TCS3 Encoder Review

Web Page Reference

http://irtfweb.ifa.hawaii.edu/~tcs3/systems/tcs3/0309_Design/06_Encoders/

Requirements

APE (Absolute Position Encoder)– Match present APE accuracy ~6 arc seconds.

IPE – (Incremental Position Encoders) – Servo model shows the current IPE resolution of 20 count/arcseconds can sufficiently meet the 0.1 arcsec resolving requirement.

TCS3 Encoder Design Highlights.

APE Design Highlights:

1. Sensors (Resolver/Transductor) is embedded in the telescope shaft. TCS3 will re-use sensor.

2. Plan is to switch sensor between TCS1 & TCS3 readout electronics.

3. TCS3 purchased new readout electronics.4. TCS3 electronic to be installed in parallel with TCS1.5. Embedded CPU to correlate and provide APE data via

RPC. Embedded CPU to sample APE data at 20Hz. TCS3 to query embedded CPU at 10 Hz.

6. Spare sensor parts purchased (transductor and resolver), but we could not replicated the mount/case.

7. After tcs3 switch over, APE input to TCS1 will be disabled.

IPE Design Highlights:1. Use the current IPE.2. Route IPE output to both TCS1 and TCS3. (TTL pulses)3. Improvement to IPE must wait until TCS1 is

decommissioned (or may not be part of this upgrade).

Ape_plan

Block_diagram

APE Schematic

APE Lab Setup

Transducers

Resolver

Converter/preamp(transducer)

Converter (resolver)

Embedded PC