Book announcement: Fluidics for Computation and Control

I have been interested in fluidics since the early 1980s, when Doug Garner, Don Hewes and Maynard Hill came out with a series of articles on low-cost autopilots for light airplanes. One of the features of the autopilot was an electro-fluidic rate sensor using a jet of air passing between two thermistors (resistors whose resistance varies with their temperature). If the attitude of the airplane changed (generally, the sensor was mounted to detect a mixture of yaw and roll deflections), the jet would be deflected and would hit – and cool – one thermistor more than the other. The thermistors were part of a Wheatstone bridge, and the resistance value of the bridge would control an electronic circuit that would in turn operate actuators. (One version of a usable actuator was pneumatic and used vacuum cleaner hose!) The same set of articles introduced me to magnetic amplifiers in the form of flux-gate compasses.

As soon as I began my search, I was overwhelmed by the range of applications of this technique, and I became even more intrigued. Fluidics has applications in both digital and analog devices, and finds its best field of application in areas where there is a continuous flow of fluid (usually air) that can be used for computation or control. Early applications or proposed applications were industrial (most plants have compressed air and/or hydraulic fluid under pressure continuously available), including counters and proximity sensors, space travel (a clever guidance system for an orbital lifeboat, running off the oxygen flow used for life support), navigation and guidance (Garner, Hewes and Hill worked for NASA).

The definitions used in this field have changed since 1960, when the Army’s Harry Diamond Laboratories published their first reports. Fluerics is now the term for mechanisms using only moving fluids - in other words, containing no moving mechanical parts. Fluidics now includes moving parts. This mainly allows displays, switches and interfaces between fluidic and conventional hydraulic and pneumatic circuits to be taken into account.

I’ve been accumulating books and technical reports ever since, always looking for one source that had general coverage and was accessible to the broadest possible class of readers.

As soon as I had a copy of this treatise, meant to promote Bendix’s advanced fluidic components and assemblies, I saw it was what I had been looking for.

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