In this paper, we address the problem of designing a landmark-based control law that robustly globally asymptotically stabilizes a rigid body at a desired equilibrium point on the SE(3) manifold. Synergistic potential...
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In this paper, we address the problem of designing a landmark-based control law that robustly globally asymptotically stabilizes a rigid body at a desired equilibrium point on the SE(3) manifold. Synergistic potential functions are combined within a hybrid systems framework to generate such a hybrid control law. The proposed control law is solely a function of vector measurements characterizing the position of some given landmarks. We provide sufficient conditions on the geometry of the landmarks to solve the given problem. Finally, the proposed solution is simulated and compared with an almost global continuous feedback control law.
The effective operation of service robots relies on developmental programs that allow the robot to expand its knowledge about its dynamic operating environment. Motivation theories from neuroscience and neuropsycholog...
The effective operation of service robots relies on developmental programs that allow the robot to expand its knowledge about its dynamic operating environment. Motivation theories from neuroscience and neuropsychology study the underlying mechanisms that drive the engagement of biological creatures to certain activities, such as learning. This research uses a physical Willow Garage PR2 robot, which is equipped with a cumulative learning mechanism driven by the intrinsic motivation of novelty detection based on computational models of biological habituation. It cumulatively learns the 360° appearance of novel real-world objects by picking them up. This paper discusses the theoretical motivations and background information on intrinsic motivations as novelty detection. The results and conclusions from the experimental study are presented.
In studies of human motor control, motor synergy hypothesis has been proposed as a solution of the well-known degree-of-freedom problem. On the other hand, controlling complex robots using optimal control also has the...
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ISBN:
(纸本)9781467321259
In studies of human motor control, motor synergy hypothesis has been proposed as a solution of the well-known degree-of-freedom problem. On the other hand, controlling complex robots using optimal control also has the increased difficulty of facing the well-known problem of dimensionality. In this paper, performance of motor synergies in application of generating goal-directed movements using optimal control is examined. Results show that computational expense could be reduced while success rate is maintained, when motor synergies with properties of achieving goal optimally are utilized. The performance of utilizing motor synergies with different properties is also investigated. It is found that the same goals can still be achieved utilizing motor synergies which possess energy efficiency properties, with satisfactory success rate and computation expense.
Modern myoelectric hand prostheses continue to increase in functionality, while their control is constrained by the limits of myoelectric input. This paper covers the development and testing of grasp control systems f...
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ISBN:
(纸本)9781457711992
Modern myoelectric hand prostheses continue to increase in functionality, while their control is constrained by the limits of myoelectric input. This paper covers the development and testing of grasp control systems for multifunctional myoelectric prosthetic hands. The functionality of modern hand prostheses is often focused on the task of grasping, which can be divided into high-level grasp planning and low-level finger control. Initially, models can used to test these control systems, but for proper evaluation actual implementation on a physical system is required. The University of Bologna (UB) Hand IV prototype is an anthropomorphic, tendon-driven robotic hand, which makes it well-suited to represent the structure of modern prostheses. One of the main control systems tested in this paper is based on the intrinsically passive controller (IPC), the structure of which offers guaranteed passivity and stability. After several grasping tests, the systems are evaluated on compliant behavior, grasping ability, and dynamic appearance. IPC proves to be a powerful approach to interaction control, without the associated sensor requirements which could be difficult to meet in modern hand prostheses.
Effective execution of a planned path by an underwater vehicle is important for proper analysis of the gathered science data, as well as to ensure the safety of the vehicle during the mission. Here, we propose the use...
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Effective execution of a planned path by an underwater vehicle is important for proper analysis of the gathered science data, as well as to ensure the safety of the vehicle during the mission. Here, we propose the use of an unscented Kalman filter to aid in determining how the planned mission is executed. Given a set of waypoints that define a planned path and a dicretization of the ocean currents from a regional ocean model, we present an approach to determine the time interval at which the glider should surface to maintain a prescribed tracking error, while also limiting its time on the ocean surface. We assume practical mission parameters provided from previous field trials for the problem set up, and provide the simulated results of the Kalman filter mission planning approach. The results are initially compared to data from prior field experiments in which an autonomous glider executed the same path without pre-planning. Then, the results are validated through field trials with multiple autonomous gliders implementing different surfacing intervals simultaneously while following the same path.
This paper describes work done towards the development of advanced geophysical-based navigation systems for autonomous underwater vehicles (AUVs). The specific problem that we tackle is that of combining terrain-aided...
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ISBN:
(纸本)9783902823199
This paper describes work done towards the development of advanced geophysical-based navigation systems for autonomous underwater vehicles (AUVs). The specific problem that we tackle is that of combining terrain-aided navigation (TAN) with single-beacon navigation (SBN) techniques. The resulting complementary TAN/SBN system has the potential to overcome some of the problems that arise with TAN navigation only, when an AUV undergoes motions that lead it temporarily across areas where the terrain below is not sufficiently "rich" in terms of topographic features. The key contribution of this paper is a formal analysis of the benefits of using complementary filtering, in opposition to TAN navigation only. To this effect, we exploit key tools of estimation theory, and in particular the Cramér-Rao lower bound inequality to obtain a lower bound on the minimum covariance of the estimation error that can be obtained with any unbiased estimator. For a real terrain profile we compute and compare the Cramér-Rao lower bounds for TAN only and TA/SB-based navigation. The increase in the expected performance that can be achieved with the second solution is clearly visible. The efficacy of the new solution proposed is illustrated with the help of computer simulations.
Wireless sensor networks (WSNs) have attracted a great deal of research due to their wide-range of potential applications. Sensor deployment and coverage problems are their important issues. This article briefly intro...
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In this paper we propose a method for handling persistent visual occlusions that disrupt visual tracking for eye-in-hand systems. This approach provides an efficient strategy for the robot to "look behind" t...
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ISBN:
(纸本)9781457710957
In this paper we propose a method for handling persistent visual occlusions that disrupt visual tracking for eye-in-hand systems. This approach provides an efficient strategy for the robot to "look behind" the occlusion while respecting the robot's physical constraints. Specifically, we propose a decoupled search strategy combining a naive pan tilt search with a sensor placement approach, to reduce the strategy's computational cost. We proceed by mapping limited environmental data into the robot configuration space and then planning within a constrained region. We use a particle filter to continuously estimate the target location, while our configuration-based cost function plans a goal location for the camera frame, taking into account robot singularity, self-collision and joint limit constraints. To validate our algorithm, we implemented it on an eye-in-hand robot system. Experimental results for various situations support the feasibility of our approach for quickly recovering fully occluded moving targets. Finally we discuss the implications of this approach to mobile robot platforms.
This paper addresses the problem of maintaining an autonomous robotic vehicle in a moving triangular formation by regulating its position with respect to two leader vehicles. The robotic vehicle has no a priori knowle...
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This paper addresses the problem of maintaining an autonomous robotic vehicle in a moving triangular formation by regulating its position with respect to two leader vehicles. The robotic vehicle has no a priori knowledge of the path described by the leaders and its goal is to follow them by constantly regulating the inter-vehicle distances to a desired fixed value, using range-only measurements. To solve this station keeping problem, we propose a control strategy that estimates the formation speed and heading from the ranges obtained to the two leading vehicles, and uses simple feedback laws for speed and heading commands to drive suitably defined common and differential errors to zero. For straight-line motion, we provide guaranteed conditions under which the proposed control strategy achieves local convergence of the distance errors to zero. We also indicate how our design procedure can be extended to full dynamic models of marine robotic vehicles equipped with inner loops for yaw and speed control. Simulation results using realistic models are described and discussed.
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