Sensor Fusion for Underwater Vehicle Navigation Compensating Misalignment Using Lie Theory

This paper presents a sensor fusion method for navigation of unmanned underwater vehicles. The method combines Lie theory into Kalman filter to estimate and compensate for the misalignment between the sensors: inertial navigation system and Doppler Velocity Log (DVL). In the process and measurement model equations, a 3-dimensional Euclidean group (SE(3)) and 3-sphere space (S3) are used to express the pose (position and attitude) and misalignment, respectively. SE(3) contains position and attitude transformation matrices, and S3 comprises unit quaternions. The increments in pose and misalignment are represented in the Lie algebra, which is a linear space. The use of Lie algebra facilitates the application of an extended Kalman filter (EKF). The previous EKF approach without Lie theory is based on the assumption that a non-differentiable space can be approximated as a differentiable space when the increments are sufficiently small. On the contrary, the proposed Lie theory approach enables exact differentiation in a differentiable space, thus enhances the accuracy of the navigation. Furthermore, the convergence and stability of the internal parameters, such as the Kalman gain and measurement innovation, are improved.

Trajectory Following Control of an Unmanned Vehicle for Marine Environment Sensing

An autonomous surface vehicle is indispensable for sensing of marine environments owing to its challenging and dynamic conditions. To accomplish this task, the vehicle has to navigate through a desired trajectory. However, due to the complexity and dynamic nature of a marine environment affected by factors such as ocean currents, waves, and wind, a robust controller is of paramount importance for maintaining the vehicle along the desired trajectory by minimizing the trajectory error. To this end, in this study, we propose a robust discrete-time super-twisting second-order sliding mode controller (DSTA). Besides, this control method effectively suppresses the chattering effect. To start with, the vehicle's model is discretized using an integral approximation with nonlinear terms including environmental disturbances treated as perturbation terms. Then, the perturbation is estimated using a time delay estimator (TDE), which further enhances the robustness of the proposed method and allows us to choose smaller controller gains. Moreover, we employ a genetic algorithm (GA) to tune the controller gains based on a quadratic cost function that considers the tracking error and control energy. The stability of the proposed sliding mode controller (SMC) is rigorously demonstrated using a Lyapunov approach. The controller is implemented using the Simulink® software. Finally, a conventional discrete-time SMC based on the reaching law (DSMR) and a heuristically tuned DSTA controller are used as benchmarks to compare the tracking accuracy and chattering attenuation capability of the proposed GA based DSTA (GA-DSTA). Simulation results are presented both with or without external disturbances. The simulation results demonstrate that the proposed controller drives the vehicle along the desired trajectory successfully and outperforms the other two controllers.

Attitude Estimation of Underwater Vehicles Using Field Measurements and Bias Compensation

This paper proposes a method of estimating the attitude of an underwater vehicle. The proposed method uses two field measurements, namely, a gravitational field and a magnetic field represented in terms of vectors in three-dimensional space. In many existing methods that convert the measured field vectors into Euler angles, the yaw accuracy is affected by the uncertainty of the gravitational measurement and by the uncertainty of the magnetic field measurement. Additionally, previous methods have used the magnetic field measurement under the assumption that the magnetic field has only a horizontal component. The proposed method utilizes all field measurement components as they are, without converting them into Euler angles. The bias in the measured magnetic field vector is estimated and compensated to take full advantage of all measured field vector components. Because the proposed method deals with the measured field independently, uncertainties in the measured vectors affect the attitude estimation separately without adding up. The proposed method was tested by conducting navigation experiments with an unmanned underwater vehicle inside test tanks. The results were compared with those obtained by other methods, wherein the Euler angles converted from the measured field vectors were used as measurements.

