Hardware Implementation of the Logarithm Function using Improved Parabolic Synthesis

This thesis presents a design that approximates the fractional part of the based two logarithm function by using Improved Parabolic Synthesis including its CMOS VLSI implementations. Improved Parabolic Synthesis is a novel methodology in favor of implementing unary functions e.g. trigonometric, logarithm, square root etc. in hardware. It is an evolved approach from Parabolic Synthesis by combining it with Second-Degree Interpolation. In the thesis, the design explores a simple and parallel architecture for fast timing and optimizes wordlengths in computing stages for a small design. The error behavior of the design is described and char- acterized to meet the desired error metrics. This implementation is compared to other approaches e.g. Parabolic Synthesis and CORDIC using 65nm standard cell libraries and it is proved to have better performance in terms of smaller chip area, lower dynamic power, and shorter critical path

Complexity Reduction in the CORDIC Algorithm by using MUXes

Nowadays, the CORDIC algorithm plays an important role to deal with the non-linear functions in hardware. In this thesis, a novel methodology is described to reduce the complexity in an unrolled CORDIC architecture, which gives higher speed, lesser area, and lower power consumption. That is, MUXes are used to replace adder stages. Five different unrolled CORDIC architectures have been implemented in ASIC using a 65nm CMOS technology with Low Power High V_T transistors. The area, computational speed, accuracy, error behavior, and power consumption have been analyzed. The design aim is to reduce the power consumption, which is more and more important depending on the area. As a result the area and power consumption get 7.9% lower and 27.2% lower separately, and the speed is 22.9% higher compared to the original unrolled CORDIC architecture

Nonlinear maneuver autopilot for the F-15 aircraft

A methodology is described for the development of flight test trajectory control laws based on singular perturbation methodology and nonlinear dynamic modeling. The control design methodology is applied to a detailed nonlinear six degree-of-freedom simulation of the F-15 and results for a level accelerations, pushover/pullup maneuver, zoom and pushover maneuver, excess thrust windup turn, constant thrust windup turn, and a constant dynamic pressure/constant load factor trajectory are presented

Analysis of dual-reflector antennas with a reflectarray as subreflector

In this paper, a modular technique is described for the analysis of dual-reflector antennas using a reflectarray as a subreflector. An antenna configuration based on a sub-reflectarray and a parabolic main reflector provides better bandwidth than a single reflectarray, and has a number of advantages compared with a conventional dual-reflector antenna. Examples include the possibility of beam shaping by adjusting the phase on the sub-reflectarray, and potential capabilities to scan or reconfigure the beam. The modular technique implemented for the antenna analysis combines different methods for the analysis of each part of the antenna. First, the real field generated by the horn is considered as the incident field on each reflectarray element. Second, the reflectarray is analyzed with the same technique as for a single reflectarray, i.e., considering local periodicity and the real angle of incidence of the wave coming from the feed for each periodic cell. Third, the main reflector is analyzed using the Physical Optics (PO) technique, where the current on the reflector surface is calculated by summing the radiation from all the reflectarray elements. Finally, the field is calculated on a rectangular periodic mesh at a projected aperture, and then a time-efficient fast Fourier transform (FFT) algorithm is used to compute the radiation pattern of the antenna. The last step significantly improves the computational efficiency. However, it introduces a phase error, which reduces the accuracy of the radiation patterns for radiation angles far away from the antenna's axis. The phase errors have been evaluated for two integration apertures. It has been demonstrated that accurate patterns are obtained in an angular range of plusmn6deg, which is sufficient for large reflectors. The method of analysis has been validated by comparing the results with simulations obtained from GRASP8. Finally, the theoretical beam-scanning performance of the antenna is analyzed

Design Specification for a Thrust-Vectoring, Actuated-Nose-Strake Flight Control Law for the High-Alpha Research Vehicle

Specifications for a flight control law are delineated in sufficient detail to support coding the control law in flight software. This control law was designed for implementation and flight test on the High-Alpha Research Vehicle (HARV), which is an F/A-18 aircraft modified to include an experimental multi-axis thrust-vectoring system and actuated nose strakes for enhanced rolling (ANSER). The control law, known as the HARV ANSER Control Law, was designed to utilize a blend of conventional aerodynamic control effectors, thrust vectoring, and actuated nose strakes to provide increased agility and good handling qualities throughout the HARV flight envelope, including angles of attack up to 70 degrees

State-dependent Riccati equation feedback stabilization for nonlinear PDEs

The synthesis of suboptimal feedback laws for controlling nonlinear dynamics arising from semi-discretized PDEs is studied. An approach based on the State-dependent Riccati Equation (SDRE) is presented for 2 and ∞ control problems. Depending on the nonlinearity and the dimension of the resulting problem, offline, online, and hybrid offline-online alternatives to the SDRE synthesis are proposed. The hybrid offline-online SDRE method reduces to the sequential solution of Lyapunov equations, effectively enabling the computation of suboptimal feedback controls for two-dimensional PDEs. Numerical tests for the Sine-Gordon, degenerate Zeldovich, and viscous Burgers’ PDEs are presented, providing a thorough experimental assessment of the proposed methodology