Slides accompanying 2.008x* video module on Robotics, Prof. John Hart, MIT, 2016.
*Fundamentals of Manufacturing Processes on edX: https://www.edx.org/course/fundamentals-manufacturing-processes-mitx-2-008x
3. 2.008-F16 | 3
Automation:
automatically controlled operation of an apparatus,
process or system by mechanical or electronic
devices that take the place of human labor*
*Wilson, Implementation of Robot Systems
4. 2.008-F16 | 4
Automation in manufacturing systems
Machines
Material flow and handling
Robotic manipulation
Local controllers (machines / workcells)
Factory network controllers (supervision, optimization)
Requirements for implementation
Coordination of process rates
Robustness against faults
Online monotoring / control
5. 2.008-F16 | 5
Automation: filling water bottles
https://www.youtube.com/watch?v=EjkOiBXI14o
Bottle molding: 2,250/hr https://www.youtube.com/watch?v=soiGsZj7hn0&list=PL167A9254F5245075&index=33
All videos from Krones: https://www.youtube.com/playlist?list=PL167A9254F5245075
6. 2.008-F16 | 6
Automation:
automatically controlled operation of an apparatus,
process or system by mechanical or electronic
devices that take the place of human labor
Industrial robot:
an automatically controlled, re-programmable,
multipurpose manipulator programmable in three or
more axes, which may be either fixed in place or
mobile for use in industrial automation applications
(according to the international federation of robotics)
from Wilson, Implementation of Robot Systems
7. 2.008-F16 | 7from Wilson, Implementation of Robot Systems
The first industrial robot, the ‘Unimate’
Invented/built by Joseph Engelberger and
George Devol (company formed 1956)
Hydraulically driven arm with instructions
read from magnetic drum
Initial use to stack die cast parts at General
Motors plant in New Jersey
First major industrial robot installation (1969)
Went from 40% to 90% automated spot welding
3000 robots in use by 1973 (mfg partnership
between Unimation and Kawasaki of Japan)
8. 2.008-F16 | 8
Today’s agenda
Why automation and robotics in manufacturing?
Common robotic manipulators used in manufacturing:
articulated, selective compliance (SCARA), delta
Geometry and workspace
Applications
Comparing performance and capability tradeoffs
Grippers (‘end effectors’)
Emerging trends and technologies
10. 2.008-F16 | 10
Why use robotics and automation in mfg?
from Wilson, Implementation of Robot Systems
(Potentially)
Improve product quality and consistency
Improve worker safety/satisfaction (by doing heavy or
dangerous jobs)
Increase production rate
Increase production flexibility
Reduce manufacturing cost
Reduce waste
Save space in high value areas
Some of the above are coupled; rarely are all true
Robots generally not good for operations requiring both
high force and high accuracy (e.g., machining); also takes
time to program and establish accurate path (calibration)
11. 2.008-F16 | 11
How can we measure whether a process (or industry in
general) is appropriate for use of robotics?
?
?
16. 2.008-F16 | 16
Now >2 million industrial robots in use worldwide
from Wilson, Implementation of Robot Systems
Total number of robots in use: Asia:Europe:Americas = 3:1.5:1
17. 2.008-F16 | 17
Predicted growth (source: Boston Consulting Group)
BCG ‘The Rise of Robotics’
https://www.bcgperspectives.com/content/articles/business_unit_strategy_innovation_rise_of_robotics/
20. 2.008-F16 | 20
Articulated robot
Sciavicco, L.; Siciliano, B. Modelling and Control of Robot Manipulators; Advanced Textbooks in Control and Signal Processing;
Springer London: London, 2000; Burckhardt C. Industrial Robots : Proceedings = Robots Industriels : Comptes Rendus = Industrie-
Roboter : Tagungsberichte [e-book]. Basel : Birkhäuser Verlag, 1975
Spherical wrist for end-effector
Waist joint
Shoulder joint
Elbow joint
Wrist
The articulated arm provides the most dexterity within the
working volume.
Errors are cumulative due to the series architecture.
Typical robot sizes range from a reach of 0.5 to over 3.5 m
and carrying capacities from 3 to over 1000 kg.
The end-effector orientation can be independent of position
using a spherical wrist.
21. 2.008-F16 | 21
Workspace of articulated manipulator
Sciavicco, L.; Siciliano, B. Modelling and Control of Robot Manipulators; Advanced Textbooks in
Control and Signal Processing; Springer London: London, 2000.
