Digital selector system for elevators

In an elevator having a car, motor means for displacing said car between a plurality of floors, speed control means for controlling said motor means, and means for generating call signals for said floors, a digital selector system comprising:

• means for storing, as absolute values, distances between adjacent floors;
• means for storing a deceleration look-up table of ideal stopping velocities, at a plurality of stopping target distances, based upon selected values of jerk, deceleration, and landing speed;
• means for generating, at a plurality of fixed reference positions, position signals representative of instantaneous car position;
• means for selecting an initial target floor as the next adjacent floor in the desired direction of car travel, and for determining target distance from the distance storing means;
• pulse generating means responsive to car movement for producing pulse signals representing incremental distances of car travel;
• means for decrementing the target distance responsive to the generation of each pulse signal for generating instantaneous target distance;
• means for periodically determining instantaneous car velocity;
• means for periodically calculating the car slowdown distance, based on instantaneous car velocity, for decelerating the car, at said selected rate of jerk, to said selected value of deceleration, for calculating a slowdown table of ideal car velocities versus distances for such car slowdown, and for calculating slowdown car velocity when selected deceleration is reached;
• means for subtracting car slowdown distance from instantaneous target distance to determine stopping target distance;
• means for comparing ideal stopping velocity, taken from said deceleration look-up table based on stopping target distance, with said slowdown car velocity value for determining critical car distances for making stopping decisions;
• means responsive to a determination that the car has not reached a critical car distance, for recalculating car slowdown distances, slowdown tables, and car slowdown velocities, based upon updated instantaneous car velocities, and for comparing slowdown velocities with ideal stopping velocities, determined from updated instantaneous target distances, until a critical car distance is reached;
• means responsive to absence of a call signal at a target floor, at critical car distance, for advancing target floor to the next adjacent floor and for adding to the instantaneous target distance the distance to the new target floor;
• and
• means responsive to the receipt of a call signal at a target floor, at a critical car distance, for issuing a stop signal to said speed control means and for periodically outputting ideal velocities from said slowdown table and said deceleration table, for issuing correction signals of car velocity, as a function of instantaneous target distances, to said speed control means.