Features of Invariant Extended Kalman Filter Applied to Unmanned Aerial Vehicle Navigation

This research used an invariant extended Kalman filter (IEKF) for the navigation of an unmanned aerial vehicle (UAV), and compared the properties and performance of this IEKF with those of an open-source navigation method based on an extended Kalman filter (EKF). The IEKF is a fairly new variant of the EKF, and its properties have been verified theoretically and through simulations and experiments. This study investigated its performance using a practical implementation and examined its distinctive features compared to the previous EKF-based approach. The test used two different types of UAVs: rotary wing and fixed wing. The method uses sensor measurements of the location and velocity from a GPS receiver; the acceleration, angular rate, and magnetic field from a microelectromechanical system-attitude heading reference system (MEMS-AHRS); and the altitude from a barometric sensor. Through flight tests, the estimated state variables and internal parameters such as the Kalman gain, state error covariance, and measurement innovation for the IEKF method and EKF-based method were compared. The estimated states and internal parameters showed that the IEKF method was more stable and convergent than the EKF-based method, although the estimated locations, velocities, and altitudes of the two methods were comparable.

Probability-Based Recognition Framework for Underwater Landmarks Using Sonar Images †

This paper proposes a probability-based framework for recognizing underwater landmarks using sonar images. Current recognition methods use a single image, which does not provide reliable results because of weaknesses of the sonar image such as unstable acoustic source, many speckle noises, low resolution images, single channel image, and so on. However, using consecutive sonar images, if the status-i.e., the existence and identity (or name)-of an object is continuously evaluated by a stochastic method, the result of the recognition method is available for calculating the uncertainty, and it is more suitable for various applications. Our proposed framework consists of three steps: (1) candidate selection, (2) continuity evaluation, and (3) Bayesian feature estimation. Two probability methods-particle filtering and Bayesian feature estimation-are used to repeatedly estimate the continuity and feature of objects in consecutive images. Thus, the status of the object is repeatedly predicted and updated by a stochastic method. Furthermore, we develop an artificial landmark to increase detectability by an imaging sonar, which we apply to the characteristics of acoustic waves, such as instability and reflection depending on the roughness of the reflector surface. The proposed method is verified by conducting basin experiments, and the results are presented.

Abstract P3-10-09: Predictors of social support among newly diagnosed breast cancer patients seeking care at an urban safety net academic medical center

Background:

Disparities in breast cancer care are a worsening problem, requiring effective interventions that seek to address the delivery of high quality cancer care. Evidence from interventions designed to improve timeliness of care routinely identify lack of social support as one of the biggest barriers to care. And, social support is associated with adherence to treatment and survival. This study explores predictors of social support in a diverse population of cancer patients.

Patients and Methods:

This is a secondary analysis of baseline preliminary data from participants enrolled in Project SUPPORT, a randomized controlled comparative effectiveness trial designed to evaluate the impact of patient navigation with or without legal support and services, among women diagnosed with Stages 0-4 breast cancer between 2014-2016. Upon enrollment (within one month of a cancer diagnosis) we administered the Medical Outcomes Survey (MOS) of social support to all participants. This validated survey tool addresses functional support, including an overall score (range 0-95) and 4 distinct domains: Emotional/Informational, Tangible, Affectionate and Positive Social Interaction. Using chi-squared and t-tests we compared MOS scores across socio-demographic variables: age, race, language, insurance, health literacy and marital status.

Results:

Of the 103 participants, mean age is 54.5 (SD = 10.6); 56% Hispanic, 19% Black, and 22% White and 2% identified as other; the majority had public insurance 76%; 66% speak English, 21% Spanish and 13% Haitian Creole. Only 36% have adequate health literacy as measured by the BRIEF. Only 32% are currently partnered. The overall mean total score for social support is 75.8 (+/- 23.6), median of 78.9 (range 60.5 – 98.7). Participants scored lowest in tangible support (mean score 67.7 +/- 33.1) and highest in affective support (83.5 +/- 25.8). Non-White participants scored significantly lower across all domains (mean overall MOS score 73.3 +/- 2.6) when compared with Whites (mean overall MOS score 84.5 +/- 4.8, p value = 0.04). There were no differences in MOS scores by language, insurance, literacy or marital status.

Conclusion:

This is the first study to describe social support scores (overall and specific domains) from the validated MOS survey tool among a racially diverse, urban cancer patient population. We found significant differences by race. Studies to identify risks for low social support can help inform future targeted interventions.

Citation Format: Ko NY, Festa K, Gunn C, Bak S, Wang N, Nelson K, Flacks J, Morton S, Battaglia TA. Predictors of social support among newly diagnosed breast cancer patients seeking care at an urban safety net academic medical center [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-10-09.

