Perancangan, Pemodelan dan Analisis Pengaruh Variasi Nilai Koefisien Redaman dan Kekakuan Terhadap Respon Dinamis Ankle Foot Orthosis (AFO)

Wulandari, Novita Nur (2018) Perancangan, Pemodelan dan Analisis Pengaruh Variasi Nilai Koefisien Redaman dan Kekakuan Terhadap Respon Dinamis Ankle Foot Orthosis (AFO). Undergraduate thesis, Institut Teknologi Sepuluh November.

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Abstract

Anggota gerak tubuh bawah menjadi hal penting bagi manusia dalam melakukan aktivitas sehari-hari, khususnya pergerakan (moving). Tetapi bilamana salah satu atau bahkan kedua anggota gerak bawah mengalami keterbatasan maka akan mengakibatkan terganggunya berbagai aktivitas kehidupan sehari-harinya. Keterbatasan ini dapat terjadi akibat 2 faktor yaitu suatu penyakit dan cedera sendi yang biasanya terjadi pada atlet. Seseorang yang mengalami keterbatasan karena 2 faktor tersebut akan mengalami peningkatan pengeluaran energy saat berjalan hampir sebesar 89% dibanding dengan pejalan kaki normal. Dalam mengatasi keterbatasan tersebut, diperlukan alat bantu untuk angota gerak bawah yang dikenal dengan Ankle Foot Orthosis (AFO). Oleh karena itu adalah sangat penting untuk merancang orthosis dengan aspek biomekanis yang memungkinkan mereka berjalan layaknya manusia normal. Dalam penelitian tugas akhir ini dimulai dari studi literatur dan studi lapangan mengenai sistem kerja Ankle Foot Orthosis (AFO) dan komponen yang menunjang kerja alat tersebut. Kemudian, membuat rancangan sistem Ankle Foot Orthosis (AFO) berdasarkan parameter-parameter yang didapatkan dari literartur. Langkah selanjutnya yaitu melakukan pemodelan dinamis dari rancangan sistem Ankle Foot Orthosis (AFO). Setelah model dinamis dari sistem Ankle Foot Orthosis (AFO) diketahui, free body diagram dari sistem dapat digambar dan dijabarkan persamaan matematisnya. Persamaan matematis yang telah diperoleh dapat digunakan sebagai dasar pembuatan model blok diagram pada MATLAB Simulink. Setelah didapatkan nilai persamaan matematis tersebut, dimasukkan nilai parameter utama yang didapatkan dari literature yaitu nilai koefisien stiffness dan konstanta redaman serta parameter-parameter yang lain agar dapat mulai disimulasikan pada blok diagram yang telah dibuat pada MATLAB Simulink. Selanjutnya, dilakukan analisa pada grafik respon dinamisnya. Pada tahapan selanjutnya, dilakukan proses simulasi untuk variasi kecepatan orang berjalan santai (2km/jam), sedang (6km/jam), normal (10km/jam) dan cepat (20 km/jam). Serta juga dilakukan variasi nilai konstanta kekakuan dan redaman dengan rasio terhadap nilai konstanta kekakuan dan redaman utama yaitu 0,5 ; 1 ; 2 agar dapat diketahui karakteristik respon dinamis Sistem Ankle Foot Orthosis (AFO) pada kondisi-kondisi tersebut dan didapatkan nilai konstanta kekakuan dan redaman yang paling baik bagi kenyamanan penggunanya. Dari hasil simulasi, didapatkan Sistem Ankle Foot Orthosis yang telah dirancang menghasilkan respon dinamis dengan nilai respon pada foot-plate yang lebih besar apabila dibandingkan dengan nilai respon dinamis yang dihasilkan oleh joint ankle. Dari hasil simulasi, juga dapat diketahui bahwa semakin besar kecepatan orang berjalan, semakin besar pula gaya reaksinya. Gaya reaksi minimum besarnya 156 N terjadi pada kecepatan 2 km/jam, sedangkan gaya reaksi maksimum besarnya 1564 N yang terjadi pada kecepatan 20 km/jam. Berdasarkan variasi konstanta redaman dan kekakuan juga didapat nilai yang paling baik yaitu yang besarnya konstanta redaman 1000 Ns/m bagian belakang midsole dan 800 Ns/m bagian depan serta konstanta kekakuan 90000 N/m bagian belakang dan 60000 N/m bagian depan. ================================================================================================================== Ankle Foot Orthosis (AFO) is one of the tools that used to improve posture and muscle contractures, to support normal joint position, and to facilitate or improve