Machine Vision

 

Basler’s new scout cameras have proven their ability to perform in a challenging machine vision application and are now running in several systems around the world. The camera design-in process for these systems started in mid 2006 and was finished by the end of 2006. This demonstrates a rapid design-in cycle and highlights the ease of integration of Basler’s Gigabit Ethernet cameras in combination with our pylon driver and software package.

In this particular type of application, an endless stream of material such as paper or steel is inspected by up to 11 scout Gigabit Ethernet cameras that are running simultaneously. The cameras are running at more than 200 frames per second and are using binning and different AOIs. Bundles of three cameras are attached to a Gigabit Ethernet switch. From each switch, a single cable is attached to a rack-mounted PC equipped with Gigabit Ethernet ports and high-powered CPUs. These small PCs are responsible for processing the captured images. Image processing is mainly designed to detect and classify defects on the inspected material. In addition, conventional Ethernet ports on the PCs deliver the results to an operator in a remote location that can be as far as several hundred meters away. “This all takes place with the highest reliability and with accurate timing,” summarizes Henning Tiarks, Product Manager at Basler-VC.

The main advantages of Gigabit Ethernet in this application include:

Gigabit Ethernet technology that replaces analog system setups

Gigabit Ethernet camera systems can quickly and efficiently replace multi-camera analog setups while increasing the price/performance ratio. In this case, a setup with 11 analog cameras was replaced and the total system cost was lowered by a two digit percentage.

Built-in image buffering

Each Basler scout and pilot camera is equipped with internal memory for lossless data transmission. This buffering capability means that missing image information can be re-requested by the PC and resent by the camera. This mechanism is part of the camera’s firmware and driver and is automatically handled by each Basler camera and the Basler pylon driver. In addition to ensuring reliable transmission, the image memory can also be used to store frames and to transmit the frames after a specified delay. This allows the user, for example, to simultaneously grab an image with all 11 cameras and then to use delays to sequentially transmit image data from the cameras to a PC.

Robust driver and reliable data transmission

Before the design-in process began, the candidate cameras were exhaustively tested. Basler scout GigE cameras were tested using two different system layouts. The first system consisted of eight cameras attached to three PCs equipped with Basler’s pylon GigE Vision filter driver. Tests using this system configuration were run non-stop for 13 days without failures, dropped frames, or hang-ups.

A second, more advanced layout consisted of three cameras attached to one computer that used two high-priority load generation threads to stress the system. With this configuration, no problems occurred during 19 days of nonstop running. During that time, several hundred million images where captured by the cameras, transported to the PC, and processed.