LRS Micro-g LaCoste FG5, Manual, Page: 84 / 149

Adjustment and Maintenance
4
4.5.1.3.2.Function:
The DROP mode has six states:
1. Standby: The motor is off and the system waits for a trigger signal from
the computer or from the internal timer (selected on front panel).
2. Lift: The cart servos to a constant lift velocity until the cart comes within
the window of the hold position.
3. Hold: The cart servos to a constant hold position.
4. Track: The cart servos to track the test mass with a separation of about 3
mm. This is adjustable.
5. Soft-catch: The cart tracks the test mass with a very slight separation.
6. Catch: The cart servos to a decreasing ramp velocity servo until about 5
mm. At this point the state-machine returns to the standby mode (1).
4.5.1.4.OSCILLATE
4.5.1.4.1.To Select:
Press INIT while the selector switch is set to OSC.
4.5.1.4.2.Function:
This mode causes the cart to move up and down smoothly (with a
constant velocity) in the dropping chamber. It is very useful for generating
fringes. DO NOT LEAVE IN OSC MODE UNATTENDED! Cumulative belt slip
can cause the cart to drive into the bottom or top of the dropping chamber and
burn out the motor.
4.5.2.Analog Servo
The analog servo has three different sections. They are: Cart-position, Cart-
velocity, and Sphere-position. The cart servos use the rotary shaft encoder as a
position/velocity sensor. The sphere servo uses the optical sensor mounted on
the cart.
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