2,059,447 research outputs found

    Results of the attitude reconstruction for the UniSat-6 microsatellite using in-orbit data

    Get PDF
    UniSat-6 is a civilian microsatellite that was launched in orbit on the 19th of June, 2014. Its main mission consisted in the in-orbit release of a number of on-board carried Cubesats and in the transmission to the UniSat-6 ground station of telemetry data and images from an on-board mounted camera. The spacecraft is equipped with a passive magnetic attitude control system. Gyros and magnetometers provide the information about the attitude of the spacecraft. The importance of reconstructing the attitude motion of UniSat-6 lies in the dual possibility, for future missions, of:controlling the direction of ejection of the on-board carried satelliteshaving an accurate pointing for remote sensing operation.The reconstruction of the attitude motion of UniSat-6 is based on the data of the on-board Commercial Off The Shelf (COTS) gyros and magnetometers, downloaded at the passages over the ground station in Roma, Italy. At ground, these data have been processed with the UnScented QUaternion Estimator (USQUE) algorithm. This estimator is an adaptation of the Unscented Filter to the problem of spacecraft attitude estimation. The USQUE is based on a dual attitude representation, which involves both quaternions and Generalized Rodrigues Parameters. In this work, the propagation phase of the algorithm contains only a kinematic model of the motion of the spacecraft. This paper presents the results of the reconstruction of the UniSat-6 attitude using on-board measurements. The results show that the spacecraft effectively stabilized its attitude motion thanks to the on-board magnetic devices

    ATTITUDE

    Get PDF

    Attitude sensor

    Get PDF
    A device for controlling the attitude of a spacecraft is described. The device consists of two light sensors on a spacecraft that are mounted beneath a baffle which divides the light from a light source such as the sun or a star. The divided light reflects off of two reflective surfaces onto the two light sensors. When the spacecraft assumes its normal attitude, the baffle divides the light source into two equal parts, causing the two light sensors to produce equal outputs. When the light is equally detected, the stabilizing system is disconnected. Deviations from the normal attitude cause unequal distribution of the light source and energize the stabilizing system

    Attitude of Counsellors towards undergoing HIV Voluntary Counselling and Testing in Ado-Odo/Ota, Nigeria

    Get PDF
    This study was an investigation into the attitude of counsellors who offer HIV pre and post counselling. Sixteen counsellors who offer HIV pre-post-test counselling were identified from the preliminary field work, of these, 9 counsellors who reported they had not presented for HIV/AIDS testing were identified and 7 eventually participated in the study. The participants were active counsellors, 27 through 46 years of age, who provided HIV pre-post-test counselling services. A purposive sampling technique was employed to select the participants. The non-scheduled structured interview was employed for data collection while the cross case method was used to analyze the data. The study found that the participants possessed negative attitude towards undergoing voluntary HIV/AIDS testing though they acknowledged the importance of HIV/AIDS test. The participants identified fear of being HIV/AIDS positive, lack of confidentiality and knowledge of HIV/AIDS as barriers to their undergoing HIV/AIDS test. Being counselled by a professional counsellor/ psychologist or someone living with HIV/AIDS, feeling too sick or being pregnant were highlighted as factors that may facilitate their undergoing HIV/AIDS test. It was also found that HIV/AIDS counsellors are as vulnerable to HIV/AIDS as the general population. Counsellors who by their training or job schedule encourage others to undergo HIV test were themselves unwilling to test for HIV. In conclusion, counsellors are advised to undergo voluntary HIV/AIDS test. Key words: HIV/AIDS counsellors, attitude, HIV/AIDS VCT, interview, confidentiality

    Attitude control system

    Get PDF
    An attitude control system is described in which angular rate signals are generated by rate gyros mounted closely adjacent to gimbaled engines at the rear of a vehicle. Error signals representative of a commanded change in vehicle angle or attitude are obtained from a precision inertial platform located in the nose region of the vehicle. The rate gyro derived signals dominate at high frequencies where dynamic effects become significant, and platform signals dominate at low frequencies where precision signals are required for a steady vehicle attitude. The blended signals are applied in a conventional manner to control the gimbaling of vehicle engines about control axes

    Spacecraft attitude sensor

    Get PDF
    A system for sensing the attitude of a spacecraft includes a pair of optical scanners having a relatively narrow field of view rotating about the spacecraft x-y plane. The spacecraft rotates about its z axis at a relatively high angular velocity while one scanner rotates at low velocity, whereby a panoramic sweep of the entire celestial sphere is derived from the scanner. In the alternative, the scanner rotates at a relatively high angular velocity about the x-y plane while the spacecraft rotates at an extremely low rate or at zero angular velocity relative to its z axis to provide a rotating horizon scan. The positions of the scanners about the x-y plane are read out to assist in a determination of attitude. While the satellite is spinning at a relatively high angular velocity, the angular positions of the bodies detected by the scanners are determined relative to the sun by providing a sun detector having a field of view different from the scanners

    Craft as Attitude

    Get PDF

    Students' Attitude Toward the Implementation of Teaching Listening Using Dictoglos Technique

    Full text link
    Listening is the basis for the development of all other skills and the main channel through which the learner makes initial contact with the target language and its culture. Dictogloss technique is a classroom dictation activity in which learners listen to a passage, note down key words and then work together to create a reconstructed version of the text. This activity combines individual and group activities. The students' attitude toward its implementation in listening teaching learning process in investigated in this study. It is a case study in the second year students of English Department Faculty of Teacher Training Nusantara PGRI Kediri University. The subject of the study was 2C class that consists of 38 students. The structured interview and closed ended questionnaire were used to know the students' attitude towards dictogloss. It was founded that the students have positive attitudes towards this technique especially in the affective aspect.It is suggested that the English teacher should use dictogloss technique in teaching listening comprehension since it the students found it interesting and challenging for them to be more active in teaching and learning process

    Two degree-of-freedom spacecraft attitude controller

    Get PDF
    Two degree-of-freedom controller is designed together with its governing equations for a spacecraft pitch attitude control. The attitude controller incorporates the Active Force Control (AFC) technique into the conventional Proportional-Derivative (PD) controller based spacecraft pitch attitude loop. The PD-AFC attitude controller is then employed to enhance the attitude pointing of the Combined Energy and Attitude Control System (CEACS). Numerical treatments are performed to validate the effectiveness of AFC, whereby the CEACS attitude performance is analysed from its accuracy point of view. The results show that the PD-AFC attitude control performance is superiorly better than that of the solely conventional PD type
    corecore