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This paper shows how tunable dampers can help control the instant centre of rotation of a 2D rigid body and its polode in planar motion, which in turn implies that the inertia tensor can also be controlled. For mechanisms equipped with some elasticity the results show that damping can also control their natural frequencies. The foundation of a general theory to control the polode is presented, exploring the chance of an optimal control formulation of the problem via a variational control principle, approached by the LQR (Linear Quadratic Regulator) method, after a suitable linearization. Application to automotive suspension linkages is presented that demonstrates the control of the instant roll centre and axis and consequently its instant roll vibration frequency to optimize the response, when excited by lateral inertia forces.

Abstract: The introduction of vibration-based Nano Electro-Mechanical Transistors (NEMT) opens a new horizon for mechanics in computer science. NEMT working principle is based on an electrical charge shuttle between two electrodes operated by a vibrating conductor body. Advantages of these novel devices would be very low power dissipation, limited influence of external electromagnetic disturbances, and improved thermal resistance. The paper introduces an analytical model for such a device, in which the matching of a mechanical resonator and an electric circuit is studied: the coupling is provided by capacitance effects, electrostatic force and the quantum tunneling. The approach is quasi-classical, describing the quantum phenomena through a non-linear conductance and using a continuous variable for the charges. Through suitably introduced simplifications, the model is reduced to a set of two differential equations in terms of pillar position and charge. These equations represent the simplest model still preserving the basic phenomenology of the investigated system. Numerical simulations show different possible motion regimes, both in the single- and multiple-module configurations, the latter able to reproduce the conventional transistor functionality. This opens the way to mechanical voltage-driven switches or amplifiers. [Copyright &y& Elsevier]