Analog controller based on sliding mode control for piezoelectric actuators

Today, the digital implementation of the controllers is mainly preferred from reprogrammability point of view. Many important control problems can be effectively solved using a digital architecture in conjunction with analog-to-digital (ADC) and/or digital-to-analog conversion (DAC). Digital solutions offer two very attractive advantages: (1)-promise to shorten design cycles, and (2)-provide the freedom to reprogram the design in simple ways. This ease-of-change stands in sharp contrast to the great effort required to redesign a typical hard-wired analog implementation. However, depending on the complexity of the plant and the degrees of freedom (DOF) to be controlled, digital implementation of an algorithm may be demanding due to the high computational power requirement to run in real time. The necessity for the acquisition of the analog signals on the other hand requires ADC and DAC conversions that compel extra conditions on the system. Hence, multi-DOF systems may require either diminish in the systems operation frequency or additional hardware to run the algorithm in parallel for each DOF. This work aims to develop an analog motion controller for single input single output (SISO) plants of complex nature. As the control algorithm, Sliding Mode Control (SMC) like the well known robust nonlinear controller is selected as a design framework. Originally designed as a system motion for dynamic systems whose essential open-loop behavior can be sufficiently modeled with ordinary differential equations, Sliding Mode Control (SMC) is one of the effective nonlinear robust control approaches that provide system invariance to uncertainties once the sliding mode motion is enforced in the system. An important aspect of sliding mode is the discontinuous nature of the control action, which switches between two values to move the system motion on so-called “sliding mode” that exist in a manifold and therefore often referred as variable structure control (VSC). The resulting feedback system is called variable structure system (VSS). The position tracking of the piezoelectric actuators (PEA) is selected as the test bed for the designed system. Piezoelectricity, the ability of the material to become strained due to an electric field, gives the possibility to user those materials as actuator in sub-micrometer domain for a range of applications. Piezoelectric effect is a crystalline effect, and therefore, piezoelectric actuators do not suffer from “stick slip” effect mainly caused by the friction between elements of a mechanical system. This property theoretically offers an unlimited resolution, and therefore piezoelectric actuators are already used in many applications to provide sub-micrometer resolution. Still the achievable resolution in practice can be limited by a number of other factors such as the piezo control amplifier (electronic noise), sensor (resolution, noise and mounting precision) and control electronics (noise and sensitivity to EMI). As a result of this work, we are aiming an analog controller for SISO systems and by the use of this controller, improvement on the tracking performance for the plant we are studying and decrease on the possible computational load on digital controllers is targeted

Large space structures and systems in the space station era: A bibliography with indexes

Bibliographies and abstracts are listed for 1219 reports, articles, and other documents introduced into the NASA scientific and technical information system between July 1, 1990 and December 31, 1990. The 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

Optical Coherence Tomography and Its Non-medical Applications

Optical coherence tomography (OCT) is a promising non-invasive non-contact 3D imaging technique that can be used to evaluate and inspect material surfaces, multilayer polymer films, fiber coils, and coatings. OCT can be used for the examination of cultural heritage objects and 3D imaging of microstructures. With subsurface 3D fingerprint imaging capability, OCT could be a valuable tool for enhancing security in biometric applications. OCT can also be used for the evaluation of fastener flushness for improving aerodynamic performance of high-speed aircraft. More and more OCT non-medical applications are emerging. In this book, we present some recent advancements in OCT technology and non-medical applications

ISMCR 1994: Topical Workshop on Virtual Reality. Proceedings of the Fourth International Symposium on Measurement and Control in Robotics

This symposium on measurement and control in robotics included sessions on: (1) rendering, including tactile perception and applied virtual reality; (2) applications in simulated medical procedures and telerobotics; (3) tracking sensors in a virtual environment; (4) displays for virtual reality applications; (5) sensory feedback including a virtual environment application with partial gravity simulation; and (6) applications in education, entertainment, technical writing, and animation

33rd Aerospace Mechanisms Symposium

The proceedings of the 33rd Aerospace Mechanisms Symposium are reported. JPL hosted the conference, which was held at the Pasadena Conference and Exhibition Center, Pasadena, California, on May 19-21, 1999. Lockheed Martin Missiles and Space cosponsored the symposium. Technology areas covered include bearings and tribology; pointing, solar array and deployment mechanisms; orbiter/space station; and other mechanisms for spacecraft

Proceedings of the NASA Conference on Space Telerobotics, volume 4

Papers presented at the NASA Conference on Space Telerobotics are compiled. The theme of the conference was man-machine collaboration in space. The conference provided a forum for researchers and engineers to exchange ideas on the research and development required for the application of telerobotic technology to the space systems planned for the 1990's and beyond. Volume 4 contains papers related to the following subject areas: manipulator control; telemanipulation; flight experiments (systems and simulators); sensor-based planning; robot kinematics, dynamics, and control; robot task planning and assembly; and research activities at the NASA Langley Research Center