ACTIVE NOISE AND VIBRATION CONTROL
Active Noise and Vibration Control (ANVC) is a way to reduce noise and vibration in products by creating a sound or vibration that cancels, or is "out of phase", with the disturbance. In certain situations noise or vibration reduction may be difficult, or even impossible, to achieve by "passive" means. In these cases active control may be an attractive alternative. Conversely, there are many situations in which ANVC is not an appropriate technique. We can speak of it, therefore, as a "target of opportunity" and it requires expertise to know when those opportunities are present.
Implementation of AVNC requires certain components, consisting of both hardware and software. Microphones, speakers or actuators and processing algorithms must be incorporated into each saleable unit. The technology is made possible by modern digital signal processing and/or instrumentation, and this must be developed specifically for each application. In considering ANVC, the applicability of the technology, the additional cost/unit, and the availability of components are issues that must be dealt with early on in the design process. RH Lyon Corp has the experience to assist clients in deciding if ANVC will work for them and then, when appropriate, in implementing the solution.
PROJECT EXAMPLES
Small Medical Device
When the footprint of a device is small the challenges of AVNC are greater. In one particular device, the challenge was to determine whether a reasonably-sized noise cancellation source transducer, suitable for the size of the medical device, could produce enough sound power to cancel the strongest tones that the device generated. A second consideration was whether the frequencies of these tones and the speed changes encountered during typical operation were low enough so as to not be a stumbling block for an active noise control system.
Reduction of Transient Disturbances
Transient disturbances can produce vibrations which persist long after the disturbance happens. In imaging devices such as medical devices or satellites, this vibration adds to the "settling time" and thus reduces the immediate usefulness of the instrument. By employing Complex Statistical Energy Analysis (CSEA), we are able to analyze the transient force and create an opposing force which demonstrably limits both the magnitude and the duration of the vibration. This work, funded by an SBIR Phase II award from the U.S. Air Force, is in the product development stage and we are seeking partners for the commercialization of the technology.
