Human Friendly Robot Design and Control -...
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Human Friendly Robot Design and Control Dongjun Shin, Irene Sardellitti Artificial Intelligence Laboratory Stanford University
Transcript of Human Friendly Robot Design and Control -...
Human Friendly Robot Design and Control
Dongjun Shin, Irene SardellittiArtificial Intelligence Laboratory
Stanford University
High Performance Robots
High stiffness High torque actuation
UNSAFE
For high bandwidth and high payload,
Stiff transmission Powerful motor / high gear reduction
Increased weight
High reflected inertia
High backdrive friction
Safety Robots
High compliance Light Structure / Drivetrain
Low Performance
For low impedance output and low reflected inertia,
Elastic components Limit power and low gear reduction
Low control bandwidthLow payload
Performance vs. Safety
SEA (MIT) PaCMMA (MIT)DLRIII (DLR)
Performance Safety
DM2 (Stanford)
Performance and SafetyDesign for performanceControl for safety
Design for safetyControl for performance
INTRINSICALLY safe.
•Rigid link / joint
•Active control (sensors and regulation)
Beyond the control bandwidth
User’s mistake
•Mechanical (passive) compliance
•Control for compensation
Failure
Misuse
Series Elastic Actuator (MIT)PaCMMA (MIT)DLRIII (DLR)
NOT intrinsically safe.
New Design Approach
Pneumatic Artificial Muscle• High power-to-weight ratio • Inherent compliance
Bone-Inspired Robotic Link• Power source Integration• Rapid Prototype w/ Glass-filled Nylon
Compact Pressure Regulator• Integration • Combination of solenoid valves
Bone-Inspired Robotic Link
Structure- Marrow Cavity- Thick head / Thin shaft Integration- Blood vessel- Tendon connection
http://www.botany.uwc.ac.za/sci_ed/grade10/mammal/bone.htm
Structure- Cavity as air tunnel / reservoir - Thick head, thin shaftIntegration- Motor slot / Air distributing system - Drive pulleyManufacturing - Selective Laser Sintering (SLS)
Compact Pressure Regulator
Commercial Regulator- Bulky size- Heavy weight- Expensive- Asymmetric flow rate
Compact Pressure Regulator- Small size- Low weight- Cost effective- Less asymmetric flow rate
Stanford Safety Robot(S2ρ)
Pulley Radius Max Torque1 Range
6.096N·m 57.869°
Elbow 0.0203m 4.064N·m 86.803°
0.0305mShoulder
Gear Ratio Max Cont. Torque2
28 0.963N·m
Elbow 10.8 0.372N·m
Shoulder
Length Weight Inertia (Izz)
1.024kg 0.253kg·m2
Elbow 0.289m 0.847kg 0.026kg·m2
0.340mShoulder
Max torque1 by pneumatic muscle
Max torque2 by electrical motor
Macro actuation: low frequency high torque generation
Mini actuation: high frequency low torque generation
+
-
++
τm
τMτd τout
GM
Gm
Torq
ue M
agni
tudeτ d
Frequency
Macro Mini Control Strategy
+-
++
GM
Gm
τm
τMτd τout
τd
GM
Gm(1- GM )
τout+
+
c
cM s
Gω
ω+
=
1=mG
10-1
100
101
102
103
104
-14
-12
-10
-8
-6
-4
-2
0
2
4
6
Frequency [ rad/sec ]
Mag
nitu
de
G M
G m(1-GM)
DM 2
Macro Mini Control Strategy
Experimental Results: Tracking
Hz1 Hz3
0 0.5 1 1.5 2 2.5
-0.1
-0.05
0
0.05
0.1
0.15
Time [ sec ]
Join
t Pos
ition
[ ra
d ]
θd es
M acro
DM 2
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
-0.1
-0.05
0
0.05
0.1
0.15
Time [ sec ]
Join
t Pos
ition
[ ra
d ]
θd es
M acro
DM 2
GM
Gm(1- GM )
τd τout+
+Glink
+-
θdes θjGC
Safety Results: Effective Inertia
impactu
S2p
Effective Mass: 1.4Kg
MSI: 2.8
DM2
Effective Mass: 3.5Kg
MSI: 8.7
PUMA560
Effective Mass: 25Kg
MSI: 30
Limited contraction ratio
Messy electronic wires
Weak point at neck
Selective Laser Sintering
Low flow rate Slow response time
Multi muscles in parallel
Embedded wire duct
Reinforced structure
Shape Deposition Manufacturing
Proportional ValveEnhanced ControllerIntegrated Manifold
New Approach
New Stanford Safety Robot Link
New Stanford Safety Robot Link
Regulator
