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A near-singular, flexure jointed, moment sensitive Stewart platform based fore-torque sensor

Bhavikatti, Shivanand and Ranganath, R and Ghosal, A (2007) A near-singular, flexure jointed, moment sensitive Stewart platform based fore-torque sensor. In: 13th National Conference on Mechanisms and Machines (NaCoMM07, December 12-13, 2007, IISc, Bangalore.

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A force-torque sensor capable of accurate measurement of the three components of externally applied forces and moments is required for force control in robotic applications involving assembly operations. The goal in this paper is to design a Stewart platform based force torque sensor at a near-singular configuration sensitive to externally applied moments. In such a configuration, we show an enhanced mechanical amplification of leg forces and thereby higher sensitivity for the applied external moments. In other directions, the sensitivity will be that of a normal load sensor determined by the sensitivity of the sensing element and the associated electronic amplification, and all the six components of the force and torque can be sensed. In a sensor application, the friction, backlash and other non-linearities at the passive spherical joints of the Stewart platform will affect the measurements in unpredictable ways. In this sensor, we use flexural hinges at the leg interfaces of the base and platform of the sensor. The design dimensions of the flexure joints in the sensor have been arrived at using FEA. The sensor has been fabricated, assembled and instrumented. It has been calibrated for low level loads and is found to show linearity and marked sensitivity to moments about the three orthogonal X, Y and Z axes. This sensor is compatible for usage as a wrist sensor for a robot under development at ISRO Satellite Centre.

Item Type: Conference Paper
Keywords: Stewart Platform Sensor;Near-singular;Flexure Joint
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Date Deposited: 28 Oct 2011 09:24
Last Modified: 28 Oct 2011 09:24
URI: http://eprints.iisc.ac.in/id/eprint/41772

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