On The Synthesis of Cams With Irregular Followers

1990 ◽  
Vol 112 (1) ◽  
pp. 36-41 ◽  
Author(s):  
C. Chan ◽  
A. P. Pisano
Keyword(s):  
Constraint Equation ◽  
Analytical Description ◽  
Geometric Constraints ◽  
Theory Method ◽  
Equation Approach ◽  
Irregular Surface ◽  
Geometry Design ◽  
Envelope Theory

This paper extends the envelope theory for plate cam geometry design to irregular-surface follower systems. Analytical description of cam profiles for general com-follower systems is derived and an example is solved to demonstrate the method carried out in the numerical form. A constraint equation approach, which uses geometric constraints between two planar objects in contact, is also described and used to verify the results provided by the envelope theory method.

Inverse kinematics and workspace analysis of the metamorphic hand

2014 ◽  
Vol 229 (5) ◽  
pp. 965-975 ◽  
Author(s):  
Zhiguang Gao ◽  
Guowu Wei ◽  
Jian S Dai
Keyword(s):  
Inverse Kinematics ◽  
Constraint Equation ◽  
Geometric Constraints ◽  
Forward Kinematics ◽  
Significant Feature ◽  
Robotic Hands ◽  
Hybrid Mechanism ◽  
Workspace Analysis ◽  
First Time ◽  
Posture Adjustment

This paper investigates for the first time inverse kinematics of a four-fingered metamorphic hand. Compared with the current existing robotic hands, the most significant feature of the metamorphic hand is the introduction of a foldable and reconfigurable palm and its function of metamorphism, which greatly improves the ability of posture adjustment and inter-coordination between fingers. Geometric constraints of the palm are analyzed by using geometric method and constraint equation method, on the basis of which, kinematics of the metamorphic hand are transformed from a hybrid mechanism into serial mechanisms and forward kinematics can be obtained directly. To avoid the complexity of inverse kinematics of the thumb, a method taking advantage of geometric constraints of the palm is introduced to simplify the inverse kinematics of the metamorphic hand and analytical solutions are obtained in a concise form. The workspace of the metamorphic hand is decomposed into palm workspace and finger workspace. A triangle determined by the mounting points is introduced to measure the palm workspace and the simulation of the finger workspace augmented by the palm reveals that the reconfigurable palm contributes tremendously to the flexibility and versatility of the metamorphic hand.

Optimization of Eight Pole Radial Active Magnetic Bearing

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
K. P. Lijesh ◽  
Harish Hirani
Keyword(s):  
Numerical Optimization ◽  
Magnetic Levitation ◽  
Constraint Equation ◽  
Magnetic Bearing ◽  
Geometric Constraints ◽  
Active Magnetic Bearing ◽  
Iron Losses ◽  
The Given ◽  
Magnetic Levitation Force ◽  
Electromagnetic Bearing

In the current paper, studies carried out to design an eight pole electromagnetic bearing have been presented. The magnetic levitation force, accounting the copper and iron losses, was maximized for the given geometric constraints. Derivation of winding constraint equation in terms of wire diameter, number of turns, and dimensions of pole has been presented. Experiments were conducted to establish the constraints related to temperature rise. Finally, the dimensions of the electromagnet for maximizing the force obtained using numerical optimization have presented.

A Simplified Method for the Assessment of Propeller Roughness Penalties

1984 ◽  
Vol 21 (01) ◽  
pp. 41-48
Author(s):  
Tor E. Svensen ◽  
John S. Medhurst
Keyword(s):  
Boundary Layer ◽  
Surface Condition ◽  
Theory Method ◽  
Irregular Surface ◽  
Texture Parameter ◽  
Simple Tool ◽  
Strip Theory ◽  
Simplified Method ◽  
Thrust Characteristics ◽  
Roughness Measurements

A procedure for calculating the changes in torque and thrust characteristics due to the presence of irregular surface roughness on the blades of a propeller is described. This procedure is based upon a well-established strip-theory method, modified to allow for the input of section drag increments due to roughness obtained separately from boundary-layer integration calculations. The method is sufficiently simple to be programmed on a desk-top computer of modest size. Results are presented for a typical four-bladed propeller in terms of power increment against a combined roughness height and texture parameter. Furthermore, these results have been related to roughness measurements on a set of commercially available roughness comparators to provide a simple tool for use by ship operators in making decisions on propeller maintenance. Comparison is made with measurements taken from three propellers in service. Economic calculations are provided to demonstrate that expenditure on the maintenance of a smooth propeller surface condition is money well spent.

