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Kinematics of Mechanisms 1Interoduction
Latifah Nurahmi
Room C.250
Course outline
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1• Introduction of kinematics and mechanisms
2• Group presentations
3-5• Position analysis and displacements
6+7• Velocity analysis
8• Mid exam (UTS)
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Course outline
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9+10• Acceleration analysis
11+12• Kinematic Synthesis
13+14• Cam mechanisms and gear mechanisms
15• Lab work – Kinematics of Mechanism
16• Mid exam (UTS)
Introduction
Determine appropriate movement of the
wipers
- View range
- Wipe angle
- Location of pivots
Timing of the wipers
Wiping velocity
The force acting on the machine
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Introduction
Machine
Devices used to alter, transmit, and direct
energy to accomplish a specific objective
Mechanism
Mechanical portion of a machine that
has the function of transferring motion
and forces
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Kinematics
The initial step…
What is the significance of the leg length
that support the platform?
Is it necessary for support legs to cross
and be connected at their midspan?
Or is it better to arrange the so that they
cross closer to the platform?
How far must the cylinder extend to raise
the platform 8 in?
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Dynamics
The second step…
What capacity (maximum force) is
required of the hydraulic cylinder?
Is the platform free of any tendency tip
over?
What cross-sectional size and material
are required of the support legs so they
don’t fail?
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Kinematic analysis and synthesis
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Kinematics : deals with the way things move
Kinematic analysis :
- Determine : position, displacement, rotation, velocity, acceleration
- Provide : geometry, dimension, motion path
Kinematic synthesis :
- Determine : geometry, dimension, operation range
- Provide : motion path, position, velocity
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Terminologies in kinematics
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Degree of freedom
Rotation about an axis
Translation along a direction
In our 3D-space we have
- 3 Rotations
- 3 Translations
X Y
Z
Terminologies in kinematics
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Lower-order joint(contact is surface)
S : Spherical joint
R : Revolute joint
E : Planar joint
P : Prismatic joint
C : Cylindrical joint
H : Helical joint
S
E
C
R
P
H
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Terminologies in kinematics
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Higher-order joint(contact is a point)
Terminologies in kinematics
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Simple link
Rigid body contains only two joints
Crank : a simple link that is able to
complete a full rotation about a fixed
center
Rocker : a simple that oscilates through
an angle
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Terminologies in kinematics
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A link with point of interest
Point of interest : is a point on a
link where the motion is of special
interest
Terminologies in kinematics
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A complex link
A rigid body contains more than
two joints
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Terminologies in kinematics
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The mechanism that works on the plane, generally on the XY-plane.
Mechanism
PlanarMechanism
Spatial Mechanism
The mechanism that works in the space, generally in the XYZ-space.
Terminologies in kinematics
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Planar mechanisms
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Terminologies in kinematics
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Spatial mechanisms
Assignment 1
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A shear press is used to cut and trim electronic circuit board.
Draw the kinematic diagram!
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Assignment 1
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1. Determine which part is fixed, which one is moving
2. Determine the number and type of joints
3. Determine the links
4. Draw the kinematic diagram
fixed
moving
Assignment 1
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Link 1 : fixed part
Link 2: handle
Link 3: Cutting blade
Link 4 : Bar that connects the
cutter and the handle
Point of interest X
Joint A, B, C : Revolute joints
Joint D : Prismatic joint
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Assignment 2
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A linkage is used to operate the water
nozzle at an automatic car wash.
Draw the kinematic diagram.
Find how many joints and links!
Grübler’s equation
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Grübler’s equation
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The degrees of freedom of the following mechanisms can be deduced by Grübler’s equation
Assignment 3
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A beverage can crusher used to reduce the size of cans for easierstorage prior to recycling.
Draw the kinematic diagram!Comput the degree of freedom!
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Assignment 3
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Exercies 3: for next week
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Make a presentation of the following mechanisms, show the video, draw the kinematic diagram,
find its DOF, and mention its applications!
1. Four-bar linkage
2. Five-bar linkage
3. Six-bar linkage
4. Scotch and yoke mechanism
5. Slider crank mechanism
6. Wanzer needle mechanism
7. Stewart-Gough platform
8. Agile eye
9. Cam and follower mechanism