Video Gallery

The video demonstrates how the Sauer Danfoss Plus +1 hardware can be used to synchronize two cylinders. The closed loop theory of what you see in the video can be expanded for much more than two cylinders.

In the video you will see the Plus +1 six inch color display unit, a demonstration platform with Plus +1 controller, and two hydraulic cylinders linked with a bubble level. What you are not able to see in the video is a joystick as well as two mechanically variable relief valves on each of the cylinders. The joystick provides a cylinder movement command and switches the system between ‘synced’ and ‘independent’ modes. The relief valves where installed to provide a restriction on the rod side of the cylinders when lifting to simulate a different load on each cylinder.

The lights on the demonstration unit point out stages of operation in the video. The far left light indicates the signal to the left cylinder’s proportional valve. Notice the intensity changes as the valves are commanded. The next light indicates the same for the right cylinder.

The far right light is illuminated when the cylinders are synced together. Notice it goes dark in the situation where the cylinders are being adjusted independently. During synchronization the cylinders will move together no matter what the difference in position, as demonstrated by the Grimstad logo that is put in place halfway through the video to offset cylinder position, but still remain level.

This synchronized movement is achieved with two Sauer Danfoss PVG32 proportional valves and two Can Bus string pots. The position of each cylinder is sent over the Can Bus network to the Plus 1 controller from each string pot. By using Can Bus network feedback devices we eliminate the need for analog inputs in the controller as well as the possibility of faulty data due to noise on the analog signal.

When the cylinders are ‘synced’ the controller uses the position feedback from one cylinder and compares it to the other. The other cylinder then ‘follows’ the first cylinder. This ‘following’ motion is achieved by varying the command to the proportional valve to make the cylinder position feedbacks match each other. The result is synced cylinder movement regardless of the load on the each of the cylinders.
Updated: 3:48PM February 20th, 2010 | URL: http://www.grimstad.com/videos/view/2

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