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Motion System Design
A formula for success

A formula for success

Engineering, as practiced in its various forms, rests squarely on the development, transfer, and application of systematic problem-solving techniques. Look no further than an introductory textbook on circuits and you will find, in just the first few chapters, a succession of laws, principles, and procedures — starting with Ohm's and Kirchhoff's laws, followed by linearity and superposition, nodal and mesh analysis, and Thevenin's and Norton's theorems — that collectively form the foundation of electrical engineering.

To my knowledge, no such concatenation of theories, rules, and formulas exists in the realm of motion engineering, nor is there a definitive framework for solving related design problems. Until another “Thevenin” or “Norton” emerges with a rigorous theory in hand, I'd like to offer some suggestions that might help you navigate the complex, uncharted waters of interdisciplinary design.

Visualize — Whether it's a new design or an upgrade, begin by envisioning the desired motion as if it's occurring freely in space, without the assistance of structural and drive components. Computers can help, but nothing tops a good imagination.

Backfill — Add structural and drive elements, but rather than work from the floor to the motion, go the other way, backfilling the required mechanical and electrical components followed by the supports on which they would mount.

Constrain — Imagine that each moving element is rendered ever more ineffective by increasing levels of friction, vibration, misalignment, inaccuracy, looseness, and wear. How does the process change, and how is it affected if electrical functions are likewise unplugged?

Picture perfect — Consider as well the effect of ideal components and operating conditions. Don't stop with mechanical functions; visualize what perfection looks like at the signal level. In the interdisciplinary domain, electrical signals — information related to sensors, actuators, mechanisms, and commands — are often the best measure of performance. In fact, in many respects, the signal is the machine.

Get it in writing — Capture as much design intent and intelligence as possible in software, including logic and math from the component to the process level. This will help simplify diagnostics and improve safety too.

Go modular — Don't re-invent the wheel. In today's age of programmability, modular machine and software architectures are a must. They are inherently re-usable and readily scalable when linked in hierarchical combinations.

Team up — There's strength in numbers, especially if you leverage time and talent residing in the supply chain. Make your suppliers responsible for low-level details, while you expand your domain knowledge, focusing on motion-centric functions and process physics within the application space where you compete.

Be careful, however. Don't put your future in the hands of a supplier sending signals that it has stopped planning ahead. In the past 20 years, I've watched many companies march into oblivion, dooming customers and employees alike. It's always the same, a disappearing act that begins when bean counters take over, letting the company fade from the motion system community and its premier learning environment, Motion System Design. I can't make any guarantees, but the manufacturers who regularly participate in the MSD community, sharing in the learning that takes place therein, are making it crystal clear that they plan to be around in the future, when you will undoubtedly need them most.

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