a basic ppt on basic machines

1. Topics to discuss today
• Simple machines
• Compound machines
• Lever
• Linkage
• Wedge
• Mechanical Advantage
• Inclined plane
• Screw

2. To do in class
• Mechanical design is an important component
of this class – how it relates to your project
• What you want to learn?
• What you plan to do?

3. • This material is easy and part of it you can
read by yourself.
• When you read it, please think how you can
apply these ideas in practical robots.
• Look also to internet to find who sells these
and similar items that can be used in your
robot

4. Conclusion on projects
• Mechanical design is an important component
of this class
• This class is not only programming, you have to
pay more attention to mechanical and
interfacing aspects of robot design.
• Robot programming is different from standard
programming, it is a real time application
programming.

6. Stages of robot design

7. Levels of robot creation
Mechanical Robot Design
MOTORS and ACTUATORS Sensor and Vision Internet
Robot System Architecture
Robot Language
Robot Application Programming Robot Teaching
Robot System Integration
• A class as a whole covers all of the above
• Your project(s) should cover few of these

8. Homework:
Kinematic
Model of the
robot

11. Part of your Homework
• Create a model, as in the previous two slides,
for your robot
• Write all necessary data for torques, angles
and length of arms etc.

12. Kinematics
• The study of motion without regard to the
forces or mass of the things moving.
• Kinematic diagrams are scaled drawings
symbolizing how mechanisms work.
• We study robot kinematics in Fall
• We study dynamics in Winter

13. 1. Gears
2. Pulleys
3. Chains
4. Cams
5. Bearings
6. Wheel and Axle
7. Inclined Plane
8. Wedge
9. Screw
10. Lever
11. Cranks and sliders
12. Ratcheting mechanisms
13. Clutches
14. Brakes
Examples of
machines

14. Machines and Tools
1. Machines and tools are mechanical devices
that work by transmitting or converting
energy.
2. Machines are made up of a variety of
mechanisms.
3. What are some examples of machines?

15. Simple Machines
Lever
Pulley
Wheel and Axle
Wedge
Screw
Inclined Plane
All of these are related to robotics.
Think how?

16. Mechanisms
1. Mechanisms help extend human capability by
creating some desired output or motion.
2. A mechanism takes an input motion or force
and creates a desired output motion or force.
MECHANISM
Motion
or force
Motion
or force

17. Types of Motion
• Common types of motion:
– Linear
– Reciprocal
– Rotary
– Oscillating
All these have
applications in robotics

18. Energy: Ability to do work
Work =Force * Distance
Force: A Push or a Pull
Definitions:

19. Linkages

20. motor
Rotating Arms
Torques in arm design are large
Use counterweights and gears to
compensate
Attach the gear to the arm
Attach the motor to the robot driven gear
gear
bolted to arm

21. Role of Linkages
• Linkages transmit the motion or force to the
desired output location.
• Linkages:
1. change the direction of the force
2. Change the length of motion of the force
3. Split the motion and force over multiple paths

23. Lever
– Downward motion at one end
results in upward motion at the
other end.
– Depending on where the pivot
point is located, a lever can
multiply either the force applied
or the distance over which the
force is applied
http://www.csmate.colostate.edu/cltw/cohortpages/viney/balance.html
Pivot point, fulcrum

24. Simple Lever Machine
Explanation
• This simple machine is based on the position of the
effort force, resistance force, and fulcrum.
• First class lever
– Fulcrum located between effort force and
resistance force
– Usually used to multiply a force
– Example: Seesaw
R
F E
This kind of lever
changes the direction
of force.
length1 length2
Effort
force
Resistance
force
R * length1 = E * lenght2

25. Simple Experiment: Balancing Act
• Using only a meter stick and a wooden block, balance two
masses in a seesaw kind of structure.
• How did you get them to balance?
– Could you do it in one try?
• Compare your setup with other possible setups
Engagement
This is
useful in
robot arm
design
Do this by
yourself, not in
class

26. Lever Forces
Exploration
• Materials
– Computer/calculator
– Force Probe
– 500g mass
– String
– Meter stick
– Wooden Block
Simple Experiment: Balancing Act
We do such projects in
High school robotics
Do not discuss next 2
slides in class

27. Lever Forces
Exploration
• Measure the Weight of the 500g mass (in Newtons).
• Balance the middle of the meter stick on the wooden block.
• Place the 500g mass at the 90 cm line.
• Attach the string to the meter stick at the 10 cm line.
• Attach the string to the force meter and pull down on the sensor
until the meter stick is balanced.
• Record the force needed to balance the meter stick.
• Repeat the above steps with the 500g mass at the 70 cm line and
the 60 cm line.
Simple Experiment: Balancing Act

