Attitude estimation for dynamic legged locomotion using range and inertial sensors

Legged robots offer exceptional mobility in uncharted terrains. Their dynamic nature yields unrivaled mobility, but serves to destabilize the motion estimation process that underlies legged operations. In particular, the discontinuous foot fall patterns and flight phases result in severe impulses, which, in turn, result in excessive accumulation of drift by inertial sensors. Ground range measurements, amongst several others, are robust to this drift yet are limited in application due to their low-bandwidth and sensitivity to ground conditions. In considering the attitude estimation problem for this dynamic legged locomotion, this paper develops a pose calculation method based on ground range measurements. This is used in conjunction with a hybrid Extended Kalman Filter that takes advantage of the ballistic nature of the flight phases. Results indicate that this combination provides rapid, robust estimates of attitude necessary for extended dynamic legged operations. In single leg experiments, which were conducted using low-cost sensing hardware, this method had an RMS error of <1°, half that of a non-hybrid EKF approach. ©2005 IEEE

System design of a quadrupedal galloping machine

In this paper we present the system design of a machine that we have constructed to study a quadrupedal gallop gait. The gallop gait is the preferred high-speed gait of most cursorial quadrupeds. To gallop, an animal must generate ballistic trajectories with characteristic strong impacts, coordinate leg movements with asymmetric footfall phasing, and effectively use compliant members, all the while maintaining dynamic stability. In this paper we seek to further understand the primary biological features necessary for galloping by building and testing a robotic quadruped similar in size to a large goat or antelope. These features include high-speed actuation, energy storage, on-line learning control, and high-performance attitude sensing. Because body dynamics are primarily influenced by the impulses delivered by the legs, the successful design and control of single leg energetics is a major focus of this work. The leg stores energy during flight by adding tension to a spring acting across an articulated knee. During stance, the spring energy is quickly released using a novel capstan design. As a precursor to quadruped control, two intelligent strategies have been developed for verification on a one-legged system. The Levenberg-Marquardt on-line learning method is applied to a simple heuristic controller and provides good control over height and forward velocity. Direct adaptive fuzzy control, which requires no system modeling but is more computationally expensive, exhibits better response. Using these techniques we have been successful in operating one leg at speeds necessary for a dynamic gallop of a machine of this scale. Another necessary component of quadruped locomotion is high-resolution and high-bandwidth attitude sensing. The large ground impact accelerations, which cause problems for any single traditional sensor, are overcome through the use of an inertial sensing approach using updates from optical sensors and vehicle kinematics

Mindfulness Trait Predicts Neurophysiological Reactivity Associated with Negativity Bias: An ERP Study

This study explored the relationship of mindfulness trait with the early and late stages of affective processing, by examining the two corresponding ERP components, P2 and LPP, collected from twenty-two male Chinese participants with a wide range of meditation experiences. Multiple regression analyses was performed on the mindfulness scores, as measured by CAMS-R, with the subjective affective ratings and ERP data collected during an emotion processing task. The results showed that increased mindfulness scores predicted increased valence ratings of negative stimuli (less negative), as well as increased P2 amplitudes at the frontocentral location for positive compared to negative stimuli. Based on these findings, a plausible mechanism of mindfulness in reducing negativity bias was discussed. Moreover, our results replicated previous findings on the age-related increase of P2 amplitudes at the frontal sites for positive compared to neutral stimuli. Since the locations at which P2 amplitudes were found as associated with age and mindfulness differed, as did the emotional contents of the stimuli being compared, indicating that the effect of age did not confound our findings on mindfulness and the two factors might operate on early affective processing from distinct sources and mechanisms.published_or_final_versio

Studi karakteristik habitat peneluran penyu di desa pekik nyaring Kecamatan Pondok Kelapa Kabupaten Bengkulu Tengah, Provinsi Bengkulu

ABSTRAKSalah satu lokasi tempat penyu mendarat dan bertelur di Provinsi Bengkulu adalah di pantai Desa Pekik Nyaring, Kecamatan Pondok Kelapa, Kabupaten Bengkulu Tengah. Mengingat penyu adalah satwa langka yang dilindungi, maka perlu dilakukan kegiatan konservasi untuk melindungi dan menyelamatkan penyu. Untuk mendukung upaya konservasi perlu mempelajari lokasi-lokasi tempat penyu bertelur. Seperti halnya penelitian terhadap lokasi pendaratan dan tempat penyu bertelur. Tujuan penelitian ini untuk menganalisis tingkat kesesuaian karakteristik kondisi bio-fisik habitat tempat peneluran penyu di wilayah pantai Desa Pekik Nyaring. Penelitian ini dilaksanakan pada bulan Februari-Mei 2017 dengan menggunakan metode survei. Kegiatan survei meliputi observasi lapangan dan pengumpulan data primer. Analisis data dilakukan dengan metode statistik deskriptif. Berdasarkan hasil observasi dapat diketahui bahwa jenis penyu yang bertelur di pantai Desa Pekik Nyaring adalah jenis penyu lekang (Lepidochelis olivácea). Hasil analisis data menunjukkan bahwa, panjang pantai yang menjadi lokasi peneluran penyu adalah 1,47 km, lebar pantai adalah 99,9 – 170 m, kemiringan pantai 2,22%-30,85%, suhu substrat 28°C - 28,66 °C, kelembaban substrat 28,77 % - 40,44 %. Untuk tekstur substrat, pada semua stasiun termasuk dalam kategori halus, sedangkan persentase vegetasi pantai 22,3 % - 60,3%. Dari ketiga stasiun pengamatan, stasiun 1 dan 2 cukup sesuai, sedangkan stasiun 3 masuk kategori tidak sesuai sebagai lokasi peneluran penyu.Kata kunci : Penyu, karateristik, tempat bertelur, Pekik Nyaring, Bengkul

RobotAssist - A platform for human robot interaction research

This paper presents RobotAssist, a robotic platform designed for use in human robot interaction research and for entry into Robocup@Home competition. The core autonomy of the system is implemented as a component based software framework that allows for integration of operating system independent components, is designed to be expandable and integrates several layers of reasoning. The approaches taken to develop the core capabilities of the platform are described, namely: path planning in a social context, Simultaneous Localisation and Mapping (SLAM), human cue sensing and perception, manipulatable object detection and manipulation

Bioprospecting the African Renaissance: The new value of muthi in South Africa

This article gives an overview of anthropological research on bioprospecting in general and of available literature related to bioprospecting particularly in South Africa. It points out how new insights on value regimes concerning plant-based medicines may be gained through further research and is meant to contribute to a critical discussion about the ethics of Access and Benefit Sharing (ABS). In South Africa, traditional healers, plant gatherers, petty traders, researchers and private investors are assembled around the issues of standardization and commercialization of knowledge about plants. This coincides with a nation-building project which promotes the revitalization of local knowledge within the so called African Renaissance. A social science analysis of the transformation of so called Traditional Medicine (TM) may shed light onto this renaissance by tracing social arenas in which different regimes of value are brought into conflict. When medicinal plants turn into assets in a national and global economy, they seem to be manipulated and transformed in relation to their capacity to promote health, their market value, and their potential to construct new ethics of development. In this context, the translation of socially and culturally situated local knowledge about muthi into global pharmaceuticals creates new forms of agency as well as new power differentials between the different actors involved