利用有限元素法建構3維的舌頭力學模型

Development of a 3D Mechanical Tongue Model with Finite Element Method

王嘉麒(Chia-Chi Wang)

指導教授 ： 吳炤民

國立中央大學/資訊電機學院/電機工程學系/碩士(2007年)

摘要

本研究的目的在利用舌頭磁振造影所重建之影像，建構出三維的舌頭有限元素力學模型。我們使用Gerard在文獻中所用的人的舌頭材料特性－二階和五階的Mooney-Rivlin 超彈性應變能量函數，且假設舌頭為不可壓縮體，來做為我們舌頭的材料特性，並以舌頭磁振造影的影像為基礎，利用ANSYS®有限元素軟體建構舌頭的模型。這舌頭模型包含發聲時主要使用到的7種肌肉，即莖突舌肌、舌骨舌肌、頦舌肌（又分成了前、中、後3個部份）、舌上縱肌、舌下縱肌、舌橫肌和舌直肌。在建構出舌頭的有限元素模型後，我們接著對舌頭模型各部份的肌肉施力，進行動態的模擬，施力的方向為沿著各個肌肉纖維的走向，由結果中可以觀察到此舌頭模型各部份的肌肉收縮時皆能達到該肌肉收縮對舌頭產生應有的變形。最後我們參考文獻的資料，進行母音[u]、[a]、[i] 及子音 [t]、[k]等舌頭發音動作的模擬，而由舌頭施力變形後的結果也觀察到發音模擬的部份，其結果也都合乎了發這些音時舌頭動作的特徵。由以上這些初步結果顯示我們所建構的三維舌頭有限元素力學模型可以做為未來更多構音動作模擬的一個雛形。

關鍵字

磁振造影 ； 有限元素法 ； 舌外肌 ； 舌內肌

並列摘要

The aim of this study is to develop a 3D finite element mechanical tongue model based on the reconstructed MR images of the human tongue. In this study, we used the second and fifth order Mooney-Rivlin hyperelastic strain-energy function that Gerard had used in his paper as the constitutive equation of our tongue model, and assumed that the tongue is incompressible. Based on the reconstructed MR images of the human tongue, we built the tongue model with ANSYS® finite element software. Our tongue model includes seven principle muscles that are involved in the human speech production. They are the Styloglossus muscles, the Hyoglossus muscles, the Genioglossus muscles (also divided into the anterior, middle and posterior three parts.), the Superior longitudinalis muscles, the Inferior longitudinalis muscles, the Transversus muscles and the Verticalis muscles. Once the tongue model was developed, dynamic simulation proceeded on each muscle of the tongue model with the force direction followed the muscle fiber direction. From the results, we could observe that contraction of each muscle in this tongue model had caused correct corresponding deformation on the tongue model, respectively. Finally, we simulated articulatory movements of vowels [u], [a], [i] and consonants [t], [k] with our tongue model. From the results, we also could see that the articulatory movements of our tongue model had conformed to the features of these phonetic articulations. These preliminary results show that our 3D finite element mechanical tongue model could be used as a basis for more phonetic articulatory simulation in the future.

並列關鍵字

intrinsic muscles ； extrinsic muscles ； MR image ； Finite element method

參考文獻

Alfonso, P.E., Honda, K., Baer, T., Harris, K.S. (1982). “Multichannel study of tongue EMG during vowel production,” J. Acoust. Soc. Am. 71, S54(A).

Bagshaw, C.R. (1993). Muscle Contraction (Chapman & Hatl, London), 2nd ed.

Dang, J., Honda, K. (2004).“Construction and control of a physiological articulatory model,”J. Acoust. Soc. Am. 115(2), 853-870.

Davis, E., Douglas, A., Stone, M. (1996).“A continuum mechanics representation of tongue motion in speech,”Proceedings of ICSLP1996, 788-792.

Feldman, A.G., Orlovsky, G.N. (1972).“The influence of different descending systems on the tonic stretch reflex in the cat,” Experimental Neurology 37, 48l-494.