Engineering topics

Frisch, H. P.

Publications and source records attributed to Frisch, H. P..

At least 19 records

NASA NTRS1994

Technology transfer of operator-in-the-loop simulation

The technology developed for operator-in-the-loop simulation in space teleoperation has been applied to Caterpillar's backhoe, wheel loader, and off-highway truck. On an SGI workstation, the simulation integrates computer modeling of kinematics and dynamics, real-time computational and visualization, and an interface with the operator through the operator's console. The console is interfaced with the workstation through an IBM-PC in which the operator's commands were digitized and sent through an RS-232 serial port. The simulation gave visual feedback adequate for the operator in the loop, with the camera's field of vision projected on a large screen in multiple view windows. The view control can emulate either stationary or moving cameras. This simulator created an innovative engineering design environment by integrating computer software and hardware with the human operator's interactions. The backhoe simulation has been adopted by Caterpillar in building a virtual reality tool for backhoe design.

Yae, K. H.↗

NASA NTRS1991

Integrated Analysis Capability Program

Integrated Analysis Capability (IAC) software system intended to provide highly effective, interactive analysis tool for integrated design of large structures. Supports needs of engineering analysis groups concerned with interdisciplinary problems. Developed to serve as software interface between computer programs from fields of structures, thermodynamics, controls, and dynamics of systems on one hand and executive software system and data base on other hand to yield highly efficient multi-disciplinary system. Special attention given to such users' requirements as handling data and online assistance with operational features and ability to add new modules of user's choice at future date. Written in FORTRAN 77.

Vos, R. G.↗

NASA NTRS1990

Integrated Analysis Capability (IAC)

IAC system interactive tool for robotics design, integrating common database with programs from fields of structures, thermodynamics, controls and system dynamics. Written in FORTRAN 77.

Frisch, H. P.↗

NASA NTRS1986

NASTRAN interfacing modules within the Integrated Analysis Capability (IAC) Program

The IAC program provides the framework required for the development of an extensive multidisciplinary analysis capability. Several NASTRAN related capabilities were developed which can all be expanded in a routine manner to meet in-house unique needs. Plans are to complete the work discussed herein and to provide it to the engineering community through COSMIC. Release is to be after the current IAC Level 2 contract work on the IAC executive system is completed and meshed with the interfacing modules and analysis capabilities under development at the GSFC.

Frisch, H. P.↗

NASA NTRS1986

Numerical Methods for Classical Sampled-System Analysis

SAMSAN provides control-system analyst with self-consistent computer algorithms that support large-order control-system design and evaluation studies. Emphasizes sampled-system analysis. SAMSAN reduces burden on analyst by providing set of algorithms well tested and documented and readily integrated for solving control-system problems.

Frisch, H. P.↗

NASA NTRS1986

NASTRAN/DISCOS/SAMSAN DMAP Bridging Program

Design of controller for flexible structure must incorporate flexible body data in format compatible with design and performance evaluation methods. Control designer works with several different programs to obtain all data and capabilities needed. Three programs for design and analysis of flexible structure controllers integrated.

Frisch, H. P.↗

NASA NTRS1985

Dynamic Simulation and Stability Analysis

Dynamic Interaction Simulation of Controls and Structure (DISCOS) program developed for dynamic simulation and stability analysis of passive and actively controlled spacecraft. In use of DISCOS, physical system undergoing analysis generally described as cluster of contiguous flexible structures (bodies) that comprise mechanical system, such as spacecraft.

Frisch, H. P.↗

NASA NTRS1984

Modern Numerical Methods for Classical Sampled System Analysis-SAMSAN

SAMSAN aids control-system analyst by providing self-consistent set of computer algorithms that support large-order control-system design and evaluation studies, with emphasis placed on sampled system analysis. Program provides set of algorithms readily integrated for solving control-system problems.

Frisch, H. P.↗

NASA NTRS1984

A passively controlled appendage deployment system for the San Marco D/L spacecraft

The analytical simulation of deployment dynamics of these two axis concepts as well as the evolution of practical designs for the add on deployable inertia boom units is described. With the boom free to swing back in response to Coriolis forces as well as outwards in response to centrifugal forces, the kinematics of motion are complex but admit the possibility of absorbing deployment energy in frictional or other damping devices about the radial axis, where large amplitude motions can occur and where the design envelope allows more available volume. An acceptable range is defined for frictional damping for any given spin rate. Inadequate damping allows boom motions which strike the spacecraft; excessive damping causes the boom to swing out and latch with damaging violence. The acceptable range is a design parameter and must accommodate spin rate tolerance and also the tolerance and repeatability of the damping mechanisms.

Lang, W. E.↗

NASA NTRS1983

Development and use of an integrated analysis capability

The paper describes a multi-discipline integrated analysis capability, designed to aid the engineering community in coupling of existing modules and in handling of the associated software and data. This capability consists of an executive program which manages tasks and data, a number of technical modules, graphics and special purpose modules, inter-module data flow interfaces, and associated user documentation. The current implementation provides specific modules and coupled solution paths for the thermal, structures and controls technologies. However, the system has been designed to serve also as a framework into which user groups may incorporate other modules and technologies. Details of the system architecture are discussed, in the context of the major design decisions and the software development and usage experience. The paper provides a brief discussion of some other integrated systems which are available or under development.

