{"id":210,"date":"2014-07-09T02:06:28","date_gmt":"2014-07-09T06:06:28","guid":{"rendered":"http:\/\/xchen.lab.uconn.edu\/?page_id=210"},"modified":"2020-07-07T08:06:55","modified_gmt":"2020-07-07T08:06:55","slug":"adaptive-control-and-vib-rejection","status":"publish","type":"page","link":"https:\/\/depts.washington.edu\/xchenlab\/adaptive-control-and-vib-rejection\/","title":{"rendered":"Adaptive Control, Active Vibration Rejection"},"content":{"rendered":"

A signature capability of humans and intelligent systems, adaptation has been not only a frequent scientific inquiry but also a central pillar in feedback controls. Adaptive control and system identification are central for understanding system models and high-performance control in unknown and\/or time-varying control environments. While local convergence in stochastic adaptive control has been the norm and flexible adaptation to combined fast and slow time-varying dynamics is difficult with limited computation power, we achieved to show that efficient minimum-parameter adaptation can remedy such challenges. The result is a class of stability-assured adaptive controls that achieve highly robust feedback performance under unknown and\/or extremely time-varying disturbances.<\/p>\n

\n

<\/a>Active vibration control<\/h2>\n

The following are examples of our achieved results for time-varying vibration identification and rejection in an active suspension system.<\/p>\n

\"\"<\/a><\/p>\n

Single-frequency tracking:<\/p>\n

\"\"<\/a>
Frequency of a time-varying vibration disturbance applied to an active suspension<\/figcaption><\/figure>\n
\"\"<\/a>
Online identified frequencies via adaptive control on the physical system<\/figcaption><\/figure>\n

Multiple narrow-band disturbances (with abrupt frequency changes) identification and adaptive rejection:<\/p>\n

\"\"<\/a>
Frequency of a time-varying vibration disturbance applied to an active suspension<\/figcaption><\/figure>\n
\"\"<\/a>
Online identified frequencies via adaptive control on the physical system<\/figcaption><\/figure>\n
\"\"<\/a>
Online rejection of the time-varying disturbances using our designed adaptive control algorithm: red-without control; blue-with proposed control<\/figcaption><\/figure>\n

Detailed time- and frequency-domain performances are here<\/a><\/span>.<\/p>\n

Interested readers can read more about the active suspension benchmark problem from the benchmark\u00a0website<\/a><\/span>, the\u00a0summary slides<\/a><\/span>, and\u00a0summary paper<\/a><\/span>. The benchmark was organized by Professor\u00a0Ioan D. Landau<\/a><\/span>\u00a0in\u00a0GIPSA-Lab at Grenoble (France)\u00a0and was supported by the European Control Association. Results from the benchmark were published in a\u00a0special issue of European Journal of Controls<\/a><\/span>\u00a0in 2013 and in an invited session at the 2013 European Control Conference. Different algorithms\u00a0were compared in various evaluation metrics including performance, robustness, complexity, etc.<\/p>\n

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Hard disk drives (Past Project)<\/h2>\n

Adaptive compensation for multiple narrow-band disturbances<\/h3>\n

Narrow-band disturbances show up as spikes in the spectrum of the position error signal (PES). In HDD systems, sources of the narrow-band disturbances include track eccentricity (or repeatable runout), disk modes, and external vibrations. Since the frequencies of the narrow-band disturbances are often unknown, adaptive control is key for effective rejection of the disturbances. We have designed\u00a0indirect and direct adaptive control schemes that compensate for single and multiple narrow-band disturbances with minimum-parameter adaptation to drastically improve the servo performance in track following.<\/p>\n

\"\"<\/a><\/p>\n

Adaptive audio-vibration rejection<\/h3>\n

With the ever-increasing demand for HDD applications in multimedia environments, external vibrations generated from sounds and environments are becoming the\u00a0dominating sources of Track Mis-registration (TMR) in various HDD products. These audio vibrations from, e.g., the computer\/TV speakers and dynamic vibrations in compact enclosures in data centers, contaminate the HDD servo performance by introducing strong and wide peaks to the PES spectrum. Such band-limited disturbances differ in products and can additionally be time dependent. In contrast to conventional narrow-band disturbances, the induced vibrations are wide in the spectrum and occur at very high frequencies. These characteristics\u00a0make audio vibrations a significant\u00a0challenge in high-speed high-performance\u00a0controls.<\/p>\n

\"\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

A signature capability of humans and intelligent systems, adaptation has…<\/p>\n

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