Adaptive control of large space structures using recursive lattice filters

The use of recursive lattice filters for identification and adaptive control of large space structures is studied. Lattice filters were used to identify the structural dynamics model of the flexible structures. This identification model is then used for adaptive control. Before the identified model and control laws are integrated, the identified model is passed through a series of validation procedures and only when the model passes these validation procedures is control engaged. This type of validation scheme prevents instability when the overall loop is closed. Another important area of research, namely that of robust controller synthesis, was investigated using frequency domain multivariable controller synthesis methods. The method uses the Linear Quadratic Guassian/Loop Transfer Recovery (LQG/LTR) approach to ensure stability against unmodeled higher frequency modes and achieves the desired performance

Application of the LQG/LTR technique to robust controller synthesis for a large flexible space antenna

The problem of synthesizing a robust controller is considered for a large, flexible space-based antenna by using the linear-quadratic-Gaussian (LQG)/loop transfer recovery (LTR) method. The study is based on a finite-element model of the 122-m hoop/column antenna, which consists of three rigid-body rotational modes and the first 10 elastic modes. A robust compensator design for achieving the required performance bandwidth in the presence of modeling uncertainties is obtained using the LQG/LTR method for loop-shaping in the frequency domain. Different sensor actuator locations are analyzed in terms of the pole/zero locations of the multivariable systems and possible best locations are indicated. The computations are performed by using the LQG design package ORACLS augmented with frequency domain singular value analysis software

Adaptive identification and control of structural dynamics systems using recursive lattice filters

A new approach for adaptive identification and control of structural dynamic systems by using least squares lattice filters thar are widely used in the signal processing area is presented. Testing procedures for interfacing the lattice filter identification methods and modal control method for stable closed loop adaptive control are presented. The methods are illustrated for a free-free beam and for a complex flexible grid, with the basic control objective being vibration suppression. The approach is validated by using both simulations and experimental facilities available at the Langley Research Center

STUDY OF INTERNAL ROLLER BURNISHING OPERATION ON EN8 MATERIAL

Burnishing is a cold working, a surface treatment process in which plastic deformation of surface irregularities occurs by exerting pressure through a very hard and smooth roller on a surface to generate a uniform and work-hardened surface. In this work, a simple internal roller burnishing tool is used to perform roller burnishing process on the holes drilled in EN8 material by varying the spindle speeds of drilling machine. The speed which produces maximum smoothness or minimum roughness on the surface is considered to be an optimal speed for carrying out burnishing operation in the drilled holes

FABRICATION OF COCONUT HUSK REMOVER WITH SHELL CUTTER

This project is to fabricate a coconut husk remover with shell cutter. At present coconut husk is being removed manually, which employs more time and more manpower. This coconut husk remover peels off the coconut husk from coconut fruit to obtain de-husked coconut fruit via pneumatic controlled de-husking device. An operator is required to handle the machine during the de-husking process. It can be used to de-husk both matured coconut and young coconut. This project consists of pneumatic cylinder, solenoid valve, linkages, husk remover and base frame.In this there are two main parts are there. One part is for removing the husk from the coconut and the other is cutting part. In both parts, pneumatic systems are used. The husk is removed with the help of hinge joint which connects to the pneumatic actuator. By connecting these two parts we fabricated as "coconut husk remover with shell cutter"

Effect of Clamping Rigidity of the Armour on Ballistic Performance

Influence of the manner in which the armour plates are held during their ballistic testing on the armour performance, has been evaluated. One armour plate was clamped rigidly to the test stand while a second plate of identical composition, hardness, and dimensions was hung loosely from the target holder. Both these plates were impacted with the same type of projectiles and over the same impact velocity range. The nature of ballistic damage evaluated indicates that the manner in which the armour is held during ballistic testing has a negligible influence on its performance at least when the mass of the plate is substantially higher than that of the projectile

