How to Center Guide with Two Sensors with the SCU6x Controller

So, one of the other things with the SC6X controller is that we can do center guiding with two sensors and it can be done automatically. We talked about how to set up the different sensors for different configurations. So, please take a look at those videos. In this video, we're just going to show you how it works with an actuator, how things look, and how to reset the guide point for center guiding.

What we have is a couple of sensors connected here. One of the things with center guiding is that we would like the two sensors to be of the same range. Even though the system would work when you have two different ranges just on the display to make it simpler and not cause any confusion, it's better to use two sensors of the same range. Right now, I have an infrared sensor and a white light sensor just for illustrative purposes.

In reality, anytime we are doing edge or center guiding based on the edge of the material, we're going to always use an infrared sensor. So, let's go back to the screen and see how it looks. This sensor is set to see the left edge and this sensor is set to see the right edge. So, if I have a material that is presented, you can see that it's seeing the left edge and the right edge.

The green in the middle is showing the center line position. And in this particular case, we got the guide point offset to be zero. So if I set it to automatic, then the actuator is going to move back and forth based on if the center position is within the guide point to the left or to the right. And that's essentially how the center guiding works.

There are two main reasons why somebody would use center guiding. One is if you're changing web widths and you want to align the material to the center of the machine, then center guiding is the best option where you would place two sensors on either side and the those sensors are equidistant from the center line of the machine. So when the web width changes, you don't ever have to move the sensors and it automatically adjusts itself because it's going to look at the left portion of the web seen by the left sensor and the right portion seen by the right sensor. This is one of the common features that we have or common value proposition from our products is that our sensors can go anywhere from 48 mm up to 960 mm.

That means you can have a width change of about 96 mm up to about 1920 mm without needing to move the sensor. This provides a lot of range and flexibility to be able to have a system that can adapt to wick changes on the flight. The older generation systems might have some actuators that move the sensors based on the wick change. And more often than not, what happens is that those actuators have their own control loop that needs to be tuned.

The actuators can wear. These are the actuators for the sensors that could wear over time. And that creates an issue. And then the response time, especially when you do a wid change on the fly with those kind of systems, is going to be much lower than compared to a system with a sensor that is wide enough to cover all the width changes.

So that's one of the main reasons for using center guiding is that you can do different widths without moving the sensors whenever the width changes. The second main reason why you would use center guiding is that let's say you have an edge especially some kind of an extruded edge and the edge quality might not be great. So before it goes into a slitter you you have an edge and the edge is not that great. Instead of aligning to one edge of the web, in that case if you use two sensors and then use the center line position, it takes the average of the left edge and the right edge and does the measurement that is going to be the center line measurement and it's going to guide the web to the center.

This is one of the biggest advantage for using two sensors and doing the center guiding and especially when you have irregular edges, those edges variations are not going to be identical on both sides. This smooths out your edge profile and allows you to guide the web in the middle of the machine and that significantly improves the wound roll quality especially if you don't have a pretty good slit edge. So the advantage is that you are averaging based on two edge measurements and this helps in smoothing out the edge position. Those are the two main reasons why you would use center guide.

One of the other things that I want to show with center guiding is that you can do the reset guide point just like what we did with edge or center guiding with two sensors. Let me show you that. Going back to the screen here, we have the web now and the green position indicates the center line position. If the web is moved that way and for whatever reason you need to do that, you could do the same reset guide point and accept.

Now the guide point offset is there. If the edge position goes on either side, the actuator changes its direction back and forth. This is for doing the center guiding with the point offset. Now, like I said, it's not usual for you to change the guide point offset with center guiding just because you want the material to be aligned to the middle of the machine.

The reason why we allow you to do that is that let's say you had not installed the sensor at the right location to begin with. Instead of going and physically moving the sensor, you could just move the offset. And that's the reason why we allow a guidepoint offset even when we do center guide.