Geometric Improvement on Ribbed Globoidal Cams for Unsymmetrical Motion Controls

1995 ◽  
Author(s):  
Der Min Tsay ◽  
Bor Jeng Lin
Keyword(s):  
Analytical Description ◽  
Angular Motion ◽  
Traditional Methods ◽  
B Splines ◽  
Motion Constraints ◽  
Pressure Angle ◽  
Envelope Theory

Abstract A procedure with design and machining considerations is developed to define unsymmetrical turret motions of ribbed globoidal cams. Adjusting the parameters of rational B-splines to interpolate required angular motion constraints, one can refine the turret motion that is superior to those obtained by other traditional methods. To judge the geometric performance of the spatial cam surface corresponding to its turret motion, the envelope theory is applied to derive the analytical description of the cam surface. As a result, the pressure angle and the curvature of the cam surface can be investigated. A real example is illustrated to show the effectiveness of the procedure and the favorable results compared to those obtained by other means.

Quantitative Analysis Of X-Ray Images From Geological Materials

1990 ◽  
Vol 48 (2) ◽  
pp. 244-245
Author(s):  
J. M. Paque ◽  
R. Browning ◽  
P. L. King ◽  
P. Pianetta
Keyword(s):  
Quantitative Analysis ◽  
Bulk Composition ◽  
Principal Component ◽  
Analytical Description ◽  
Bulk Sample ◽  
Geological Samples ◽  
X Ray ◽  
Software And Hardware ◽  
And Storage ◽  
Insight Into

Geological samples typically contain many minerals (phases) with multiple element compositions. A complete analytical description should give the number of phases present, the volume occupied by each phase in the bulk sample, the average and range of composition of each phase, and the bulk composition of the sample. A practical approach to providing such a complete description is from quantitative analysis of multi-elemental x-ray images.With the advances in recent years in the speed and storage capabilities of laboratory computers, large quantities of data can be efficiently manipulated. Commercial software and hardware presently available allow simultaneous collection of multiple x-ray images from a sample (up to 16 for the Kevex Delta system). Thus, high resolution x-ray images of the majority of the detectable elements in a sample can be collected. The use of statistical techniques, including principal component analysis (PCA), can provide insight into mineral phase composition and the distribution of minerals within a sample.

AN INTEGRAL EQUATION APPROACH TO PHASE TRANSITIONS IN FERROFLUIDS

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1847-C8-1848
Author(s):  
G. A. R. Martin ◽  
A. Bradbury ◽  
R. W. Chantrell
Keyword(s):  
Integral Equation ◽  
Phase Transitions ◽  
Equation Approach ◽  
Integral Equation Approach

Parallel Glide: A Fundamentally Different Type of Dislocation Motion in Ultrathin Metal Films

2003 ◽  
Vol 779 ◽  
Author(s):  
T. John Balk ◽  
Gerhard Dehm ◽  
Eduard Arzt
Keyword(s):  
Thermal Cycling ◽  
Grain Boundaries ◽  
Film Surface ◽  
Metal Films ◽  
Geometric Constraints ◽  
Film Stress ◽  
Diffusional Creep ◽  
Creep Model ◽  
Substrate Interface ◽  
Film Substrate

AbstractWhen confronted by severe geometric constraints, dislocations may respond in unforeseen ways. One example of such unexpected behavior is parallel glide in unpassivated, ultrathin (200 nm and thinner) metal films. This involves the glide of dislocations parallel to and very near the film/substrate interface, following their emission from grain boundaries. In situ transmission electron microscopy reveals that this mechanism dominates the thermomechanical behavior of ultrathin, unpassivated copper films. However, according to Schmid's law, the biaxial film stress that evolves during thermal cycling does not generate a resolved shear stress parallel to the film/substrate interface and therefore should not drive such motion. Instead, it is proposed that the observed dislocations are generated as a result of atomic diffusion into the grain boundaries. This provides experimental support for the constrained diffusional creep model of Gao et al.[1], in which they described the diffusional exchange of atoms between the unpassivated film surface and grain boundaries at high temperatures, a process that can locally relax the film stress near those boundaries. In the grains where it is observed, parallel glide can account for the plastic strain generated within a film during thermal cycling. One feature of this mechanism at the nanoscale is that, as grain size decreases, eventually a single dislocation suffices to mediate plasticity in an entire grain during thermal cycling. Parallel glide is a new example of the interactions between dislocations and the surface/interface, which are likely to increase in importance during the persistent miniaturization of thin film geometries.

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