Andrei M. Shkel

Bio: Andrei M. Shkel is an academic researcher from University of California, Irvine. The author has contributed to research in topics: Gyroscope & Inertial navigation system. The author has an hindex of 45, co-authored 296 publications receiving 6593 citations. Previous affiliations of Andrei M. Shkel include University of California & DARPA.

MEMS Vibratory Gyroscopes: Structural Approaches to Improve Robustness

Abstract: Fundamentals of Micromachined Vibratory Gyroscopes.- Fundamentals of Micromachined Gyroscopes.- Fabrication Technologies.- Mechanical Design of MEMS Gyroscopes.- Electrical Design of MEMS Gyroscopes.- Structural Approaches to Improve Robustness.- Linear Multi DOF Architecture.- Torsional Multi DOF Architecture.- Distributed Mass Architecture.- Conclusions and Future Trends.

Type I and Type II Micromachined Vibratory Gyroscopes

Abstract: All Micromachined Vibratory Gyroscopes (MVG) are based on the principle that the Coriolis forces produced by rotation of the gyro cause a transfer of energy between two of the gyro's modes of vibration. Vibratory Gyroscopes can be classified into two broad types, angle gyroscopes (or Type I) and rate gyroscopes (or Type II). Gyroscopes of the first type measure orientation angles directly, while gyroscopes of the second type measure rotational rate. Most MVG implementations to date are found exclusively in the angular rate measuring variety, however there are opportunities for implementation on the micro-scale angle gyroscopes. This paper introduces a unified approach for description of MVGs and emphasizes the differences between the two types of devices. We also review our recent results in development of Type I and Type II gyroscopes. I. INTRODUCTION All vibratory gyroscopes use the Coriolis acceleration that arises in rotating reference frames to measure rotation. The Coriolis forces produced by vibration of the sensing element and rotation of the system cause a transfer of energy between two of the gyro's modes of vibration. Vibratory gyros divide naturally into two classes depending on whether the two modes are of the same kind or different. In the classical tuning fork gyro (Fig. 1), for example, the two modes are different. One consists of a flexural vibration of the tines and the other a torsional vibration about the stem. Vibratory gyros utilizing similar modes include the vibrating string, the vibrating rectangular bar, the vibrating cylinder, and the hemispherical resonator gyro, Fig. 2. Vibratory gyros utilizing similar modes can be operated in the whole angle mode (direct angle measurement mode) or the open-loop mode(or force-to-rebalance modes) to measure rotational rate. Conventionally, different modes gyros are used for angular rate measurement. We introduced the classification of vibratory gyroscopes based on phenomena they measure - angle gyroscopes (or Type I) and rate gyroscopes (or Type II). Almost all reported to date Micromachined Vibratory Gy- roscopes (MVG) are of Type II. They operate on the Coriolis principle of a vibrating proof mass suspended above the substrate. The proof mass is supported by anchored flexures, which serve as the flexible suspension between the proof mass and the substrate, making the mass free to oscillate in two orthogonal directions: the drive direction and the sense direction. In Type II implementation, the overall dynamical

Dynamics and control of micromachined gyroscopes

Abstract: We summarize principles of operation of micromachined gyroscopes, analyze dynamics of ideal and non-ideal systems, and propose an approach for formulation and solving problems of control. The suggested approach uses active nonlinear feedback control for drive and compensation of errors. Both non-adaptive and adaptive strategies are presented. These strategies can be used for a broad class of micromachined vibratory gyroscopes including those for angle and angular rate measurement.

Experimental evaluation and comparative analysis of commercial variable-capacitance MEMS accelerometers

Abstract: This paper reports the experimental analysis of commercially available variable-capacitance MEMS accelerometers, characterized under standardized tests. Capacitive MEMS sensors of the same low-level input acceleration range with various mechanical sensing element designs, materials, fabrication technologies and price ranges were selected for evaluation. The selected sensors were characterized using ANSI and NIST certified testing equipment and under the same testing conditions; and their sensitivity, resolution, linearity, frequency response, transverse sensitivity, temperature response, noise level and long-term stability were tested and compared. The experimental results are then interpreted to provide an insight to advantages and disadvantages for using a particular mechanical design, fabrication technology, sensor material and the techniques for electronics integration and packaging of each specific sensor design.

Planning Algorithms: Introductory Material

Abstract: Planning algorithms are impacting technical disciplines and industries around the world, including robotics, computer-aided design, manufacturing, computer graphics, aerospace applications, drug design, and protein folding. This coherent and comprehensive book unifies material from several sources, including robotics, control theory, artificial intelligence, and algorithms. The treatment is centered on robot motion planning but integrates material on planning in discrete spaces. A major part of the book is devoted to planning under uncertainty, including decision theory, Markov decision processes, and information spaces, which are the “configuration spaces” of all sensor-based planning problems. The last part of the book delves into planning under differential constraints that arise when automating the motions of virtually any mechanical system. Developed from courses taught by the author, the book is intended for students, engineers, and researchers in robotics, artificial intelligence, and control theory as well as computer graphics, algorithms, and computational biology.

Randomized kinodynamic planning

Abstract: This paper presents the first randomized approach to kinodynamic planning (also known as trajectory planning or trajectory design). The task is to determine control inputs to drive a robot from an ...

Randomized kinodynamic planning

Abstract: The paper presents a state-space perspective on the kinodynamic planning problem, and introduces a randomized path planning technique that computes collision-free kinodynamic trajectories for high degree-of-freedom problems. By using a state space formulation, the kinodynamic planning problem is treated as a 2n-dimensional nonholonomic planning problem, derived from an n-dimensional configuration space. The state space serves the same role as the configuration space for basic path planning. The bases for the approach is the construction of a tree that attempts to rapidly and uniformly explore the state space, offering benefits that are similar to those obtained by successful randomized planning methods, but applies to a much broader class of problems. Some preliminary results are discussed for an implementation that determines the kinodynamic trajectories for hovercrafts and satellites in cluttered environments resulting in state spaces of up to twelve dimensions.

Art of electronics

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Real-Time Motion Planning With Applications to Autonomous Urban Driving

Abstract: This paper describes a real-time motion planning algorithm, based on the rapidly-exploring random tree (RRT) approach, applicable to autonomous vehicles operating in an urban environment. Extensions to the standard RRT are predominantly motivated by: 1) the need to generate dynamically feasible plans in real-time; 2) safety requirements; 3) the constraints dictated by the uncertain operating (urban) environment. The primary novelty is in the use of closed-loop prediction in the framework of RRT. The proposed algorithm was at the core of the planning and control software for Team MIT's entry for the 2007 DARPA Urban Challenge, where the vehicle demonstrated the ability to complete a 60 mile simulated military supply mission, while safely interacting with other autonomous and human driven vehicles.