Diana Pelinescu, Michael Yu Wang, University of Maryland, USA
This paper addresses a major issue in fixture layout design: to evaluate the acceptable fixture designs based on several quality criteria and to select an optimal fixture appropriate with practical demands. The performance objectives considered are related to the fundamental requirements of kinematic localization and total fixturing (form-closure) and are defined as the workpiece localization accuracy and the norm and distribution of the locator contact forces. An efficient interchange algorithm is uaed in a multiple-criteria optimization process for different practical cases, leading toproper trade-off strategies for performing fixture synthesis.
12:10―12:30 |
S. Bruni, F. Resta, Politecnico di Milano, Italy
The paper deals with the application of active control to increase the operating speed of high speed trains by avoiding the occurrence of hunting instability. To this end, an innovative controlled electro-mechanic damper was designed to substitute traditional yaw dampers currently in use. The main components of this system are a brushless motor, with gear and spindle, used to apply a longitudinal force between the carbody and the bogie of the vehicle, and a velocity transducer used to measure the yaw vibrations of the bogie. The electric motor is controlled in order to apply a force to the bogie opposite to its yawing velocity, thereby maximising the amount of energy dissipation. In order to compare the performances of this new device to those of traditional oil dampers, a prototype was built and tested in a laboratory test rig reproducing the yawing behavior of an unstable bogie. A mathematical model … | Design Algorithm for Automated Dynamic Grasping of Live Birds
Kok-Meng Lee, Xuecheng Yin, Georgia Institute of Technology, USA
This paper presents a method for designing a dynamic grasper for handling natural objects (such as live birds) for subsequent processing. The dynamic grasper uses flexible fingers to accommodate a limited range of varying sizes, shapes, and some motion due to the live object's natural reaction to mechanical grasping. As compared to fingers with multiple active joints, flexible fingers have many potential advantages, because they are lightweight and they have no relative individual moving parts in each of the fingers. The advantages of flexible fingers are seldom exploited for grasping, however, because of complicated analysis involved in their design. For this reason, we present an analytical method for designing a dynamic grasper for handling natural objects on a moving conveyor.
| 12:30―12:50 | Experimental Campaign on a Servo-Actuated Pantograph
B. Allotta, Scuola Sant’Anna, M. Papi, Trenitalia SpA, L. Pugi, P. Toni, Università di Firenze, A.G. Violi, Trenitalia SpA, Italy
Many interesting technical problems arise from the development of high speed trains current collection is one of the more important. The dynamic behaviour of pantograph-catenary system make the electrical contact between the catenary and the contact-shoe unreliable. An insufficient quality of Current Collection causes a lot of negative consequences such as: insufficient current pick up excessive wear of contact shoes and wires power and control electronics malfunction high EMI. Many Researchers have investigated the problem of optimum current pick up and many different solutions have been proposed in the past years. Since 1993 the Researchers of University of Florence have proposed the idea of a servo-actuated pantograph. The purpose of these studies was the development of a system … |
Xiangyang Zhu, Southeast University, Han Ding, Hanxiong Li, City University of Hong Kong, PRC
By using the concept of gauge function, a pseudo metric is defined in the wrench space. On this basis, we present a quality index for multi-fingered grasp, which measures the maximum magnitude of the wrench that can be resisted by the grasp in the worst case. The proposed measure can be formulated as a set of linear programming problem, hence can be calculated efficiently. An optimal grasp synthesis algorithm, which can be used to compute the optimal grasp configuration, is also proposed. Moreover, we present an approach for calculating all grasp configurations that verify quantitative constraint for polygonal objects. | 12:50―13:10 | Actively Controlled Pantograph: an Application
F. Resta, Politecnico di Milano, A. Collina, F. Fossati, Univ. Catania, Italy
In the present paper an active control for high speed train pantograph is proposed in order to improve power collection at high speed (i.e. V>220km/h) allowing the speedup of the existing lines. The control is based on an available commercial actuator, and its feasibility and effectiveness have been investigated by means of numerical simulation. At this purpose, the dynamics of the actuator (a permanent DC motor) has been included in a detailed pantograph-catenary interaction model. the actuators can be placed a) on the articulated frame, or b) in correspondence of the collector head suspension. It has also been suggested to apply the control force directly to the collector head, from the locomotive roof, in order to make a compromise between the two configurations a) and b), previously mentioned. The first configuration has the advantage that there're no strict limitation to …
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