Comparison of manual or electronic control of drop distances from bulk produce conveyors

Abstract An ultrasonic distance sensing system was used in conjunction with a proportional hydraulic valve for automatic control of harvester conveyor height above a bulk pile of potatoes during three harvesting seasons. Tuber bruise tests showed no detectable difference between automatic or manual control of the conveyor. Electronic recording of the drop distance, for both modes of control, showed a more uniform distance and fewer large excursions when in automatic control. The control system was also used for two seasons on telescoping pilers for unloading potato storages. Drop distance recordings indicated considerably better performance for automatic control versus manual control. When automatic control of the piler was used, transport trailers were more accurately loaded to the desired amount to stay within legal licensed limits. Detection of the side of the trailer, with an infrared proximity sensor, enabled switching of the ultrasonic sensor signal between elevating and telescoping functions. This feature permitted height control of the bulk produce pile relative to the top of the trailer side.