(February 21, 2016) HRL Laboratories, LLC, announced that
researchers in its Sensors and Materials Laboratory have developed an active
variable stiffness vibration isolator capable of 100x stiffness changes and
millisecond actuation times, independent of the static load. According to
Principal Investigator Christopher Churchill, “This performance surpasses
existing mechanisms by at least 20 times in either speed or useful stiffness
change.”
Churchill says that the human body is home to a range of variable
stiffness structures that enable efficient load-bearing and nimble activity.
“The most ubiquitous tunable stiffness structures are our own joints, which use
antagonistic muscle contractions to vary joint stiffness continuously,” he
said. “For example, limbs will stiffen to lift a bowling ball, but soften to
paint with the tip of a brush.”
Yet these features in the human body are rarely replicated
in engineered systems due to the complexity, power, and cost of doing so.
Churchill says that the traditional approach – building a soft system and then
adding damping and force – is expensive and low-bandwidth. “We developed a new
paradigm, and instead built a stiff system and then softened it,” he said. The
result is a low-cost and high-bandwidth solution to long-standing challenges.
© 2016 HRL
Laboratories.Photo by Dan Little.
This breakthrough has broad applications for makers of
automobiles, aircraft, watercraft, rotorcraft, and robotics. “Advanced
lightweight materials are increasingly finding their way into transportation
platforms to achieve low mass and high stiffness,” Churchill said. “Utilizing
adaptive negative stiffness to soften stiff systems on demand has the potential
to solve shock and vibration problems that only get more difficult with these
next-generation platforms.”