System and method for determining the position of an elevator car of an elevator unit, the elevator car being movable in an elevator shaft

A system for determining a position of an elevator car movable in an elevator shaft of an elevator system, the system comprising:

• a 3D sensor;
• an evaluation unit in communication with the 3D sensor;
• a marking element, wherein one of the 3D sensor and the marking element is arranged immovably in the elevator shaft and another of the 3D sensor and the marking element is arranged on the elevator car;
• wherein the 3D sensor has a plurality of sensor cells that generate measurement data when an object is detected and the evaluation unit is adapted to determine a distance of each of the sensor cells from a part of the object detected by the sensor cell;
• wherein the 3D sensor, in a normal mode of the system, detects the marking element as the object and the evaluation unit determines a position of the elevator car in the elevator shaft based on ones of the sensor cells that detect the marking element;
• and
• wherein the evaluation unit continuously tests whether the 3D sensor detects the marking element and brings the system into an error mode when the test is negative for detection of the marking element.