National Aerospace Laboratories

About: National Aerospace Laboratories is a facility organization based out in Bengaluru, India. It is known for research contribution in the topics: Coating & Corrosion. The organization has 1838 authors who have published 2349 publications receiving 36888 citations.

Guidance and control law for automatic landing flight experiment of reentry space vehicle

Abstract: An automatic landing flight experiment with a sub-scale model is being prepared for a planned future reentry space vehicle by the National Aerospace Laboratory and the National Space Development Agency of Japan. The sub-scale model is dropped from a helicopter at a 1500m altitude, and, controlled by a n on-board navigation, guidance, and control system, it automatically lands on a lOOOm runway. This paper discusses preliminary study results obtained from numerical simulation by the National Aerospace Laboratory. The guidance and control law was designed using a multiple delay model and multiple design point approach (MDM/MDP). Control system robustness against uncertain and time varying dynamics is especially considered in this approach. The control performances are evaluated with appropriately defined quadratic indices of tracking error. Simple control structures are assumed and parameters are obtained with numerical optimization. The approach was successfully applied to the design, and feasibility of the experiment has been verified with numerical simulations.

Target geo-localization based on camera vision simulation of UAV

Abstract: This paper presents a simulation study on estimating the Geo-Location of a target based on multiple image of the target taken from a gimbaled camera mounted on a unmanned aerial vehicle (UAV), which orbits around the target with a radius such that the target is always in the field of camera vision. The Camera Vision Simulation of the UAV is implemented by using an ortho Geo-TIFF (Geo-Spatial Tagged Information File Format) as imagery reference, positional and attitude attributes of UAV, Gimbal and Camera and internal characteristic of the simulated Camera. Target is localized using the simulation images taken from multiple bearing waypoints by applying the Geo-Location algorithm using the simulation parameters as reference. For improving the accuracy of the estimation, error reduction techniques like true average, moving average and recursive least square are also suggested and implemented.

Fatigue de-bond growth in adhesively bonded single lap joints

Abstract: The fatigue de-bond growth studies have been conducted on adhesively bonded lap joint specimens between aluminium and aluminium with Redux-319A adhesive with a pre-defined crack of 3 mm at the bond end. The correlations between fracture parameters and the de-bond growth data are established using both numerical and experimental techniques. In the numerical method, geometrically non-linear finite element analyses were carried out on adhesively bonded joint specimen for various de-bond lengths measured from the lap end along the mid-bond line of the adhesive. The finite element results were post processed to estimate the SERR components GI and GII using the Modified Virtual Crack Closure Integral (MVCCI) procedure. In experimental work, specimens were fabricated and fatigue de-bond growth tests were conducted at a stress ratio R = − 1. The results obtained from both numerical analyses and testing have been used to generate de-bond growth curve and establish de-bond growth law in the Paris regime for such joints. The de-bond growth rate is primarily function of mode-I SERR component GI since the rate of growth in shear mode is relatively small. The value of Paris exponent m is found to be 6.55. The high value of de-bond growth exponent in Paris regime is expected, since the adhesive is less ductile than conventional metallic materials. This study is important for estimating the life of adhesively bonded joints under both constant and variable amplitude fatigue loads.

The control of bearing stiffness using shape memory

Abstract: The problem addressed in this paper is the control of the effective stiffness of a bearing pedestal by means of a series of shape memory alloy wires. The bearing is mounted on elastomer O-rings whose preload (and hence stiffness) is controlled by a set of shape memory allow wires. In the first part of the paper a discussion of the rig design is given together with the predictive calculations of performance. These predictions are then compared with measurement taken from the rig. Steady state and transient solutions are examined in order to ascertain the likely requirements in terms of heating and cooling rates. Having established the viability of this technology, options for extending the design to control stiffness in both orthogonal directions are discussed together with an assessment of the future problems and potential benefits of extending this study.