Abstract P3-10-08: Socio-demographic predictors for delay of treatment among a racially diverse, urban breast cancer population

Background:

Racial and ethnic disparity in breast cancer outcomes is a long-standing problem that continues to worsen. Recent evidence has underscored the importance of timely care, as delays in treatment can lead to decreased survival. We sought to understand predictors of delay to first treatment among a racially diverse cancer population.

Methods:

This is a retrospective study of breast cancer cases diagnosed between the years 2000 to 2014. Data was extracted from the cancer registry at Boston Medical Center (BMC), an urban safety net hospital. Inclusion criteria were any breast cancer diagnosis from 2000-2014, receiving first treatment at BMC, and disease stage 0-III. Cox Proportional Hazards regression analysis was performed to identify predictors of time to first treatment, defined as days from date of diagnosis to date of first treatment with surgery or neo-adjuvant chemotherapy. Covariates included age, sex, race, type of insurance, marital status, US birth, disease stage and year of diagnosis.

Results:

Patients were 99% female and with a mean age of 58 years (range 23-96). Among a sample of 1545 breast cancer cases, 1372 (89%) had surgery as first treatment and 173 (11%) had neoadjuvant chemotherapy. Median days to treatment was 45 days (IQR 27, 71). In the multi-variable adjusted models for both treatment groups, race, and insurance were significantly associated with delay. In the surgical group, Black race, public or no insurance, non-US born, later stage and unmarried status were associated with increased risk of delay. For example, Blacks were at higher risk for delay (HR= 1.2; 95% CI 1.37-1.04) compared to the Hispanic or White (reference) groups. Public insurance (HR = 1.19; 95%CI 1.37-1.04) and no insurance (HR = 1.43; 95%CI 1.85-1.09) was significantly associated with increased delay when compared to private insurance (reference). In patients with neoadjuvant chemotherapy as first treatment, additional significant predictors of delay were age and year of diagnosis.

Conclusion:

Race and insurance status were significant predictors of delay to first treatment in a population of diverse breast cancer patients seeking care at a safety net hospital. Intervention efforts need to target patients at greatest risk for treatment delays.

Citation Format: Ko NY, Patts G, Battaglia TA, Wang C, Denis GV, Hirsch A, Weinberg J. Socio-demographic predictors for delay of treatment among a racially diverse, urban breast cancer population [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-10-08.

Synchronous and Asynchronous Application of a Filtering Method for Underwater Robot Localization

This paper reports a method that fuses multiple sensor measurements for location estimation of an underwater robot. Synchronous and asynchronous (AS) implementation of the method are also proposed. Extended Kalman filter (EKF) is used to fuse four types of measurements: linear velocity by Doppler velocity log (DVL), angular velocity by gyroscope, ranges to acoustic beacons, and depth. The EKF approach is implemented in three ways to deal with asynchrony in measurements in correction step. The three implementation methods are synchronous collective (SC), synchronous individual (SI), and AS application. These methods are verified and compared through simulation and test tank experiments. The test reveals that the application methods need to be selected depending on the measurement properties: dependency between the measurements and degree of asynchrony. The distinctive features proposed in this study are three application methods together with derivation of an EKF approach to sensor fusion for underwater navigation.

Extended RMRC and its Application to the Motion of a Mobile Manipulator

This paper proposes a method calculating joint velocities of a robot which moves the end effector at desired velocity where some of the joint motions are constrained. It is an extension of the Resolved Motion Rate Control (RMRC) method which has been used in cases where there is no constraint on the motion of the joints. The proposed method is called the extended RMRC (E-RMRC). Though the E-RMRC is expressed in a simple form, application of the E-RMRC to a specific robot system is not straightforward and sometimes calls for elaboration. So, the paper describes the application of the E-RMRC to the motion of a mobile manipulator. The example explains how the proposed method is applied to find the joint rate to move the end effector of the mobile manipulator through a desired trajectory while the trajectory of the mobile base is constrained. The application is tested and verified through simulation and experiments.

