Real-Time Control of Magnetic Bearings Using RTLinux

RTLinux meets one of the engineering world's most demanding control requirements, without requiring separate controller hardware and costing substantially less than comparable proprietary systems.

Figure 3. Oscilloscope Trace Showing Both the Test Signal (Yellow) and Analog Output (Blue)

A more intuitive way to test the operation of the system is to hook the analog output to an audio amplifier and speaker and input a sine wave from an external signal generator. I did this, and the tone was clean and steady. The original analog controller is a simple lead-lag filter on each of the four bearing axes, which is duplicated with the difference equation:

[ y(n) = 0.7467*y(n-1 )+ 4.6380*x(n) - 4.5189*x(n-1)]

Figure 4 shows the digital and analog controller responses to a mechanical impulse on the shaft. The responses are virtually identical. In this figure, the digital controller response is shown at the top, and the analog controller response is at the bottom. The time shown in the figure is 100 milliseconds. The digital loop is operating at 10kHz in a MIMO configuration, which has five input channels and eight output channels.

Figure 4. Oscilloscope Trace Comparing Digital (Upper) to Analog (Lower) Controller Response to a Mechanical Impulse


White Paper
Linux Management with Red Hat Satellite: Measuring Business Impact and ROI

Linux has become a key foundation for supporting today's rapidly growing IT environments. Linux is being used to deploy business applications and databases, trading on its reputation as a low-cost operating environment. For many IT organizations, Linux is a mainstay for deploying Web servers and has evolved from handling basic file, print, and utility workloads to running mission-critical applications and databases, physically, virtually, and in the cloud. As Linux grows in importance in terms of value to the business, managing Linux environments to high standards of service quality — availability, security, and performance — becomes an essential requirement for business success.

Learn More

Sponsored by Red Hat

White Paper
Private PaaS for the Agile Enterprise

If you already use virtualized infrastructure, you are well on your way to leveraging the power of the cloud. Virtualization offers the promise of limitless resources, but how do you manage that scalability when your DevOps team doesn’t scale? In today’s hypercompetitive markets, fast results can make a difference between leading the pack vs. obsolescence. Organizations need more benefits from cloud computing than just raw resources. They need agility, flexibility, convenience, ROI, and control.

Stackato private Platform-as-a-Service technology from ActiveState extends your private cloud infrastructure by creating a private PaaS to provide on-demand availability, flexibility, control, and ultimately, faster time-to-market for your enterprise.

Learn More

Sponsored by ActiveState