Dear Dennis... EN-Genius Network's Dennis Feucht answers your design queries in his new Circuit Design Clinic! May, 2006

EN-Genius Network presents a new, interactive analog design service to readers! Send us your design questions (with relevant data; schematics in JPEG or GIF, please) for some free engineering advice from EN-Genius Network's circuit consultant, Dennis Feucht, on how you might solve a design problem or improve circuit performance. Submissions may be edited for clarity or brevity, and submitters and their email addresses will remain anonymous (unless otherwise indicated). Please send your questions to Dennis here.

Mechatronics: Principles and Applications
by Dennis L. Feucht

Mechatronics is an interdisciplinary field that combines mechanics with analog and digital electronics. It is not exactly electromechanics nor is it robotics, though both are close. It is closer to electromechanics with a computer-control emphasis. The author is an engineering professor at the University of the South Pacific on Fiji. The book is intended as a textbook for university students.

This multidisciplinary book presents an introductory coverage of topics typical of technician-level circuits books. Of the 18 chapters and 2 appendices, 13 are primarily about electronics and 3 on control theory.

Chapter 5, on Analog Electronics, emphasizes pre-conversion signal-conditioning circuitry. A survey of op amp circuits with gain formulae is presented, then active filters. The one op amp presented is the venerable 741, not likely to be used by students later in industry. (A better choice might have been the LM324, also an established part that still finds wide use and is easier to understand.) The 741 circuit diagram is given, but the 741 is not so simple for beginners to understand as the single-supply or current-mirror-based, all-CMOS op amps.

Some of the terminology is decades out of date (such as emf for voltage). Light coverage is given to passive circuits, semiconductors, and combinatorial and sequential digital logic. The coverage of transistors is disappointingly obsolete, using two-port parameter (h-parameter) BJT models instead of circuit-independent physical models such as the Ebers-Moll or Gummel-Poon models. Except for these anachronisms, the basic material is presented in a readable manner.

Microcontrollers are the next topic, with emphasis and some detail upon the PIC 16F84. Architecture and some hardware is covered before turning to assembly language programming. The chapter on microcontroller interfacing to actuators presents some very simple examples, such as relay drivers, yet fails to include basic design considerations such as the need for a clamp diode around the inductor. Particular interface IC examples are given without revealing what is functionally important inside the IC. Specifics often are short on demonstrating general principles.

The control theory covers s-domain application-to-passive networks, then to op amps and electromechanical systems. Although coverage is not as thorough as is typically found in control textbooks, the theory is applied to both electronic and mechanical systems, showing how control theory transcends any one technology. State-space representation is included, and helpful attention is paid to block-diagram algebra. Stability analysis places emphasis on the Routh-Hurwitz method, which is based on the mathematical theory of equations and does not require factoring high-degree polynomials. However, it also does not provide much insight into the design aspects of the system by not revealing where the poles are in the s-plane. The teaching emphasis is to teach control principles by presenting copious examples of how to do the analysis. Graphical methods of root locus, Bode plots, and Nyquist diagrams are covered in just enough detail to be begin to be used.

The mechanical aspect of mechatronics is elaborated in a basic coverage of robotic arms and some matrix formulation of their kinematics of serial linkages. Mechanical components covered include gears, cams, ratchets, clutches and brakes. Hydraulics and pneumatics make somewhat more than a cameo appearance. The coverage is about right for an electronics engineer wanting some background knowledge of mechanics.

The book ends with quaint topics for electromechanics, of IC and circuit-board manufacturing and the basics of reliability theory. A final chapter offers extended examples in the form of case studies. The appendices present basic engineering problem-solving, detailed machine design principles, and a cursory CircuitMaker 2000 schematic-diagram editor tutorial.

I would give this book a rating of 2 out of a perfect 5. While it rises to the challenge of covering much subject-matter in a single volume, it falls short in two main ways: first, too much of the terminology and technology is outdated, or inaccurate, and bound to mislead or misdirect readers; second, the emphasis in the electronics sections is on presentation of examples without explaining the underlying principles they exemplify. On the strong side, the book covers topics other than analog electronics to the depth that many practicing engineers might care to know, and therefore can be a reference book to that extent. Overall the book mixes a cookbook approach with a conceptual approach, and offers some of the better and worse of both.