See Photo:  ANCO Pitch/Roll/Yaw Motion Table

Recently ANCO delivered to NORTHROP CORPORATION a pair of fixtures for assembly line testing of Tacit Rainbow Cruise missiles. These fixtures, which are designed and built to exacting requirements specified by the customer, perform simulated flight maneuvers on the missile under computer control. While the three axes are in motion, velocity and altitude measurements are captured by a host test computer from instruments on the fixture and the rate gyros in the missile.

DIGITAL SERVO CONTROLLERS

Fixture axes are actuated and controlled by a computer-based closed loop digital servo system. It is programmed to accelerate the missile to a commanded test velocity within 5 degrees of axis travel and then traverse the axis at that velocity within 5 degrees of axis travel and then traverse the axis at that velocity, within close limits, during data acquisition. The axis is then decelerated to stop at a previously specified position.

STRUCTURAL ANALYSIS OF 3D FRAME

Significant inertial forces are generated in these maneuvers, and consequently, torsional stiffness and structural rigidity were major considerations. Restrictions on the use of ferrous metals in close proximity to the missile necessitated the majority of the structural members being fabricated from aluminum. Missile access requirements and space limitations imposed other constraints on the structural configuration. To hold static deflection and dynamic oscillation within allowable limits under the most severe loading, ANCO performed extensive finite element analysis as part of the design task.

REDUNDANT POSITION RESOLVERS

Each axis is equipped with dual resolvers one of which serves two purposes: 1) It provides position feedback signals to the servo system, and 2) it provides axis position to the customer’s test computer. The second resolver provides a duplicate axis position signal to the test computer. By comparing the signals from this pair of instruments, the accuracy of axis movement can be verified during each movement and also during self-test routines.

SOFTWARE DEVELOPMENT

ANCO developed application software for fixture control. These programs allow the fixture to respond to commands and report position and velocity data to a Hewlett Packard host computer that is part of the client’s test facility. For testing purposes, ANCO created additional software that permitted a PC to emulate the host.

The software includes program modules that provide the system with diagnostic capability. Self testing of the axis measuring instrumentation and axis control system is automatic on power up and can be performed at any time on command

SAFE OPERATION ASSURED

Operator and equipment safety were mandatory requirements imposed by the specifications. These were given major emphasis during the design process and were the subject of extensive collaboration between the customer and ANCO the design staff.