Experiments in identification and control of flexible-link manipulators

Interest in the study of flexible-link manipulators for space-based applications has risen strongly in recent years. Moreover, numerous experimental results have appeared for the various problems in the modeling, identification and control of such systems. Nevertheless, relatively little literature has appeared involving laboratory verification of tuning controllers for certain types of realistic flexible-link manipulators. Specifically flexible-link manipulators which are required to maintain endpoint accuracy while manipulating loads that are possibly unknown and varying as they undergo disturbance effects from the environment and workspace. Endpoint position control of flexible-link manipulators in these areas are discussed, with laboratory setups consisting of one and two-link manipulators

SPECIFIED MOTION AND FEEDBACK CONTROL OF ENGINEERING STRUCTURES WITH DISTRIBUTED SENSORS AND ACTUATORS

This dissertation addresses the control of flexible structures using distributed sensors and actuators. The objective to determine the required distributed actuation inputs such that the desired output is obtained. Two interrelated facets of this problem are considered. First, we develop a dynamic-inversion solution method for determining the distributed actuation inputs, as a function of time, that yield a specified motion. The solution is shown to be useful for intelligent structure design, in particular, for sizing actuators and choosing their placement. Secondly, we develop a new feedback control method, which is based on dynamic inversion. In particular, filtered dynamic inversion combines dynamic inversion with a low-pass filter, resulting in a high-parameter-stabilizing controller, where the parameter gain is the filter cutoff frequency. For sufficiently large parameter gain, the controller stabilizes the closed-loop system and makes the L2-gain of the performance arbitrarily small, despite unknown-and-unmeasured disturbances. The controller is considered for both linear and nonlinear structural models

Middeck Active Control Experiment (MACE), phase A

A rationale to determine which structural experiments are sufficient to verify the design of structures employing Controlled Structures Technology was derived. A survey of proposed NASA missions was undertaken to identify candidate test articles for use in the Middeck Active Control Experiment (MACE). The survey revealed that potential test articles could be classified into one of three roles: development, demonstration, and qualification, depending on the maturity of the technology and the mission the structure must fulfill. A set of criteria was derived that allowed determination of which role a potential test article must fulfill. A review of the capabilities and limitations of the STS middeck was conducted. A reference design for the MACE test article was presented. Computing requirements for running typical closed-loop controllers was determined, and various computer configurations were studied. The various components required to manufacture the structure were identified. A management plan was established for the remainder of the program experiment development, flight and ground systems development, and integration to the carrier. Procedures for configuration control, fiscal control, and safety, reliabilty, and quality assurance were developed

Experimental Verification of Attitude Control Techniques for Slew Maneuvers of Flexible Spacecraft

The article of record as published may be found at http://dx.doi.org/10.2514/6.1992-4456This paper presents experimental verification of modern and classical control laws on flexible spacecraft structures. The Flexible Spacecraft Simulator at the Naval Postgraduate School is designed to test a variety of control theory on a two-dimensional representation of an antenna at the end of a low-frequency astromast. The Simulator represents motion about the pitch axis and is restricted to rotatation only. Control laws are implemented through a momentum wheel mounted on the rigid main body. Feedback is obtained through a rotary variable differential transformer (RVDT) which senses the body's rotation angle and a rate-gyro giving body rate. The analytical model contains the linearized equations of motion accounting for the flexible dynamics. Slewing maneuvers are conducted for positioning the main body by using proportional- derivative (PD), torque profiles and optimal controllers. No active control is applied to the flexible structure. A new technique for state estimation is developed for the optimal controller since the standard estimation methods prove to be unsatisfactory. In all cases, the experimental results are in close agreement with the analytical predictions. This paper presents experimental verification of modern and classical control laws on flexible spacecraft structures. The Flexible Spacecraft Simulator at the Naval Postgraduate School is designed to test a variety of control theory on a two-dimensional representation of an antenna at the end of a low-frequency astromast. The Simulator represents motion about the pitch axis and is restricted to rotatation only. Control laws are implemented through a momentum wheel mounted on the rigid main body. Feedback is obtained through a rotary variable differential transformer (RVDT) which senses the body's rotation angle and a rate-gyro giving body rate. The analytical model contains the linearized equations of motion accounting for the flexible dynamics. Slewing maneuvers are conducted for positioning the main body by using proportional- derivative (PD), torque profiles and optimal controllers. No active control is applied to the flexible structure. A new technique for state estimation is developed for the optimal controller since the standard estimation methods prove to be unsatisfactory. In all cases, the experimental results are in close agreement with the analytical predictions. This paper presents experimental verification of modern and classical control laws on flexible spacecraft structures. The Flexible Spacecraft Simulator at the Naval Postgraduate School is designed to test a variety of control theory on a two-dimensional representation of an antenna at the end of a low-frequency astromast. The Simulator represents motion about the pitch axis and is restricted to rotatation only. Control laws are implemented through a momentum wheel mounted on the rigid main body. Feedback is obtained through a rotary variable differential transformer (RVDT) which senses the body's rotation angle and a rate-gyro giving body rate. The analytical model contains the linearized equations of motion accounting for the flexible dynamics. Slewing maneuvers are conducted for positioning the main body by using proportional- derivative (PD), torque profiles and optimal controllers. No active control is applied to the flexible structure. A new technique for state estimation is developed for the optimal controller since the standard estimation methods prove to be unsatisfactory. In all cases, the experimental results are in close agreement with the analytical predictions. This paper presents experimental verification of modern and classical control laws on flexible spacecraft structures. The Flexible Spacecraft Simulator at the Naval Postgraduate School is designed to test a variety of control theory on a two-dimensional representation of an antenna at the end of a low-frequency astromast. The Simulator represents motion about the pitch axis and is restricted to rotatation only. Control laws are implemented through a momentum wheel mounted on the rigid main body. Feedback is obtained through a rotary variable differential transformer (RVDT) which senses the body's rotation angle and a rate-gyro giving body rate. The analytical model contains the linearized equations of motion accounting for the flexible dynamics. Slewing maneuvers are conducted for positioning the main body by using proportional- derivative (PD), torque profiles and optimal controllers. No active control is applied to the flexible structure. A new technique for state estimation is developed for the optimal controller since the standard estimation methods prove to be unsatisfactory. In all cases, the experimental results are in close agreement with the analytical predictions

Proceedings of the Workshop on Computational Aspects in the Control of Flexible Systems, part 2

The Control/Structures Integration Program, a survey of available software for control of flexible structures, computational efficiency and capability, modeling and parameter estimation, and control synthesis and optimization software are discussed

Technology for large space systems: A bibliography with indexes (supplement 19)

This bibliography lists 526 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1988 and June 30, 1988. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems

Technology for large space systems: A bibliography with indexes (supplement 17)

This bibliography lists 512 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1987 and June 30, 1987. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems