Position controlled elevator door motion

An elevator for servicing a plurality of floor landings adjacent an elevator hoistway in a building, comprising:

• hall call means for registering requests for up or down service at each of said landings;
• a car movably disposed in said hoistway;
• car motion means for providing and arresting the motion of said car;
• car controller means for providing signals indicative of conditions of said car and of said car motion means, for exchanging signals with said car, for controlling said car motion means to cause said car to move in a selected up or down direction in said hoistway and to stop in response to said signals indicative of conditions of said car and of said car motion means and to signals received from said car;
• said car including a door for providing access to and from said car, a door motion means for opening and closing said door, switch means for registering calls for service by passengers in said car, and a cab controller for providing cab signals indicative of calls for service registered by said switch means, conditions of said door and the position of said car relative to any adjacent one of said landings, for exchanging signals with said car controller, and for controlling said door motion means in response to said cab signals and in response to signals received from said car controller;
• characterized by said cab controller comprising signal processing means for providing a first dictated door velocity signal as an increase at a predetermined acceleration from a small initial door velocity to a predetermined maximum velocity, for providing a second dictated velocity signal as a function of the difference between the present position of the door indicated by said signals indicative of conditions of said door and a predetermined target position for said door, for providing a selected dictated velocity signal as the lower valued one of said first dictated velocity signal and said second dictated velocity signal, and for providing a door-motion commanding signal to said door motion means as a function of the difference between said selected dictated velocity signal and the actual velocity of said door as indicated by said signals indicative of conditions of said door.