motion function based on biomechanical aspects. The lower body is important for humans in performing daily activities, especially moving. But if one or even both of the motion experience the limitations, it will result in disruption of various activities of daily life. This limitation can occur due to 2 factors that is a disease and joint injury that usually occurs in athletes. The disease factors that cause these limitations generally occur in stroke patients known as Hemiplegic disease and cause many problems of walking patterns. Hemiplegic is reduced walking speed, asymmetric walking patterns, increased energy, and decreased muscle function. As for factors of joint injury, used as an injury prevention tool for athletes, namely to reduce pain and help walk the athletes. Someone who is experiencing limitations because of these 2 factors will experience an increase in energy expenditure when running almost equal to 89% compared with normal human. In overcoming these limitations, we need a tool for the lower body motion known as Ankle Foot Orthosis (AFO). Therefore it is very important to design orthoses with biomechanical aspects that enable them to walk like normal human beings. In this research is started from literature study and field study on Ankle Foot Orthosis (AFO) working system and the components that support the work of the tool. Then, design the Ankle Foot Orthosis (AFO) system based on the parameters obtained from the literartur. The next step is to do dynamic modeling of Ankle Foot Orthosis (AFO) system design. After the dynamic model of Ankle Foot Orthosis (AFO) system is known, free body diagram of the system can be drawn and described mathematical equations. The mathematical equations that have been obtained can be used as the basis for making block diagram models in MATLAB Simulink. After obtaining the value of mathematical equations, the value of the main parameters obtained from the literature is the value of stiffness coefficient and damping constant and other parameters to be simulated in the block diagram that has been created on MATLAB Simulink. Furthermore, an analysis is done on the graph of the dynamic response. At the next stage, a simulation process is performed for variations of the speed of the person walking casually (2km / hr), medium (6km / hr), normal (10km / hr) and fast (20 km / hr). As well as variations in stiffness and damping constant values with the ratio to the main parameter, those are 0,5 ; 1 ; 2 in order to know the dynamic characteristic of Ankle Foot Orthosis (AFO) in these conditions. From the simulation results, the Ankle Foot Orthosis System has been designed to produce dynamic response with a response value on a larger foot-plate when compared to the dynamic response value generated by the joint ankle. From the simulation results, also can be seen that the greater the speed of people walking, the greater the reaction force. The minimum reaction force of 156 N occurs at a speed of 2 km / h, while the maximum reaction force of 1564 N occurs at speeds of 20 km / h. Based on the variation of damping and stiffness constant also obtained the best value that is the amount of damping constant 1000 Ns / m back of midsole and 800 Ns / m front and stiffness constant 90000 N / m back and 60000 N / m front.

Item Type: Thesis (Undergraduate)
Additional Information: RSM 612.014 41 Wul p-1 3100018074606
Uncontrolled Keywords: Ankle Foot Orthosis (AFO); Biomekanis; Hemiplegic; koefisien kekakuan; koefisien redaman Ankle Foot Orthosis (AFO); Biomechanical; Hemiplegic; coefficient of damping; stiffness coefficient.
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ230 Machine design
Divisions: Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User: Novita nur wulandari
Date Deposited: 23 Mar 2018 07:35
Last Modified: 07 Sep 2020 02:56
URI: https://repository.its.ac.id/id/eprint/50352

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