order nonlinear coupled system. It consists of a control link and a pendulum link connect..

Acl-98-004 Input-Output Feedback Linearization Control Of A Load-Sensing Hydraulic Servo System

The objective of this project is to analyze the feasibility of designing a non-linear controller for a load-sensing hydraulic servo system. The nonlinear controller is obtained using InputOutput Feedback Linearization. By using this technique, the system is not restricted to operate locally about a certain set of operating points. Hence, it shows improved performance over the system described by Kim [1], which uses a Taylor expansion linearization technique and, thus, is limited to operate about a chosen set of operating points. 1 Introduction The dynamics of a load-sensing hydraulic servo system are unstable under certain conditions, complex, and highly nonlinear. The stability of this system has already been analyzed by Kim[2], and a suboptimal PID controller was also designed, based on a perturbation model of the plant obtained through Taylor series expansion. The main difference between the work described in this paper and that proposed by Kim [1] is that no particular operating p..