Notes_09_02
1 of 17
Lagrangian Dynamics for Simple Pendulum
Y
gravity
a
m, JG
G
T
B
A
q
q=
X
Q=T
x a sin
y a cos
xG = a cos
yG = a sin
K 12 m x 2 y 2 12 J G 2 12 m a 2 2 sin 2 a 2 2 cos 2 12 J G 2
1
2
J
P = m g y = m g a sin
L KP
1
2
J
G
ma 2 2 m g a sin
d L L
Q
dt q q
d L L
T
dt
L
J G ma 2
d L
2
J G ma
dt
J
G
ma 2 m g a cos T
L
m g a cos
G
ma 2 2
Notes_09_02
2 of 17
Lagrangian Dynamics for Spring-Mass
x
x
k
m
q=x
q x
K 12 mx 2
Q = FEXT
P 12 kx 2
d L L
Q
dt q q
L
mx
x
mx kx FEXT
L=K-P=
1
2
mx 2 12 kx 2
d L L
FEXT
dt x x
d L
mx
dt x
L
kx
x
FEXT
Notes_09_02
3 of 17
Lagrangian Dynamics for Cylindrical Coordinate Manipulator
Y
Y
Y
r
r3
T
F
a
X
X
Both links
X
Link 2
Link 3
Main body link 2 - Shaft and end-effector link 3
Mass centers at a and r3 from waist rotation axis, a=constant, r3 = variable
Masses m2 and m3 - centroidal mass moments of inertia J2 and J3
CCW from positive x axis – a and r3 radial from rotation axis
T is rotary actuator torque of ground on body 2 about waist measured CCW positive
F is radial actuator force of body 2 on body 3 measured positive outward
Gravity g acts along negative y axis
q2 =
q3 = r
q 2
q 3 r3
Q3 = F
x 2 a sin
y 2 a cos
x2 = a cos
y2 = a sin
x 3 r3 cos r3 sin
y r sin r cos
x3 = r3 cos
y3 = r3 sin
Q2 = T
3
3
3
K 12 m 2 x 22 y 22 12 m 3 x 32 y 32 12 J 2 2 12 J 3 2
K 12 m 2 a 2 2 12 m 3 r32 2 12 m 3 r32 12 (J 2 J 3 ) 2
P = m2 y2 g + m3 y3 g
P = m2 g a sin + m3 g r3 sin
L=K-P
L 12 m 2 a 2 2 12 m 3 r32 2 12 m 3 r32 12 (J 2 J 3 ) 2 g(m 2 a m 3 r3 ) sin
Notes_09_02
d L L
Qi
dt q i q i
d L L
T
dt
d L L
F
dt r3 r3
L
m 2 a 2 m 3 r32 J 2 J 3
d L
2
2
m 2 a m 3 r3 J 2 J 3 2m 3 r3 r3
dt
L
gm 2 a m 3 r3 cos
T m 2 a 2 m 3 r32 J 2 J 3 2m 3 r3 r3 gm 2 a m 3 r3 cos
L
m 3 r3
r3
d L
m 3r3
dt r3
L
m 3 r3 2 m 3 g sin
r3
F m 3r3 m 3 r3 2 m 3 g sin
m 2 a 2 m 3 r32 J 2 J 3
0
0
T 2m 3 r3 r3 gm 2 a m 3 r3 cos
2
m 3 r3
F m 3 r3 m 3 g sin
4 of 17
Notes_09_02
5 of 17
Lagrangian Dynamics for Two Link Anthropomorphic Manipulator (Double
Pendulum)
Y
C
3
d2
m 3 , J3
a2
d3
a3
T3
m 2 , J2
2
T2
B
A
X
Two solid rigid bars with revolute joints A and B
Lengths d2 and d3 - mass centers at a2 and a3 from proximal ends
