What are some of the notable changes that you've seen in motion control in recent years? Linear motors are becoming mainstream, as are high-speed digital signal processors that allow very-high-speed servo rates. Analog sinusoidal encoders also are making a big comeback, although they are processed digitally to get very high resolution. In addition, you see more options for high-speed serial communications such as Ethernet, USB, serial encoders, and fieldbuses.
What is Delta Tau's niche in motion control? We focus on applications that demand high speed and very high resolution, though we also provide solutions for general purpose automation. We believe that our controllers give customers the flexibility they need, so they are less likely to hit a brick wall. Many applications involve sophisticated multi-axis systems with complex trajectories that require intense calculations. In semiconductors and disk drives, our controllers perform in the picometer range in resolution. Nanometer control has become everyday for us. And in very-high-speed applications, our controllers incorporate look-ahead algorithms that anticipate when a tight corner or sudden stop is required and slow the system to manage these situations.
To what extent are customers still willing to shop for "best in class" components for motion control systems, versus a turnkey solution from one vendor? We still encounter a lot of customers who are willing to go after best in class, especially in applications that push the performance envelope. We don't sell motors, so we depend on our distributors to answer that need. However, we do sell fully digital amplifiers-rather than hybrid digital-analog amplifiers—as well as an integrated controller/amplifier, the Geo PMAC.
Can you cite a recent application that demonstrates the benefits of well-executed motion control? A good example is laser cutting. More-powerful lasers translate into faster cutting, but you need sophisticated look-ahead control algorithms to slow the system down for sharp corners and the like. Here, our controller performs all the real-time calculations and communicates with the PC front end with the operator interface, network, and math storage interface. The controller supervises the motion trajectories, closes the feedback loop, and even does the commutation of multiphase brushless motors. It also provides the on/off signal for the laser cutter itself.
How do you address the demand for more-compact motion control solutions? In communications, Delta Tau offers MACRO (Motion and Control Ring Optical), a non-proprietary, Ethernet-based digital interface that provides a single-wire connection between multi-axis controllers, amplifiers, and I/O. This system dramatically minimizes wiring complexity, reduces hardware, and eliminates noise in large systems. For small systems, we offer our PC/104 embedded controller, which measures just 4×4×2 inches. I call it a "bullet solution," and it can be applied directly to analog servos or pulse-and-direction stepper drives. We see demand for it in clean rooms for semiconductor fabs, where space is at premium.
Curt Wilson is Vice President of Engineering and Research for Delta Tau Systems.