17 research outputs found
Three Fundamental Paradigms for Aerial Physical Interaction Using Nonlinear Model Predictive Control
Get PDFThis paper introduces and compares the three most relevant approaches in which an Aerial Physical Interaction (APhI) control can include a Nonlinear Model Predictive Control (NMPC) paradigm in its design. All these methods have the advantage of being able to cope seamlessly with input and state constraints when compared to reactive controllers, however, they substantially differ in the design of the cost function. In the NMPC impedance control the cost function includes the error from the desired impedance dynamics; in the NMPC cascaded control the cost function includes the error from a reference trajectory which is generated online by an admittance filter driven by the force measurement; and in the NMPC hybrid position/force control the cost function contains both the trajectory and direct force error. The three architectures are proposed, implemented, analysed, validated, and compared with real-time simulations of interaction tasks with different environments. The numerical investigation provides a set of insights about the performances, advantages, and dependency on the design assumptions of the three methods
External-Wrench Estimation for Aerial Robots Exploiting a Learned Model
Get PDFThis paper presents an external wrench estimator that uses a hybrid dynamics model consisting of a first-principles model and a neural network. This framework addresses one of the limitations of the state-of-the-art model-based wrench observers: the wrench estimation of these observers comprises the external wrench (e.g. collision, physical interaction, wind); in addition to residual wrench (e.g. model parameters uncertainty or unmodeled dynamics). This is a problem if these wrench estimations are to be used as wrench feedback to a force controller, for example. In the proposed framework, a neural network is combined with a first-principles model to estimate the residual dynamics arising from unmodeled dynamics and parameters uncertainties, then, the hybrid trained model is used to estimate the external wrench, leading to a wrench estimation that has smaller contributions from the residual dynamics, and affected more by the external wrench. This method is validated with numerical simulations of an aerial robot in different flying scenarios and different types of residual dynamics, and the statistical analysis of the results shows that the wrench estimation error has improved significantly compared to a model-based wrench observer using only a first-principles model.<br/
Sarax:An Open-Source Software/Hardware Framework for Aerial Manipulators
Get PDFThe use of Multi-Rotor Aerial Vehicles (MRAVs) in tasks that require physical interaction has been an active research field in the last decade which resulted in an increasing interest in Aerial Manipulators (AMs). This raises many challenges in the modeling, control, perception, and planning of these robots. However, designing and realizing an AM testbed is a complicated multi-disciplinary task, and there is a lack of standardization in the relatively new field of AMs. For this purpose, we introduce Sarax, an open-source hardware and software framework tailored for AMs research and innovation. The software of Sarax is built on top of open-source projects such as the Robot Operating System (ROS) and PX4 Autopilot, while the hardware is designed to be customizable, modular, and easily scalable through parameterized models. We verified and validated the proposed framework through indoor and outdoor experiments. We aim to open the door to accelerate AMs research and innovation, allow researchers and developers to focus on their core contributions, and take AMs technology to a higher readiness level
RL-based Control of UAS Subject to Significant Disturbance
Get PDFThis paper proposes a Reinforcement Learning (RL)-based control framework for position and attitude control of an Unmanned Aerial System (UAS) subjected to significant disturbance that can be associated with an uncertain trigger signal. The proposed method learns the relationship between the trigger signal and disturbance force, enabling the system to anticipate and counteract the impending disturbances before they occur. We train and evaluate three policies: a baseline policy trained without exposure to the disturbance, a reactive policy trained with the disturbance but without the trigger signal, and a predictive policy that incorporates the trigger signal as an observation and is exposed to the disturbance during training. Our simulation results show that the predictive policy outperforms the other policies by minimizing position deviations through a proactive correction maneuver. This work highlights the potential of integrating predictive cues into RL frameworks to improve UAS performance
