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Construction and maintenance of on-orbit crew-operated hardware is
currently done mostly by extra-vehicular astronauts. Use of robotics for
some of these tasks provides the opportunity for both increased safety
for the astronauts and major cost savings. An effective space robotic
manipulator must be lightweight, have a large workspace, and be capab...
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Space robot assistants are envisaged as semi-autonomous co-workers deployed to lighten the workload of astronauts in cumbersome and dangerous situations. In view of this, this work considers the prospects on the technology requirements for future space robot operations, by presenting a novel mission control concept for close astronaut-robot collabo...
Citations
... Fonte: adaptado de [60] Os manipuladores montados sobre estruturas flexíveis podem ser tratados como casos especiais de sistemas macro-micro manipuladores. Nestes casos, a base na qual o robô está fixadoé excitada pelo movimento do braço robótico e aparecem grandes deslocamentos devidoà elasticidade da estrutura da base. ...
PT/BR -- Apresenta-se um método para prever a falha de um manipulador robótico ao realizar uma tarefa, devido à flexibilidade dos corpos elásticos que lhe servem como base. Os erros podem ser de posição, velocidade e orientação da ferramenta na extremidade do robô. O método também fornece um meio para verificar como modificações no projeto da base podem alterar o comportamento dinâmico do sistema acoplado. A motivação de tal análise se dá pelo crescente emprego de robôs de serviço para aplicações in situ, onde o uso de uma estrutura leve e esbelta pode ser a melhor e mais viável solução para posicionar o robô dentro do ambiente de serviço. A análise se divide em: modelar pelo método de Kane, os sistemas dinâmicos multicorpos do robô, da base e do sistema acoplado robô e base; encontrar a matriz de rigidez da base, pela análise por Elementos Finitos; e encontrar os parâmetros de Rayleigh da matriz de amortecimento proporcional, por análise Modal Experimental. Um sistema para revestimento robótico in situ (EMMA) é escolhido para estudo de caso. Simulações são realizadas para duas trajetórias e três bases diferentes. Os resultados do modelo de referência (base rígida) e o modelo acoplado (robô - base flexível) são então comparados e apresentam as mudanças que ocorrem, devido à flexibilidade da base, nos parâmetros controlados da tarefa. Esta análise permite a verificação da conformidade aos requisitos do processo de revestimento robótico, como posição, velocidade e orientação dadas à flexibilidade e o amortecimento da base.
EN -- Presents a method to predict the failure of a robotic manipulator’s task due to the flexibility of the elastic bodies that serves as a base. The errors can be the position, velocity and orientation of the tool attached to the tip of the robot. The method also provides a way to verify how modifications in the base design can change the dynamic behaviour of the coupled system. The motivation of such analysis is the crescent employment of service robots for in situ applications, where the use of a light and slender structure for the base may be the best and more feasible solution for placing the robot in the service environment. The analysis are divided as: model the Dynamic Multibody Systems of the robot, the base and the coupled base-robot, by Kane’s method; find the stiffness matrix of the base, by Finite Element Analysis; find the Rayleigh parameters of the proportional damping matrix of the base, by Experimental Modal Analysis. An in situ robotic hardcoating system (EMMA) is chosen as the case of study. Simulations are done for two different trajectories and three different bases. The results of the reference model (rigid base) and the coupled model (robot - flexible base) are then compared and shows the changes in the controled parameters due to the flexibility of the base. This analysis allows the verification of compliance to the hardcoating requirements like position, velocity and orientation of the gun with respect to the surface.
... This was extended to support end-point feedback compensation for positioning accuracy by Yang et al. [73]. Schubert [58] developed a controller for a flexible macro-micro system by extending the impedance control methods introduced by Khatib [29]. In impedance control the desired dynamics are given in the task space and these are transformed to the joint space by suitable control laws. ...
In this dissertation, we develop an efficient method of generating minimal jerk trajectories for redundant robots in trajectory following problems. We show that high jerk is a local phenomenon, and therefore focus on optimizing regions of high jerk that occur when using traditional trajectory generation methods. The optimal trajectory is shown to be located on the foliation of self-motion manifolds, and this property is exploited to express the problem as a minimal dimension Bolza optimal control problem. A numerical algorithm based on ideas from pseudo-spectral optimization methods is proposed and applied to two example planar robot structures with two redundant degrees of freedom. When compared with existing trajectory generation methods, the proposed algorithm reduces the integral jerk of the examples by 75% and 13%. Peak jerk is reduced by 98% and 33%. Finally a real time controller is proposed to accurately track the planned trajectory given real-time measurements of the tool-tip's following error.
... Through consideration of the fundamental results of the analysis step and existing knowledge of robotics, an applicable robot control architecture was identified -Object-Based Task-Level Control. Originally created for controlling field robot systems in space applications [23], Object-Based Task-Level Control (OBTLC) technologies had been applied to autonomous underwater vehicles (AUVs) [24], flexible manipulators [25], and factory workcells [26]. In OBTLC, the robot handles its own low-level control locally while the operator provides high-level task commands to the robot. ...
