Patent US 4,046,229

An elevator system which includes speed control apparatus which provides an error count representing the deviation of an elevator car from a desired speed versus distance reference pattern. Both the instantaneous and cumulative errors are indicated by the error count, and both are simultaneously corrected with digital precision by direct utilization of the error count. Anticipatory control of non-linear actuators responsive to the rate at which the cumulative error is corrected makes the system time optimal.