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1. MECH572AIntroduction To Robotics Lecture 5
2. Midterm Exam Date & Time: 19:00 - 21:00 ,Oct 25, 2004
Open Book
Chapters 2 & 3 of the text book
Note: Regular lecture will take place 18:00 –18:45 on Oct 25
3. Review New concepts
Twist of rigid body
Wrench (static analysis)
Instantaneous Screw of rigid-body motion
Define by direction + one point
Similarity between Velocity and Force/Moment Analysis
Screw-like force and moment property: Wrench axis
4. Review Acceleration Analysis
Fixed reference frame:
Moving Reference frame
Corilios term in the expression
Basics in Rigid Body Dynamics
Mass properties - Mass 1st & 2nd Moment; Parallel Axes Theorem;
Principle Axes/Moments (Eigenvectors/values)
Equation of Motion – Newton-Euler Equations
5. Robotic Kinematics Overview Basic Concepts
Robot Kinematics - Study robot motion without resorting to force and mass properties. Dealing with position, velocity and acceleration
Kinematic Chain - A set of rigid bodies connected by kinematic pairs
Kinematic Pairs
Upper Pair - Line/point contact (gear, cam-follower)
Lower Pair - Surface contact (revolute, prismatic)
6. Robotic Kinematics Overview Basic Concepts (cont'd)
Typical Lower Kinematic Pairs
Revolute (R) - 1 Dof (Rotation)
Prismatic (P) - 1 Dof (Translation)
Cylindrical (C) - 2 Dof (Rotation + Translation)
Helical (H) - 1 Dof (Coupled Rotation/Translation)
Planar (E) - 2 Dof (Translation in 2 directions)
Spherical (S) - 3 Dof (Rotation in 3 directions)
7. Robotic Kinematics Overview Basic Concepts (cont'd)
Two Basic Types of Kinematic Pairs - R & P
All six lower pairs can be produced from Revolute (R) and Prismatic (P)
8. Robot Kinematics Overview Robot Manipulators
Kinematic Chains : Link + Joint
Rigid bodies Kinematic Pairs
Basic Topologies of Kinematic Chain
9. Robot Kinematics Overview Basic Problems in Robotic Kinematics
Direct Kinematics
Inverse Kinematics
10. Denavit-Hartenberg Notation Purpose
To uniquely define architecture of robot manipulator (Kinematic chains)
Assumptions
Links : 0, 1, …, n - n+1 links
Pairs: 1, 2, … , n - n pairs
Frame Fi (Oi - Xi -Yi -Zi) is attached to (i-1)st frame (NOT ith frame)
11. Denavite-Hartenberg Notation Definition of Axes
Zi - Axes of the pair (Rotational/translational)
12. Denavite-Hartenberg Notation Definition of Axes (cont'd)
Xi - Common perpendicular to Zi+1 and Zi directed from Zi+1 to Zi (Follow right hand rule if intersect)
Yi = Zi ? Xi
13. DH Notation Joint Parameters & Joint Variables
ai - Distance between Zi and Zi+1
bi - Z-coordinate of Zi and Xi+1 intersection point (absolute value = distance between Xi and Xi+1 )
?i - Angle between Zi and Zi+1 along +Xi+1 (R.H.R)
?i - Angle between Xi and Xi+1 along +Zi (R.H.R)
Joint Variables
?i - R joint
bi - P joint
14. DH Notation Summary
15. DH Notation Summary – Prismatic joint
16. DH Notation Example - PUMA
17. DH Notation Example - PUMA
18. DH Notation Example – PUMA
DH Parameters of PUMA Robot
19. DH Notation Example - Stanford Arm
20. DH Notation Example - Stanford Arm
21. DH Notation Example - Stanford Arm (cont'd)
DH Parameters of Stanford Arm
22. DH Notation Summary
23. DH Notation Relative Orientation and Position Analysis
Orientation
24. DH Notation Relative Orientation and Position Analysis
Orientation (cont'd)
(Xi, Yi, Zi) (Xi', Yi', Zi')
(Xi', Yi', Zi') (Xi+1, Yi+1, Zi+1)
25. DH Notation Relative Orientation and Position Analysis
Orientation (cont'd)
26. DH Notation Relative Orientation and Position Analysis
Position
To find the position vector ai in Fi frame (position vector connecting Oi to Oi+1
27. DH Notation Relative Orientation and Position Analysis
Position
Observation:
28. DH Notation Relative Orientation and Position Analysis
Summary
Orientation
Position
29. Direct Kinematics 6-R Serial Manipulator
Problem description:
Known ?1 … ?n, find Q and p in the base frame
30. Direct Kinematics 6-R Serial Manipulator
1. Orientation
With DH Parameter defined, Q1, … Q6 can be calculated.
31. Direct Kinematics 6-R Serial Manipulator
2. Position
3. Homogeneous form (position + orientation)
32. Direct Kinematics Some useful properties of Qi