Advances in Mechanical Systems Dynamics 2020

The fundamentals of mechanical system dynamics were established before the beginning of the industrial era. The 18th century was a very important time for science and was characterized by the development of classical mechanics. This development progressed in the 19th century, and new, important applications related to industrialization were found and studied. The development of computers in the 20th century revolutionized mechanical system dynamics owing to the development of numerical simulation. We are now in the presence of the fourth industrial revolution. Mechanical systems are increasingly integrated with electrical, fluidic, and electronic systems, and the industrial environment has become characterized by the cyber-physical systems of industry 4.0. Within this framework, the status-of-the-art has become represented by integrated mechanical systems and supported by accurate dynamic models able to predict their dynamic behavior. Therefore, mechanical systems dynamics will play a central role in forthcoming years. This Special Issue aims to disseminate the latest research findings and ideas in the field of mechanical systems dynamics, with particular emphasis on novel trends and applications

Примитивы движения робота в задаче планирования траектории с кинематическими ограничениями

Automatic trajectory planning is an urgent scientific and technical problem, whose solutions are in demand in many fields: unmanned transportation, robotic logistics, social robotics, etc. Often, when planning a trajectory, it is necessary to consider the fact that the agent (robot, unmanned car, etc.) cannot arbitrarily change its orientation while moving, in other words, it is necessary to consider kinematic constraints when planning. One widespread approach to solving this problem is the approach that relies on the construction of a trajectory from prepared parts, motion primitives, each of which satisfies kinematic constraints. Often, the emphasis in the development of methods implementing this approach is on reducing the combinations of choices in planning (heuristic search), with the set of available primitives itself being regarded as externally defined. In this paper, on the contrary, we aim to investigate and analyze the effect of different available motion primitives on the quality of solving the planning problem with a fixed search algorithm. Specifically, we consider 3 different sets of motion primitives for a wheeled robot with differential drive. As a search algorithm, the A* algorithm well known in artificial intelligence and robotics is used. The solution quality is evaluated by 6 metrics, including planning time, length and curvature of the resulting trajectory. Based on the study, conclusions are made about the factors that have the strongest influence on the planning result, and recommendations are given on the construction of motion primitives, the use of which allows to achieve a balance between the speed of the planning algorithm and the quality of the trajectories found.Автоматическое планирование траектории – актуальная научно-техническая задача, решения которой востребованы во многих областях: беспилотный транспорт, роботизированная логистика, социальная робототехника и т.д. Зачастую при планировании траектории необходимо учитывать тот факт, что агент (робот, беспилотный автомобиль и др.) не может произвольно менять ориентацию при движении, другими словами – необходимо учитывать кинематические ограничения при планировании. Одним из широко-распространенных подходов к решению этой задачи является подход, опирающийся на конструирование траектории из заранее подготовленных фрагментов, примитивов движения, каждый из которых в свою очередь удовлетворяет кинематическим ограничениям. Зачастую, акцент при разработке методов, реализующих этот подход, делается на сокращении перебора вариантов при планировании (эвристический поиск), при этом сам набор доступных примитивов считается заданным извне. В этой же работе, мы наоборот ставим своей целью провести исследование и анализ влияния различных доступных примитивов движения на качество решения задачи планирования при фиксированном алгоритме поиска. В частности, рассматриваются 3 различных набора примитивов движения для колесного робота с дифференциальным приводом. В качестве алгоритма поиска используется известный в искусственном интеллекте и робототехнике алгоритм A*. Качество решения оценивается по 6 метрикам, включая время планирования, длину и кривизну результирующей траектории. На основании проведенного исследования делаются выводы о факторах, оказывающих наибольшее влияние на результат планирования, и даются рекомендации по построению примитивов движения, использование которых позволяет достичь баланса между скоростью работы алгоритма планирования и качеством отыскиваемых траекторий

System Design, Motion Modelling and Planning for a Recon figurable Wheeled Mobile Robot

Over the past ve decades the use of mobile robotic rovers to perform in-situ scienti c investigations on the surfaces of the Moon and Mars has been tremendously in uential in shaping our understanding of these extraterrestrial environments. As robotic missions have evolved there has been a greater desire to explore more unstructured terrain. This has exposed mobility limitations with conventional rover designs such as getting stuck in soft soil or simply not being able to access rugged terrain. Increased mobility and terrain traversability are key requirements when considering designs for next generation planetary rovers. Coupled with these requirements is the need to autonomously navigate unstructured terrain by taking full advantage of increased mobility. To address these issues, a high degree-of-freedom recon gurable platform that is capable of energy intensive legged locomotion in obstacle-rich terrain as well as wheeled locomotion in benign terrain is proposed. The complexities of the planning task that considers the high degree-of-freedom state space of this platform are considerable. A variant of asymptotically optimal sampling-based planners that exploits the presence of dominant sub-spaces within a recon gurable mobile robot's kinematic structure is proposed to increase path quality and ensure platform safety. The contributions of this thesis include: the design and implementation of a highly mobile planetary analogue rover; motion modelling of the platform to enable novel locomotion modes, along with experimental validation of each of these capabilities; the sampling-based HBFMT* planner that hierarchically considers sub-spaces to better guide search of the complete state space; and experimental validation of the planner with the physical platform that demonstrates how the planner exploits the robot's capabilities to uidly transition between various physical geometric con gurations and wheeled/legged locomotion modes

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version