Understanding SE(3) & Angular Velocity in Robotics: Kinematics & Rigid Body Motion - Prof., Study notes of Robotics

A lecture note from rpi ecse/csci 4480 robotics i, focusing on differential kinematics and rigid body motion in the context of se(3) and angular velocity. The lecture covers the exponential formula for rotation representation, the relationship between angular velocity and rotation, and the differentiation of vectors and transforms. It also discusses the representation jacobian and singularities in the context of unit quaternions.

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Robotics & Automation
Lecture 05
Differential Kinematics and Rigid Body Motion SE(3)
John T. Wen
September 8, 2008
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Download Understanding SE(3) & Angular Velocity in Robotics: Kinematics & Rigid Body Motion - Prof. and more Study notes Robotics in PDF only on Docsity!

Robotics & Automation

Lecture

Differential Kinematics and Rigid Body Motion

SE

John T. Wen

September 8, 2008

RPI ECSE/CSCI 4480 Robotics I

Last Time

Matrix exponential representation of rotation:

Rot

k , (^) θ

) =

(^) e

kˆ θ .

p eters, Euler angles.Other representations: unit quaternion, vector quaternion, Euler-Rodrigues param-

is a representation of

SO

if

p

=

f (^) ( R )

is a

local

one-to-one and onto mapping

(i.e., every

R

corresponds to a unique

p

and every

p

corresponds to a unique

R

, in a

neighborhood). Locally, the mapping is therefore invertible,

R

f (^) −

1 ( p ) .

Today: differential kinematics, what if

R

is a time varying and we would like to

compute

R

(and

˙p )?

Copyrighted by John T. Wen

Page 1

RPI ECSE/CSCI 4480 Robotics I

Differentiation of

R

and Angular Velocity

Robotics literature:

R

ab

( ω b / a ) a R

ab

,

or just

R

ωˆ

R .

This is also sometimes written as

R

R

ω

) b .

Spacecraft literature:

R

ba

( ω a / b ) b R

ba

( ω b / a ) b R

ba

,

or just

R

(^) ˆω

R .

This is also sometimes written as

R

R

ω

) a , where

ω

) a

is the same

ω

as in the

The collection of skew symmetric matrices of the formrobotics literature.

ωˆ

for

ω

R

3

is called

so

(considered to be the “tangent” of

R

Copyrighted by John T. Wen

Page 3

RPI ECSE/CSCI 4480 Robotics I

Differentiation of vectors and transforms

˙v a

d ( R ab

v b )

dt

R

ab

v b (^) +

R

ab

(^) ˙v b

=

( ω b / a ) a v a

R

ab

(^) ˙v b

L ˙

a

d ( R ab

L b R ba

)

dt

( ω b / a ) a R

ab

L b R

ba

R

ab

L b R

ba

ω b / a ) a

R

ab

(^) L˙

b R ba

( ω b / a ) a L a

L

a ( ω b / a ) a +

R

ab

L˙ b R

ba

.

Copyrighted by John T. Wen

Page 4