Historical and dynamical study of piano actions: A multibody modelling approach
(2016) Journal of Cultural Heritage — Vol. 27S, p. S120-S130 (2017)
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- Piano actions are striking mechanisms whose functioning is based on dynamic principles; producinga sound on a struck keyboard instrument by pressing a key slowly is impossible because the hammerneeds momentum to hit the strings. This is also the reason why mechanisms intended for struck keyboardinstruments are difficult to study; their normal functioning speed is beyond human observation capa-bilities. For this reason, many modern studies on the piano take advantage of engineering tools in orderto measure the exact behaviour of their actions in terms of time response, involved forces and displace-ment values. A complementary approach to study piano actions consists in modelling them, giving us avirtual mechanism to work with. In this case, the above-mentioned motion and behaviour are computedinstead of being measured. The modelling technique used and described in this paper, called multibodydynamics, consists in computing the motion and the forces acting upon each component of the action.Subsequently, the response of the mechanism to a certain keystroke can be computed and a slow-motionanimation can be produced. The aim of this paper is to give an overview of an ongoing research projectin which two distinctive piano actions are modelled. Each of them is studied with a different objective inmind. Starting with the most modern, well-known but also most complex, the model of a double escape-ment action found in grand pianos is used to explain its functioning. This pedagogical goal is achievedwith three progressive models; the first one is a simplified version of the action to which components ofthe complete action have been (virtually) removed. The stepwise progression leads to a single escape-ment action for the second model, and finally to the full double escapement action for the third. Timingof the action events and response to different types of touch are studied and compared with literature.The results show that our model is able to reproduce the same behaviour as real actions. Going back intime, the second instrument that is studied is a Prellzungenmechanik built by Johan Andreas Stein at theend of the 1780s. In this context, a model has been achieved to evaluate the influence of the so-called“escapement height” (a regulation parameter of the action) on the playing characteristics of the action.As with the grand piano action, timing analysis and touch comparison are performed with the model.
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Bokiau, B., Ceulemans, A.-E., & Fisette, P. (2016). Historical and dynamical study of piano actions: A multibody modelling approach. Journal of Cultural Heritage, 27S, S120-S130. https://doi.org/10.1016/j.culher.2016.04.010 (Original work published 2017)