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Design and Analysis of Novel Actuation Mechanism with Controllable Stiffness

Mechanical Engineering Department, Cleveland State University, 2121 Euclid Ave, Cleveland, OH 44115, USA
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Actuators 2019, 8(1), 12; https://doi.org/10.3390/act8010012
Received: 3 December 2018 / Revised: 31 January 2019 / Accepted: 6 February 2019 / Published: 9 February 2019
Actuators intended for human–machine interaction systems are usually designed to be mechanically compliant. Conventional actuators are not suitable for this purpose due to typically high stiffness. Advanced powered prosthetic and orthotic devices can vary their stiffness during a motion cycle and are power-efficient. This paper proposes a novel actuator design that modulates stiffness by means of a flexible beam. A motorized drive system varies the active length of the cantilever beam, thus achieving stiffness modulation. New large deflection formulation for cantilever beams with rolling contact constraints is used to determine the moment produced by the actuator. To validate the proposed solution method, an experiment was performed to measure large static deformations of a cantilever beam with the same boundary conditions as in the actuator design. The experiments indicate excellent agreement between measured and calculated contact forces between beam and roller, from which the actuator moment is determined. View Full-Text
Keywords: variable-stiffness actuators; human-assist devices; flexible beams; energy-efficient actuators variable-stiffness actuators; human-assist devices; flexible beams; energy-efficient actuators
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dos Santos, E.G.; Richter, H. Design and Analysis of Novel Actuation Mechanism with Controllable Stiffness. Actuators 2019, 8, 12.

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