Alan Scottedward Hodel

A Low-Cost Solution for an Integrated Multisensor Lane Departure Warning System

The responsibility of a vision-based lane departure warning (LDW) system is to alert a driver of an unintended lane departure. Because these systems solely rely on the vision sensors ability to detect the lane markings on the roadway, these systems are extremely sensitive to the roadway conditions. When a vehicles LDW system fails to detect lane markers on the roadway, it loses its ability to alert the driver of an unintended lane departure. The goal of this research is to use GPS combined with inertial sensors and a high-accuracy map to assist a vision-based LDW system. GPS navigation systems are available in many automobiles, along with automotive-grade inertial sensors. The low accuracy of a typical GPS receiver found in an automotive navigation system is largely attributed to a position error. This error is too large to allow the GPS receiver to locate a vehicle in a particular lane on a roadway. A method to measure this error using a vision-based LDW system, together with a high-accuracy map, is presented in this paper. With the error known, the accuracy of the GPS receiver is increased to a high-enough level to localize the vehicle on a particular lane. Next, a method fusing GPS/inertial navigation sensor/vision and a high-accuracy map for highway lane tracking is presented. This method provides a backup lateral offset measurement that can be used for LDW when the LDW vision system loses track of the lane markings.

An interdisciplinary laboratory sequence in electrical and computer engineering: curriculum design and assessment results

In the fall quarter of 1997, the Auburn University Electrical Engineering Department (USA) implemented a new, interdisciplinary core laboratory sequence. This new laboratory sequence was one outcome of a complete curriculum revision based on four years of work by the departmental Curriculum Study Committee. This paper presents the laboratory curriculum design, and the results of a multi-part assessment conducted beginning one year after implementation. Many students are initially surprised by the level of challenge provided in the first laboratory course, but readily accommodate as they progress through the sequence. A multifaceted assessment strategy has evolved which uses end-of-term student evaluations, retrospective student evaluations, student oral interviews, and faculty interviews. The assessment information is used to improve the laboratories through modification of the laboratory manuals, better instructions to graduate teaching assistants, modifications of experiments, and a purposeful effort to keep all faculty informed of laboratory course content so they can build upon the laboratory experience in classroom teaching. The overall result of the new laboratory experience is that students have a more integrated approach to design and a much better understanding of the hardware, software and instrumentation used in electrical engineering practice. In addition, students who complete the sequence have better oral and written communication skills, and are more confident in approaching job interviews and initial job challenges.

A Characterization of the Performance of a MEMS Gyroscope in Acoustically Harsh Environments

Microelectromechanical systems (MEMS) gyroscopes are typically smaller and less expensive than their macroscale counterparts. For this reason, they are being used in many new applications, including in harsh environments. It has been well documented that the performance of unprotected MEMS gyroscopes can be deleteriously affected by exposure to mechanical shock or high-frequency vibrations. The results of this investigation experimentally demonstrate that MEMS gyroscopes are also susceptible to high-power high-frequency acoustic noise when acoustic energy frequency components are close to the resonating frequency of the gyroscopes proof mass. Additionally, due to microfabrication tolerances and the resulting differences between otherwise identical devices, there can be significant differences in the acoustically sensitive bandwidth between otherwise identical MEMS gyroscopes. This phenomenon is characterized for the ADXRS300 MEMS gyroscope.

Underactuated Robot Control: Comparing LQR, Subspace Stabilization, and Combined Error Metric Approaches

In this paper, three techniques for robust control of underactuated robots are experimentally compared on the classical ball and beam system. An adaptive tracking controller is first designed and implemented to identify the nominal friction characteristic. Then, designs for a linear quadratic regulator (LQR), subspace stabilization controller, and combined error metric controller are presented. Step response tests confirm that both nonlinear approaches exhibit better stability properties than the standard LQR design. In addition, the subspace stabilization approach permits a much more aggressive beam motion, resulting in shorter settling time with excellent control of overshoot.

On the Degradation of MEMS Gyroscope Performance in the Presence of High Power Acoustic Noise

Due to their reduced size, cost, and power requirements relative to traditional gyroscopes, MEMS gyroscopic sensors are finding increasing use in many applications. It is well known that unshielded MEMS gyroscopes can be vulnerable to both mechanical shock and high frequency vibrations. The results of this investigation indicate that MEMS gyroscopes are also susceptible to high power, high frequency content acoustic noise. Acoustic energy frequency components that are close to the resonating frequency of the proof mass in the MEMS gyroscope can produce undesirable motion of the proof mass, resulting in corruption in the angular rate measurement. If the acoustic signals possess enough power in the vicinity of the sensor resonating frequency, the resulting degradation in sensor performance can be severe enough to render the angular rate measurements useless.