The dynamic indentation behavior of steel at large depths of penetration

The objective of the present study is to investigate the dynamic indentation behavior of steel plate material when impacted by ogive-shaped projectiles and in particular under indentation conditions involving large depths of penetration (i.e., depth of penetration greater than projectile radius). Toward the above purpose, dynamic indentation of steel plates of thickness 20, 40, and 80 mm have been carried out using projectiles of diameter 6.2 and 20 mm, and over a range of impact velocities so as to attain depths of penetration in the range 1.4 to 3.6 times the projectile radius. The results indicate that the dynamic hardness, the plastic zone size, specific energy consumed in plastic deformation within the plastic zone, and the average plastic strain within the plastic zone increases continuously with increasing values of depth of penetration normalized by projectile radius. Certain subtle differences regarding the nature of plastic deformation between indentation at large and shallow depths of penetration are presented. However, on a macroscopic scale, the indentation mechanisms and processes are broadly similar and show continuity in terms of behavior across the whole penetration depth range

Shrimp farming by private enterprise- A case study

In view of the encouraging results shown by the research organisations of India and other countries in prawn culture on scientific methods, a commercial research and development project on prawn culture was established by the TATA Oil Mills Co. Ltd., at Pulicat. Experiments were conducted in aarthern ponds of size ranging from 0.4 to 1.25 ha- Stocking rates ranging from 6.5 to 15 prawns/mz were attempted and production to the tune of 0.5 to 1.0 tonne/ha/crop was achieved. Survival rate over 80% could be maintained in all the crops. An artificial feed formulated with shrimp meal, trash fish and vitamin mineral mix along with other usual ingredients, with a protein content of 40%, proved to be better than the other conventional feed. Effect of design of a pond, aging of pond, stocking density, stocking size and various hydrobioiogical parameters viz. salinity, dissolved oxygen and pH were also studied. The intensive stocking rate, the successful feed formula and the effective water managements adopted were the important reasons for the successful production of shrimps in this farm. The cost of production of 1 kg of shrimps considering the variable cost, varied from Ks 20.00 to 34.00 and thus a net revenue of Rg. 8000.00 to 20,000.00/ha/crop was achieved

Studies on species of Halimeda from Lakshadweep

Four Species of Halimeda viz. H. incrassata, H. opuntia. H simulans and H taenicola collected from Lakshadweep islands are described in detail

A Novel Design Approach for Low Speed Recovery of High Performance Fighter Aircraft

In this paper, a novel design approach for low-speed recovery of a high-performance fighter aircraft is presented. It is shown that the phugoid mode has an important bearing on the problem of low-speed departure. Based on the analysis of the phugoid mode trajectories, a novel low-speed protection algorithm is presented in this paper. The proposed low speed recovery is achieved in three phases. The first phase consists of detecting the incipient departure followed in the second phase by the application of suitable recovery controls and finally the third phase ends with the transfer of controls to the pilot. The design of the first and the third phase consist of choosing the correct trigger conditions which ensures safe recovery of the aircraft in all conditions. The proposed Automatic low speed recovery is triggered when the aircraft trajectory crosses a fixed boundary in the region spanned by the dynamic pressure and its rate of decrease. It is observed that this boundary is approximately a straight line, implying that it is equivalent to a forward prediction in time to indicate when the aircraft will reach the lowest controllable airspeed. This Automatic Low Speed Recovery with Forward Prediction (ALSR-FP) algorithm is found to be simpler than other existing design methods and effective in preventing low speed departure for a variety of pilot inputs that result in the aircraft losing airspeed leading to stall. In the second phase control inputs are chosen to align the velocity vector to the direction of local gravity. The recovery phase is considered complete after the aircraft reaches the dynamic pressure which is approximately 10 % higher than the minimum dynamic pressure for control. Performance of the ALSR-FP is demonstrated using the high-performance fighter aircraft ADMIRE model which has a delta wing configuration, canards and multiple redundant controls. It is also shown that the proposed algorithm can be easily implemented on board for any other fighter and civil aircraft