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

Improving robustness of tuned vibration absorbers using shape memory alloys

Abstract. A conventional passive tuned vibration absorber (TVA) is effective when it is precisely tuned to the frequency of a vibration mode; otherwise, it may amplify the vibrations of the primary system. In many applications, the frequency often changes over time. For example, adding or subtracting external mass on the existing primary system results in changes in the system's natural frequency. The frequency changes of the primary system can significantly degrade the performance of TVA. To cope with this problem, many alternative TVAs (such as semiactive, adaptive, and active TVAs) have been studied. As another alternative, this paper investigates the use of Shape Memory Alloys (SMAs) in passive TVAs in order to improve the robustness of the TVAs subject to mass change in the primary system. The proposed SMA-TVA employs SMA wires, which exhibit variable stiffness, as the spring element of the TVA. This allows us to tune effective stiffness of the TVA to adapt to the changes in the primary system's natural frequency. The simulation model, presented in this paper, contains the dynamics of the TVA along with the SMA wire model that includes phase transformation, heat transfer, and the constitutive relations. Additionally, a PID controller is included for regulating the applied voltage to the SMA wires in order to maintain the desired stiffness. The robustness analysis is then performed on both the SMA-TVA and the equivalent passive TVA. For our robustness analysis, the mass of the primary system is varied by ± 30% of its nominal mass. The simulation results show that the SMA-TVA is more robust than the equivalent passive TVA in reducing peak vibrations in the primary system subject to change of its mass

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

This paper presents a robust nonlinear control that use

IMECE2003-42013 APPLICATION OF THE EXTENDED KALMAN FILTER TO CONTROL OF A SHAPE MEMORY ALLOY ARM

Abstract This paper presents a robust nonlinear control that uses a state variable estimator for control of a single degree of freedom rotary manipulator actuated by Shape Memory Alloy (SMA) wire. A model for SMA actuated manipulator is presented. The model includes nonlinear dynamics of the manipulator, a constitutive model of the Shape Memory Alloy, and the electrical and heat transfer behavior of SMA wire. The current experimental setup allows for the measurement of only one state variable which is the angular position of the arm. Due to measurement difficulties, the other three state variables, arm angular velocity and SMA wire stress and temperature, cannot be directly measured. A model-based state estimator that works with noisy measurements is presented based on the Extended Kalman Filter (EKF). This estimator predicts the state vector at each time step and corrects its prediction based on the angular position measurements. The estimator is then used in a nonlinear and robust control algorithm based on Variable Structure Control (VSC). The VSC algorithm is a control gain switching technique based on the arm angular position (and velocity) feedback and EKF estimated SMA wire stress and temperature. The state vector estimates help reduce or avoid the undesirable and inefficient overshoot problem in SMA one-way actuation control

Modeling and Control of Ferromagnetic Shape Memory Alloy Actuators”.

ABSTRACT FSMAs like Introduction Lightweight electro-hydraulic-actuators, such as pumps or linear actuators, are needed in the aerospace industry Compared with piezoelectric and magnetostrictive materials, FSMAs, such as Ni-Mn-Ga, exhibit significantly larger strain of up to 9.5%, which is induced by external magnetic fields of less than 400kA/

VARIABLE STRUCTURE CONTROL OF A FERROMAGNETIC SHAPE MEMORY ALLOY ACTUATOR

ABSTRAC

Vibration Isolation for Parallel Hydraulic Hybrid Vehicles

In recent decades, several types of hybrid vehicles have been developed in order to improve the fuel economy and to reduce the pollution. Hybrid electric vehicles (HEV) have shown a significant improvement in fuel efficiency for small and medium-sized passenger vehicles and SUVs. HEV has several limitations when applied to heavy vehicles; one is that larger vehicles demand more power, which requires significantly larger battery capacities. As an alternative solution, hydraulic hybrid technology has been found effective for heavy duty vehicle because of its high power density. The mechanical batteries used in hydraulic hybrid vehicles (HHV) can be charged and discharged remarkably faster than chemical batteries. This feature is essential for heavy vehicle hybridization. One of the main problems that should be solved for the successful commercialization of HHV is the excessive noise and vibration involving with the hydraulic systems. This study focuses on using magnetorheological (MR) technology to reduce the noise and vibration transmissibility from the hydraulic system to the vehicle body. In order to study the noise and vibration of HHV, a hydraulic hybrid subsystem in parallel design is analyzed. This research shows that the MR elements play an important role in reducing the transmitted noise and vibration to the vehicle body. Additionally, locations and orientations of the isolation system also affect the efficiency of the noise and vibration mitigation. In simulations, a skyhook control algorithm is used to achieve the highest possible effectiveness of the MR isolation system

RESEARCH AND EDUCATION WITH A HYDRAULIC HYBRID VEHICLE LABORATORY

ABSTRACT This paper presents the development of a hydraulic hybrid vehicle (HHV) based laboratory course for the Mechanical, Industrial, and Manufacturing Engineering Department at the University of Toledo. The objective of the laboratory course is to serve as both an educative tool as well as a tool in advancing the research of HHV technologies. The laboratory consists of a HHV test stand that approximates the workings of a series type HHV and an accompanying simulation model of the system. The course is based on a problem-solving learning approach that will aid students in gaining a fuller understanding of the fundamentals from core mechanical engineering curriculum including: Fluid Dynamics, Energy Systems, Vibrations, Mechatronics and Control. This course is unique in that the instructor serves a guide or manager for the students and does not evaluate the student based on exams rather, the student is evaluated based on his/her ability to apply engineering principles. After learning some basics of research and performing a literature review of the subject, the students will be asked to solve a problem and report their findings in a technical publication format. The students are evaluated based on their performance in applying engineering principles towards the solution of a relevant engineering problem and effectively communicating that via a conference publication candidate. In this way, a better index for evaluating student mastery of engineering principles is achieved and a gaping hole in the Mechanical Engineering curriculum is filled while at the same time offering an efficient means of advancing HHV technology