Abstract: A hydraulic elevator system includes a hydraulic jack for raising and lowering the car and a distributed intelligence microprocessor control system, containing a number of subsystems, each having designated control responsibilities. A door operator microprocessor subsystem initiates stored open and close cycles responsive to external commands. A selector microprocessor subsystem determines target floor and distance values, produces slowdown interrupt signals when the car nears a target floor, and produces levelling signals for stopping the car at a landing. A car logic controller includes a microprocessor for issuing run commands to a relay-based power controller, issuing door open and door closed commands to the door operator microprocessor, issuing run signals to the selector microprocessor, and controlling elevator slowdown. A serial communications link is provided among the various microprocessors in the system.

Abstract: An apparatus and method for controlling the velocity of a moving member like, for example, a print head carrier. The apparatus includes motor means which drives the carrier along the platen of a printer. The motor is driven by alternately energizng it during an "on" period and deenergizing it during an "off" period. A velocity detector detects the actual velocity of the carrier and a processor determines whether an overspeed or an underspeed condition exists relative to a desired velocity. A counter capable of counting pulses relative to the on and off periods receives the output of the processor and is utilized to effectively shorten or lengthen the "on" period, respectively, whenever an overspeed or underspeed condition exists.