Experimental Characterization of a T-Shaped Programmable Multistable Mechanism

Programmable multistable mechanisms (PMM) exhibit a modifiable stability behavior in which the number of stable states, stiffness, and reaction force characteristics are controlled via their programming inputs. In this paper, we present experimental characterization for the concept of stability programing introduced in our previous work (Zanaty et al., 2018, "Programmable Multistable Mechanisms: Synthesis and Modeling," ASME J. Mech. Des., 140(4), p. 042301.) A prototype of the T-combined axially loaded double parallelogram mechanisms (DPM) with rectangular hinges is manufactured using electrodischarge machining (EDM). An analytical model based on Euler-Bernoulli equations of the T-mechanism is derived from which the stability behavior is extracted. Numerical simulations and experimental measurements are conducted on programming the mechanism as monostable, bistable, tristable, and quadrastable, and show good agreement with our analytical derivations within 10%.

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Simon Nessim Henein, Mohamed Gamal Abdelrahman Ahmed Zanaty
ASME, 2018
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https://infoscience.epfl.ch/record/262335?ln=fr

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Programmable Constant-Force Multistable Mechanisms

Simon Nessim Henein, Mohamed Gamal Abdelrahman Ahmed Zanaty

Programmable multistable mechanisms exhibit stability behavior whereby the stiffness and the number of stable states can be controlled via programming inputs. In this paper, we report the zero stiffness behavior of a 2-degree of programming (DOP) T-combined, axially loaded double parallelogram multistable mechanism. We demonstrate zero force monostability, constant force monostability, zero force bistability, constant force bistability and zero force tristability behaviors by tuning the programming input. We derive analytically the reaction force of the mechanism for each configuration and verify our analytical results using numerical simulations and experimental measurements, showing less than 10% discrepancy. The concept of constant force programming can be extended to N-DOP T-combined, serial combined and parallel combined programmable multistable mechanisms. Finally, we present potential applications of stability programming.

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Reconfigurable Logic Gates Based on Programable Multistable Mechanisms

Simon Nessim Henein, Hubert Pierre-Marie Benoît Schneegans, Ilan Vardi, Mohamed Gamal Abdelrahman Ahmed Zanaty

Binary logic gates are building blocks of computing machines, in particular, electronic computers. One variant is the programable logic gate, also known as the reconfigurable logic gate, in which the logical function implemented can be modified. In this paper, we construct a mechanism to implement a reconfigurable logic gate. This mechanism is based on the concept of programable multistable mechanisms which we introduced in previous work. The application of a programable multistable mechanism is superior to the different bistable mechanisms previously used to implement logic gates since a single mechanism can be used to implement several logic functions. Our reconfigurable logic gates use a novel geometric construction where the geometric data depend on the stability behavior of the mechanism. There are 16 binary logic gates and our construction can theoretically produce nine of these and our physical model produces six logical gates. Input and output of the mechanism are displacement and the mechanisms can be combined serially, i.e., output of a mechanism is an input for another. We show that we can implement NOR and NAND gates, so combinations of our mechanism can express any logical function. The mechanism is therefore theoretically universal, i.e., implement any computation. We give an analytic model of the mechanism based on Euler-Bernoulli beam theory to find the geometric data, then validate it using finite element analysis and experimental demonstration.

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