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
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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
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Automation in manufacturing systems
ï§ Machines
ï§ Material flow and handling
ï§ Robotic manipulation
ï§ Local controllers (machines / workcells)
ï§ Factory network controllers (supervision, optimization)
Requirements for implementation
ï Coordination of process rates
ï Robustness against faults
ï Online monotoring / control
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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
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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 âUnimateâ
ï§ Invented/built by Joseph Engelberger and
George Devol (company formed 1956)
ï§ Hydraulically driven arm with instructions
read from magnetic drum
ï§ Initial use to stack die cast parts at General
Motors plant in New Jersey
First major industrial robot installation (1969)
ï§ Went from 40% to 90% automated spot welding
ï§ 3000 robots in use by 1973 (mfg partnership
between Unimation and Kawasaki of Japan)
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Todayâs agenda
ï§ Why automation and robotics in manufacturing?
ï§ Common robotic manipulators used in manufacturing:
articulated, selective compliance (SCARA), delta
ï§ Geometry and workspace
ï§ Applications
ï§ Comparing performance and capability tradeoffs
ï§ Grippers (âend effectorsâ)
ï§ Emerging trends and technologies
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Why use robotics and automation in mfg?
from Wilson, Implementation of Robot Systems
(Potentially)
ï§ Improve product quality and consistency
ï§ Improve worker safety/satisfaction (by doing heavy or
dangerous jobs)
ï§ Increase production rate
ï§ Increase production flexibility
ï§ Reduce manufacturing cost
ï§ Reduce waste
ï§ Save space in high value areas
ï Some of the above are coupled; rarely are all true
ï 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)
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How can we measure whether a process (or industry in
general) is appropriate for use of robotics?
?
?
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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
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Predicted growth (source: Boston Consulting Group)
BCG âThe Rise of Roboticsâ
https://www.bcgperspectives.com/content/articles/business_unit_strategy_innovation_rise_of_robotics/
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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 : BirkhÀuser Verlag, 1975
Spherical wrist for end-effector
Waist joint
Shoulder joint
Elbow joint
Wrist
ï§ The articulated arm provides the most dexterity within the
working volume.
ï§ Errors are cumulative due to the series architecture.
ï§ Typical robot sizes range from a reach of 0.5 to over 3.5 m
and carrying capacities from 3 to over 1000 kg.
ï§ The end-effector orientation can be independent of position
using a spherical wrist.
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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
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Verifying the workspace [: donât try this with
your robot]
https://www.youtube.com/watch?v=bxbjZiKAZP4 (see description)
Thereâs a real ride: https://www.youtube.com/watch?v=bSdA_oq1EgU
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Planetary gear
in Axis 6
Power transmission
belts for axes 4, 5, & 6
Motors and Transmissions of Axes 4, 5, and 6
Motors
Transmission
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Brushless AC Servomotor
âą Rotor has a rotating permanent magnet and a fixed
armature
âą Electronic controller replaces the brush/commutator
assembly of the brushed motor
âą High torque to weight ratio, high efficiency and
reliability (compared to brushed motors)
âą 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
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Wave Generator
Flex Spline
Circular Spline
Strain Wave Gear Components
âą Motor is connected to the Wave generator
âą When the wave generator rotates CW by 3600, Flex Spline
rotates CCW by 2 teeth w.r.t. the Circular Spline (fixed)
âą High gear reduction ratios in a small volume (30:1 to 320:1 is
possible Vs 10:1 from planetary gears)
âą High positioning accuracy and repeatability (+/- 3 arc
seconds) [1 arc second = 1/3600th of a degree]
âą High torque capacity and torsional stiffness
âą Low tooth friction losses and wear ï longer life and high
reliability
Strain wave gear
Operating Principle
Video : Strain Wave Gear Principle
Reference
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Maintaining an accurate 3D path
True (exact) value
Repeatability
Accuracy
Probabilitydensity
Consider discrete vs.
continuous toolpaths (what are
some applications of each?)
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Lightweighting using 3D printing
http://spectrum.ieee.org/automaton/robotics/humanoids/boston-
dynamics-marc-raibert-on-nextgen-atlas
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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 : BirkhÀuser Verlag, 1975
ï§ Four-axis arm: positioning in x,y,z and rotation about z
ï§ 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
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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
ï§ The parallel or delta configuration
differs from the articulated arm
because the constraints (or
degrees of mobility) are in parallel.
ï§ 3 degrees of freedom; typically
low payload capacity.
ï§ Errors are non-cumulative unlike
the case of series constraint in the
kinematic arm. Also provides high
stiffness (relative to weight) and
high speed.
ï§ Mainly used in pick and place
operations, especially in the food
industry and also in some
assembly applications.
Rotations
controlled by
actuators
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Flexible automation: Rethink Robotics âBaxterâ
ï§ Programmable manually (âteachâ by holding the robotâs end effector and
moving it through the path)
ï§ Tolerant to variabilities e.g. in part position on conveyor
ï§ Force feedback enabling the robot to adapt to variations without damage ï but LOW
STIFFNESS
ï§ Working radius = 1210 mm; maximum payload (including end-effector) = 2.2 kg
ï§ 7 degrees of freedom per arm Degrees of mobility = 7 per arm
ï§ 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