Q&A: Jacob Paso on High-performance Motion Control

MD: At a more granular level, can you give me an example of how that works in its execution?

JP: Sensors, some years ago, could go down to maybe 10 or 5 µm of resolution. Now we’re seeing down to 0.1 µm of resolution. Hydraulic proportional valve frequency response of 100 Hz used to be really, really good. Now we’re seeing 300, 400, 500 Hz valves. And not just the speed, but the quality of these valves being manufactured makes position control and force control just a lot easier to do, assuming we have the algorithms to take advantage of that.

MD: What has been your company’s most recent achievement in innovation?

JP: Our biggest recent achievement is increasing the number of axes our controllers support from 8 to 50 axes. And this is done while not only maintaining the same update rate of one kilohertz but also improving that update rate. Customers benefit from reduced costs of not having to buy multiple motion controllers for large machines—especially in wood products where they have large sawmill lines—and better synchronization between more axes and easier troubleshooting of large systems because you can see all the axes at once. So that’s Delta’s recent great achievement. 

MD: The other area that I like to look at is how digitalization is playing into motion control and providing better access and a better understanding of what is going on. Can you give me a sense of how Delta is tapping into that opportunity?

JP: I think it’s amazing how you phrased this question of digitalization because it leads right into the greatest impact that we have seen. We know that commonly it’s spoken of with digitalization that we have improvements in predictive maintenance or analysis of large data that improves energy usage and so on. But we haven’t been seeing great changes in that. Rather, we’ve seen exactly what you referred to of better access and understanding, that the most impactful result and universal result is a vast improvement in technical support.

So that’s a result of high-speed internet advancements in video conference technology, more data available in motion controllers to give us the information we need to do good support, as well as better control algorithms that are enabled by faster microprocessors. All of the improvements in digital technology are coming together to really improve that support.

It's interesting that it’s happening now because this has all been accelerated by the pandemic. It’s erased a generational divide that we observed two to three years ago where our younger support engineers were quick to connect remotely to a customer’s PC to troubleshoot systems, but the older engineers were a little more hesitant. But now the whole world has been forced into remote meetings, with bandwidth also increased to support it.

All of our support engineers frequently connect remotely to customers’ PCs. Many of our OEM customers support their own customers as well. So, this improved support results in better and less expensive transfer of expertise from the manufacturer to the end customer. That leads to improved product quality and less downtime.

A recent example really highlights this. We had a customer whose machine wasn't producing parts within specs, and they needed our assistance with their most controller. Their IT department didn’t allow remote access, so they had to schedule support with one of our engineers a couple of weeks in advance and pay thousands of dollars for the travel time. When the engineer arrived, it took him literally 10 minutes to tune the machine so that it was producing parts within spec and even better than it had before.

Had the IT department allowed remote access, we could have fixed it immediately, for free because this is what we normally do in the process of our free remote technical support. It is very common for many, many customers to do that. I like this example. It just accentuates the difference between how things used to commonly be done and what we can do now. And hopefully IT departments will get their security in line so they can allow more remote access.

MD: Focusing on Delta’s core, where do you see growth coming from then in the next few years?

JP: We see growth in international markets—especially Asia, with its heavy industry. That means it has a large hydraulic market, and coupled with its push for higher quality, this is just a great growth area for high-performance hydraulic motion control. Also, new technology—especially battery development, for which there’s a huge push worldwide. That’s driving growth as well for hydraulic control.

MD: What would you say is now required for a machine’s optimized performance? What technologies or processes should we need to be looking to?

JP: I generally divide that into three areas: high-performance components, simple design and a motion controller designed for hydraulics. Components include high-resolution position, pressure or force sensors, and of course, it be torque or other sensors, and high-response valves.

By simple design, I mean a proper hydraulic design. And the basics are very simple: We have a constant supply pressure from the hydraulic power unit, a valve that’s mounted on or very close to the cylinder with nothing other than perhaps a blocking valve for safety, and a motion controller designed for hydraulics.

