İnsansı robot kolunun optimizasyonu ve dinamika analizi
Optimization and dynamic analysis of humanoid robot arm
Yazar: OZAN KAYA
Danışman: PROF. DR. ŞENİZ ERTUĞRUL
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Mekatronik Mühendisliği Ana Bilim Dalı / Mekatronik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2016
Konu: Mekatronik Mühendisliği = Mechatronics Engineering

Özet:
Sanayide ve günlük yaşantımızın içinde belirli görevleri gerçekleştirilmesi için
tasarlanmış olan robotlar günümüzde insandan esinlenerek tasarlanmaya başlanmıştır.
İnsansı robotlar günümüzde birçok disiplinde araştırma konusu olarak araştırmacıların
büyük bir ilgisini çekmektedir. Günümüzde insansı robotlar askeri amaçlı, saĞlık
sektöründe, sanayide ve günlük ya¸santımızda insanlara yardımcı olması için devam
etmekte olan geliştirme çalışmalarının temelini oluşturmaktadır. İnsansı robotlardan,
insansı hareket kabiliyeti, çeviklik, kuvvet ve dayanıklılık gibi konularda yüksek
kabiliyete sahip olmaları için farklı çalışmalara halen devam edilmektedir. Bu
çalı¸smada bir insansı robot kolunun tasarımı ve üretimi gerçekle¸stirilmiştir. İnsansı
robot kolunun uç kısmında meydana gelen şekil değişimi değerini iyileştirebilmek için
statik analizler yardımıyla belirlenen kol parçalarına parametre optimizasyon i¸slemi
uygulanmıştır. İnsansı robot kolunun hareket kabiliyetini belirleyebilmek için kolun
dinamik analizleri gerçekleştirilmiştir.
˙Insansı robot kolunun eklem eksen takımları belirlenmiş, motor dişli sistemi
seçilmiş ve tasarımı gerçekleştirilmiştir. Tasarlanan insansı robot kolunun parçaları
üretilip birle¸stirme i¸slemi yapılmı¸stır. Birle¸stirme a¸samasında kar¸sıla¸sılan zorluklara
değinilmiş ve yapılan değişiklikler açıklanmıştır.
İnsansı robot kolunun eklem eksen dizilimlerinin ve kol uzunluklarının insansı robot
kolunun ucunun erişebildiği sınırlarına etkisini belirleyebilmek için çalışma uzayı
analizleri gerçekleştirilmiştir.
İnsansı robot kolunda meydana gelen ¸sekil değişimini azaltmak için statik analizler
sonucu belirlenen kol parçalarına parametre optimizasyon işlemi uygulanmı¸stır. Bu
parçalar, kolun sonlu elemanlar yöntemi ile statik analizleri gerçekleştirilip gerilme
yığılmaları ve şekil değişimleri değerlerinden yararlanılarak belirlenmiştir. Bu
parçalara kolda meydana gelen şekil değişiminin matematiksel denklemi oluşturulup
parça kesit parametreleri MATLAB yardımıyla değiştirilerek sonuçlar elde edilmiş,
parametre optimizasyonu işlemi uygulanmıştır. Bu çalışmada ANSYS yardımıyla
parametre optimizasyon işlemi tekrarlanmıştır. Bu sayede matematiksel denklemler
sonucu elde edilen değerlerin doğruluğu gösterilmiştir. Parametre optimizasyonu
için ANSYS programını kullanmanın en uygun parametrenin seçilmesinde kolaylık
sa˘gladı˘gı görülmü¸stür. Kesit parametrelerindeki de˘gi¸simlerin kol ucunda meydana
gelen şekil değişimine, kolda meydana gelen maksimum gerilmeye ve kolun toplam
ağırlığına etkisi anlatılmıştır. Bu sonuçlar doğrultusunda bu parçaların boyutlarına
karar verilmi¸stir.
