Linear Negative Stiffness Honeycomb Actuator with Integrated Force Sensing

Negative stiffness honeycombs (NSHs) have unique features, such as recoverable elastic buckling, impact absorption, and shock isolation. Another advantage of NSH is its variable stiffness property. Due to these advantages, they have substantial potential in applications related to vibration isolation, haptic devices, and variable impedance actuators. In this paper, the utilization of NSH as an impedance element to design a variable impedance actuator (VIA) is explored. Specifically, we focus on the force and displacement measurement problem of NSH. The integration of traditional force and position sensors would complicate the design of a NSH-based VIA actuator, increase its cost and volumetric envelope. Instead, arrays of magnets and magnetic sensors are proposed to measure both the force and compression of NSH. In order to test the hypothesis, a linear NSH actuator was designed and built. Experiments were performed to test the feasibility of the proposed approach. Results demonstrate the feasibility of using NSHs in VIA design and that magnetic sensors can be reliably used to estimate both the force and compression of NSHs.