RL-based Control of UAS Subject to Significant Disturbance
Get PDFThis paper proposes a Reinforcement Learning (RL)-based control framework for position and attitude control of an Unmanned Aerial System (UAS) subjected to significant disturbance that can be associated with an uncertain trigger signal. The proposed method learns the relationship between the trigger signal and disturbance force, enabling the system to anticipate and counteract the impending disturbances before they occur. We train and evaluate three policies: a baseline policy trained without exposure to the disturbance, a reactive policy trained with the disturbance but without the trigger signal, and a predictive policy that incorporates the trigger signal as an observation and is exposed to the disturbance during training. Our simulation results show that the predictive policy outperforms the other policies by minimizing position deviations through a proactive correction maneuver. This work highlights the potential of integrating predictive cues into RL frameworks to improve UAS performance
External-Wrench Estimation for Aerial Robots Exploiting a Learned Model
Get PDFThis paper presents an external wrench estimator that uses a hybrid dynamics model consisting of a first-principles model and a neural network. This framework addresses one of the limitations of the state-of-the-art model-based wrench observers: the wrench estimation of these observers comprises the external wrench (e.g. collision, physical interaction, wind); in addition to residual wrench (e.g. model parameters uncertainty or unmodeled dynamics). This is a problem if these wrench estimations are to be used as wrench feedback to a force controller, for example. In the proposed framework, a neural network is combined with a first-principles model to estimate the residual dynamics arising from unmodeled dynamics and parameters uncertainties, then, the hybrid trained model is used to estimate the external wrench, leading to a wrench estimation that has smaller contributions from the residual dynamics, and affected more by the external wrench. This method is validated with numerical simulations of an aerial robot in different flying scenarios and different types of residual dynamics, and the statistical analysis of the results shows that the wrench estimation error has improved significantly compared to a model-based wrench observer using only a first-principles model.<br/
Multirotor UAV—A Multidisciplinary Platform for Teaching Mechatronics Engineering
Get PDFThis paper provides a comprehensive guide for educators on how multirotor UAV platforms can be utilized to achieve various learning outcomes in undergraduate mechatronics education. This study is based on a PX4 ecosystem combined with the MATLAB Simulink programming environment, covering both hardware and software aspects to support engineering education. The paper explains (i) which learning outcomes can be obtained, (ii) how mathematical models can be derived and implemented in simulation software, (iii) which hardware components are essential, their approximate costs, and possible upgrades based on available budgets, and (iv) which experiments students can perform using the UAV platform. A proposed educational prototype integrates airframe parts produced using additive manufacturing technologies with standard multirotor components. Additionally, a series of experiments were designed, including extensive testing of the multirotor control module. Three learning outcomes related to UAV hardware were incorporated into the engineering curriculum, while two software-related outcomes were addressed through student workshops. Future plans include the implementation of multiple UAV platforms in the educational process to further enhance learning outcomes.</p
THE PROBLEMS OF SUSTAINABLE DEVELOPMENT OF HISTORIC CITIES
No full textThe article is devoted to studying sustainable development of historical cities. The author considers the concept of a historical city on the basis of international documents, and specifies the following groups of factors of negative impact on the historical cities: 1. Human factors; 2. Geographical, natural and climatic factors; 3. Demographic and migration factors. The article reveals the role and importance of government, business, the third sector and science in the context of the mechanism which provides sustainable development of historic cities.
The article considers the necessity of development of cultural tourism as an integrated approach and one of the main tools for the development of historical cities and the expediency of integrating stakeholders into a cultural tourism cluster to ensure integrated sustainable development.