˙Insansı robot kolunun üzerinde kullanılacak olan motor dişli sistemi seçilmiş
olduğundan tasarlanan kolun eklemlerin sahip olduğu hareket kabiliyetleri dinamik
denklemler ve benzetim işlemleri ile elde edilmiştir. Bu çalı¸smada kullanılan
eklemlerin çevik bir hareket kabiliyetine sahip olması beklendiğinden dolayı eklemlere
uygulanan hareket profillerinin eklemlerde olu¸sturdu zamana bağlı moment değerleri
benzetim işlemleri yardımıyla elde edilmiştir. ˙Insansı robot kolu belirli görevleri
gerçekle¸stirmek için çoğu zaman birden fazla eklemin hareket etmesi gerekmektedir.
Bu yüzden hareket eden eklem sayısının elde edilen moment de˘gerlerine etkisi
gözlemlenmiştir. Hareket eden eklemlerin hareket yönlerinin benzetim işlemi
yardımıyla elde edilen zamana bağlı moment değerlerine etkisi incelenmiştir. ˙Ileriki
çalışmalarda gerçekle¸stirilen dinamik analizlerde kullanılan robot kolu modelinin
parçalarının şekil değiştirebilir olması ile elde edilen sonuçlar için analizler
tekrarlanıp sonuçlar karşılaştırılacaktır. Elde edilen bu sonuçlar yardımıyla sonlu
elemanlar yöntemi ile gerçekleştirilen parametre optimizasyon işleminin tekrarlanması
amaçlanmaktadır.

Abstract:
Robots which are used for different tasks in daily life and industry begin to be
created in form of human. Humanoid robots provide new investigating areas for
the researchers. Besides, the development of humanoid robot technologies are
incrementally continued. The humanoid robots, which are the basis of the development
of the newly technologies in designing machinery area, are used for helping people
in military, industry, medical and daily life. Humanoid robots are expected to have
durability, agility and powerful capability of movement like a human. Researchers
focus on increasing efficiency of movement, appearance and controllability of
humanoid robots. Because of this purpose, several electrical motor types and gear
systems are still in the process of development. One of the new developments of gear
systems is harmonic drive technology. The harmonic drives have features such as a
high ratio, repeatability and small dimensions. The harmonic drives are preferred in
the design of the humanoid robot joints due to small dimension and high ratio. One
of the new developments of electrical motor is brushless flat motors. This type motors
are preferred for features as small dimensions and high torque values. On the other
hand, this type of motors are difficult to control. In this study, a humanoid robot arm
has been designed. The harmonic drivers and brushless flat motors were used in design
of humanoid robot arm. In this study, workspace analysis of the humanoid robot arm
has been realised to define the limits of movement of the humanoid robot arm. After
that, joint parts of humanoid robot arm has been optimised. Finally, dynamic analysis
of humanoid robot arm has been realised to evaluate the limits of movement of the
humanoid robot arm's joints.
In this study, configuration of humanoid robot arm's joints were decided by comparing
with several configuration of robot arm. After that, robot arm's joint cases were
designed and produced according to dimensions of chosen electrical motor and
harmonic drive. These cases were manufactured in Istanbul Technical University.
Then, links between 2 joints were designed. At the initial state of the design these
parts, it was created as separable three part and bolts contacts were used in its assembly.
Since bending requires no extra bolt, it was decided that it can be created a whole
part by bending process so that more rigid and light parts can be obtained. After
that, whole assembly of the humanoid robot arm was made. During this assembly
process, a number of design problems were arisen. One of these problem is that
suitable connection surfaces were insufficient for assembling bearings between joint
parts. This situation was overcame by creating a new part to obtain adequate contact
surface and safe connection of these parts.