28. Lever Forces
Exploration
• After recording your data in a table, perform
the following calculations for the three trials:
– Divide the weight of the 500g mass by the force
required to balance the meter stick.
– Divide the distance between the force meter
and the wooden block by the distance between
the 500g mass and the wooden block.
• How do these numbers compare?
• What do these numbers indicate about the
lever system?
Simple Experiment: Balancing Act

29. Why use a Simple Machine?
Explanation
• Simple Machines make work easier by giving the user a mechanical
advantage.
• How do we calculate the mechanical advantage for a lever system?
• Ideal Mechanical Advantage (IMA) = Leffort / Lresistance
• Why do we stipulate that the MA is ideal? Because we’ve assumed that the
machine puts out exactly as much work as we put in. This implies 100%
efficiency
• This situation is never possible…why?
100% efficiency is never possible because of FRICTION.
Mechanical
Advantage = MA
Leffort is the distance between the effort force and the fulcrum
Lresistance is the distance between the resistance force and the fulcrum

30. Lever Example
Explanation
• A worker uses an iron bar to raise a manhole cover that weighs 90
Newtons. The effort arm of the bar is 60 cm long and the resistance
arm is 10 cm long.
• Draw a picture of this scenario
• Calculate the IMA of the lever system
IMA = Le/Lr = 60 cm/ 10cm = 6
• What force would the worker need to apply to lift the manhole?
• We need 90 N of force to lift the manhole cover, but we have a mechanical
advantage of 6.
• Now we only need 15 N of force to lift the manhole.
90 N

31. Three
Classes of
Levers

32. First Lever
Class

33. “First Class Lever”
• A first-class lever is a lever in
which the fulcrum is located
between the input effort and the
output load.
• In operation, a force is applied
(by pulling or pushing) to a
section of the bar, which causes
the lever to swing about the
fulcrum, overcoming the
resistance force on the opposite
side.
• The fulcrum may be at the center
point of the lever as in a seesaw
or at any point between the input
and output.
– This supports the effort arm and the
load.
Examples:
•Seesaw
•Scissors (double
lever)
Classes of Levers

34. Fulcrum is between EF (effort) and RF (load)
Effort moves farther than Resistance.
Multiplies EF and changes its direction
The mechanical advantage of a lever is the ratio of the length of the lever
on the applied force side of the fulcrum to the length of the lever on the
resistance force side of the fulcrum.
First Class Lever
fulcrum
Effort
Resistance

35. Common examples
of first-class levers
include
– crowbars,
– scissors,
– pliers,
– tin snips
– and seesaws.
Examples of first class levers

36. Second Lever
Class

37. RF (load) is between fulcrum and EF
Effort moves farther than Resistance.
Multiplies EF, but does not change its direction
The mechanical advantage of a lever is the ratio of the distance
from the applied force to the fulcrum to the distance from the
resistance force to the fulcrum.
Second Class Lever
Effort
Resistance

38. Three Lever Classes
Explanation
• Second class lever
– Resistance is located between the effort
force and the fulcrum.
– Example: Wheelbarrow
R
F
E
Always multiplies a force.

39. Examples:
•Paddle
•Wheelbarrow
•Wrench
Examples of Second class levers

40. • Examples of
second-class
levers include:
• nut crackers,
• wheel barrows,
• doors,
• and bottle
openers.
Examples of second-class levers

41. Third Lever
Class

42. EF is between fulcrum and RF (load)
Does not multiply force
Resistance moves farther than Effort.
Multiplies the distance the effort force travels
The mechanical advantage of a lever is the ratio of the distance
from the applied force to the fulcrum to the distance of the
resistance force to the fulcrum
Third Class Lever

43. • For this class of levers, the input
effort is higher than the output
load, which is different from
second-class levers and some
first-class levers.
• However, the distance moved by
the resistance (load) is greater
than the distance moved by the
effort.
• In third class levers, effort is
applied between the output load
on one end and the fulcrum on
the opposite end.
“Third Class Lever”
Examples:
•Hockey Stick
•Tweezers
•Fishing Rod
Classes of Levers

44. Three Lever Classes
Explanation
• Third class lever conclusions
– Effort force located between the resistance and the
fulcrum.
– Effort arm is always shorter than resistance arm
– MA is always less than one
– Example: Broom
R
F
E
There is an increase distance moved
and speed at the other end.
Other examples are baseball bat or
hockey stick.

