Machine Vision Cameras for Waste Sorting & Recycling

Advising the right setup for the waste sorting application starts with selecting a suitable machine vision camera. The vision expert of VA Imaging recommended using our 16MP camera ‘ME2S-1610-24U3C’ with the Sony IMX542 sensor because
of the following requirements requested by the customer.

Firstly, an USB3-interface was recommended as the camera interface. This was based on the fact that the customer could benefit from the four times higher bandwidth compared to a Gigabit Ethernet (GigE) camera. In addition, the USB3 interface is recommended for applications where the distance between the pc and the camera is not more than 4.6 meters because of the limited cable length. In the customer’s application, this length was approximately 4 meters. Furthermore, different colors of garbage had to be detected. That is why a color camera was advised.

Additionally, the choice was made to use a global shutter camera instead of a rolling shutter camera. Global shutter cameras are used in applications where either the camera or the object is moving while the image is being captured. In this case, the conveyor belt is moving and does not stop during image capture. A rolling shutter camera, which works great for stationary applications, is not suitable for this purpose. Using a rolling shutter camera would result in a lot of image distortion due to the movement. All cans, bottles and other garbage on the conveyor belt may appear ‘leaned’ or ‘tilted’. In industrial applications such as waste sorting, this distortion leads to inaccurate detection because some waste may not appear as it actually is. A global shutter camera prevents these errors by capturing realistic, undistorted images. More info about Global shutter vs. Rolling shutter can be found in this article in our Knowledge Center.

Our 35MM C-mount lens ‘VA-LCM-25MP-35MM-F2.4-120’ turned out to be a great lens for the 16MP camera. Using our 35MM lens on a working distance of approximately 1056mm results in a field of view of 425x242mm. This is shown in Figure 2, the lens focal length calculation.

Adding machine vision lighting to a vision system like this wastesorting application is highly recommended. The customer told VA Imaging’s machine vision expert that the factory environment where the setup will be placed was not well illuminated. That is why they decided to put a closed-off box around the conveyor belt where the waste will be detected on.   

The products on the conveyor belt are all very different. From cans to bottles, in all kinds of materials and colors, they should be detected for correct waste sorting and recycling afterwards. To illuminate all garbage as evenly as possible and with minimal reflection, it is recommended to use 2 of our LED spotlights: Industrial LED Spot light VA SL-90x80-W. One of the biggest advantages for this waste sorting system is that the LED spot lights come with three optical lenses. By choosing the right optical lens (30,60 or 90 degrees), they can be placed in the optical angle that gives the most ideal light for the application. It offers a lot of flexibility for the customer.

To exclude all ambient light in the factory, our machine vision expert also recommended building a box around the conveyor belt. The advice is to make the box, for example by painting, completely white colored from the inside. Then place the LED spots on two inner sides of the box and position them upwards. This way, the light 'bounces' to the ceiling of the box and down onto the waste that is on the conveyor belt. The light will be evenly distributed.

To power the two LED lights, our 24V 150W power supply was recommended. This power supply works as a light controller, allowing the LED spots to be triggered and dimmed. In addition, extension cables can be selected on our website if desired.