Sensor/Actuator Selection for the Constrained Variance Control Problem

The problem of designing a linear controller for systems subject to inequality variance constraints is considered. A quadratic penalty function approach is used to yield a linear controller. Both the weights in the quadratic penalty function and the locations of sensors and actuators are selected by successive approximations to obtain an optimal design which satisfies the input/output variance constraints. The method is applied to NASA's 64 meter Hoop-Column Space Antenna for satellite communications. In addition the solution for the control law, the main feature of these results is the systematic determination of actuator design requirements which allow the given input/output performance constraints to be satisfied

Parametric Design of Minimal Mass Tensegrity Bridges Under Yielding and Buckling Constraints

This paper investigates the use of the most fundamental elements; cables for tension and bars for compression, in the search for the most efficient bridges. Stable arrangements of these elements are called tensegrity structures. We show herein the minimal mass arrangement of these basic elements to satisfy both yielding and buckling constraints. We show that the minimal mass solution for a simply-supported bridge subject to buckling constraints matches Michell's 1904 paper which treats the case of only yield constraints, even though our boundary conditions differ. The necessary and sufficient condition is given for the minimal mass bridge to lie totally above (or below) deck. Furthermore this condition depends only on material properties. If one ignores joint mass, and considers only bridges above deck level, the optimal complexity (number of elements in the bridge) tends toward infinity (producing a material continuum). If joint mass is considered then the optimal complexity is finite. The optimal (minimal mass) bridge below deck has the smallest possible complexity (and therefore cheaper to build), and under reasonable material choices, yields the smallest mass bridge.Comment: 56 pages, 25 figures, 13 tables. Internal Report 2014-1: University of California, San Diego, 201

Closed-form solutions for linear regulator design of mechanical systems including optimal weighting matrix selection

Vibration in modern structural and mechanical systems can be reduced in amplitude by increasing stiffness, redistributing stiffness and mass, and/or adding damping if design techniques are available to do so. Linear Quadratic Regulator (LQR) theory in modern multivariable control design, attacks the general dissipative elastic system design problem in a global formulation. The optimal design, however, allows electronic connections and phase relations which are not physically practical or possible in passive structural-mechanical devices. The restriction of LQR solutions (to the Algebraic Riccati Equation) to design spaces which can be implemented as passive structural members and/or dampers is addressed. A general closed-form solution to the optimal free-decay control problem is presented which is tailored for structural-mechanical system. The solution includes, as subsets, special cases such as the Rayleigh Dissipation Function and total energy. Weighting matrix selection is a constrained choice among several parameters to obtain desired physical relationships. The closed-form solution is also applicable to active control design for systems where perfect, collocated actuator-sensor pairs exist

Control by model error estimation

Modern control theory relies upon the fidelity of the mathematical model of the system. Truncated modes, external disturbances, and parameter errors in linear system models are corrected by augmenting to the original system of equations an 'error system' which is designed to approximate the effects of such model errors. A Chebyshev error system is developed for application to the Large Space Telescope (LST)

Placing dynamic sensors and actuators on flexible space structures

Input/Output Cost Analysis involves decompositions of the quadratic cost function into contributions from each stochastic input and each weighted output. In the past, these suboptimal cost decomposition methods of sensor and actuator selection (SAS) have been used to locate perfect (infinite bandwidth) sensor and actuators on large scale systems. This paper extends these ideas to the more practical case of imperfect actuators and sensors with dynamics of their own. NASA's SCOLE examples demonstrate that sensor and actuator dynamics affect the optimal selection and placement of sensors and actuators

Linearized dynamical model for the NASA/IEEE SCOLE configuration

The linearized equation of motion for the NASA/IEEE SCOLE configuration are developed. The derivation is based on the method of Lagrange and the equations are assembled into matrix second order form

Testing and evaluation of Dacron parachute elements after exposure to ethylene oxide and simulated package loading and heat cycle

Testing Dacron parachute components and assemblies by exposure to ethylene oxide sterilization, simulated package loading, and heat cycl

Using radio telemetry in sauger spawning studies in Douglas Reservoir, Tennessee

Twenty-two sauger were tagged with externally-attached radio transmitters in December 1990 and February 1991 to determine spawning movements in Douglas Reservoir. The tagged fish began a concerted movement toward the headwaters of the reservoir in late February when water temperatures were 8-9 C. By March 30, five tagged male sauger were staging near the confluence of the Nolichucky and French Broad Rivers (FBRM 68.8). These fish moved upstream to an area just below Rankin Bridge (FBRM 71.2) on April 5, where they remained for approximately 10 days. Gill-netting and electro-fishing techniques were used to sample fish in the spawning area from April 5 to April 15. Several sauger and saugeye males in spawning condition and one gravid female sauger were caught, indicating that spawning was taking place. Stizostedion spp. eggs were collected from the area using an epibenthic egg sled, a larval drift net, and a larval kick seine. A 10-m wide strip approximately 300-m long stretching between the two Rankin Bridges was the only major spawning site found. The substrate in the spawning area consisted of a mix of cobble, pebble, gravel, coarse sand, and boulder. During the interval of spawning activities, current velocity near the substrate was 18-20 cm/sec and temperatures ranged from 14.0-17.2 C. Cove rotenone data from the Tennessee Wildlife Resources Agency indicated that the sauger spawn for 1991 was not as successful as the spawn of 1990. In 1990, samples contained 8.1 young-of-year sauger per hectare while only a single young-of-year sauger was collected in 1991