compliant parallel kinematic machines
TRANSCRIPT
Compliant Parallel Kinematic Machines Applying Distributed Compliance to PKMs for sub-micron
accuracy and durability.
Compliant Parallel Kinematic Machine A 3-D manipulator with sub-micron accuracy
Ultra-Precision Mobile Control Surface (platform) • Solid-state mechanism with no pivots
• No conventional pivots; hence no joint play
• No conventional flexures; hence no stress concentrations
• Employs large displacement compliant joints • Very high off-axis stiffness • Embedded sensors to directly read 3d positions and orientations
Existing Parallel Kinematic Machines
3 DoF CPKM
x
z
Compliant Parallel Kinematic Machine Design
Compliant Joints
Compliant Revolute Joint and Universal Joints Compliant Translational Joint
• Notch type Flexible Joint – Limited range of motion – Stress concentration – Axis drift
Compliant Parallel Kinematic Machine Design
CPKM Synthesis with Dual Vector
1. Mo&on Modeling – The required mo&on is represented in dual vector form: (Magnitude)
(Pitch){Direc&on +ε Posi&on}
– The mo&on is decomposed into single DoF to match with joints
2. Constraining Leg Design – The compliant joints are represented in dual vector:
(mo&on range)(1+ ε 0) {Direc&on +ε Posi&on} ⇒ CR Joint (mo&on range)(0+ ε 1) {Direc&on +ε Posi&on} ⇒ CT Joint
3. Ac&ve Leg Design – The generic ac&ve legs are added according to the required DoF – The legs should be linearly independent – Detail design of joints through kinema&c analysis
Compliant Parallel Kinematic Machine Design
Case #1: Design for DoF
The motion requirement is specified only by DoF
1. Select joints with corresponding dof by comparing pitches
2. Align the selected joints using dual-vectors
3. Add active legs
Compliant Parallel Kinematic Machine Design
Case #2: Design for Analytic Motion
X!
Y!
Z!
Ellipse Generating 3-DoF problem
Decomposed Motions
Compliant Parallel Kinematic Machine Design
Constraining Leg Design
1. Match Pitches
2. Locate with Line Vectors
Compliant Parallel Kinematic Machine Design
Active Leg Design
• Active Legs are generic: CU+2DoF Actuator+CU=6-DoF (1 active)
• The final dimensions of the joints are determined through kinematic analysis.
• The active legs are located so that all the legs are linearly independent.
Compliant Parallel Kinematic Machine Design
Summary of CPKM Design Example
• Generalized design method for parallel kinema&c machines – Constraining leg for arbitrary DoF – Building block approach using dual vector for kinema&c
analysis and synthesis – Forward kinema&cs of the Parallel Kinema&c Machines is
straight forward by embedding a sensor in the constraining leg
• High precision mechanism design with compliant joints – Large displacement compliant joints that eliminate the
problems of generic mechanical joints
Novel Devices and Ideas (with Northwest University)
Embedded Sensor with Compliant Joint
Artificial Muscle
Polymer
Composite
Conventionally assembled design versus a compliant system with an embedded actuator
A three-degree-of-freedom parallel kinematic platform comprising of highly accurate and precision zero-play compliant “joints” assembled with error-prone pneumatic actuators
Conceptual rendering of a single-piece multi-material, compliant gripper with embedded artificial muscle – an example of no-assembly, bio-inspired, compliant system
Compliant Parallel Kinematic Machine A 3-D manipulator with sub-micron accuracy
Ultra-Precision Mobile Control Surface (platform) • Solid-state mechanism with no pivots
• No conventional pivots; hence no joint play
• No conventional flexures; hence no stress concentrations
• Employs large displacement compliant joints • Very high off-axis stiffness • Embedded sensors to directly read 3d positions and orientations
Manipulating, pointing and tracking applications for Missile seekers
Adaptive Optics
x
z
Compliant Parallel Kinematic Machine Design
Compliant Joints
Compliant Revolute Joint and Universal Joints Compliant Translational Joint
• Notch type Flexible Joint – Limited range of motion – Stress concentration – Axis drift
2 Dof CPKM (Y.M. Moon & S, Kota 2001)"
Ultra-Precision Mobile Control Surface (platform) • Employs large displacement compliant joints • Very high off-axis stiffness • Embedded sensors to directly read
3d positions and orientations
Compliant Parallel Kinematic Machine A 3-D manipulator with sub-micron accuracy
Ultra-Precision Mobile Control Surface (platform) • Solid-state mechanism with no pivots
• No conventional pivots; hence no joint play
• No conventional flexures; hence no stress concentrations
• Employs large displacement compliant joints • Very high off-axis stiffness • Embedded sensors to directly read 3d positions and orientations
Manipulating, pointing and tracking applications for Missile seekers
Adaptive Optics
Compliant Parallel Kinematic Machine Design
3 DoF CPKM
Steel Construction