... OBTLC was used to develop a wide variety of capabilities that automate what a skilled teleoperator could do with robots meant for near-earth orbit space applications, and it was then extended to a range of tasks that would not have been possible whatsoever through manual operation. Capture of a moving, spinning object, slewing it to a new position, and inserting the object into a fixture was done using the OBTLC framework by arms on a fixed base (the arms had both rigid [23] and flexible drive train [25]) and a free-floating base [102]. ...
Today's field robots, such as the Sojourner Mars rover or the Predator unmanned aerial vehicle, work alone to accomplish dirty, dull, or dangerous missions. Plans for the next generation of robotic systems call for multiple field robots to conduct these missions cooperatively under the direction of a single operator. This research examines the role of the operator in multiple-robot missions and creates a human-robot interaction framework that supports this role---a vital step toward the successful deployment of these future robots. In a typical user-centered approach to the development of a human-robot interaction framework, the work practices of the robot operator would be observed, characterized, and integrated into the design. Unfortunately, there are no settings where one can study the operator of multiple robots at work because no such systems have been deployed. As an alternative, this research incorporated a surrogate setting that could be used to inform the early interaction design of multiple-robot systems. Police Special Weapons and Tactics (SWAT) teams were chosen as this setting, and an ethnographic study of SWAT commanders was conducted. Concepts from the interdisciplinary study of geographically distributed work, including common ground, shared mental models, and information sharing, were used to understand and characterize the ethnographic observations. Using lessons learned from the surrogate setting, an implementation of a new human-robot interaction framework was demonstrated on the Micro Autonomous Rovers (MAR) platform in the Aerospace Robotics Laboratory at Stanford University. This interaction framework, which is based on the sensing and manipulation of physical objects by the robots, was derived from the finding that references to physical objects serve as an essential communication and coordination tool for SWAT commanders. A human-computer interface that utilizes direct manipulation techniques and three-dimensional computer graphics was created to test the new interaction paradigm. Using this interface, a single operator can coordinate the actions of multiple robots. Operators with many different levels of experience with robot operation were able to conduct a variety of complex missions using the MAR robots.
Attaching a small manipulator (mini) with fast dynamic response at the end of a bigger manipulator (macro) with larger workspace leads to the concept of macro-mini manipulator, which is seen as a way to improve the system performance as compared to the macro manipulator acting alone, for example in terms of positioning accuracy. However, cross coupling between the two counterparts could undermine the practicality of the concept. In this paper, an adaptive neural network decoupler is presented to reduce the coupling effect of the macro-mini manipulators, without the need to have a proper dynamic model of the macro, and without alteration to the macro's controller. The stability of the proposed scheme is analyzed through the use of Lyapunov criterion. Simulation results show that by using the proposed neural network decoupler, the positioning accuracy of the macro-mini system can be improved significantly even when the macro manipulator is perturbed by external disturbances.
This paper proposes LQGR/LQG control for trajectory tracking control of flexible joint robotic system. In order to estimate the full variables states, plant uncertainty and disturbances, an estimator is used. The controller does not requires knowledge of plant uncertainty and external disturbances. The perturbation is efficiently compensated by feedback of estimated values.
This paper introduces a general control framework for macro mini manipulator to improve the force and compliant motion control of robotic manipulators. RMRC (Resolved Motion Rate Control) is used as the controller for the industrial (macro) manipulator, while a switching between position control and force control is applied for the mini. The algorithm shows that it can work well in searching and contacting the workpiece, even with limited information of the location of the workpiece. It is also suitable for the compliant motion when it deals with an unknown contour of the workpiece. The framework is validated through experiments which utilize 7-DOF Mitsubishi PA-10 as the macro manipulator and 1-DOF voice coil as the mini manipulator.
Emerging applications in multiview streaming look for providing interactive
navigation services to video players. The user can ask for information from any
viewpoint with a minimum transmission delay. The purpose is to provide user
with as much information as possible with least number of redundancies. The
recent concept of navigation segment representation consists of regrouping a
given number of viewpoints in one signal and transmitting them to the users
according to their navigation path. The question of the best description
strategy of these navigation segments is however still open. In this paper, we
propose to represent and code navigation segments by a method that extends the
recent layered depth image (LDI) format. It consists of describing the scene
from a viewpoint with multiple images organized in layers corresponding to the
different levels of occluded objects. The notion of extended LDI comes from the
fact that the size of this image is adapted to take into account the sides of
the scene also, in contrary to classical LDI. The obtained results show a
significant rate-distortion gain compared to classical multiview compression
approaches in navigation scenario.
Este artículo presenta una panorámica de la investigación realizada hasta la fecha en el campo de la robótica flexible, es decir, en la categoría de los robots que presentan un grado de elasticidad apreciable en sus eslabones. Estos robots poseen interesantes propiedades mecánicas como su alta relación carga útil/peso del robot pero a cambio presentan importantes problemas desde los puntos de vista de modelado dinámico y control que suponen ¿ aún hoy en día ¿ retos importantes para los investigadores en robótica. El autor además aprovecha este artículo para verter sus propios puntos de vista sobre este tema y avanzar la evolución futura del mismo.