Electrical Noise in MEMS Capacitive Elements Resulting From Environmental Mechanical Vibrations in Harsh Environments

Many microelectromechanical systems (MEMS) devices possess charged capacitor structures where the suspension system allows relative electrode motion due to internal or external stimuli. When such a device is subjected to external mechanical vibrations present in a harsh operating environment, unwanted movement between the capacitor plates can generate a noise current which is injected into the connected circuitry. This paper analyzes this phenomenon and presents a model for the dynamics of a MEMS device with capacitive plates experiencing relative motion due to external stimuli. A Fourier series expansion of the current is developed to characterize the frequency content of the signal in closed form for a given vibration frequency, and simulation and experimental results are presented.

Characterization and Experimental Verification of the Nonlinear Distortion in a Technique for Measuring the Relative Velocity Between Micromachined Structures in Normal Translational Motion

Applications exist for microelectromechanical systems (MEMS) devices where the measurement or estimation of the relative velocity, or at least the direction of instantaneous relative velocity, between two microstructures in normal translational motion is required. A technique for directly measuring the relative velocity has not been available. This paper presents a technique for directly measuring the relative velocity between two microstructures in normal translational motion. The technique consists of measuring the current flowing into the capacitance formed between the two microstructures when a constant voltage is applied across them. The technique and the resulting nonlinear distortion in the velocity measurement are characterized. A prototype relative velocity sensor is fabricated and evaluated to verify the measurement technique

Solution and applications of the Lyapunov equation for control systems

Recent advances in control systems analysis and design have implied new uses for the Lyapunov equation of the form AX+XA/sup T/+Q=0. Implementation requirements for the incorporation of the use of Lyapunov equations in practical design, however, point out the need for a set of specialized numerical procedures. This special set of numerical procedures must efficiently solve large, sparse Lyapunov equations, solve sets of Lyapunov equations that differ only in the coefficient matrix Q, and provide good low rank estimates of the Lyapunov equation solution X in the case where low rank approximations are applicable. Discussions of the motivations for the solution of these problems and of candidate solution approaches are provided. >

A Hybrid Improvement to Traditional Nonlinear Control

Well-known nonlinear control system design techniques are Lyapunov control design, input-output lin- earizing control design, input-state linearizing control de- sign, and integrator backstepping control design. In this paper, the authors examine several example plants where these methods fail. A hybrid method is proposed as an alternative nonlinear control system design method. The proposed hybrid design procedure combines Lyapunov and linear design techniques, but the Lyapunov-based control design technique is restricted to a subset of the plant state variables. I. INTRODUCTION Nonlinear control system design techniques are finding increased usage within industrial electronics applications such as robotics, electric machines, and power electronics. Some of the most well-known techniques include Lya- punov stability design, input-output linearization, input- state linearization, and integrator backstepping. These design techniques have been very successfully applied to a wide range of plants, but there are cases where these techniques fail. For some plants, these techniques are either excessively difficult to apply, or the resulting control designs have singularities under certain operating conditions (divide by zero or infinite gain). In other cases, the structure of the plant may preclude the use of a candidate design approach. In this paper, several standard nonlinear control design techniques are reviewed and applied to five example nonlinear plant models. For each of the five example models, at least one of the control design procedures fails to produce an acceptable feedback control law. In every example, however, a linear systems design approach yields a stabilizing control when the initial condition of the plant is sufficiently close to the a selected operation point. Therefore, a hybrid linear/nonlinear control design methods is proposed. The hybrid control preserves closed- loop stability of the nominal linear control, but signifi- cantly expands the region of stability by using a simple Lyapunov-based, secondary, nonlinear control that assists the nominal linear control. The remainder of this paper is organized as follows. Four standard nonlinear control design methods are re- viewed in Sec. II. The proposed hybrid control design approach is described in Sec. III. Five nonlinear plants are presented as case studies in Sec. IV.

An interdisciplinary senior design course utilizing electronically guided model rockets

Electrical engineering graduates are faced with a wide variety of technological and managerial decisions. The ability of the engineer to interact with the entire spectrum of individuals involved in marketing a product is a critical component of the overall success of a project. A senior level design course is presented that integrates the numerous phases of project development in order to prepare the student for the industrial environment. The course consisted of designing and flight testing an electronically guided model rocket. An analysis of the rockets anticipated flight path was performed using a FORTRAN program which took into account such factors as stability, center of gravity, center of pressure, and engine thrust. The rocket was flight tested for three successful controlled flights and recoveries. Test flight results proved the design of the rocket to be very stable and respond quickly in flight. >