The authors describe experiments wherein a carefully built passive compliant device emulates the dynamic behavior of multifingered grasps. The device is used to demonstrate the change in the time response of three typ...
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The authors describe experiments wherein a carefully built passive compliant device emulates the dynamic behavior of multifingered grasps. The device is used to demonstrate the change in the time response of three types of grasps: (i) a grasp in a general situation, (ii) a grasp with a compliance center only, and (iii) a grasp with an admittance center. The experimental results (photographic records) of the time response of the three grasps clearly indicate the directionally decoupled dynamic behavior of an admittance center grasp, and the absence of such a behavior in general grasps and in grasps with a compliance center only. Such decoupled behavior is highly desirable in tasks involving constrained manipulation of delicate objects.< >
Active sensing and perception of material properties and of phenomena like slip and contact are proposed as a basis for efficient control and execution of tasks in unknown and unstructured environments. The author pro...
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Active sensing and perception of material properties and of phenomena like slip and contact are proposed as a basis for efficient control and execution of tasks in unknown and unstructured environments. The author proposes that force/torque and displacement sensing be combined with the motion capabilities of robotic manipulators to actively sense material properties like penetrability, compliance, and surface friction and phenomena like slip and contact to simultaneously determine and follow desired force and motion trajectories for a given task. The applicability of such an active perception scheme is demonstrated for the case of legged locomotion. Possible extension and application of the scheme to manipulation are also proposed.< >
Three potential problems exist in multifingered hands. The impact forces that result during each instant of grasping a rigid object can affect the functioning of the finger tip sensor. A hand with hard fingers cannot ...
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Three potential problems exist in multifingered hands. The impact forces that result during each instant of grasping a rigid object can affect the functioning of the finger tip sensor. A hand with hard fingers cannot securely grasp objects that have uneven surfaces due to the poor conformability of the fingers. Repetitive strains are induced into the fingers throughout manipulation task. Carefully chosen materials-plastic, rubber sponge, a fine powder, a paste, and a gel-were experimentally compared for their ability to overcome these three problems. Results showed that sponge is the most suitable and plastic is the least suitable for the application. For practical reasons, however, the gel was a good compromise over the sponge. It is recommended that future robotic hands constitute a soft finger or at least fingers with soft tips, constructed out of carefully chosen materials.< >
A method for robot program synthesis is developed. The conceptual graph-based approach is proposed for the development of a robot programming support system. The system provides a means toward automated conversion of ...
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A method for robot program synthesis is developed. The conceptual graph-based approach is proposed for the development of a robot programming support system. The system provides a means toward automated conversion of a user's request expressed in natural language to the appropriate conceptual model of the required task. This approximate model of the dynamically changing real world of robotic assembly incorporates the information necessary for understanding, planning, and sensory-guided performance of the required robotic task. The overall framework of the system is defined, and the authors present the first phase of an assembly program synthesis: request specification, planning of valid assembly sequences, and required resources determination. A case study illustrates the approach on a large family of multi-axisymmetric components.< >
作者：
S.S. KrishnanA.C. SandersonElectrical
Computer and Systems Engineering Department Center for Advanced Technology in Automation and Robotics Rensselaer Polytechnic Institute Troy NY USA
The feasible path problem is solved for planning a collision-free path to translate an arbitrary polyhedral robot from an initial position to some goal position in a polyhedral environment. The shortest path problem e...
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The feasible path problem is solved for planning a collision-free path to translate an arbitrary polyhedral robot from an initial position to some goal position in a polyhedral environment. The shortest path problem entails finding the shortest feasible path. The authors present two versions of the window corner (WC) algorithm, which is a novel solution to the problems for the case of single and multistep translational paths for two dimensions, and then summarize the extension to the three-dimensional WC algorithm, for feasible paths. The concept of window corners in the polyhedral cone representation (PCR) is introduced, which reduces the search space. The PCR cones store constraints between boundary elements. The PCO representation has O(m) vertices compared to O(m/sup 2/) in a C-space representation. The WC algorithm was tested and an example from assembly path planning is presented.< >
The paper proposes a two-stage design approach to optimal H 2/ and H ∞ decentralized control problems. In the first stage, an optimal centralized controller is computed. Then based on the parametrization results fo...
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The paper proposes a two-stage design approach to optimal H 2/ and H ∞ decentralized control problems. In the first stage, an optimal centralized controller is computed. Then based on the parametrization results for centralized controllers, in the second stage, the parameter that decentralizes the controller is optimized. The design approach is applied to an observer-based decentralized controller. Optimality conditions are derived.
This paper presents an approach for designing robust tracking controller for lumped mass model of a vibrating link (VL) robot manipulator. The control methodology is intuitively simple since it is based on concepts wh...
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This paper presents an approach for designing robust tracking controller for lumped mass model of a vibrating link (VL) robot manipulator. The control methodology is intuitively simple since it is based on concepts which are familiar to most control engineers. The approach is illustrated by developing a robust tracking controller that achieves global uniform ultimate boundedness (GUUB) stability of the link tracking error in spite of model uncertainty and the additional link dynamics.
Fast procedures for computing fuzzy proximity measures between a multifingered robot hand and an object to be grasped are presented. T.N. Nguyen and H.E. Stephanou (1990) presented a fuzzy approach for prehension, ide...
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Fast procedures for computing fuzzy proximity measures between a multifingered robot hand and an object to be grasped are presented. T.N. Nguyen and H.E. Stephanou (1990) presented a fuzzy approach for prehension, identified sources of fuzziness, and proposed a fuzzy algorithm for multifingered prehension. These ideas are extended by assuming fuzziness in the object location and geometric hand configuration, computing information on proximity of the hand and object, analyzing the computational efficiencies, and indicating how geometric information can be used in the process of prehension. The implementation details are outlined. The computation is useful in grasp planning and in analyzing the local behavior of the robot hand in the vicinity of the object.< >
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