303 research outputs found
Grasping
No full textThis chapter introduces fundamental models of grasp analysis. The overall model is a coupling of models that define contact behavior with widely used models of rigid-body kinematics and dynamics. The contact model essentially boils down to the selection of components of contact force and moment that are transmitted through each contact. Mathematical properties of the complete model naturally give rise to five primary grasp types whose physical interpretations provide insight for grasp and manipulation planning. After introducing the basic model and types of grasps, this chapter focuses on the most important grasp characteristic: complete restraint. A grasp with complete restraint prevents loss of contact and thus is very secure. Two primary restraint properties are form closure and force closure. A form closure grasp guarantees maintenance of contact as long as the links of the hand and the object are well approximated as rigid and as long as the joint actuators are sufficiently strong. As will be seen, the primary difference between form closure and force closure grasps is the latter’s reliance on contact friction. This translates into requiring fewer contacts to achieve force closure than form closure
Grasping
No full textThis chapter introduces fundamental models of grasp analysis. The overall model is a coupling of models that define contact behavior with widely used models of rigid-body kinematics and dynamics. The contact model essentially boils down to the selection of components of contact force and moment that are transmitted through each contact. Mathematical properties of the complete model naturally give rise to five primary grasp types whose physical interpretations provide insight for grasp and manipulation planning.
After introducing the basic models and types of grasps, this chapter focuses on the most important grasp characteristic: complete restraint. A grasp with complete restraint prevents loss of contact and thus is very secure. Two primary restraint properties are form closure and force closure. A form closure grasp guarantees maintenance of contact as long as the links of the hand and the object are well-approximated as rigid and as long as the joint actuators are sufficiently strong. As will be seen, the primary difference between form closure and force closure grasps is the latter’s reliance on contact friction. This translates into requiring fewer contacts to achieve force closure than form closure.
The goal of this chapter is to give a thorough understanding of the all-important grasp properties of form and force closure. This will be done through detailed derivations of grasp models and discussions of illustrative examples. For an in-depth historical perspective and a treasure-trove bibliography of papers addressing a wide range of topics in grasping, the reader is referred to [38.1]
A hand/arm controller that simultaneously regulates internal grasp forces and the impedance of contacts with the environment
No full textThis paper presents a control framework for arm/hand systems aimed at controlling internal forces exchanged between the fingers and the grasped object, and enforcing a compliant behavior in presence of environmental interactions. A dynamic planner computes the motion references for the fingers by using the feedback of the contact forces, while an impedance control, in which dynamic effects exerted by the hand on the wrist are explicitly taken into account, is designed for the arm. The approach is experimentally validated on a 7-DOFs Barrett WAM with a Barrett Hand280
Zero-IF receivers for phased array radars
No full textCopyright © 2008 IEEEThis paper considers the suitability of zero-IF receivers for inclusion into the transmit/receive (T/R) modules in modern phased array radars. The main performance measures are the overall system dynamic range and tuning range. The achievable dynamic range is estimated based on currently available components and compared against the results of a prototype system. The overall results indicate that a dynamic range of more than 60 dB is achievable in a 50 MHz bandwidth.Matthew Trinkle and Joy L
Null-steering LMS dual-polarised adaptive antenna arrays for GPS
No full textThe implementation of a null steering antenna array using dual polarised patch antennas is considered. The best optimality criterion for a dual polarised GPS antenna array is briefly discussed, followed by a description of the associated LMS algorithm. To prevent weight vector drift a version of the circular leakage LMS algorithm was used. The implementation details of a simplified circular leakage algorithm that is more suited to an FPGA implementation are presented.W C Cheuk, M Trinkle & D A Gra
Ku-Band Phased Array Reflector Array for Bistatic Radar Experiments
No full textThis paper describes the design of Ku-band 16 element parabolic trough reflector antenna suitable for bistatie radar experiments using geo-stationary satellite TV signals. The array can steer electronically in azimuth and mechanically in elevation. The test results from a smaller four element model trough array are also presented. © 2008 IEEE.Cooke P., Trinkle M., Hansen H. and Palmer, J.http://trove.nla.gov.au/work/3188839
Data files for ab initio calculations of the lattice parameter and elastic stiffness coefficients of bcc Fe with solutes
No full textAbstractWe present computed datasets on changes in the lattice parameter and elastic stiffness coefficients of bcc Fe due to substitutional Al, B, Cu, Mn, and Si solutes, and octahedral interstitial C and N solutes. The data is calculated using the methodology based on density functional theory (DFT) presented in Ref. (M.R. Fellinger, L.G. Hector Jr., D.R. Trinkle, 2017) [1]. All the DFT calculations were performed using the Vienna Ab initio Simulations Package (VASP) (G. Kresse, J. Furthmüller, 1996) [2]. The data is stored in the NIST dSpace repository (http://hdl.handle.net/11256/671)
Design of Part Feeding and Assembly Processes with Dynamics
No full textWe introduce computational support tools for the analysis and design of systems with multiple frictional contacts, with a focus on applications to part feeding and assembly processes. The tools rely on dynamic models of the processes. We describe two approaches to modeling, the Stewart-Trinkle model [1] and the Song-Pang-Kumar model [2], that allow the designer to experiment with different geometric, material and dynamic properties and optimize the design for performance. In order to accomodate contact transitions, we introduce a smooth cone model for friction. We illustrate the models and the design process by describing the design optimization of a part feeder
Southern Ornamental Iron Works
No full textA photograph of a group of employees at Southern Ornamental Iron Works. In the back row is Ron Higgenbotham, Bill Prince, Jack Scroggins, Jack Robuck, Wildon Brusten, E. A. Smith, and Lukon Ward. In the second row is Floyd Smith, Bill Fry, Cyrus Jones, Herman Trinkle, J. T. Duning, Hal Grady, Clim Cable, Author Hart, Ed Bowen, C. F. Tubbs, and Olin Spurling. In the front row is A. J. Rud, M. C. Arnold, John Crouch, Jim McRike, Rufus Rinehart, R. G. Sielen, Lewis Thomasson, J. W. Blackwell, and Robert Wilson.https://mavmatrix.uta.edu/specialcollections_jwdunlopphotograph/1315/thumbnail.jp
Southern Industrial Steel Company
No full textA photograph pf a group of emplpyees of Southern Industrial Steel Company. In the top row is L. H. Blanscat, B. M. Cavanaugh, E. C. Bratchen, Pit Hayword, Author Rinehart, R. W. Austin, and Rush Hart. In the second row is Jack Lowery, Gary Waits, H. V. Breven, Fred Burns, Ben Chism, Bill Leath, J. C. Day, and D. L. Walls. In the third row is R. G. Seilen, J. B. Castleberry, A. P. Bogel, Jack Gray, J. H. Kincely, B. M. Morales, H. P. Harris, N. Burton, and W. R. Palmen. In the fourth row is J. P. Jolon, Herman Trinkle, A. C. Bowen, Author Hart, Al Wilson, Maggie Purdue, J. E. Vernon, Frances Akeman, amd J. T. Riening. In the front row is J. A. Hope, M. C. Arnold, Bobby Riening, Roland Manen, A. N. McMurray, Alen Cribbs, H. J. Mausen, and J. E. Reed.https://mavmatrix.uta.edu/specialcollections_jwdunlopphotograph/1308/thumbnail.jp
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