Masses m2 and m3 - centroidal mass moments of inertia J2 and J3
2 CCW from positive x axis
T2 is torque of ground on bar 2 about pin A, CCW positive
3 CCW from centerline of bar 2
T3 is torque of bar 2 on bar 3 about pin B, CCW positive
Gravity g acts along negative y axis
q 2 2
q 3 3
q 2 2
q 3 3
Q 2 T2
Q 3 T3
x 2 a 2 2 sin 2
y 2 a 2 2 cos 2
x 2 a 2 cos 2
y 2 a 2 sin 2
x 3 d 2 cos 2 a 3 cos 2 3
y 3 d 2 sin 2 a 3 sin 2 3
K 12 m 2 x 22 y 22 12 m 3 x 32 y 32 12 J 2 22 12 J 3 2 3
K 12 m 2 a 22 22 12 m 3 d 22 22 12 m 3 a 32 2 3
12 J 2 22 12 J 3 2 3
P m 2 y 2 g m3 y 3g
2
x 3 d 2 2 sin 2 a 3 2 3 sin 2 3
y 3 d 2 2 cos 2 a 3 2 3 cos 2 3
2
2
m 3 d 2 a 3 2 2 3 cos 3
Notes_09_02
6 of 17
P m 2 a 2 m 3 d 2 g sin 2 m 3 a 3 g sin 2 3
d L L
Qi
dt q i q i
L KP
d L L
T2
dt 2 2
L
m 2 a 22 m 3 d 22 J 2 2 m 3 a 32 J 3 2 3 m 3 d 2 a 3 2 2 3 cos 3
2
d L
dt 2
m 2 a 22 m 3 d 22 J 2 2 m 3 a 32 J 3 2 3
m 3 d 2 a 3 2 2 3 cos 3 m 3 d 2 a 3 2 2 3 32 sin 3
L
m 2 a 2 m 3 d 2 cos 2 g m 3 a 3 cos 2 3 g
2
T2 m 2 a 22 m 3 d 22 J 2 2 m 3 a 32 J 3 2 3
m 3 d 2 a 3 2 2 3 cos 3 m 3 d 2 a 3 2 2 3 32 sin 3
m 2 a 2 m 3 d 2 cos 2 g m 3 a 3 cos 2 3 g
T2 m 2 a 22 m 3 d 22 J 2 m 3 a 32 J 3 2m 3 d 2 a 3 cos 3 2
m a 2 J m d a cos
3
3
3
2
3
3
2
3
3
2m 3 d 2 a 3 sin 3 2 3
m d a sin 2
3
3
3
3
m 2 a 2 m 3 d 2 cos 2 g m 3 a 3 cos 2 3 g
d L L
T3
dt 3 3
L
m 3 a 32 J 3
3
2
d L
m 3 a 32 J 3
dt 3
3 m 3 d 2 a 3 2 cos 3
2
3 m 3 d 2 a 3 2 cos 3 m 3 d 2 a 3 2 3 sin 3
Notes_09_02
L
m 3 d 2 a 3 2 2 3 sin 3 m 3 a 3 cos 2 3 g
3
3 m 3 d 2 a 3 2 cos 3 m 3 d 2 a 3 2 3 sin 3
m 3 d 2 a 3 2 2 3 sin 3 m 3 a 3 cos 2 3 g
T3 m 3 a 32 J 3
2
T3 m 3 a 32 J 3 m 3 d 2 a 3 cos 3 2
m a 2 J
3
3
3
3
m 3 d 2 a 3 sin 3 22
m 3 a 3 cos 2 3 g
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
J B m 3 a 32 J 3
J A J B m 2 a 22 m 3 d 22 J 2 2m 3 d 2 a 3 cos 3
C J B m 3 d 2 a 3 cos 3
D m 3 d 2 a 3 sin 3
G 2 m 2 a 2 m 3 d 2 g cos 2
G 3 m 3 a 3 g cos ( 2 3 )
T2 J A 2 C 3 2D 2 3 D 32 G 2 G 3
T3 C 2 J B 3 D 22 G 3
2
T2 J A C
2
D 3 2D 2 3
G 2 G 3
2
T3 C J B
3
D 2
G3
1
2
2
J A C T2
D 3 2D 2 3
G 2 G 3
T3 D 2
C
J
B
2
3
G 3
7 of 17
Notes_09_02
8 of 17
Validated with harmonic drivers using Haug's inverse dynamics and then calculate torques per
above
-15
8
