Renishaw has collaborated with Tesat-Spacecom GmbH to develop a new space-qualified encoder featuring high radiation hardness, very high accuracy and qualification for 15 years’ lifetime in a GEO space environment.
Combining Renishaw's advanced encoder technology with Tesat-Spacecom's knowledge and experience in ruggedised electronic systems for use in space applications, the new GEO space angle encoders are designed to withstand harsh environments, with 150 g vibration resistance and wide operating temperature range, combined with an extremely robust optical detection principle.
Its radiation hardness has resulted in the encoder achieving qualification for 15 years’ use in GEO space conditions. The readhead has a mass of only 300 g and power consumption is typically less than 1 W.
The scale comprises of a stainless steel ring with graduations marked directly onto the periphery, thus eliminating shock/ vibration-induced breakages associated with traditional glass discs. The graduations include IN-TRAC reference marks that are directly embedded into the incremental channel, arranged in a distance-coded pattern so that the distance between any two adjacent reference marks is unique. This means that only a small rotation is required before absolute position is determined by the on-board FPGA.
The ring format enables easy integration into rotary axes, with a large through-hole to allow easy routing of supplies. The ring is mounted directly to the rotor, with the head mounted to the stator. With no contact between the two parts, there is no need for separate bearings or flexible couplings, improving reliability and eliminating backlash, shaft wind-up (torsion) and other irregular metrology effects that impact traditional enclosed encoders.
High accuracy is achieved with short-range error less than 0.5 µrad RMS and long-range error less than 5 µrad (without mechanical errors). Combined with resolution of less than 0.5 µrad, the system is well-suited to applications demanding precision metrology.
Renishaw Oceania represents the Renishaw Group in Australia.