Automatic positioner with nonlinear drive

Abstract

A motor driven mechanical positioner is provided which will position a movable arm to any one of 840 discrete angular positions. A total angular range of +/-42.degree. can be covered in 0.1.degree. increments. Electronic circuitry controls the nonlinear drive mechanism. A drive shaft wheel has six evenly spaced holes through which light from an IR LED is allowed to shine on a phototransistor placed on the other side of the wheel. As a result of the intermittent light striking the phototransistor, six clock pulses are generated for every revolution of the drive shaft. A desired angular position is entered into the electronics via thumb wheel BCD switches. The BCD information from the switches is transformed into binary information to address EPROMs. For each possible binary address representative of a desired angular position, the selected EPROMs output binary data that is representative of the clock pulse count for that particular angular position. In order to compensate for the nonlinearity of the drive mechanism, the clock pulse count is incremented at a nonlinear rate as the angular position is increased. Additional circuitry in the automatic positioner senses when the mechanism is within a preset distance from where it should be, and when this occurs a presettable slow drive speed is implemented to minimize overshoot.

Dependencies are inferred from the claim text.