45. Examples of Third Class Levers
• Examples of
third-class
levers include:
– tweezers,
– arm hammers,
– and shovels.
Third class lever in
human body.

46. Natural Levers
in Human Body

47. Natural Levers
Elaboration
• Identify an
example of a
1st class lever
in the human
body
Remember to relax the body
and feel the muscle groups
working to move the bones
Example of first
class lever in
human body

48. Natural Levers in human body
• Identify an
example of
a 2nd class
lever in the
human
body
Elaboration
Remember to relax the body and feel the muscle groups working to move the
bones
Second class
lever in human
body

49. Natural Levers in human body
• Identify an example of a 3rd class lever in the human body
Remember to relax the body and feel the muscle groups working to
move the bones

50. Mechanical
Advantage and
Velocity Ratio

51. Mechanical Advantage
• Mechanical Advantage is the ratio between
the load and effort.
• Mechanical Advantage deals only with forces.
• Mechanical Advantage > 1 means that the
output force will be greater than the input
force.
– (But the input distance will need to be greater
than the output distance.)

52. •First and Second class levers have a positive mechanical
advantage.
•Third class levers have a mechanical disadvantage,
meaning you use more force that the force of the load you
lift.
Mechanical Advantage

53. Velocity Ratio
• Velocity Ratio deals with the distance gained
or lost due to a mechanical advantage.
• Velocity Ratio >1 means that the input
distance (or effort) to move a load will be
greater than the output distance of the load.

54. Mechanical Advantage: Example
Mechanical Advantage =
effort arm
resistance arm
Crazy Joe is moving bricks to build his cabin.
With the use of his simple machine, a lever, he moves them easily.
The “effort arm” of his wheel barrow is 4ft., while the resistance
arm of his wheelbarrow is 1 ft.
4/1 is his mechanical advantage. MA= 4.

55. How the Lever changes
the Force?
“The length of the effort arm is the same number of
times greater than the length of the resistance arm as
the resistance to be overcome is greater than the
effort you must apply.”
Plugging these into an equation gives you the change
in force by using a lever.
where
L = length of effort arm,
l = length of resistance arm,
R = resistance weight or force, and
E= effort force.
One convenience of
machines is that you can
determine in advance the
forces required for their
operation, as well as the
forces they will exert.

56. F o r c e C h a n g e
• Suppose you want to pry up the lid of a paint can with a 6-inch file scraper, and you
know that the average force holding the lid is 50 pounds.
• If the distance from the edge of the paint can to the edge of the cover is 1 inch,
what force will you have to apply on the end of the file scraper?
L = 5 inches
l = 1 inch
R = 50 pounds, and
E is unknown.
= 10 pounds
• You will need to apply a force of only 10 pounds.

57. Rotary
Mechanisms

58. Rotary Mechanisms
• Gears, Pulleys, Cams, Ratchets, Wheels, etc.
• These rotary mechanisms transfer or change input
rotational motion and force to output motion and
force.
• Output force can be either rotational or
reciprocating.
Rotary
mechanism
rotational motion and force rotational or reciprocating motion
and force.

59. Belts/Pulleys & Chains/Sprockets
• Use belts and chains to convert motion and
force.
• Uses the same measures of Mechanical
advantage and Velocity Ratio also for belts,
pulleys, chains, sprockets and gears.

60. Inclined
Plane

61. Inclined Plane
– Sloping surface used to lift heavy loads with less effort
http://www.sirinet.net/~jgjohnso/simple.html
Knowledge of inclined plane is useful when designing a wheelchair robot

62. Inclined Plane in antiquity

63. Inclined Plane - Egyptians
• The Egyptians used simple machines to build the pyramids.
• One method was to build a very long incline out of dirt that rose
upward to the top of the pyramid very gently.
• The blocks of stone were placed on large logs (another type of
simple machine - the wheel and axle) and pushed slowly up the
long, gentle inclined plane to the top of the pyramid.

64. Inclined Plane Principles
• An inclined plane is a flat
surface that is higher on one
end
• Inclined planes make the
work of moving things easier
• A sloping surface, such as a ramp.
• An inclined plane can be used to alter the
effort and distance involved in doing work,
such as lifting loads.
• The trade-off is that an object must be
moved a longer distance than if it was lifted
straight up, but less force is needed.
• You can use this machine to move an object
to a lower or higher place.
• Inclined planes make the work of moving
things easier.
• You would need less energy and force to
move objects with an inclined plane.