Fusing range measurements from ultrasonic beacons and a laser range finder for localization of a mobile robot

This paper proposes a method for mobile robot localization in a partially unknown indoor environment. The method fuses two types of range measurements: the range from the robot to the beacons measured by ultrasonic sensors and the range from the robot to the walls surrounding the robot measured by a laser range finder (LRF). For the fusion, the unscented Kalman filter (UKF) is utilized. Because finding the Jacobian matrix is not feasible for range measurement using an LRF, UKF has an advantage in this situation over the extended KF. The locations of the beacons and range data from the beacons are available, whereas the correspondence of the range data to the beacon is not given. Therefore, the proposed method also deals with the problem of data association to determine which beacon corresponds to the given range data. The proposed approach is evaluated using different sets of design parameter values and is compared with the method that uses only an LRF or ultrasonic beacons. Comparative analysis shows that even though ultrasonic beacons are sparsely populated, have a large error and have a slow update rate, they improve the localization performance when fused with the LRF measurement. In addition, proper adjustment of the UKF design parameters is crucial for full utilization of the UKF approach for sensor fusion. This study contributes to the derivation of a UKF-based design methodology to fuse two exteroceptive measurements that are complementary to each other in localization.

Implementation of Humanoid Robot Arm Based on SERCOS Network

Designing, implementing and evaluating the performance of a humanoid robot arm, we verified its applicability and effectiveness based on the Serial Real-Time Communication System (SERCOS), which follows the concept of modularization corresponding to projected research. We also proposed single joint design modular for humanoid robot arm systems.

Prevailing discourses among AIDS care professionals about childbearing by couples with HIV in Taiwan

The aim of this study was to analyze the dynamics of ideology, power and language in the dominant discourses about childbearing by couples with HIV that were expressed by AIDS care professionals in Taiwan. Critical discourse analysis of the interview texts with 11 AIDS care professionals identified three prevailing discourses on childbearing by couples with HIV/AIDS: pro-children, conditional pro-choice and pro-rights. The pro-children and conditional pro-choice were the predominant discourses. The two discourses both medicalized childbearing among couples with HIV/AIDS by identifying medical authorities as the proper persons to decide which reproductive choices people with HIV/AIDS should make under what conditions. Even though the pro-rights discourse embodied an ideology of individualism, empowerment and autonomy, it was weak and relatively rare in the other two discourses.

Cancer symptom control: feasibility of a tailored, interactive computerized program for patients

This study evaluated the feasibility of an innovative computerized symptom assessment tool, SymptomReport, and a computerized, tailored education tool, SymptomConsult, in a sample of 41 outpatients with cancer. After patients completed the computerized programs, an audiotaped telephone interview was conducted to assess patients' impressions. The study found that patients required less than 40 minutes on average to complete SymptomReport. The mean acceptability score was high 11 +/- 2. The 12 patients who completed SymptomConsult did so in an average of 20 minutes. The majority of participants indicated that the computer programs were easy, enjoyable, and informative tools. Initial formative research supports further study of these feasible computerized programs.

Detection of elevated serum beta-chemokine levels in seronegative Chinese individuals exposed to human immunodeficiency virus type 1

The mutations in the CCR5 coding region, such as CCR5Delta32 and CCR5m303, that suppress the transmission of human immunodeficiency virus (HIV) type 1 do not exist in Chinese people. However, 9 Chinese subjects in Taiwan with histories of multiple sexual exposures to HIV remained uninfected, suggesting that certain anti-HIV factors do indeed exist. Experiments were therefore designed to investigate the immune mechanism that protects this cohort against HIV infection. Peripheral blood samples from these 9 subjects and 7 healthy people who had not been exposed to HIV were obtained for the quantitation of the levels for beta-chemokines and interleukin 16 (IL-16) in serum samples or secreted by peripheral blood lymphocytes. Significantly higher serum levels for nearly all 3 beta-chemokines, regulation on activation, normal T cell-expressed and secreted, macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta (P<.05, P<.05, and P=.05, respectively), but not IL-16, were detected in the 9 HIV-uninfected subjects as compared with control subjects. The result suggests that among the host genes and cellular factors thus far identified, beta-chemokines are the major HIV-suppressive factors that protect Chinese people from infection with HIV.

