Gimbal_SOW.pdf

Electro-Optics Lab (EOL) Optical Bench Gimbal Replacement

1.0 TASK OVERVIEW

The Electro-Optics Lab optical bench will be used to perform ground calibration of the Orion optical navigation cameras.

This includes any prototypes, engineering development units (EDU) and flight units. Each Orion mission will require a new unit to be calibrated prior to flight.

The optical bench includes a high precision and accurate 2-axis gimbal that points the camera at various angles relative to a collimated star projector. Many images are collected at various prescribed orientations relative to the projected star to calibrate the camera. A camera distortion map is determined from this collection of images so any optical distortion produced by the camera can be canceled.

The existing gimbal is approximately 25 years old and is no longer supported. Although the gimbal still functions, the lack of available maintenance poses a risk in relying on it to perform the ground calibration task. A supported modern replacement is needed to mitigate the risk of a gimbal failure rendering the optical bench nonfunctional.

1.1 TECHNICAL REQUIREMENTS:

The gimbal shall meet the following requirements:

Two axis gimbal (azimuth and elevation)

Computer controlled positioning o Support local scripts for controlling gimbal motions o Support control interface with external computer

Pointing accuracy better than 2 arc-seconds in both axes over a +/-10 degree Field of View (FOV)

Repeatability better than 0.5 arc-seconds in both axes

Absolute encoder

Must support a 180 degree “plunge-&-turn” operation in both axes to determine camera alignment relative to the gimbal’s elevation axis

Orthogonality of axes: < +/- 2 arc-seconds

Payload weight (includes mounting plates): >= 25 lbs

Diameter of ring: >= 400mm (15.75”)

Rotation rate (each axis) > 30 deg/sec

Acceleration rate (each axis) > 90 deg/sec/sec

Provide adjustable hardware stops with shock absorbers

Gimbal frame must have a turning radius less than 356 mm (14”) at heights less than 343mm (13.5”) above the granite table top1.

Power: 115V AC 60Hz

Electronics are mountable in 19” rack

Optical alignment cube mounted on elevation axis

The vendor will be responsible for:

On-site installation (Gimbal and collimator are both mounted on a 4’ x 8’ granite flat table)

On-site alignment to existing collimator

a. Include adaptor platform so gimbal elevation axis matches collimator height above the table surface.

(21.4” +/-0.1 above granite table surface)

On-site calibration and checkout

Training

1 This is to allow clearance for a nearby second table upon which the collimator is supported. The rotation space is clear 13.5” above the granite top.