Kent H. Lundberg

A Web-based linear-systems iLab

This paper describes a Web-based laboratory for students in courses on feedback systems. This project uses the iLab architecture, which provides a framework for remote-lab development and deployment, using a three-tiered client/broker/server architecture. This three-tiered approach simplifies the development of remote labs by providing reusable components for laboratory-administration functions. In the specific lab described here, students use a Java-based Lab Client to configure system parameters of a state-variable filter and submit jobs to the Lab Server. The Lab Server computer uses a dynamic signal analyzer to take frequency-response measurements of the configured filter.

Initial conditions, generalized functions, and the laplace transform troubles at the origin

The unilateral Laplace transform is widely used to analyze signals, linear models, and control systems, and is consequently taught to most engineering undergraduates. In our courses at MIT in electrical engineering and computer science, mathematics, and mechanical engineering, we have found some significant pitfalls associated with teaching students to understand and apply the Laplace transform. We have independently concluded that one reason students find the Laplace transform difficult is that there is significant confusion present in many of the standard textbook presentations of this subject, in all three of our disciplines

Low-cost magnetic levitation project kits

These low-cost magnetic suspension kits provide students with an open-ended design problem. The performance of the basic system is designed to be inadequate, allowing students to apply their knowledge to implement improvements in sensors, magnetics, power electronics, and compensation electronics. In the first offering of this lab project, student reaction was positive. The low cost of the kits allows each student to personalize their kit and keep the finished product at the end of the term. This laboratory assignment was successful in providing an open-ended design challenge, providing the students with real hardware experience and providing publicity for the class.

Classical dual-inverted-pendulum control

A cart with two independent inverted pendula, called a dual-inverted-pendulum system, is analyzed and compared to the single-inverted-pendulum system using classical linear methods. Using only the angles of the pendula and the position of the cart, a classical controller is designed that stabilizes the pendula in the inverted position with the cart at the center of the track. Simulations of the transient response to initial conditions are presented. Intuitive reasoning and an insightful approach to the control design are major emphases of this effort.

A Self-Resonant MEMS-based Electrostatic Field Sensor with 4V/m/Hz Sensitivity

An electric-field sensor is presented for applications such as xerography. The sensor architecture combines a vibrating MEMS structure with synchronous detection-based electronics. Prototyped in a MEMS process, the noise floor is 4.0V/m/radicHz and the INL is 20V/m over a range of +/-700kV/m, an order-of-magnitude improvement over existing MEMS devices

The history of analog computing: introduction to the special section

This special issue is one in a series of occasional issues of IEEE Control Systems Magazine dedicated to history. The present issue continues the previous contributions by focusing on the development and impact of a pivotal technology. Analog computers played a key role in enabling the simulation of control systems for several decades, leading to a better understanding of theory and better designs in practice. Here we take a closer look at analog-computer technology in its historical context. a collection of eight articles - an analog-simulation tutorial, four personal histories, and three reports of current activities - written by well-known authors in the fields of analog computing and history.

A self-resonant MEMS-based electrostatic field sensor

An electric-field sensor is presented for applications such as xerography. The sensor combines a vibrating MEMS structure with synchronous-detection electronics. The sensor architecture has three major blocks: a MEMS shutter, a sense interface, and a self-resonant drive loop that feeds back to the MEMS shutter. The self-resonant feedback loop is the enabling technology that provides the improved performance reported here. Prototyped in the iMEMS3 process at Analog Devices, the noise floor is 4.0 V/m/radic(Hz) and the integral nonlinearity is 20 V/m over a range of plusmn700 kV/m, which is an order-of-magnitude improvement over existing MEMS devices

Feedback loop design for an electrostatic voltmeter

The integration of MEMS sensors and interface circuitry has yielded low-cost, high-performance instruments with excellent reliability. In inertial sensing, deterministic electrical waveforms are applied to a MEMS capacitive element to determine an unknown deflection. The inverse of this measurement method can also be exploited: the MEMS element can be deterministically modulated to measure an unknown electrical variable. This paper presents the design of a non-contact electrostatic voltmeter using a MEMS-based electrostatic field meter

Pole-zero phase maps: visualization helps students develop s-plane intuition

This paper illustrates how pole-zero phase maps can help students to determine the phase of a transfer function from a plot of the poles and zeros. This visualization of the phase of L(s) helps students develop s-plane intuition and facilitates the introduction of the analytical tools of classical control, such as Bode plots, Nyquist diagrams, and Evans root-locus plots.

A Self-Resonant MEMS-Based Electrometer

A configurable MEMS electrometer that allows for isolated, high-input-impedance voltage measurements is presented. By adjusting the separation between the measurement surface and a vibrating MEMS element, the noise floor and/or maximum dynamic range can be tailored to the specific application. This device is useful for a broad range of applications, including pH meters, biopotential amplifiers, xerography, and measuring leakage on high-voltage capacitors.