The DSi from Renishaw Inc., Hoffman Estates, IL, combines two error-correcting SiGNUM SR readheads on an RESM ring and is capable of total installed accuracy of better than ±1 arc second for use in high-accuracy positioning in medical, scientific, and industrial rotating devices. A customer-selectable propoZ reference position is unaffected by bearing wander or power cycling. Located in 180° opposition, the two readheads eliminate odd error harmonics, including eccentricity, and compensate for the effect of bearing wander. Combining the readheads' incremental signals and using reference mark processing, the DSi appears to the controller as a single high-accuracy encoder.
Dual-Readhead Rotary Encoder from Renishaw