Comparison of sexual behaviors between male homosexuals and male heterosexuals in Taiwan

BACKGROUND

Homosexuality and sexual behavior have attracted great attention in the acquired immunodeficiency syndrome (AIDS) epidemic. This study primarily explores the risky behaviors and patterns of sexual behavior of male homosexuals in Taiwan.

METHODS

Comparison study methodology was adopted. Ninety-two male homosexuals, as the study group, were recruited from gay bars and gay organizations, and 91 male heterosexuals, with similar ages and educational levels, were recruited as a control group for comparison. Semi-structured interviews were carried out and anonymous questionnaires were self-administered.

RESULTS

(1) The mean age at the time of first sexual intercourse of the study group was younger than that of the control group. (2) The rate of having two or more sexual partners in the study group was significantly higher. (3) However, the rate of condom use during recent intercourse was higher in the control group than in the study group. (4) Sexual knowledge and attitudes toward sexuality in the study group were more open, but their sexual desires, as rated by the questionnaire, were more suppressed than those of the control group. (5) In terms of courtship, the study group was less constrained by the social values of marriage and tended to separate sex from love.

CONCLUSION

Similar to western studies, our study found that the study group in Taiwan adopted more risky sexual behaviors. Each group had its particular sexual behavioral pattern and subculture of sexuality. However, a longitudinal follow-up study with ethnographic perspective is necessary for a more sophisticated understanding of the trends and changes of sexual behavior in homosexuals.

[Informational needs and information-seeking behaviors of recently diagnosed HIV seropositive gay man]

In recent years, substantial changes in doctor-patient relations and consumer oriented attitudes have occurred. Many patients need more information regarding their diagnosis and treatment for developing positive coping strategies to face their disease. This case report uses an informational needs theoretical framework to present the informational needs and information-seeking behaviors of a recently diagnosed HIV seropositive gay man. The data was collected through continuous contacts with the patient during October 1994 to January 1995. This report's findings indicated that need for information after diagnosis fall into eight categories of concern: process in hospitalization, physical symptoms related to HIV/AIDS, side effects of anti-viral drugs, death, insurance, future planning, self care and how to disclose to others. Information seeking behaviors included actively or passively gathering information, asking others' experience and counseling with caregiver. Non-judgmental and supportive attitudes were significant factors for reducing the effects of social stigmatization as an obstacle to the patient during the information seeking process.

[Concerns and nursing care of a family living with AIDS]

AIDS is not solely a medical issue but also has profound implications for family relationships. This case report using the concepts of family nursing and case management presents the concerns of a family living with AIDS. The data was collected through continuous contacts with a patient during December 1994 to August 1996. This report's findings indicate that the concerns of the family living with AIDS fall into seven categories: The reasons for HIV infection, how to meet the patient's sexual needs, suffering during health care seeking, the effectiveness and side-effects of anti-viral drugs, home care skills, the light of hope, death issues. Professional nurses should provide care to both the AIDS patient and the family members. Using social resources and cooperating with other health professionals can promote the quality of life for families living with AIDS.

[Assessing the effect of health belief, knowledge, and social support on compliance behaviors in chronic hemodialysis patients]

The purposes of this study were to investigate the effects of hemodialysis patients' health belief, knowledge on uremia, and social support upon their compliance behavior. The convenience sample of 330 hemodialysis (HD) patients was obtained at HD centers in southern Taiwan. With the use of a questionnaire developed by the researcher, all subjects were interviewed during hemodialysis. Data analyses were processed by a personal computer with SPSS/PC. Pearson correlation, ANOVA, chi-square, multiple regression and factor analysis were selected as the analysis methods for this study. The results indicated: (1) The average overall rate of compliance was 72.1% by patient self report for fluid limit, diet restriction and taking PBM. (2) Two factors of subject's health belief were identified by factor analysis. (3) Those who had more positive motivation for compliance with therapeutic regiments, more knowledge on uremia and stronger social support were positively correlated with compliance behaviors. (4) The best predictive variables of compliance behaviors of HD patients included positive motivation, knowledge on uremia, educational level, current daily urine amount and age; these five variables explained 23% of variance in compliance behaviors. (5) The instruments with a satisfactory validity and reliability developed by the researcher could provide a valuable basis for relevant future research. Implications of these findings for nursing practice are also discussed.