Signal correlation for missing step detection in conveyors

摘要

A device and method for detecting a misaligned or missing step of a conveyor are disclosed. The missing step detector includes various sensors for detecting the drive speed of the conveyor and for detecting the presence of pallets or steps. The sensor output signals are correlated to determine fixed values characteristic of the specific conveyor in question. Using the fixed values as reference, the missing step detector is able to effectively monitor the conveyor for misaligned or missing steps independent of conveyor speed and time.

主权项

1. An apparatus for detecting a missing or misaligned step of a conveyor extending between a first platform and a second platform, comprising:
at least one drive speed sensor configured to detect a drive speed and output a drive pulse signal corresponding to the drive speed; at least one first step sensor and at least one second step sensor, the first step sensor configured to detect each step at the first platform and outputting a first step pulse signal corresponding to the steps at the first platform, the second step sensor configured to detect each step at the second platform and outputting a second step pulse signal corresponding to the steps at the second platform; and a control unit that receives the drive pulse signal and first and second step pulse signals, the control unit being configured to determine a frequency of the drive pulse signal, determine a ratio of drive pulses per step pitch based on the frequency of the drive pulse signal and at least one of the first step pulse signal and the second step pulse signal, determine a phase difference between the first and second step pulse signals, monitor the pulses per step pitch ratio and the step pulse signal phase difference for variance, and provide instructions to adjust operation of the conveyor in response to detected variance.