Empty Tote Detection: Which Sensor Solution is Best for Your Application?

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There’s more than one way to confirm an empty tote. Here’s an overview of the full range of sensor options.

With the profusion of automation deployed to support today’s high-volume, high-throughput piece picking for e-commerce and omni-channel order fulfillment, nearly every application utilizes reusable plastic totes. They hold products stored in automated storage and retrieval systems (AS/RS). Picked items are placed in them for order consolidation. Conveyors and autonomous mobile robots (AMRs) transport them from one location to another within a facility.

Yet even the most carefully designed picking process can experience an error, such as a product accidentally being left inside a tote. With automated warehouses and distribution centers needing precise and accurate inventory information in real-time at all times to maintain high levels of customer service and to optimize order fulfillment, such an error can be costly.

That’s why there are a variety of sensors available to scan and verify that each and every tote is empty. But which type is right for a given application?

When evaluating potential sensor solutions, it’s first important to consider the specific detection challenges associated with tote handling within a facility. These typically fall into three primary categories:

  • Conveyor characteristics, including the variability of tote orientation and positioning on the belt or rollers, operating speed of the conveyor and the amplitude of vibrations generated by its movement.
  • Tote characteristics, such as floor and wall surface texture, reflectivity, color, size uniformity or diversity, and shape.
  • Product characteristics, like dimensions, color, transparency, reflectivity, and shape.

Depending on the conveyance, tote and product characteristics in a facility, one or more of the following types of sensors can be deployed to overcome or compensate for empty tote detection challenges. They include:

  • Ultrasonic sensors emit a sonic pulse that is reflected by the object being detected. Highly adaptable, these sensors identify an item regardless of its color.
  • 2D LiDAR (light detection and ranging) sensors with high-definition distance measurement (HDDM) are immune to ambient light, while their monitored area can be set without a computer. This allows the sensor to accommodate a broad range of tote shapes and sizes.
  • 2D vision sensors quickly detect objects left in totes by capturing a 2D image as each tote passes by. Ideal for high-speed applications, they can be equipped with different optics, color filters and illumination options to overcome color, reflectivity and speed challenges.
  • 3D vision sensors combine laser line height profiles of detected objects with images obtained via a camera to create a high-resolution 3D image at a range of speeds while accommodating a variety of totes.

For more information about SICK’s scalable solutions for empty tote detection download the flyer below!

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