Elevator position controlling apparatus and method

An elevator system, comprising:

• a plurality of hall call buttons for providing a signal indicating a car call of a passenger at a landing of each floor in a building;
• an elevator car moving along a hoistway and provided with destination floor selection buttons therein;
• a counter weight;
• a rope of which an end is fixed to the elevator car and the other end is fixed to the counter weight;
• a sheave for moving the elevator car by winding or releasing the rope;
• an alternating current motor connected with the sheave for rotating the same;
• an encoder for providing a pulse signal corresponding to the rotation of the motor;
• a position detector arranged on a upper part of the elevator car for detecting arrival of the elevator car at a predetermined position of each floor and outputting a floor identifying signal of each floor;
• a shielding board installed at a predetermined position of each floor of the hoistway for operating the position detector;
• a travelled-distance computing means for computing and outputting a distance for which the elevator car has travelled in accordance with the pulse signal supplied from the encoder;
• a destination floor determining means for outputting a signal which identifies a destination floor to which the elevator travels responding to a hall call from the hall call buttons or a car call from the destination floor selection buttons;
• a floor distance storing means for storing distance data from a predetermined base floor to each of respective floors in accordance with an output of the travelled-distance computing means;
• a distance-to-go computing means for, responding to the destination floor identifying signal outputted from the destination floor determining means, computing and outputting a distance to go from a present floor to the destination floor according to the distance data supplied from the floor distance storing means and the distance data of the present floor outputted from the floor distance storing means, being indicated by the identifying signal of the present floor supplied from the position detector;
• a first velocity command generator for generating and outputting a first velocity command signal which follows a velocity profile having an acceleration region, a uniform velocity region and a deceleration region, corresponding to the distance-to-go output supplied from the distance-to-go computing means:
• a floor distance correcting means for computing a distance of each floor dependent upon the travelled distance supplied from the travelled-distance computing means whenever receiving the floor identifying signal from the position detector, comparing the computed distance value of each floor with the distance data value of the corresponding floor supplied from floor distance storing means and, if there is a difference between the compared distance values, storing the newly computed distance in the floor distance storing means as the distance data for the corresponding floor;
• a deceleration starting point determining means for determining and outputting a deceleration starting point, depending upon the first velocity command signal outputted from the first velocity command generator;
• a second velocity command generating means for, if there is an output from the deceleration starting point determining means, computing a second velocity command value of the deceleration region and outputting the resultant value as a second velocity command signal, corresponding to the command position of the elevator car which has been stored by each time elapsed since the deceleration starting point;
• a signal switching means for outputting the second velocity command signal if there is the output of the second velocity command signal from the second velocity command generating means, and outputting the first velocity command signal supplied from the first velocity command generator if there is no output of the second velocity command signal;
• and
• a motor controller for outputting a motor control signal in accordance with the output from the signal switching means.

In a method for controlling a position of an elevator car by generating a first velocity command signal to follow a velocity profile which has an acceleration profile region corresponding to a linear function profile of a time during which speed increases in accordance with the time elapsed, a uniform velocity profile region maintaining a velocity value of an end point of the acceleration profile region and a deceleration profile region wherein the speed decreases from the uniform velocity value of the uniform velocity profile region to zero in accordance the time elapsed, an elevator position controlling method, comprising:

• determining a deceleration starting point of the deceleration profile region;
• previously storing a command position corresponding to the time elapsed after the deceleration starting point;
• dividing the command position into a plurality of position regions;
• differently establishing computing formulas of a velocity command by each position region;
• determining the position region to which the command position at a present time belongs;
• computing a second velocity command value in accordance with a time a using the computing formula corresponding to the determined position region at the present time;
• and
• controlling a position of the elevator car in accordance with the second velocity command value after the deceleration starting point.