Active vibration control

About: Active vibration control is a research topic. Over the lifetime, 6770 publications have been published within this topic receiving 76599 citations. The topic is also known as: active vibration damping.

Development of Adaptive Seat Mounts for Helicopter Aircrew Body Vibration Reduction

Abstract: Helicopter aircrew are exposed to high levels of vibration and noise during flight. This paper presents the investigation of adaptive seat mount approaches to reducing vibration on the helicopter seat. A flight test on a helicopter with typical pilot configurations showed that the vibration spectra on the pilot’s helmet not only included the dominant N/rev harmonic peaks of the rotor speed, but also consisted of a low-frequency resonant peak in the frequency range of human abdominal and spine resonant frequencies. Long-term exposure to this vibration may lead to occupational health issues such as damage to the pilot’s spine and neck. In order to address this issue, a novel adaptive seat mount concept was developed to mitigate the vibration levels transmitted to the aircrew. As a proof-of-concept demonstration, a miniature modal shaker was installed between the cabin floor and the seat bottom as an adaptive mount that provided the actuation authority. The objective was to reduce the vertical vibration transmitted to the aircrew helmet in order to decrease aircrew neck and spine injuries that are caused by the transmitted vibration. Extensive closed-loop control tests have been conducted on a full-scale helicopter seat and a mannequin with varying physical properties. A 10,000 lb(f) mechanical shaker was used to provide representative helicopter vibration profiles to the seat. Significant vibration reductions on the N/rev vibration peaks were achieved1 the low-frequency resonant peak was also suppressed simultaneously.

Active control of vibration

Abstract: A method of and system for active vibration control in an elongate member such as a pipe (2), wherein an actuator which comprises at least one constrictive element (3) capable of changing its length is attached between flanges (1) spaced along the member and is controlled to produce deformations of the member which inhibit the transmission of unwanted vibration from the member to one side of the attached actuator to the other side.

Adaptive learning algorithms for vibration energy harvesting

Abstract: By scavenging energy from their local environment, portable electronic devices such as MEMS devices, mobile phones, radios and wireless sensors can achieve greater run times with potentially lower weight. Vibration energy harvesting is one such approach where energy from parasitic vibrations can be converted into electrical energy through the use of piezoelectric and electromagnetic transducers. Parasitic vibrations come from a range of sources such as human movement, wind, seismic forces and traffic. Existing approaches to vibration energy harvesting typically utilize a rectifier circuit, which is tuned to the resonant frequency of the harvesting structure and the dominant frequency of vibration. We have developed a novel approach to vibration energy harvesting, including adaptation to non-periodic vibrations so as to extract the maximum amount of vibration energy available. Experimental results of an experimental apparatus using an off-the-shelf transducer (i.e. speaker coil) show mechanical vibration to electrical energy conversion efficiencies of 27–34%.

Vibration isolation with magnet springs

Abstract: We describe a vibration isolation apparatus where four couples of repelling magnets ensure the loading force to a suspended table. This table is mechanically confined within its otherwise unstable equilibrium position with four ball bearings connected to the table and sliding along four vertical shafts. The vibration isolation efficiency of this device is excellent and its performances can be directly compared to those attained with state of the art optical tables at a fraction of their cost and weight. Another advantage is that no external supply of energy or compressed air is needed.