In this example, a motor was used to drive a loaded shaft using a belt and two pulleys. The SensorPlot™ was used to monitor the two pulleys to see if the belt slipped during motor startup. To accomplish the task of monitoring the pulleys, an encoder was attached to the end of the shaft extending past the end of each pulley.
Measurements
- To measure and plot pulley velocity, the built-in (standard) measurements velocity were simply added to a graph display.
- Because the pulleys were not identical in size (pulley ratio=0.671), an equation based measurement was used to mathematically translate the pulley position of the motor to the position of the load. This trace was called MotionPosition as illustrated by the blue trace located in the legend of the graph displays.
- To compute the position difference between the two pulleys, another equation-based measurement was constructed. This custom measurement was placed on the right Y-axis of the display plotting the measurements of absolute position.
- Using the external trigger mode, SensorPlot™ was configured to begin acquiring data as soon as the motor driving the pulleys was turned on.
Comments
- As illustrated by the sudden change in velocity on the part of the motor (leftmost graph), a slip occurred in the first couple of seconds after the motor was started.
- As indicated by the rightmost graph, the slip started to occur at about 0.8 seconds. As indicated by the numerical displays, the amount of slip was measured to be 1.7 revolutions and it occurred at 1.497 seconds.
- Although the total test time was 10 seconds, SensorPlot™ evaluates equation-based measurements in real time. Subsequently, even the difference computation was plotted as data was acquired.
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