65. Inclined Plane -
Mechanical Advantage
• The mechanical advantage of
an inclined plane is equal to
the length of the slope
divided by the height of the
inclined plane.
• The inclined plane produces
a mechanical advantage
• It does so by increasing the
distance through which the
force must move.

66. Work input and output
• Work input is the amount of work done on
a machine.
–Input force x input distance
• Work output is the amount of work done
by a machine.
–Output force x output distance
15 m
3 m
Wout = Win
Fout * Dout = Fin * Din
10N * 3m = 2N * 15m 10 N Fin
Din
Dout

68. Screw
The mechanical advantage of an screw can be
calculated by dividing the circumference by the pitch of
the screw.
Pitch equals 1/ number of turns per inch.
A screw is an inclined plane
wound around a central cylinder

69. Screw
– Converts a rotary motion into a forward or
backward motion
http://www.sirinet.net/~jgjohnso/simple.html

70. Wedges

71. Wedge
–Converts motion in
one direction into a
splitting motion that
acts at right angles to
the blade
–A lifting machine may
use a wedge to get
under a load
http://www.mos.org/sln/Leonardo/InventorsToolbox.html

72. Wedges
• Two inclined
planes joined
back to back.
• Wedges are used
to split things.

73. Wedge – Mechanical Advantage
• The mechanical advantage of a wedge can be found by
dividing the length of either slope (S) by the thickness (T)
of the big end.
S
• As an example, assume that the length of the slope is 10
inches and the thickness is 4 inches.
• The mechanical advantage is equal to 10/4 or 2 1/2.
• As with the inclined plane, the mechanical advantage
gained by using a wedge requires a corresponding
increase in distance.
T
S/T

74. How Does a Wedge
Change the Force?
• Wedges change the direction of an applied
force.
• When force is applied downward on a
wedge, it distributes the force outward in
two directions, separating a material.

75. Compound
Machines
… more examples of …

76. Compound Machine #1
• Bowflex:
• Pulley lifts the weight,
• the seat is an inclined
plane,
• and the lever is what you
pull to adjust the seat

77. Compound Machine #2
• Crane:
• The lever is the
horizontal beam that
lifts the object,
• the pulley is used to
make the rope tight so
that it is easier for the
crane to lift the object

78. Compound Machine #3
• Ski Lift: It is an
inclined plane to
travel up a
mountain.
• The pulley is used to
pull the ski lift to the
top of the mountain

79. A Wedge in a Compound
Machine: Stapler
• Staples are wedges:
they cut through paper
because their ends are
pointed in a wedge
shape.
• There are two simple
machines in a stapler:
1. Wedge
2. Lever
Examples of compound machines

80. A Wedge in a Compound Machine: Can
Opener
• The cutting edge of a
can opener cuts
through metal
because it is shaped
like a wedge.
• Simple machines in a
can opener:
– Wedge
– Lever
– Gear
– Wheel and axle
Examples of compound machines

81. A Wedge in a Compound Machine:
Scissors
• The cutting edge of
scissors is a wedge.
• Simple machines in a
pair of scissors:
– Wedge
– Lever
Examples of compound machines

82. Project Related
1. Create a kinematic model of your robot
2. Relate it to pulleys, gears, levers,
linkages, etc
3. Perform simple calculations related to
torque, speed and power

83. Levers and Linkages: Conclusions
• Fulcrum
• Load
• Effort
• Classes
– First
– Second
– Third
Concepts
discussed
Understanding of levers and
linkages is important for those
who build robots, especially
humanoids
It is useful to look to Nature for examples of mechanical
designs (Leonardo Da Vinci)

84. Philosophy
• Be able to see and appreciate simple
machines around you
• Be able to steal every mechanical idea from
any kind of machines for the robot that you
are building.

85. Questions and
Problems

86. 1. Gears
2. Pulleys
3. Chains
4. Cams
5. Bearings
6. Wheel and Axle
7. Inclined Plane
8. Wedge
9. Screw
10. Lever
11. Cranks and sliders
12. Ratcheting mechanisms
13. Clutches
14. Brakes
Quizz Questions
for students:
1. Explain the following
concepts
2. Give examples of
each
3. How each can be
used in robotics?