In older hydraulics we would often have valve cushions and counterbalance valves and all kinds of things that complicate it. With a simple design and high-performance components, the motion controller is able to perform very complex motion with a high degree of accuracy.

MD: Let me bring it back to the design engineer. For the best electrohydraulic outcome, what design characteristics would you say the design engineer should keep top of mind when selecting an electronic motion controller?

JP: The most important thing is to ensure that the electronic motion controller has been designed for hydraulics. It must have the signals to connect to sensors and actuators. For position sensors that means magnetostrictive. We generally prefer synchronized SSI (synchronous serial interface), as that gives us the best synchronized low jitter data and the highest resolution. Valves, with either analog signals or fieldbuses that are becoming very common, must be fast enough for high-performance motion.

The controller’s tuning should accommodate the difference in piston area on both sides of the cylinder, as well as handling the compressibility of oil and the special characteristics of various valves. And lastly, the manufacturer of that motion controller should have knowledgeable tech support in the field of hydraulics.

MD: Tell us about your most challenging hydraulic motion control project to date. What was the challenge for you? How did you come to your solution?

JP: It’s hard to pick the most challenging one because we run into all kinds of various challenges, but maybe I can talk about a very large press where we controlled the cushion. The cushion is the bottom of the press. And for best forming characteristics, they want the top platen to push into the cushion, and the cushion has to catch it and have proper force control so it slowly can press up at whatever speed they need. For this, we needed our synchronized platen leveling algorithm to keep these cylinders level while controlling force. That’s a bit challenging, but we do have the algorithms for that.

On this particular press, the cylinders on the cushion were undersized and the cushioned platen, of course, is large. These presses are many stories tall. The combination of an undersized cylinder—that means the bore is too narrow—and a large mass, means that the cylinder will tend to oscillate given the compressibility of the oil. This was causing a lot of control issues. Some of our competitors’ controllers had been tried and they failed.

We came in there and did the synchronized platen leveling, and then we applied what we call our second order control. That’s a higher order of algorithms in our PID control. We were able to get rid of the oscillation and produce parts within spec. That was fairly early on in our development of some of these algorithms. And so, this was just a great win for us, combining both of those difficult algorithms in one.

MD: That’s a great example. It’s natural for a machine builder, for example, to deploy technologies that they’re comfortable with, or that they have experience with. And oftentimes, it makes financial sense to continue to do that. But new problems, I would say, often present new opportunities—and opportunities for technology improvements. What misconceptions can you clear up about optimizing legacy technologies?

JP: The main misconception that we encounter with optimizing legacy technology, for example legacy hydraulic systems, is that it’s necessary to move to electromechanical actuators. That’s totally false. Modern hydraulic motion controllers, along with new sensors and other components that I talked about, allow hydraulic control that wouldn’t even have been dreamed of, say, 10 years ago. And in many cases, even better performance with hydraulics can be achieved than electromechanical.

Also, especially in high shock or heavy load applications, hydraulics lasts a lot longer and maintenance costs are reduced because of that. And hydraulics can often be rebuilt and serviced at relatively lower cost versus electromechanical actuators, which generally have to be wastefully discarded.

All of this bodes very well for the large machines that hydraulics are often applied to. Those machines can be 30, 50 years old. And if you update the sensors and controllers and valves, you can vastly increase the productivity and quality of the parts produced by the machine.

MD: If you were to sum up, what does the future hold? Explain why hydraulic motion control remains critical.

JP: The future for hydraulic motion is bright. It is and will continue to be important for industrial applications that require positioning heavy loads, handling high shock or applying pressure. All of these are ideally suited to hydraulics. This includes all the heavy manufacturing, large precision presses—of which there are many kinds—wood products machinery and a wide range of testing applications. And I should throw in there, explosion-proof environments, as well, that often cause a lot of environmental challenges that hydraulics are well-suited to.