COMBINED SENSING AND ACTUATION: A NEW CONTROL LABORATORY EXPERIMENT

Abstract This paper describes a new control experiment developed for Mechanical Engineering undergraduate students. The experiment with a Shape Memory Alloy (SMA) actuated robotic arm is designed for the senior undergraduate laboratory (ME4006) in the Department of Mechanical Engineering at Virginia Tech. ME4006 is designed to provide the students with experience in experimental investigation of mechanical engineering systems. In designing this control experiment it was intended for the students to have a hands-on experiment with smart materials. Furthermore, students learn about control problems and limitations of theses materials along with sensing and actuation advantages of the SMAs. The experiment uses a problem solving approach; students are not given a procedure to follow for conducting the experiment. The problem is described in a memorandum to the students from a supervisor, who defines the purpose of the problem and defines the audience for the report. Background As smart materials are changing the practice of Engineering, providing undergraduate engineering students with experiences with these materials has become necessary. To address the educational needs, several engineering departments have developed elective courses or laboratory experiments on smart materials. California State University at Fullerton, for example, has recently established an Intelligent Systems Laboratory to provide Mechanical Engineering students with hands-on experience on integrated design and manufacturing of intelligent systems ME4006 (Experimenta

A temperature-based controller for a shape memory alloy actuator”.

This paper presents a robust nonlinear control that use

IMECE2005-81355 A MAGNETOREOLOGICAL VIBRATION ISOLATOR FOR HYDRAULIC HYBRID VEHICLES

ABSTRACT This paper presents the results of vibration isolation analysis for the pump/motor component of hydraulic hybrid vehicles (HHV). The hybrid subsystem can potentially improve the fuel efficiency of the vehicle by recovering some of the energy that is otherwise wasted in friction brakes. High pressure hydraulic fluid "assists" the engine in the initial acceleration period. Noise and vibration are an issue with these systems due to the variable hydraulic loads that are applied to the regenerative hybrid element. This study looks into the possibility of reducing the transmitted noise and vibration to the vehicle's chassis by using smart magnetorheological (MR) dampers. MR dampers utilize MR fluid which is made of pure iron particles suspended in a carrier fluid. MR fluids deliver variable yield stress under the effect of a controllable electromagnetic field. To this end, an MR damper is modeled and simulated. In the simulation both shock and vibration loads are considered. The simulation results are compared with the performance of regular elastomer isolators. It is shown that the MR damper can effectively reduce the vibration for different working cycles of the regenerative system. INTRODUCTION Over the past decade, magnetorheological (MR) fluids have been researched and applied in many engineering disciplines. MR fluids were invented by Jacob Rabinow in early 1940's and have attracted attention due to their unique properties. MR fluids are made of micron-sized iron particles that are suspended in a carrier liquid. These controllable fluids can produce variable yield stresses under the effect of magnetic fields. In the presence of a magnetic field, the particles form chain clusters that resist the fluid flow and as a result the fluid becomes semi-solid with a yield stress

Heat transfer analysis of shape memory alloy actuators

ABSTRACT In recent years, shape memory alloys (SMAs) have become widely used in engineering applications due to their simplicity in use and high power density. These smart materials are characterized by their unique temperature dependent phase transformations. An accurate heat transfer model is of the utmost importance for modeling the SMA actuator dynamics. This is due to the SMA constitutive and phase kinetic behaviors being directly dependent on the heat transfer model. The research shown in this paper was conducted to investigate the adequacy of the exiting heat transfer models for SMA wire actuators. Particularly, the convection heat transfer for SMA wires with diameter of a few hundred micrometers is studied. To this end, an SMA wire actuating a dead weight was used to experimentally determine how the heat transfer coefficient varies during transformation at varying levels of applied current. These results are then compared to several existing heat transfer models. In the experiments, the temperature of the wire was measured along with the strain and stress of the SMA wire. A detailed discussion of the theoretical models and experimental findings is presented in this paper

IMECE2006-13777 A PROBLEM SOLVING APPROACH FOR TEACHING ENGINEERING LABORATORIES

ABSTRACT This paper presents the redevelopment method and process of the laboratory experiments for the Mechanics and Vibration Laboratory, MIME3390, in the Mechanical, Industrial, and Manufacturing Engineering Department at the University of Toledo. The redevelopment objective was to transform the learning process from a subject-based learning to a problem-solving learning. Particular objective was to provide the students with more hands-on experience and to challenge them by requesting the procedure for each laboratory experiment to be designed and carried out by each group of students. This senior level laboratory course consists of experiments in deformable solid mechanics including stress and deflection analysis, fatigue life evaluation, stability and mechanical vibration. Prerequisite courses for this laboratory are Mechanical Design I and Mechanical Vibrations. In line with the program objectives of the department, the following list of objectives has been defined for this course: "Upon successful completion of this course, the students should have: (1) become knowledgeable in the use of standard instrumentation for static and dynamic structural testing, such as strain gages, load frames, impact hammers, and spectrum analyzers; (2) reinforced material studied in previous mechanics and vibrations courses; (3) improved data analysis skills, and (4) further developed laboratory and technical writing skills." Prior to this redevelopment, as part of the subjectbased approach, a classroom lecture preceded each laboratory session. The lecture consisted of the review of the theory pertaining to each experiment to help students refresh their knowledge on the subject. Additionally the description and procedure of the laboratory experiment was covered during this lecture. Prior to each class, the lecture notes, along with the laboratory procedures, were posted on the course website. The step-by-step instructions for each experiment were provided to assist the students in setting up and conducting each experiment. Throughout the semester, eleven experiments were performed. The students wrote individual reports on the experiments consisting of a summary of the acquired data, data analysis, and observations. However, due to the number of students and limited number of lab sessions it was difficult to provide the students with the real hands-on experience with the instrumentation and lab setup. As a result, during the lab the student mostly collected data according to the lab procedure and compiled a report that sometimes was inspired by samples of reports written by former students