As technology advances, manufacturing is becoming more and more automated. Robots are becoming the standard in most manufacturing lines that require fast, repetitive, precise placement of components. Many other types of automated equipment are being used for inspection to ensure components are placed in specified locations, check for missing components, and ensure fluid levels are at the exact level. Traceability information is collected by reading barcodes on parts in production so Operations knows exactly where every product in the manufacturing plant is at any given time and where each product has been. In order to achieve this type of automation we embed devices like machine vision cameras to give equipment eyes for visual inspection, and auto ID imagers and laser scanners to allow equipment to trace product through the manufacturing process. When developing your automated equipment it is imperative to choose a machine vision system, auto ID imager, or laser scanner that fits your precise requirements. There are five things to consider when choosing an embedded machine vision camera, auto ID imager, or laser scanner for an application: barcode type and orientation, inspection parameters, application speed, integration space, and data communication needs.
1. Barcode Type and Orientation
There are over 100 types of barcode symbologies that may be employed in automated operations. The three most common symbology types are: linear (1D) barcode like UPC or stacked symbols, which can be decoded by both laser scanners and barcode imagers; 2D symbols like QR Code and Data Matrix, which must be read by barcode imagers; and direct part marks (either 1D or 2D), which must also be read by imagers.
Space restrictions or specific design requirements for integrated equipment may dictate that barcodes be fed into a machine at a particular orientation. How a barcode reader or machine vision camera is oriented in relation to the barcode and the direction the barcode is traveling are important considerations when selecting such a device for an application. For example, a laser scanner must always be oriented such that the laser scan line is perpendicular to the bars of the barcode. This can be accomplished by either using " picket fence" (code horizontal, lines vertical) or " ladder" (code vertical, lines horizontal) orientation. Picket fence orientation is generally recommended over ladder orientation because the scanner has more time to scan the entire barcode as it passes through the scan width area.
Unlike 1D laser scanners, imagers can read barcodes in multiple orientations, capturing 2D images to acquire symbol data. For this reason, a 2D barcode imager or machine vision camera can be positioned in any orientation within equipment to read codes. In applications where code orientation in relation to the reader cannot be predicted, an imager may be the preferable choice.
2. Inspection Requirements
Applications requiring automated data acquisition beyond simple barcode reading (such as barcode quality verification; code, label, or part presence and orientation; product defect detection; color inspection; and other visual inspection processes), require the use of machine vision cameras and software. In embedded applications where reducing the me chanical footprint is important, choosing a fully-integrated machine vision system allows design engineers to ensure that high-quality images are captured without the need to plan for and install excess equipment like lighting or added optics.
3. Application Speed
Time is of the essence in automated applications, and time savings is one of the main reasons for adding automated devices to equipment. Laser scanners can be faster at decoding 1D barcodes than imagers - as fast as 1,000 real-time decodes per second. Camera-based imagers, on the other hand, must capture and process complete 2D images, including barcodes, part features, and any elements surrounding the actual area of interest, and then extract meaningful data. This means that imagers can be more precise, but may also have longer decode times depending on the device and application.
When designing equipment, it is also important to take into consideration the data communication rate. How fast does the reader or camera need to communicate decoded data or data-dense images to the outside world? Devices with high-speed USB or Ethernet interfaces are commonly used to transmit these images for storage over a high-speed connection without impacting overall application speeds.
4. Integration Space
Integration space within turnkey systems is precious real estate. Every component in a system has its place, but the more efficiently that space is used, the smaller the footprint of the overall machine. Many embedded imagers are designed with constrained and geometrically-complex spatial requirements in mind. When choosing an embedded device for an application, it's critical to find a device with the proper mechanical envelope and optical envelope to read each barcode or perform inspections reliably. Mechanical envelope encompasses the dimensions of the device and any peripheral equipment, such as lighting, triggers, cabling, etc. The total dimensional space required by a particular device to decode a symbol or inspect a part at a specified distance is called its optical envelope (also sometimes called the " read" or " inspection" envelope). The challenge when reading barcodes or inspecting parts at close range is achieving a field of view large enough to span the entire symbol or large enough to capture an object of interest. Device size, mounting angle, and the distance from the device to the part or code all comprise the optical envelope and directly affect how much space must be available within a machine for a specific device to perform data acquisition tasks with reliability and repeatability.
5. Data Communication Needs
The final consideration to make about an application before choosing an embedded device is how the system will communicate with the device, and how the device will communicate data back to the system. Communication specifications can determine the physical space occupied by the device and its accessories, the speed at which an embedded device must perform, the type of connectivity to the system, and the software used to set up and control the device. These specifications can be addressed by a device's electrical functionality and software interface, and considerations should be made to ensure a device fits the mechanical envelope for electrical requirements (power requirements, connectivity, inputs/outputs, and trigger methods) and has scalability via software to adapt to changing requirements.
The type of software interface needed to control the device should optimize a device for the life of the equipment into which it's embedded. Barcode readers and machine vision cameras today are capable of more than just interpreting images and outputting data. Instead, these devices function like independent computers with their own algorithms and processors, reducing the amount of programming required on the device to process data and putting the power in the hands of the operator to control the imager from outside the machine. If a device's software allows external manipulation of device focal range, triggering, activating tools for inspection and more, equipment is less likely to need physical adjustment or redesign to meet new requirements in the future.
Understanding an application's requirements is critical to choosing the best embedded device for successful data acquisition and automation. By planning for application specifications early in the design process, and incorporating these specifications into the design, engineers can dramatically increase the reliability and accuracy of their data acquisition processes for the life of their equipment. The correct embedded barcode reader or machine vision camera provides the flexibility to meet expanding requirements without the need for future design adjustments, significantly lowering the cost of ownership for the life of the entire system.
For more guidance on choosing an embedded device, read Microscan's latest white paper " Five Things to Know Before Choosing an Embedded Data Acquisition Device."
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