A performance measure for computing the reverse kinematic solution for robots with redundant degrees of freedom

This paper aims to develop a performance measure for underactuated grasping devices, which is useful in making design decisions to obtain an optimally performing device. Underactuated fingers, defined as having more degrees of freedom than degrees of actuation, intrinsically adapt their shape to the object. However, the equilibrium configuration and grasp forces of these fingers are not fully controllable, which may limit their performance. The grasp performance measure defined in this paper consists of three aspects: (1) the ability to grasp objects, which is limited by the equilibrium conditions and constraints of both the underactuated fingers and the freely movable object; (2) the grasp stability, which takes the passive compliance of the fingers into account; (3) the ability to oppose disturbance forces on the grasped object by passively adapting the frictional grasp forces. This measure was applied to optimize a planar grasping device with two underactuated fingers, each consisting of two phalanges, able to grasp freely moving circular objects.

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On the dependence structure and bounds of correlated parallel queues and their applications to synchronized stochastic systems

Journal of Applied Probability ◽

10.1017/s0021900200018209 ◽

2000 ◽

Vol 37 (04) ◽

pp. 1020-1043 ◽

Cited By ~ 4

Author(s):

Haijun Li ◽

Susan H. Xu

Keyword(s):

Stochastic Systems ◽

Queueing Systems ◽

Performance Measure ◽

Upper And Lower Bounds ◽

Dependence Structure ◽

Single Server ◽

Joint Performance ◽

Comparison Results ◽

Arrival Processes ◽

A Performance

This paper studies the dependence structure and bounds of several basic prototypical parallel queueing systems with correlated arrival processes to different queues. The marked feature of our systems is that each queue viewed alone is a standard single-server queuing system extensively studied in the literature, but those queues are statistically dependent due to correlated arrival streams. The major difficulty in analysing those systems is that the presence of correlation makes the explicit computation of a joint performance measure either intractable or computationally intensive. In addition, it is not well understood how and in what sense arrival correlation will improve or deteriorate a system performance measure. The objective of this paper is to provide a better understanding of the dependence structure of correlated queueing systems and to derive computable bounds for the statistics of a joint performance measure. In this paper, we obtain conditions on arrival processes under which a performance measure in two systems can be compared, in the sense of orthant and supermodular orders, among different queues and over different arrival times. Such strong comparison results enable us to study both spatial dependence (dependence among different queues) and temporal dependence (dependence over different time instances) for a joint performance measure. Further, we derive a variety of upper and lower bounds for the statistics of a stationary joint performance measure. Finally, we apply our results to synchronized queueing systems, using the ideas combined from the theory of orthant and supermodular dependence orders and majorization with respect to weighted trees (Xu and Li (2000)). Our results reveal how a performance measure can be affected, favourably or adversely, by different types of dependencies.

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Incentives and Innovation: A Multitasking Approach

American Economic Journal Microeconomics ◽

10.1257/mic.3.1.78 ◽

2011 ◽

Vol 3 (1) ◽

pp. 78-128 ◽

Cited By ~ 25

Author(s):

Thomas Hellmann ◽

Veikko Thiele

Keyword(s):

Intellectual Property ◽

Property Rights ◽

Intellectual Property Rights ◽

Performance Metrics ◽

Performance Measure ◽

Ex Post ◽

A Performance

This paper develops a multitask model where employees make choices between their assigned standard tasks, for which the firm has a performance measure and provides incentives, and privately observed innovation opportunities that fall outside of the performance metrics, and require ex post bargaining. If innovations are highly firm specific, firms provide lower-powered incentives for standard tasks to encourage more innovation, yet in equilibrium employees undertake too few innovations. The opposite occurs if innovations are less firm specific. We also investigate the effectiveness of several possibilities to encourage innovation, such as tolerance for failure, stock-based compensation, and the allocation of intellectual property rights. (JEL D21, J33, M12, O31, O34)

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