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


One Click, Universal Protection: Implementing Centralized Security Policies on Linux Systems

As Linux continues to play an ever increasing role in corporate data centers and institutions, ensuring the integrity and protection of these systems must be a priority. With 60% of the world's websites and an increasing share of organization's mission-critical workloads running on Linux, failing to stop malware and other advanced threats on Linux can increasingly impact an organization's reputation and bottom line.

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Linux Backup and Recovery Webinar

Most companies incorporate backup procedures for critical data, which can be restored quickly if a loss occurs. However, fewer companies are prepared for catastrophic system failures, in which they lose all data, the entire operating system, applications, settings, patches and more, reducing their system(s) to “bare metal.” After all, before data can be restored to a system, there must be a system to restore it to.

In this one hour webinar, learn how to enhance your existing backup strategies for better disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible bare-metal recovery solution for UNIX and Linux systems.

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