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Robotic Actuators ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Robotic Actuators
• Taxonomy of Prime Movers • Types of Electric Motors • Brakes • Transmissions • Bearings • Seals
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© 2018 David L. Akin - All rights reserved http://spacecraft.ssl.umd.edu
Robotic Actuators ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Fundamental Elements of Robotics
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SensingPlanning
and Reasoning
Actuation
Environment
Robotic Actuators ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Mechatronics
• “Smart components” • Combination of (or technologies for)
– Sensors – Actuators – Structures and mechanisms – Processors and control systems
• Subsumes microelectromechanical systems (MEMS)
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Prime Mover Taxonomy
• Electrical – Direct Current – Alternating Current
• Non-Electrical – Hydraulics – Pneumatics – Chemical – Thermal – Stored Energy
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Hydraulics and Pneumatics
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Hydraulic Spool Valve Schematic
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Hydraulic System Schematic
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Pneumatic Actuator Cutaway
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Brushed DC Motor Schematic
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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DC Brushed Motor Schematic
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Brushed DC Motor Commutator
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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DC Brushed vs. Brushless Motors
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Brushless DC Motor
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Brushless Outrunner Motor
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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DC Brushless Motor Schematic
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Basic DC Motor Drive Characteristics
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Effects of Temperature on DC Motors
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Effects of Temperature on DC Motors
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Speed as a Function of Torque
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Standard DC Motor Characteristics
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Motor Power
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P = ⌧!
P = ⌧ (!NL + E⌧) = ⌧!NL + E⌧2
! = E⌧ + !NL (E < 0)
dP
d⌧= !NL + 2E⌧ = 0
⌧max power
= �!NL
2E
Robotic Actuators ENAE 788X - Planetary Surface Robotics
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DC Motor Power and Efficiency
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Standard Motor Specifications
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Typical DC Motor Specification
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Axial Flux Motor
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Stepper Motor Exploded Image
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Stepper Motor Schematic
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Gearhead Motor Cutaway
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Gear Forms
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Gearing Calculations
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Gear ratio ⌘ N
⌧output
= N⌘gear
⌧input
!output
=!input
N
Ioutput
= N2Iinput
⌧ = I!̇ =) I =⌧
!̇
Ioutput
=⌧output
!̇output
Ioutput
=N⌘
gear
⌧input
!̇input
N
Ioutput
= N2⌘gear
Iinput
!̇output
=!̇input
NFor ideal gearing,
Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Spur Gears
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Spur Gear Parameters
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Helical Gears
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Planetary Gears
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Bevel Gears
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Bevel Gear Kinematics
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Automotive Differential Schematic
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Automotive Differential (more realistic)
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Worm Gear
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Chain Drives
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Chain Drive with Idler
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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V-Belt Drive
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Toothed Belt Drive
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Rack and Pinion Gears
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Screw Drive Schematic
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Linear Actuator Cutaway
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Cup-Style Harmonic Drive
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Pancake Harmonic Drive
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Shallow-Cup Harmonic
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Operating Principle of Harmonic Drives
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Actuator Mass Estimating Relations
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mact = 0.6071⌧peak � 0.2796Speak + 2.5067
mact ⌘ Actuator mass <kg>⌧peak ⌘ Peak actuator torque <N-m>
Speak ⌘ Peak actuator speed <kRPM>
Toutput
⌘ Peak output torque<N-m>
Mharmonic
⌘ harmonic drive mass<kg>
Mharmonic
= 0.0078⌧output
Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Ball Bearings
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Types of Bearings
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Angular Contact Bearing
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Dual-Row Angular Contact Bearing
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Thrust Bearing
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Tapered Roller Bearings
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Wheel Hub Cutaway
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Ideal Bearing Applications
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O-Ring and Groove
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Lip Seals
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Robotic Actuators ENAE 788X - Planetary Surface Robotics
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Spring Energized Seals
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Labyrinth Seals
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