B. N. Agrawal

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Again, these quantities will be more sensitive if the moments of inertia are close than if they are widely spaced. For a vehicle with nominal inertias satisfying I1 D 2I3 and I2 D 1:5I3, and the 1% normalized inertia perturbations considered earlier, arctan ° can vary from 31.8 to 38.7 deg, a total range of 6.9 deg. Using Eqs. (13) and (14) together allows(More)
A Satellite Attitude Dynamics Simulator (SADS) has been developed to facilitate the research and development of spacecraft flight attitude control software at the Naval Postgraduate School in Monterey, CA. The simulator provides a real-time 3 degree of freedom (3DOF) synthetic spacecraft hardware-in-the-loop environment, that includes realistic angular(More)
For a large Adaptive Optics (AO) system such as a large Segmented Mirror Telescope (SMT), it is often difficult, although not impossible, to directly apply common Multi-Input Multi-Output (MIMO) controller design methods due to the computational burden imposed by the large dimension of the system model. In this paper, a practical controller design method is(More)
This paper discusses two optical beam control testbeds developed at the Spacecraft Research and Design Center, Naval Postgraduate School, to evaluate and develop control techniques for jitter and adaptive optics control. The first testbed, a Jitter Control Testbed is used to develop control techniques for optical beam jitter. In the second testbed, the(More)
This paper presents experimental results of vibration suppressicln of a flexible structure using a miniaturized digital controller, called Modular Control Patch (MCP). The h4CP employs a TIC30 digital signal processor and was developed by TRW for the United States Air Force for future space vibration control. In this research, the MCP is used to implement(More)
Space based bifocal relay mirrors are potentially an enabling/enhancing piece of any architecture making use of longrange laser propagation. Inherent in the bifocal concept is dual line of sight control. This is especially challenging in this space-based application due to spacecraft attitude control issues. This paper presents a summary ofthe research into(More)
A mode synthesis technique is presented for determining the normal modes. natural frequencies. and responses of three-dimensional complex structure with flexible joints. Lagrange's equations are used to develop the equations of motion of the structures. Based on this technique a computer program called MODSYN has been developed for both free-free and(More)
A comparative study of the robustness of various spacecraft body at t i tude control systems with structural flexibility is presented in this paper. The control systems examined are: (a) 3-Reaction Wheels (b) Body-fixed momentum wheel with offset thrusters (c) Skewed body-fixed momentum wheels with offset thrusters and (d) Body-fixed momentum wheel with two(More)