Vos, R. G.↗

NASA NTRS1982

Analysis of Feedback Control Systems

BLOCK IT implements algorithm that obtains reduced-order feedback control equations for use in both time and frequency domain analysis. BLOCK IT computes real nonsingular similarity-transformation matrix-reduces real nonsymmetric matrix to block-diagonal form; each block is real quasi-upper triangular matrix. Algorithm works with defective and derogatory matrices. If program fails, algorithm generates data output used as guide for reformulation of mathematical equations that lead to ill-conditioned matrix not block-diagonalized.

Frisch, H. P.↗

NASA NTRS1982

IAC control system analysis development

The MultiOptimal Differential Equation Language (MODEL) is described. It provides a means for generating numerical solutions to systems of differential equations using a digital computer. The notation of this language is similar to that usually used in describing physical systems by differential equations. Thus, the learning process is simplified, programming becomes easier, and debugging is more readily accomplished. Programs written in the MultiOptimal Differential Equation Language are machine translated into FORTRAN 4 code which is optimal in several respects. The interactive version of MODEL makes use of interactive system routines so that the user may observe the solution as it is being generated and interact with the program in a manner similar to that associated with analog simulation. The DISCOS-Control version of the MODEL simulation language is used to describe the control system for a plant which is modelled by the DISCOS program. DISCOS plant variables may be referenced in the control system description and all the sensor signals, coupling torques, momentum devices and external loads are automatically linked to the DISCOS plant model.

Frisch, H. P.↗

NASA NTRS1981

Pitfalls and guidelines for the numerical evaluation of moderate-order system frequency response

The design and evaluation of a feedback control system via frequency response methods relies heavily upon numerical methods. In application, one can usually develop low order simulation models which for the most part are devoid of numerical problems. However, when complex feedback interactions, for example, between instrument control systems and their flexible mounting structure, must be evaluated, simulation models become moderate to large order and numerical problems become common. A large body of relevant numerical error analysis literature is summarized in a large language understandable to nonspecialists. The intent is to provide engineers using simulation models with an engineering feel for potential numerical problems without getting intertwined in the complexities of the associated mathematical theory. Guidelines are also provided by suggesting alternate state of the art methods which have good numerical evaluation characteristics.

Frisch, H. P.↗

NASA NTRS1981

Time and frequency domain analysis of sampled data controllers via mixed operation equations

Specification of the mathematical equations required to define the dynamic response of a linear continuous plant, subject to sampled data control, is complicated by the fact that the digital components of the control system cannot be modeled via linear ordinary differential equations. This complication can be overcome by introducing two new mathematical operations; namely, the operation of zero order hold and digial delay. It is shown that by direct utilization of these operations, a set of linear mixed operation equations can be written and used to define the dynamic response characteristics of the controlled system. It also is shown how these linear mixed operation equations lead, in an automatable manner, directly to a set of finite difference equations which are in a format compatible with follow on time and frequency domain analysis methods.

Frisch, H. P.↗

NASA NTRS1981

Reduced order feedback control equations for linear time and frequency domain analysis

An algorithm was developed which can be used to obtain the equations. In a more general context, the algorithm computes a real nonsingular similarity transformation matrix which reduces a real nonsymmetric matrix to block diagonal form, each block of which is a real quasi upper triangular matrix. The algorithm works with both defective and derogatory matrices and when and if it fails, the resultant output can be used as a guide for the reformulation of the mathematical equations that lead up to the ill conditioned matrix which could not be block diagonalized.

Frisch, H. P.↗

NASA NTRS1980

Equations of motion for coupled n-body systems

Computer program, developed to analyze spacecraft attitude dynamics, can be applied to large class of problems involving objects that can be simplified into component parts. Systems of coupled rigid bodies, point masses, symmetric wheels, and elastically flexible bodies can be analyzed. Program derives complete set of non-linear equations of motion in vectordyadic format. Numerical solutions may be printed out. Program is in FORTRAN IV for batch execution and has been implemented on IBM 360.

Frisch, H. P.↗

NASA NTRS1980

Interactive analysis program activity

The development of an analysis software system capable of performing interdisciplinary preliminary design analyses of large space structure configurations is discussed. Disciplines such as thermal, structures, and controls are to be integrated into a highly user oriented analysis capability. The key feature of the integrated analysis capability, a rapid and efficient system that will minimize solution turnaround time, is discussed.

Young, J. P.↗

NASA NTRS1980

Thermally induced response of flexible structures - A method for analysis

The phenomenon of a thermally induced spacecraft instability became apparent during the flight of the OGO-IV spacecraft in the late 1960s. The paper presents a generalized approach to the problem of obtaining a computationally practical simulation model for a thermally driven structure. The formulation is such that it can be utilized in a stand-along manner or be meshed into a general multibody simulation model such as that reported by Bodley et al. (1978). As presented, the formulation is restricted to the dynamic range for which linearized radiation is a valid assumption.

Frisch, H. P.↗