Force

Conventional mechanism (i.e. rigid link mechanisms) has limited accuracy and repeatability because of friction, backlash. Mechanism offers a relative motion between rigid links via joints. Conventionally these joints are pin, sliding, rolling, liquid film etc. These joints have inherent nonlinear frictional characteristics which are creating difficulty in control micro-nano positioning in precision mechanisms. To achieve high resolution and precision problems of friction, backlash in mechanism needs to be removed. These joints are replaced by flexible elements such as flexural hinge, flexural links which offers advantage of frictionless and smooth motion. Flexural mechanisms are developed using basic building blocks such as hinges and planar type. Flexural building blocks should be such that it offers lesser / zero resistance to motion in desired direction and maximum / infinite resistance in orthogonal direction. Motion generated in orthogonal direction is called parasitic motion. Double Flexural Manipulator (DFM) is a planar type building block which offers theoretically zero parasitic error motion with negligible amount of rotation of motion stage. This article presents design, development, system integration, system identification and PID control implementation on DFM. Developed flexural stage is integrated with desktop PC via dSPACE micro-controller. System identification (Static and Dynamic) is carried out and performance parameters such as stiffness, natural frequency, damping characteristics and frequency characterization of DFM are estimated and validated via due experimentations. Estimated transfer function of DFM is further used for development of control system, and PID control parameters are tuned. Real time PID implementation gives a position accuracy of few microns at high scanning speed of 2.5 mm/s.

Ductile iron can acquire enhanced thermal and mechanical properties from austempering heat treatment. The present study aims to identify the function of different cutting parameters affecting machinability and to quantify its effects. Turning was performed to test machinability according to the ISO3685-1993 (E) standard. After austenitizing at 900 °C for 90 min, austempered ductile iron (ADI) specimens were quenched in a salt bath at 380 °C for 90 min. The cutting force signals along three directions were measured in real time, whereas flank wear and surface roughness were measured offline. For the cutting parameters, the cutting speed and depth of cut were varied, but the feed rate was kept constant. In the flank wear tests, machining length was corresponded to tool life. In addition, in order to find out the effect of cutting parameters on surface roughness (Ra), tangential force (Ft), and flank wear (VB) during turning, response surface methodology (RSM) was utilized by using exp...

An MR damper is a device that exhibits a high nonlinear and complex behavior with a hysteresis phenomenon. A comparison between different state-of-the-art and a Linear Parameter Varying (LPV) models for Magneto-Rheological (MR) dampers is presented. Several experimental datasets validate that Linear Parameter Varying (LPV)-based model outperforms the classical MR damper models for 51% than any structures considering the Error to Signal Ratio index and 37% better considering the Squared root of Sum of Squared Errors index.

The biomechanics of skin and underlying tissues plays a fundamental role in the human sense of touch. It governs the mechanics of contact between the skin and an object, the transmission of the mechanical signals through the skin, and their transduction into neural signals by the mechanoreceptors. To better understand the mechanics of touch, it is necessary to establish quantitative relationships between the loads imposed on the skin by an object, the state of stresses/strains at mechanoreceptor locations, and the resulting neural response. Towards this goal, 3-D finite-element models of human and monkey fingertips with realistic external geometries were developed. By computing fingertip model deformations under line loads, it was shown that a multi-layered model was necessary to match previously obtained in vivo data on skin surface displacements. An optimal ratio of elastic moduli of the layers was determined through numerical experiments whose results were matched with empirical ...

The vibration control of rotors for gas or steam turbines is usually performed using passive dampers when hydrodynamic bearings are not used. In layouts where the rotating parts are supported by rolling bearings, the damping is usually provided by squeeze film dampers. Their passive nature and the variability of their performances with temperature and frequency represent the main disadvantages. Dampers with magnetorheological and electrorheological fluid allow solving only a part of the abovementioned drawbacks. Active magnetic bearings (AMBs) are promising since they are very effective in controlling the vibration of the rotor and offering the possibility of monitoring the rotor’s behavior using their displacement sensors. However they show serious drawbacks related to their stiffness. Electromagnetic dampers seem to be a valid alternative to visco-elastic, hydraulic dampers due to, among the others, the absence of all fatigue and tribology issues resulting from the absence of cont...

A wearable robot with linear actuators is required to maintain over the desired payload over whole range of knee joint angle even when the user is walking, sitting down/standing up while holding up weights. However, in knee-flexion posture, the lifting payload at the knee joint decreases drastically by the moment arm of linear actuators and the cosine of joint angle. In order to solve the problem of the payload decrease, the sub-links attaching on actuators and the sub-link with shank bending method are proposed. As the result, two methods are successfully proved to increase the payload by simulation.

This article presents a method for determination of meshing force distribution on contact region of spur gear teeth. In this method it is assumed that there are inter-connected springs on the teeth profile. These springs treat as capacitive fields. The compliance matrices of these fields are determined from the results of finite element analysis done on 3-D model of a gear. The tooth compliance matrix is used as a reference data to determine the tooth deformations for any meshing situation. The meshing force distribution is calculated using this reference data and Hertz theory for contacting bodies. The results of this analysis help in stress analysis under real operation conditions and more reliable design of gears without needing 3-D contact model. So by this method the volume of the calculations is reduced remarkably. The method is applied to a spur gear pair, and the meshing force distribution and meshing stiffness is determined for two cases of ideal and misaligned contacts.Copyright © 2008 by ASME

ARTICLE INFO Detection of the Distorted Fingerprints major causes to non-match in fingerprint at time matching fingerprint sample. This problem causes all the recognition of fingerprint algorithm application. It is complicated in negative type matching application. That means watch list and duplication application. In such way criminal user porpusly hide his fingerprint identification. In this paper we use the K-means, Canny-edge algorithm to detect and rectify distorted fingerprint image. Distortion and rectification is view as a regression problem where user input skein distorted fingerprint output is distortion field. To solve this problem K-means & Canny-edge fingerprint algorithm is use.