In this study, workspace analysis of humanoid robot arm was made. It is important
to define where humanoid robot arm can reach. That's why, workspace analysis is significant in showing limits of humanoid robot arm movement. In this study,
maximum and minimum movement limits were defined by using capability of joints'
rotation in MATLAB. Mathematical equations described movement of humanoid robot
arm had to be obtained primarily. 2-D workspace area was obtained relevant to vertical
joint rotation limits by using movement mathematical equation, since limits of joints'
rotation were known. For this purpose, last joint was rotated to its last position
value whereas second and fourth joint were in initial position. So first minimum
limit was obtained. Then, fourth joint was rotated up to its capacity whereas others
were maintaining their position. After that, only second joint was rotated up to its
limit. By means of these operations, Minimum limits were obtained. For defining
maximum limits, only second joint was rotated up to its limit while fourth and sixth
were in zero position. Thus, the workspace analysis of joint configuration used in the
humanoid robot arm was obtained. In this study, the workspace analysis was repeated
for different types of configurations of robot arm by using their vertical joints. The
results for the configurations were mentioned in this study. Finally, 3-D image of
workspace of arm was obtained by using limits of both vertical and horizontal joints.
Advantages and disadvantages of these configuration models for the humanoid robot
arm were evaluated in this section.
Humanoid robot arm is supposed to have capability of rigid structure and agility.
The purpose of the rigid structure, parts of humanoid robot arm was optimised. But
during this process, weight of arm must be as low as possible due to capacity of both
electrical motor and harmonic drive which were selected. There were two boundaries
to limit the optimization process. One of these boundaries was more rigid structure
that means less deformation of humanoid robot arm. The other requirement is light
arm design. First, statical analysis was made to define parts which cause more
deformation than other parts. After that, inertia of these parts had to be increased
for rigid structure. But it means that the more inertia of parts, the more mass of
parts. In this case, more mass is not tolerable by means of capacity of joints in
which selected electrical and harmonic drive is used. The purpose of light and rigid
structure, there are two method of optimization. One of is that mathematical equation
of deformation of humanoid arm is obtained. Other is using ANSYS. In our case,
parameter optimization which changes parameter of part's section to increase inertia of
part was made. First, matematical equations of deformation were obtained. Besides,
some assumptions were made to obtain equations. After that, the results of the arm
deformation was obtained by changing parameters of part section in MATLAB. These
results were checked via ANSYS. Then, optimization process was made by using
ANSYS parameter tool. It is easier to obtain best results than using mathematical
equation in MATLAB. Owing to sheet metal bending process, these parts' section was
designed as centroid. Specific dimensions were used in parameter optimization of these
parts due to available thickness of sheet metal. So, optimization was made by using
these thickness dimension. In this study, the results of the whole arm deformation ,
maximum stress in the arm and weight of the arm related to different thickness of these
parts section was mentioned. The most suitable dimensions was selected eventually.
In this study, definition of joint rotation limits had to be obtained due to capacity of
motor and harmonic drive. That's why, dynamic analysis was made for all joints.
In the dynamic analysis, different rotation profile such as sine, 2nd, 3th and 5th
degree of rotation functions were used to observe the effects of the motion profile.
It was aim to obtain necessary torque value in different rotation profile which were
supplied to joints. Effects of using different rotation profile was observed and results
were discussed. Then, it was aim to observe simultaneously moving two joint effects
since two or more joints of the humanoid robot arm are generally rotated in any task.
After obtained results, the effects on necessary torque value was observer different
directional rotation of these joints. Thus, effects of rotation direction was observed.
The effect of number of rotating joint was evaluated by dynamic analysis in ANSYS.
Finally, dynamic analysis was performed in different rotation profile and by increasing
number of moving joints simultaneously. For the purpose of defining capability of
joints in specific task, the dynamic analysis which is performed by rotating one of
robot arm's joints is certainly insufficient. Different combination of rotating joint and
kind of drastic rotation profile must be used for dynamic analysis. In the next study,
dynamic analysis will be repeated with using flexible body and the results will be
compared with previous results. Thus, the effect of flexible body which can cause the
oscillation will be observed. The parameter optimization process will be done over
again by using data in the flexible body dynamic analysis.