This paper addresses the development of an adaptive control system for keyhole arc welding process. The system developed adjusts the amperage of the peak current to achieve the desired peak current period under varyin...
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When a distributed robotic system is assigned to perform reconnaissance or surveillance, restrictions inherent to the design of an individual robot limit the system's performance in certain environments. Finding a...
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When a distributed robotic system is assigned to perform reconnaissance or surveillance, restrictions inherent to the design of an individual robot limit the system's performance in certain environments. Finding an ideal portable robotic platform capable of deploying and returning information in spatially restrictive areas is not a simple task. The Scout robot, developed at the University of Minnesota, is a viable robotic platform for these types of missions. The small form factor of the Scout allows for deployment, placement, and concealment of a team of robots equipped with a variety of sensory packages. However, the design of the Scout requires a compromise in power, sensor types, locomotion, and size; together these factors prevent an individual Scout from operating ideally in some environments. Several attempts to address these deficiencies have been implemented and are discussed. Among the prototype solutions are actuating wheels, allowing the Scout to increase ground clearance in varying terrains, a grappling hook enabling the Scout to obtain a position of elevated observation, and infrared emitters to facilitate low light operation.
One of the most useful devices that give the disabled the self-locomotion opportunity is wheelchair. The motorized wheelchair is designed for disabled with severe disability. Since there is no controller on the tradit...
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One of the most useful devices that give the disabled the self-locomotion opportunity is wheelchair. The motorized wheelchair is designed for disabled with severe disability. Since there is no controller on the traditional and cheap motorized wheelchairs, a collision-free navigation in an indoor environment is somewhat difficult. Improving user's driving skill is achieved by practicing in different risk-free environments. Building a virtual environment to train motorized wheelchair driving is a cost-effective and safe solution. In this paper, we developed a desktop-VR system that uses a cost-effective platform to receive user's wheelchair motion and feedback environment impulses to the wheelchair. The impulse feedback makes the VE more realistic.
One of the fundamental issues in the field of Evolutionary robotics (ER) is that of selection and formulation of an appropriate performance training metric. In recent years, proof-of-concept studies have shown that si...
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Keyhole arc welding is a cost-effective process to weld thick materials. To successfully apply this process, the state of the keyhole must be accurately detected and used in feedback control. In this paper, the dynami...
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Keyhole arc welding is a cost-effective process to weld thick materials. To successfully apply this process, the state of the keyhole must be accurately detected and used in feedback control. In this paper, the dynamic behavior of the plasma reflection is described using the reflection arc angle (RAA). It is found that the RAA series can be considered an autoregressive moving-average (ARMA) process. The parameters of the ARMA are recursively estimated using the extended least squares algorithm. It is found that the recursive estimates of the model parameters change as the state of the keyhole changes. A discriminator has been proposed to determine the state of the keyhole based on the recursive estimates of the model parameters.
Search and rescue operations in large disaster sites require quick gathering of relevant information. Both the knowledge of the location of victims and the environmental/structural conditions must be available to safe...
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Search and rescue operations in large disaster sites require quick gathering of relevant information. Both the knowledge of the location of victims and the environmental/structural conditions must be available to safely and efficiently guide rescue personnel. A major hurdle for robots in such scenarios is stairs. A system for autonomous surmounting of stairs is proposed in which a Scout robot jumps from step to step. The robot's height is only about a quarter step in size. Control of the Scout is accomplished using visual servoing. An external observer such as another robot is brought into the control loop to provide the Scout with an estimation of its pose with respect to the stairs. This cooperation is necessary as the Scout must refrain from ill-fated motions that may lead it back down to where it started its ascend. Initial experimental results are presented along with a discussion of the issues involved.
Presents a method for localizing miniature mobile robots (Scouts) using dynamic contours. An observer robot with a camera follows the miniature robot as it moves and jumps in the workspace. Dynamic contours are very e...
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Presents a method for localizing miniature mobile robots (Scouts) using dynamic contours. An observer robot with a camera follows the miniature robot as it moves and jumps in the workspace. Dynamic contours are very effective in tracking the fast accelerations and decelerations of the Scout robot. We show initial experimental results with particular emphasis on the task of monitoring a Scout during jumps.
Small scale distributed robotic systems are ideal for tasks that larger, more expensive robots may not be able to undertake such as surveillance or inspection in enclosed areas. Small scale robots also have the advant...
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Small scale distributed robotic systems are ideal for tasks that larger, more expensive robots may not be able to undertake such as surveillance or inspection in enclosed areas. Small scale robots also have the advantage of being easily portable to an area of interest. However, the advantages related to the small size and portability cause an increase in the complexity of development. In addition, the more pronounced effects of interacting with the environment in terms of mobility and communications lead to robotic systems of limited functionality. In order to address such deficiencies, several novel developments and improvements have been made to the Scout robot, which will be discussed. These improvements include the development of a communication relay system facilitating longer distance operation, an improved actuating wheel system increasing the Scout's mobility and a grappling hook system to elevate the Scout. By enhancing the Scout robotic team in this way, the functional use of the team is expanded, allowing more practical use.
This paper addresses the development of an adaptive control system for keyhole arc welding process. The system developed adjusts the amperage of the peak current to achieve the desired peak current period under varyin...
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This paper addresses the development of an adaptive control system for keyhole arc welding process. The system developed adjusts the amperage of the peak current to achieve the desired peak current period under varying manufacturing conditions. A nominal model is selected from models identified using experimental data and is used as the a prior model of the controlled process. A predictive control algorithm has been designed for the nominal model structure. Closed-loop control experiments have been conducted to verify the effectiveness of the developed system under varying set-point and varying travel speed.
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