Machine vision systems have evolved from advanced sensors to inspection systems integrated into controllers. Choosing the right PC-based automation platform can make them even better.
For years, global semiconductor chip manufacturers have been advocating the concept of hardware integration, and integrating machine vision and PC-based control is one such opportunity.
CPUs with ever-increasing power and performance can now handle complex computational tasks previously processed by separate devices. Machine vision technology is no exception; as it continues to evolve, engineers are seeing more and more exciting new capabilities.
With higher resolution and faster image processing capabilities, vision systems have transcended the role of advanced sensors, becoming complete, integrated inspection solutions. While proper illumination and lenses still determine image quality, significant progress is being made in other areas.
Integrating machine vision into the machine's main controller enables the technology to meet requirements even in the most complex, high-speed applications, while reducing the need for separate hardware. This approach ensures that everything from triggering an image to acting on the result is executed in real-time code within the machine control. Utilizing image processing within the machine's main controller, tightly synchronized with fieldbus updates, axis positions, and other coded variables, provides seamless synchronization with the machine, triggers, and lighting, enabling immediate action on visual results.
01 Real-time Functionality and Machine Vision Applications
In automation and control, real-time performance is defined by the automation controller, which runs all necessary code and updates input/output (I/O) devices at a uniform, known rate. For example, a motion controller updates the position of an axis at a predefined rate or frequency. Real-time also means that real-time scheduling is unaffected by tasks outside the real-time environment, such as operating systems or other non-real-time software. This consistent, known controller update rate is what is meant by real-time processing as defined in the DIN 44300 standard, "Information Processing".
The processing speed setting varies depending on the specific machine vision application. For example, one application might require inspecting images at a rate of 5 images per second, while another might require 50 images per second. Both cases can define and process the inspections in a real-time environment and send the results to the main automation controller. The type of solution chosen will affect the ability to achieve real-time functionality.
02 Four methods for running visual inspection software
Some common methods for running modern visual inspection software include:
■ Smart cameras equipped with onboard processors to provide the necessary processing power;
■PC Vision: A dedicated multi-core CPU runs vision algorithms as a process within an operating system (such as Microsoft Windows).
■ Vision Controller: A standalone piece of hardware running a proprietary operating system that provides image processing for one or more remote cameras;
■ Advanced, multi-core, PC-based automation software capable of handling real-time machine control and real-time vision processing.
When running visual inspection code on a dedicated processor, the time required to complete the inspection is directly related to the processor, processing speed, the code being executed, and the images. Need it to run faster? These options include reducing the amount of image data being processed, optimizing the code, or acquiring faster hardware.
In a Microsoft Windows operating system running on a dedicated multi-core CPU, traditional PC-based visual inspection code operates under various factors. While using multiple cores can reduce overall processing time, other processes can also access these cores, and managing shared cores between processes can cause fluctuations in the time required to fully execute the visual inspection code. This introduces unpredictable factors into the processing time required for inspection. Hardware selection often exceeds actual needs, increasing costs due to factors beyond the processor, such as larger racks, additional power supplies, and the need for cooling within the rack to handle the extra heat.
Another requirement for smart camera, PC vision, and vision controller systems is that, once inspection results are determined, these results must also be communicated to the host controller. These results can be simple pass/fail statements or images composed of large amounts of data. The time required to transmit this data to the machine controller can have an impact and must therefore be considered.
03 Real-time PC for machine vision and machine control modules
A novel approach involves processing visual inspection data on an isolated core of an advanced, PC-based real-time automation platform and its accompanying software. On such platforms, numerous discrete machine control modules, including those for visual inspection, can run on powerful hardware. The PC-based software platform provides a framework for real-time invocation of modular software.
By modularizing components in this real-time environment, multiple PLC, C++, or vision inspection modules can be executed independently on a single piece of hardware. PC-based automation also provides the ability to isolate the processor core from the system.
For example, dedicating one or more isolated cores to vision processing prevents other processes from affecting the time required to complete a vision inspection. Other processes or modules running on the same platform will not cause changes to the timing results. Another benefit is that the inspection results (including images) can be immediately used in primary machine automation applications running in parallel on the same automation software platform.
Using advanced PC-based real-time automation software platforms can bring considerable practical benefits. These include higher real-time throughput and system availability compared to when machine vision and machine control platforms are separate. It's not just a different way of handling machine vision; it also helps improve the performance of the entire machine and process.
04 Integrated machine vision optimization and automated component assembly
Aixemtec GmbH, headquartered in Germany, specializes in developing automated solutions for the precision assembly of optoelectronic systems. Assembly solutions across various applications are based on a comprehensive modular platform. Previously, multiple PCs were required to implement vision, human-machine interface (HMI), sequential control, and machine control functions. Now, a single PC-based real-time automation software platform can accomplish these tasks. On the software side, vision, programmable logic controller (PLC), motion control, safety, and HMI modules are used.
Some of the process preparation is performed outside the real-time environment in a specially developed high-level language program. The PC-based control system allows for seamless integration of software modules and user-customized programs on the same industrial PC. The automation software also utilizes a common communication interface to support necessary communication with other software systems.
