Magnetic Encoding Technology
Control of equipment and machinery depends in part upon sensing the movement and location of components within it. Until recently, there has not been a reliable, accurate, and inexpensive means to sense the motion and location of machine components such as hydraulic cylinders. To meet this need, SRI has developed a novel technology, available for license.
Rather than exploit optical devices or precise, but costly, mechanical schemes, SRI researchers have determined the feasibility of applying a ferromagnetic (magnetizable) alloy to a typical hydraulic cylinder rod. In this method, the cylinder rod can be encoded in a manner similar to a magnetic tape or a hard disk, in any desired pattern.
SRI has developed, tested, and fielded systems with an alloy electroplated on a standard steel cylinder rod. This alloy is encoded and can be read by very small, widely available magnetic read sensors. SRI created special-purpose perpendicular write heads, circuitry, and algorithms to decode signals for a great variety of applications, and has adapted alloys to nearly any substrate, whether conductive or not.
SRI has a portfolio of issued patents for the technology, and we continue to develop it for other sensing applications.
Key Features
- Linear resolutions of a half-millimeter, with much greater resolution expected in the near future
- Absolute and relative position
- Resistance to severe environmental conditions that are encountered by heavy machinery
- Orders of magnitude less expensive than competing technologies
- Several application methods, including electroplating, sputtering, and chemical vapor deposition
- Usability for rotary motion, acceleration, and torsion sensing, such as for dynamometers and wind generators