Planar two link manipulator
x 10
T2
T3
Validate torque equations [N.m]
6
4
2
0
-2
-4
-6
-8
0
0.2
0.4
0.6
0.8
1
1.2
Time [sec]
1.4
1.6
1.8
2
Notes_09_02
9 of 17
Lagrangian Dynamics for Three Link Anthropomorphic Manipulator
D
4
m 4 , J4
d4
a4
Y
T4
3
C
d2
m 3 , J3
T3
a2
m 2 , J2
T2
B
2
d3
a3
A
X
Three solid rigid bars with revolute joints A, B and C
Lengths d2 d3 d4 - mass centers at a2 a3 a4 from proximal ends
Masses m2 m3 m4 - centroidal mass moments of inertia J2 J3 J4
2 CCW from positive x axis
T2 is torque of ground on bar 2 about pin A, CCW positive
3 CCW from centerline of bar 2
T3 is torque of bar 2 on bar 3 about pin B, CCW positive
4 CCW from centerline of bar 3
T4 is torque of bar 3 on bar 4 about pin C, CCW positive
Gravity g acts along negative y axis
q 2 2
q 3 3
q 4 4
q 2 2
q 3 3
q
x 2 a 2 cos 2
y 2 a 2 sin 2
4
4
Q 2 T2
Q 3 T3
Q 4 T4
x 2 a 2 2 sin 2
y 2 a 2 2 cos 2
x 3 d 2 cos 2 a 3 cos 2 3
y 3 d 2 sin 2 a 3 sin 2 3
x 3 d 2 2 sin 2 a 3 2 3 sin 2 3
y 3 d 2 2 cos 2 a 3 2 3 cos 2 3
Notes_09_02
10 of 17
x 4 d 2 cos 2 d 3 cos 2 3 a 4 cos 2 3 4
x 4 d 2 2 sin 2 d 3 2 3 sin 2 3 a 4 2 3 4 sin 2 3 4
y 4 d 2 sin 2 d 3 sin 2 3 a 4 sin 2 3 4
y 4 d 2 2 cos 2 d 3 2 3 cos 2 3 a 4 2 3 4 cos 2 3 4
K 12 m 2 x 22 y 22 12 m 3 x 32 y 32 12 m 4 x 24 y 24
12 J 2 22 12 J 3 2 3
2
12 J 4 2 3
K 12 m 2 a 22 22 12 m 3 d 22 22 12 m 3 a 32 2 3
2
4
m 3 d 2 a 3 2 2 3 cos 3
2
12 m 4 d 22 22 12 m 4 d 32 2 3 12 m 4 a 24 2 3 4
m 4 d 2 d 3 2 2 3 cos 3 m 4 d 2 a 4 2 2 3 4 cos 3 4
m d a cos
4
3
4
2
3
2
12 J 2 22 12 J 3 2 3
2
2
3
4
2
4
12 J 4 2 3 4
2
P m 2 y 2 g m3 y 3g m 4 y 4 g
P m 2 a 2 m 3 d 2 m 4 d 2 g sin 2 m 3 a 3 m 4 d 3 g sin 2 3 m 4 a 4 g sin 2 3 4
d L L
Qi
dt q i q i
L KP
d L L
T2
dt 2 2
L
m 2 a 22 m 3 d 22 m 4 d 22 J 2 2 m 3 a 32 m 4 d 32 J 3 2 3 m 4 a 24 J 4 2 3 4
2
m 3 d 2 a 3 m 4 d 2 d 3 2 2 3 cos 3 m 4 d 2 a 4 2 2 3 4 cos 3 4
m d a 2 2 cos
4
d L
dt 2
3
4
2
3
4
4
m 2 a 22 m 3 d 22 m 4 d 22 J 2 2 m 3 a 32 m 4 d 32 J 3 2 3 m 4 a 24 J 4 2 3 4
m 3 d 2 a 3 m 4 d 2 d 3 2 2 3 cos 3 m 3 d 2 a 3 m 4 d 2 d 3 3 2 2 3 sin 3
m d a 2 cos m d a 2 sin
4
2
4
m 4 d 3a 4
2
2
2
3
4
3
4
4
2
4
3
4
2
3
2 3 4 cos 4 m 4 d 3 a 4 4 2 2 2 3 4 sin 4
4
3
4
Notes_09_02
11 of 17
L
