Motor control differential

After calibration, a block-shear specimen was positioned in the profilometer. Two stepper motors, controlled by timed relays, were used to maneuver the specimen under the laser. Specimen position was measured by two linear variable differential transformers (LVDTs), one placed on each axis. A data acquisition system was configured to capture sensor outputs at the rate of 30 Hz. Initially the specimen was scanned across the non-bonded portion of the adherend (Fig. 5). About 1000 sensor readings were acquired for each profile (or about one reading per 25 pm). The specimen was then advanced 1 mm lengthwise and ain scanned across its width. This process was repeated up to 25 times to define a precise beam grid (Fig. 5) for scanning all specimens. 

Motor-control circuits have been designed to provide sequential startup of the main HCF ventilation fans in a manner that ensures that the zone differential pressure hierarchy is maintained. Interlocks are employed to shut down the necessary fans to avoid adverse pressure differentials in the event of fan failures. 

Where evaporative condensers and water cooling towers have only one fan (or fan drive motor), coarse control can he effected hy on-off switching. The time lag will then depend on the mass of water in the circuit, and the sensing element needs to have a wide differential to prevent frequent motor starts. Towers should have thermostatic control of the fan to prevent water freezing on the packing in winter. 

More advanced techniques that rely on learned behavior of animals (i.e., operant behavior) can provide controls for such nonmotoric behavioral factors and thus provide a more specific indication of changes in endurance and coordination. Rats can be trained to depress a lever with a specified amount of force in order to obtain a reward, for example, food delivery. The amount of force required to depress the lever can then be successively increased until the maximal force that can be exerted is reached. In addition, the force that the animal can sustain over time can also be measured as an indication of endurance. The ability to manipulate reward conditions facilitates the ability to differentiate motoric impairments from motivational deficits. 

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