Working
envelopeEnd-
effector
23. 2.008-F16 | 23
Verifying the workspace [: don’t try this with
your robot]
https://www.youtube.com/watch?v=bxbjZiKAZP4 (see description)
There’s a real ride: https://www.youtube.com/watch?v=bSdA_oq1EgU
25. 2.008-F16 | 25
Planetary gear
in Axis 6
Power transmission
belts for axes 4, 5, & 6
Motors and Transmissions of Axes 4, 5, and 6
Motors
Transmission
26. 2.008-F16 | 26
Brushless AC Servomotor
• Rotor has a rotating permanent magnet and a fixed
armature
• Electronic controller replaces the brush/commutator
assembly of the brushed motor
• High torque to weight ratio, high efficiency and
reliability (compared to brushed motors)
• With windings in the housing, cooling is done by
conduction
AC Servomotor
(Kollmorgen AKM series used in KUKA robots)
Torque is kept (nearly)
constant with speed and
load changes
Reference
27. 2.008-F16 | 27
Wave Generator
Flex Spline
Circular Spline
Strain Wave Gear Components
• Motor is connected to the Wave generator
• When the wave generator rotates CW by 3600, Flex Spline
rotates CCW by 2 teeth w.r.t. the Circular Spline (fixed)
• High gear reduction ratios in a small volume (30:1 to 320:1 is
possible Vs 10:1 from planetary gears)
• High positioning accuracy and repeatability (+/- 3 arc
seconds) [1 arc second = 1/3600th of a degree]
• High torque capacity and torsional stiffness
• Low tooth friction losses and wear longer life and high
reliability
Strain wave gear
Operating Principle
Video : Strain Wave Gear Principle
Reference
29. 2.008-F16 | 29
Maintaining an accurate 3D path
True (exact) value
Repeatability
Accuracy
Probabilitydensity
Consider discrete vs.
continuous toolpaths (what are
some applications of each?)
30. 2.008-F16 | 30
Serial kinematics by HTM (Homogeneous Transformation Matrices)
ú
ú
ú
ú
û
ù
ê
ê
ê
ê
ë
é -
1000
0100
100001
200010
Yz
y
x
Z
X
200
100
n
Hn+1
=
Rn
n+1
pn+1
n
01´3
1
é
ë
ê
ê
ù
û
ú
ú
T = 1
H0
2
H1
....G
31. 2.008-F16 | 31
What influences accuracy and repeatability of end
effector position?
Structural design (stiffness)
Actuator performance: accuracy, repeatability, stiffness
Manufacturing and assembly tolerances
Calibration
Use case: loads, toolpath dynamics
38. 2.008-F16 | 38
Lightweighting using 3D printing
http://spectrum.ieee.org/automaton/robotics/humanoids/boston-
dynamics-marc-raibert-on-nextgen-atlas
39. 2.008-F16 | 39
SCARA (Selective Compliance Assembly Robot Arm)
Sciavicco, L.; Siciliano, B. Modelling and Control of Robot Manipulators; Advanced Textbooks in Control and Signal Processing; Springer
London: London, 2000; Burckhardt C. Industrial Robots : Proceedings = Robots Industriels : Comptes Rendus = Industrie-Roboter :
Tagungsberichte [e-book]. Basel : Birkhäuser Verlag, 1975
Four-axis arm: positioning in x,y,z and rotation about z
Very rigid in the vertical direction and with compliance in the horizontal plane;
useful for high accuracy positioning in x-y plane (e.g., part insertion)
Planar rotary
motion 1
Planar rotary
motion 2
Vertical motion
Working envelope
Base rotation
41. 2.008-F16 | 41
Delta (parallel kinematics) robot
http://www.ohio.edu/people/williar4/html/pdf/DeltaKin.pdf; http://www.adept.com/products/robots/parallel/quattro-s650h/intro
Working envelope (example
The parallel or delta configuration
differs from the articulated arm
because the constraints (or
degrees of mobility) are in parallel.
3 degrees of freedom; typically
low payload capacity.
Errors are non-cumulative unlike
the case of series constraint in the
kinematic arm. Also provides high
stiffness (relative to weight) and
high speed.
Mainly used in pick and place
operations, especially in the food
industry and also in some
assembly applications.
Rotations
controlled by
actuators
50. 2.008-F16 | 50
Tooling cost
+
Equipment cost
+
Material cost
+
Overhead cost
How would we determine cost of adding robots?
n
C
C oh
4
[$/part]
C3
=
mCm
1- f( )
CT
=C1
+C2
+C3
+C4
t
t
n
N
N
C
C Roundup1
55. 2.008-F16 | 55
Flexible automation: Rethink Robotics “Baxter”
Programmable manually (‘teach’ by holding the robot’s end effector and
moving it through the path)
Tolerant to variabilities e.g. in part position on conveyor
Force feedback enabling the robot to adapt to variations without damage but LOW
STIFFNESS
Working radius = 1210 mm; maximum payload (including end-effector) = 2.2 kg
7 degrees of freedom per arm Degrees of mobility = 7 per arm
Embedded vision system
http://www.rethinkrobotics.com
https://www.youtube.com/watch?v=DKg-GvPyNLc
https://www.youtube.com/watch?v=KpqaBKyZGeE&feature=youtu.be