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Ammán: Leer la ciudad a través del desplazamiento
Get PDFAmman is a city shaped by multiple displacements. In 1952 and 1955, two refugee camps, called Al-Hussein and Al-Wihdat, respectively, were established for displaced Palestinians near the city centre. Shortly after, the city began to experience rapid growth due to continuous waves of displacements. A few years later, the camps blended with the emergent urban fabric of the city. This paper elucidates this urban transformation and how it led to the polarization of the city into two sides: the impoverished east dictated by informal arrangements and the rich west with formal support structures. After 2011, Jordan received Syrian refugees, many of whom settled in Amman. This paper discusses the following question: how did Amman grow vis-à-vis displacement? And considering the relatively recent arrival of Syrians to the city (in comparison with other refugees), how did they encounter the city and navigate its socioeconomic disparities? Building on fieldwork conducted in Amman in 2022-23, the author shows how Syrians were split between the two parts of the city, and how those with fewer resources ended up living in the east with its Palestinian camps, while those who have more resources struggle to survive in west Amman.Ammán es una ciudad moldeada por múltiples desplazamientos. En 1952 y 1955 se crearon dos campos de refugiados, llamados Al-Hussein y Al-Wihdat, respectivamente, para palestinos desplazados cerca del centro de la ciudad. Poco después la ciudad empezó a experimentar un rápido crecimiento debido a las continuas oleadas de desplazamientos. Unos años más tarde, los campos se mezclaron con el tejido urbano emergente de la ciudad. Este artículo explica esta transformación urbana y cómo provocó la polarización de la ciudad en dos partes: el empobrecido este, regido por acuerdos informales, y el rico oeste, con estructuras de apoyo formales. Después de 2011, Jordania recibió refugiados sirios, muchos de los cuales se asentaron en Ammán. Este documento aborda la siguiente cuestión: ¿cómo creció Ammán frente al desplazamiento? Y teniendo en cuenta la llegada relativamente reciente de sirios a la ciudad (en comparación con otros refugiados), ¿cómo se encontraron con la ciudad y sortearon sus disparidades socioeconómicas? Basándose en el trabajo de campo realizado en Ammán en 2022-23, el autor muestra cómo los sirios se dividieron entre las dos partes de la ciudad, y cómo los que tenían menos recursos acabaron viviendo en el este con sus campos palestinos, mientras que los que tenían más recursos luchaban por sobrevivir en el oeste de Ammán
Ammán: Reading the city through displacement
No full textAmman is a city shaped by multiple displacements. In 1952 and 1955, two refugee camps, called Al-Hussein and Al-Wihdat, respectively, were established for displaced Palestinians near the city centre. Shortly after, the city began to experience rapid growth due to continuous waves of displacements. A few years later, the camps blended with the emergent urban fabric of the city. This paper elucidates this urban transformation and how it led to the polarization of the city into two sides: the impoverished east dictated by informal arrangements and the rich west with formal support structures. After 2011, Jordan received Syrian refugees, many of whom settled in Amman. This paper discusses the following question: how did Amman grow vis-à-vis displacement? And considering the relatively recent arrival of Syrians to the city (in comparison with other refugees), how did they encounter the city and navigate its socioeconomic disparities? Building on fieldwork conducted in Amman in 2022-23, the author shows how Syrians were split between the two parts of the city, and how those with fewer resources ended up living in the east with its Palestinian camps, while those who have more resources struggle to survive in west Amman.Ammán es una ciudad moldeada por múltiples desplazamientos. En 1952 y 1955 se crearon dos campos de refugiados, llamados Al-Hussein y Al-Wihdat, respectivamente, para palestinos desplazados cerca del centro de la ciudad. Poco después la ciudad empezó a experimentar un rápido crecimiento debido a las continuas oleadas de desplazamientos. Unos años más tarde, los campos se mezclaron con el tejido urbano emergente de la ciudad. Este artículo explica esta transformación urbana y cómo provocó la polarización de la ciudad en dos partes: el empobrecido este, regido por acuerdos informales, y el rico oeste, con estructuras de apoyo formales. Después de 2011, Jordania recibió refugiados sirios, muchos de los cuales se asentaron en Ammán. Este documento aborda la siguiente cuestión: ¿cómo creció Ammán frente al desplazamiento? Y teniendo en cuenta la llegada relativamente reciente de sirios a la ciudad (en comparación con otros refugiados), ¿cómo se encontraron con la ciudad y sortearon sus disparidades socioeconómicas? Basándose en el trabajo de campo realizado en Ammán en 2022-23, el autor muestra cómo los sirios se dividieron entre las dos partes de la ciudad, y cómo los que tenían menos recursos acabaron viviendo en el este con sus campos palestinos, mientras que los que tenían más recursos luchaban por sobrevivir en el oeste de Ammán
