Method and apparatus for determining the movement and/or the position of an elevator car

An apparatus for determining a movement and/or a position of an elevator car of an elevator system comprising:

• a first monitoring unit connected to a first sensor device for analyzing first signals from the first sensor device for obtaining information about the movement and/or position of the elevator car and for detecting a faulty behavior of the elevator system and initiating corresponding safety measures;
• a second monitoring unit connected to a second sensor device, which second sensor device does not operate on the principle of the first sensor device, the second sensor device registering changes of a movement state of the elevator car and generating corresponding second signals to the second monitoring unit for analyzing the second signals;
• a checking module connected to the first and second monitoring units for checking whether the movement signals that are determined by the first monitoring unit and the changes of the movement state of the elevator car that are detected by the second monitoring unit are mutually coherent, and in response to incoherence, generating a first fault signal;
• and
• a time basis connected to the first and second monitoring units for establishing a time-window during which the mutual coherence is checked by the checking module.

An elevator system comprising:

• an elevator car;
• a first monitoring unit connected to a first sensor device for analyzing first signals from the first sensor device for obtaining information about movement and/or position of the elevator car and for detecting a faulty behavior of the elevator system and initiating corresponding safety measures;
• a second monitoring unit connected to a second sensor device, which second sensor device does not operate on the principle of the first sensor device, the second sensor device registering changes of a movement state of the elevator car and generating corresponding second signals to the second monitoring unit for analyzing the second signals;
• a checking module connected to the first and second monitoring units for checking whether the movement signals that are determined by the first monitoring unit and the changes of the movement state of the elevator car that are detected by the second monitoring unit are mutually coherent, and in response to incoherence, generating a first fault signal;
• a time basis connected to the first and second monitoring units for establishing a time-window during which the mutual coherence is checked by the checking module;
• and
• at least one of a central control unit and a hoistway information system being connected to at least one of the first and second monitoring units for receiving at least one of position data and movement information of the elevator car.