Structural health monitoring of an escalator drive system

1. A structural health monitoring system comprising:

a drive system of an escalator or moving walkway comprising:

a first drive member;

a second drive member operationally connected to the first drive member; and

a tension member operationally connecting the first drive member to the second drive member;

at least one first sensor configured to monitor a characteristic of the first drive member;

a processor in communication with the at least one sensor and configured to determine if the structural health of the tension member is compromised based on the monitored characteristic, the processor further configured to perform a safety response action when the structural health of the tension member is determined to be compromised, and

at least one second sensor configured to monitor a characteristic of the second drive member,

wherein the processor is configured to monitor a transfer function between the first and second drive members to determine if the structural health of the tension member is compromised, wherein the transfer function comprises signal averaging of signals received from the at least one first sensor and the at least one second sensor and wherein frequency domain curve fitting is employed to compensate for noise in the system.

2. The structural health monitoring system of claim 1 , wherein the at least one first sensor is disposed on or located proximal to the first drive member.

3. The structural health monitoring system of claim 1 , further comprising a motor operationally connected to at least one of the first drive member and the second drive member.

4. The structural health monitoring system of claim 1 , wherein the first drive member and the second drive member each comprise a sheave, a pulley, a gear, a wheel, a sprocket, a cog, or a pinion.

5. The structural health monitoring system of any of claim 1 , wherein the tension member comprises a chain, a belt, a cable, a ribbon, a band, or a strip.

6. The structural health monitoring system of claim 1 , wherein the at least one first sensor and the at least one second sensor each comprise an accelerometer, a resistance temperature detector, a thermocouple, a non-contact eddy current probe displacement sensor, a contact linear variable displacement transducer, a velocity sensor, a strain sensor, a load sensor, a pressure sensor, a microphone, or a non-contact chain vibration measurement device.

7. The structural health monitoring system of claim 1 , wherein the safety response action comprises at least one of powering off the drive system, providing a displayed notification on a display screen, transmitting a notice to an external device, and providing an indicator light and/or sound indicating that the structural health of the drive system is compromised.

8. The structural health monitoring system of claim 1 , wherein the processor and the at least one sensor form a single device.

9. A structural health monitoring system comprising:

a drive system of an escalator or moving walkway comprising:

a first drive member;

a second drive member operationally connected to the first drive member; and

a tension member operationally connecting the first drive member to the second drive member;

at least one first sensor configured to monitor a characteristic of the first drive member;

at least one second sensor configured to monitor a characteristic of the second drive member; and

a processor in communication with the first and second sensors and configured to measure and monitor a transfer function between the first and second drive members to determine if the structural health of the drive system is compromised,

wherein the processor is configured to monitor a transfer function between the first and second drive members to determine if the structural health of the tension member is compromised, wherein the transfer function comprises signal averaging of signals received from the at least one first sensor and the at least one second sensor and wherein frequency domain curve fitting is employed to compensate for noise in the system.

10. The structural health monitoring system of claim 9 , wherein the processor is configured to perform a safety response action when the structural health of the drive system is determined to be compromised.

11. A method of monitoring the structural health of an escalator or moving walkway drive system, the drive system includes a first drive member, a second drive member, and a tension member operationally connecting the first and second drive members, the method comprising:

measuring a characteristic of at least one of the first and second drive members;

determining if the structural health of the tension member is compromised based on the measured characteristic; and

performing a safety response action when it is determined that the structural health of the tension member is compromised,

wherein the measuring step comprises measuring a transfer function between the first drive member and the second drive member based on the measured characteristic, wherein the transfer function comprises signal averaging of signals received from the at least one first sensor and the at least one second sensor and wherein frequency domain curve fitting is employed to compensate for noise in the system.

12. The method of claim 11 , wherein the determining step comprises comparing the measured characteristic to a known quantity.

13. The method of claim 12 , wherein the known quantity is analytically determined.

14. The method of claim 12 , wherein the known quantity is a measured characteristic of the structural health of the tension member when the tension member is known to be healthy.