DEVELOPMENT OF FORCED BALANCE ACCELEROMETER USING LVDT

Abstract

In the measurement of low frequency low intensity acceleration the best accuracy characteristics are provided by force balance (servo) accelerometers. This thesis r o describes a servo accelerometer which may be readily constructed with commonly availab components and materials. Our main objective is to develop a model of this accelerometer which may lead to the development of a full-fledged one if it gets succeeded at the grass root level. A small shaketable to test our accelerometer also has been made on which the accelerometer can be mounted easily. Suitable arrangements to vary the damping and natural frequency are incorporated. The damping is achieved by electronic means. Special attention has been ade in designing and fabrication of LVDT. The transfer function of the accelerometer has been derived from which the design details were obtained. Later, frequency response plot of the accelerometer has been obtained from which the actual damping and natural frequency are evaluated and compared with the theoretical values for different cases. A comparison of theoretical and actual transfer functions was made for different ground acceleration signals. Though enough calibration tests have not been made due to the timely non-availability of standard accelerometers and shaketable, simple static tests for calibration have been made to evaluate the performance parameters. The Virtual Reality tool kit of MATLAB6.5 has been used to visualize the actual working of the accelerometer. Although its performance does not equal that of the better commercial devices, it should be adequate for many applications in which the utmost levels of performance are not required.