Dynamic Modelling and Experimental Testing of a Piano Action Mechanism

Hirschkorn, Martin; McPhee, John; Birkett, Stephen

doi:10.1115/detc2005-84511

Cited by 3 publications

References 9 publications

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Dynamic Modeling and Experimental Testing of a Piano Action Mechanism

Hirschkorn

McPhee

Birkett

2005

Journal of Computational and Nonlinear Dynamics

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A model for a grand piano action is proposed in this paper. The multibody dynamic model treats each of the five main action components (key, whippen, jack, repetition lever, and hammer) as a rigid body, and incorporates a contact model to determine the normal and friction forces at 13 locations between each of the contacting bodies. All parameters in the model are directly measured from experiments on individual action components, allowing the model to be used as a prototyping tool for actions that have not yet been designed or built. The behavior of the model was compared to the behavior of an experimental grand piano action and found to be very accurate for high force blows, and reasonably accurate for low force blows.

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Dynamic Modeling and Experimental Testing of a Piano Action Mechanism

Hirschkorn

McPhee

Birkett

2005

Journal of Computational and Nonlinear Dynamics

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Dynamic Modeling and Experimental Testing of a Piano Action Mechanism With a Flexible Hammer Shank

Izadbakhsh

McPhee

Birkett

2007

Volume 5: 6th International Conference on Multibody Systems, Nonlinear Dynamics, and Control, Parts A, B, and C

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The piano action is the mechanism that transforms the finger force applied to a key into a motion of a hammer that strikes a piano string. This paper presents a state-of-the-art model of a grand piano action, which is based on the five main components of the action mechanism (key, whippen, jack, repetition lever, and hammer). Even though Askenfelt and Jansson [1] detected some flexibility for the hammer shank in their experiments, all previous piano models have assumed the hammers to be rigid bodies. In this paper, we have accounted for the hammer shank flexibility using a Rayleigh beam model. It turns out that the flexibility of the hammer shank does not significantly affect the rotation of the other parts of the piano mechanism, compared with the case that the hammer shank has been modeled as a rigid part. However, the flexibility of the hammer shank changes the impact velocity of the hammer head, and also causes a greater scuffing motion for the hammer head during the contact with the string. To validate the theoretical results, experimental measurements were taken by two strain gauges mounted on the hammer shank, and by optical encoders at three of the joints.

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Modelling the Dynamics of the Piano Action: Is Apparent Success Real?

Thorin¹,

Boutillon²,

Lozada³

2014

Acta Acustica united with Acustica

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The kinematics and the dynamics of the piano action mechanism have been much studied in the last 50 years and fairly sophisticated models have been proposed in the last decade. Surprisingly,simple as well as sophisticated models seem to yield very valuable simulations when compared to measurements. We propose here avery simple model, with only 1-degree of freedom, and compare its outcome with force and motion measurements obtained by playing areal piano mechanism. The model, purposely chosen as obviously too simple to be predictive of the dynamics of the grand piano action, appears either as very good or as very bad, depending on which physical quantities are used as the input and output. We discuss the sensitivity of the simulation results to the initial conditions and to noise and the sensitivity of the experimental/simulation comparisons to the chosen dynamical model. It is shown that force-drivensimulations with position comparisons, as theyare proposed in the literature, do not validate the dynamical models of the piano action. It is suggested that these models be validated with position-drivensimulations and force comparisons.

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Dynamic Modelling and Experimental Testing of a Piano Action Mechanism

Cited by 3 publications

References 9 publications

Dynamic Modeling and Experimental Testing of a Piano Action Mechanism

Dynamic Modeling and Experimental Testing of a Piano Action Mechanism

Dynamic Modeling and Experimental Testing of a Piano Action Mechanism With a Flexible Hammer Shank

Modelling the Dynamics of the Piano Action: Is Apparent Success Real?

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