87. 1. Give definitions of energy, work and force
2. Give examples of these types of motion in robotics:
– Linear
– Reciprocal
– Rotary
3. Oscillating
4. What are linkages?
5. What are the types of linkages?
6. Give examples of different types of linkages?
7. What is a lever?
8. Explain the definitions and give examples of three
classes of levers.

88. 1. Give definition of mechanical advantage
2. Give examples of mechanical advantages in simple
machines such as various classes of levers.
3. Give at least three examples of compound
machines.
4. What are Parallel Linkages, Treadle Linkages amd
Toggle Linkages
5. What is a rotary mechanism?
6. Describe a humanoid arm as a compund machine.
7. The same for a leg
8. The same for a torso
9. The same for a head and neck combination.

89. Simple problems for quizz
1. How much effort will be needed to lift a 100
pound load if distance to effort is five feet
and distance to resistance is one foot?
2. How much effort will be needed to lift a 48
pound load if distance to effort is two feet
and distance to resistance is 8 feet?

90. Compound machine:
Can Opener
Simple machines
1. lever
2. wheel and axel
3. gear
4. wedge
More quiz problems
There are as many as 4 simple machines in a stupid CAN OPENER!
Build a simple model of can opener and
perform power/linkage/MA calculations

91. Compound Machine:
Stapler
Simple Machines:
-Lever
-Wedge
Every complex mechanism can be decomposed to a
network of simple machines
More quiz problems
1. Build a simple model of can opener and perform
power/linkage/MA calculations
2. Analyze an arbitrary other compound machine that
you know from real life using the above method.

92. Compound Machine:
Wheelbarrow
Simple Machines:
-Lever
-Inclined Plane
-Wheel and Axel
Where can I find compound
machines?
Wheelbarrow
More quiz problems

93. Questions and Problems
1. What is kinematics? Why is kinematics important for robot design and
programming?
2. Draw a kinematic model of Jimmy robot.
3. Draw a kinematic model of new robot Meccanoid
4. Draw a kinematic model of InMooV robot.
5. Give example of First Lever Class in a robot, especially a humanoid robot.
6. Give example of Second Lever Class in a robot, especially a humanoid robot.
7. Give example of Third Lever Class in a robot, especially a humanoid robot.
8. How the Lever changes the Force?
9. Propose your own design of a robotic arm with four degrees of freedom, using
as many as possible concepts from this set of slides. Optimize the robot arm
envelope, and assume low cost motors. Add gears, pulleys, levers.
10. Perform calculations for robot arms that were requested in last few sets of
slides. Now you can do them as you learned the theory!

94. • http://en.wikipedia.org/wiki/Lever
I got the three types of levers, examples and their functions. (used)
• http://www.tpub.com/machines/1c.htm
I got the formula for mechanical advantage and example. (used)
• http://www.edheads.org/activities/simple-machines/frame_loader.htm
I found a list of compound machines and how simple machines were used in
them. (used)
• http://www.coe.uh.edu/archive/science/science_lessons/scienceles1/lever.ht
m
I found examples of levers and how they work.
Bibliography

95. Bibliography
• http://dictionary.reference.com/browse/wedge
• http://www.uark.edu/depts/aeedhp/agscience/si
mpmach.htm
• http://www.sciencetech.technomuses.ca/englis
h/schoolzone/Info_Simple_Machines2.cfm
• http://www.edheads.org/activities/simple-
machines/frame_loader.htm
• http://www.teachervision.fen.com/machines/print
able/45019.html

96. Bibliography
• http://library.thinkquest.org/27948/pulley.html
– This site explains the use of the pulley system. Also
provides an equation to figure out the force needed to lift
an object with the pulley.
• *http://library.thinkquest.org/J002079F/pulley.htm
– This site defines a pulley and explains how it makes lifting
easier. This site also shows simple examples of pulleys.
• http://www.science.jrank.org/pages/4060/Machines-Simple.html
I used this site to find mechanical advantages, examples, and how a basic
lever works.

97. Bibliography (Cont.)
*http://en.wikipedia.org/wiki/Pulley
– This site gave the definition of a pulley, different types of pulley
systems, and explains how these systems work.
• http://www.swe.org/iac/lp/pulley_03.html
– This site gives a detailed explanation about pulleys. It shows how it
was invented, by whom it was invented, and provides pictures to show
how a pulley works.
• *http://library.thinkquest.org/CR0210120/MA%20of
%20PS.html
– This site showed how to get the mechanical advantage for a pulley.

98. Sources
Shawni Yeagley
Nate Yavoich
Raquel y Victoria