Showing papers by "Andrew A. Goldenberg published in 2002"

Control system design for a dielectric elastomer actuator: the sensory subsystem

Abstract: The development of a sensory subsystem for use in the position control of a dielectric elastomer transducer (DET) is reported. In this study, the dielectric elastomer serves as both a source of sensory feedback and as the primary actuator. Specifically, stretched film DETs are considered to test the sensory subsystem. The capacitance of the film is measured in real-time using a low-voltage carrier signal that is superimposed on the control signal for actuation of the film. The relationship between the capacitance of the DET and applied voltage is presented for operating conditions outside of the elastic-buckling mode. The inference of strain made by the sensory subsystem is compared to that measured from digital images of the DET taken during operation and close correlation between the two measurements is confirmed. The capacitance measured during operation within the elastic-buckling mode shows a surprising drop under conditions of low frequency excitation and aged carbon grease electrodes. The measured capacitance in the elastic-buckling mode shows a dramatic increase during high-frequency excitation and with newly fabricated carbon grease electrodes.

Robust damping control of mobile manipulators

Abstract: A novel robust control technique, robust damping control (RDC), is introduced. An RDC controller is further developed for the motion control of a mobile manipulator subject to kinematic constraints. The knowledge of dynamic parameters of the mobile manipulator is assumed to be completely unknown. The proposed RDC controller is capable of disturbance-rejection in the presence of unknown bounded disturbance, without requiring the knowledge of its bound. The stability of the closed-loop system is guaranteed. The controller has a simple structure and can be easily implemented in applications. Experimental tests on a 2-DOF robotic manipulator illustrate that the proposed control is significantly better than conventional robust control.

Friction compensation with estimated velocity

Abstract: The problem of friction compensation at very low velocity is investigated experimentally. Two published friction compensation strategies, based on two well-known friction models, are evaluated experimentally on a direct drive robot arm. One is an adaptive nonlinear dynamic friction compensation method using the LuGre friction model, and the other is a decomposition-based friction compensation method based on a friction model parameter linearization approach. In the experiments, a new velocity estimation method is implemented. The method significantly improves the effectiveness of friction compensation for all tested methods.

Micromachined L-switching matrix

Abstract: Explosion in Internet applications has stimulated active research activities in expanding the capability of the current telecommunication networks. These activities include implementing faster electronics to process the higher data bit rates, or developing wavelength division multiplexing (WDM) techniques, and novel optical networks components to increase the information carrying capacity of the optical networks. As the data bit rates increases, it will become increasingly difficult to implement an electronic switching fabric solution. It is known that the information carrying laser beams should be dealt with at the optical level. One of most promising optical network components is micromachined optical cross connect switches. We present a new crossbar switching design methodology that decreases the number of mirrors and electrodes needed while maintaining the same non-blocking port switching capability. More importantly, this new architecture also reduces the distance of free-space propagation of light beams, thus reducing the loss due to Guassian-beam divergence during free-space propagation of light.

Modal force based input shaper for vibration suppression of flexible payloads

Abstract: Input shaping is a simple but effective method for vibration reduction of linear flexible systems. When systems exhibit nonlinear dynamics, the performance of an input shaper may be degraded. In this paper, a new shaper design scheme is developed for a nonlinear system which consists of a rigid robotic manipulator and a flexible sheet metal payload being grasped at several points by the robot gripper. The new scheme utilizes a parallel shaper structure based on the modal forces of payload vibration. A feedforward/feedback control law is also presented to drive the system to follow its shaped trajectory and to stabilize it at its desired position. Simulation results of a rest-to-rest robot motion control illustrate improved performance of the proposed input shaper, and verify the effectiveness of the control strategy.

An expert system for generation of anti-G control schedule for jet fighter pilots

Abstract: The high maneuverability of modern jet fighters often subjects the pilots to high G z acceleration. One of the adverse effects of G z acceleration is the G -induced loss of consciousness. The current protection scheme includes a pressure mask that supplies the pilots with nominal positive pressure breathing and a nominal pressurized G -suit. This paper presents a novel approach based on a combination of expert knowledge, pilots' anthropometric and physiologic data to generate control schedules of the G -suit and mask pressures of jet fighter pilots.

A low-voltage electrostatically actuated MEMS scanner for in vivo biomedical imaging

Abstract: With the inherent advantages of micromachining technologies such as small size, small mass, low cost, low power consumption and high reliability, there will be radical changes to biomedical devices and how clinical diagnoses are made. One of the most promising applications of microtechnologies is in the biomedical field. This paper presents a low-voltage high-torque MEMS 2D scanner well suited for in vivo biomedical imaging.

Simulation of Contact Interaction of Nanometer Objects Pushing Using AFM Cantilever as Manipulator

Abstract: This paper deals with contact interactions when the atomic force microscopy (AFM) cantilever is used as the manipulation tool for nanometer scale objects pushing. The AFM cantilever is modeled as a three-dimensional force transducer. It can transfer the three-dimensional deflection signals measured by the detection system into threedimensional force signals. The Johnson-Kendall-Roberts (JKR) contact model, which is selected to describe the contact interactions, is linearized by spring-damping systems. System parameters that may have an effect on the system dynamics are investigated by computer simulation.