m 2 a 2 m 3 d 2 m 4 d 2 g cos 2 m 3 a 3 m 4 d 3 g cos 2 3 m 4 a 4 g cos 2 3 4
2
3
T2 m 2 a 22 m 3 d 22 m 4 d 22 J 2 2 m 3 a 32 m 4 d 32 J 3 2 3 m 4 a 24 J 4 2 3 4
m 3 d 2 a 3 m 4 d 2 d 3 2 2 3 cos 3 m 3 d 2 a 3 m 4 d 2 d 3 3 2 2 3 sin 3
m d a 2 cos m d a 2 sin
4
2
4
m 4 d 3a 4
2
2
2
3
4
4
4
2
4
3
4
2
3
4
3
4
2 3 4 cos 4 m 4 d 3 a 4 4 2 2 2 3 4 sin 4
m 2 a 2 m 3 d 2 m 4 d 2 g cos 2 m 3 a 3 m 4 d 3 g cos 2 3 m 4 a 4 g cos 2 3 4
m a 2 m 3 d 22 m 3 a 32 m 4 d 22 m 4 d 32 m 4 a 24 J 2 J 3 J 4
2
T2 2 2
2m 3 d 2 a 3 m 4 d 2 d 3 cos 3 2m 4 d 2 a 4 cos 3 4 2m 4 d 3 a 4 cos 4
m 3 a 32 m 4 d 32 m 4 a 24 J 4 J 3
3
m
d
a
m
d
d
cos
m
d
a
cos
2
m
d
a
cos
3 2 3
4 2 3
3
4 2 4
3
4
4 3 4
4
m 4 a 24 J 4 m 4 d 2 a 4 cos 3 4 m 4 d 3 a 4 cos 4 4
m d a m d d sin m d a sin 2
3
2
3
4
2
3
3
4
2
4
3
m 4 d 2 a 4 sin 3 4 m 4 d 3 a 4 sin 4 24
4
3
2m 3 d 2 a 3 m 4 d 2 d 3 sin 3 m 4 d 2 a 4 sin 3 4 2 3
2m d a sin m d a sin
4
2
4
3
4
4
3
4
4
2
4
2m 4 d 2 a 4 sin 3 4 m 4 d 3 a 4 sin 4 3 4
m 2 a 2 m 3 d 2 m 4 d 2 g cos 2 m 3 a 3 m 4 d 3 g cos 2 3 m 4 a 4 g cos 2 3 4
T2 J A 2 A 3 B 4 2D E 2 3 2E F 2 4 2E F 3 4
D E 2 E F 2 G G G
3
4
2
3
4
d L L
T3
dt 3 3
L
m 3 a 32 m 4 d 32 J 3 2 3 m 4 a 24 J 4 2 3 4
3
m 3 d 2 a 3 m 4 d 2 d 3 2 cos 3 m 4 d 2 a 4 2 cos 3 4 m 4 d 3 a 4 2 2 2 3 4 cos 4
Notes_09_02
12 of 17
d L
m 3 a 32 m 4 d 32 J 3 2 3 m 4 a 24 J 4 2 3 4
dt 3
m 3 d 2 a 3 m 4 d 2 d 3 2 cos 3 m 3 d 2 a 3 m 4 d 2 d 3 2 3 sin 3
m d a cos m d a sin
4
2
4
2
3
4
4
2
4
2
3
4
3
4
m 4 d 3 a 4 2 2 2 3 4 cos 4 m 4 d 3 a 4 2 2 2 3 4 4 sin 4
L
m 3 d 2 a 3 2 2 3 sin 3 m 4 d 2 d 3 2 2 3 sin 3 m 4 d 2 a 4 2 2 3 4 sin 3 4
3
m 3 a 3 m 4 d 3 g cos 2 3 m 4 a 4 g cos 2 3 4
T3 m 3 a 32 m 4 d 32 J 3 2 3 m 4 a 24 J 4 2 3 4
m 3 d 2 a 3 m 4 d 2 d 3 2 cos 3 m 3 d 2 a 3 m 4 d 2 d 3 2 3 sin 3
m d a cos m d a sin
4
2
4
2
3
4
4
2
4
2
3
4
3
4
m 4 d 3 a 4 2 2 2 3 4 cos 4 m 4 d 3 a 4 2 2 2 3 4 4 sin 4
m 3 d 2 a 3 2 2 3 sin 3 m 4 d 2 d 3 2 2 3 sin 3 m 4 d 2 a 4 2 2 3 4 sin 3 4
m 3 a 3 m 4 d 3 g cos 2 3 m 4 a 4 g cos 2 3 4
m 3 a 32 m 4 d 32 m 4 a 24 J 3 J 4
2
T3
m
d
a
m
d
d
cos
m
d
a
cos
2
m
d
a
cos
3 2 3
4 2 3
3
4 2 4
3
4
4 3 4
4
m 3 a 32 m 4 d 32 m 4 a 24 J 3 J 4
3
2
m
d
a
cos
4 3 4
4
2
m 4 a 4 J 4 m 4 d 3 a 4 cos 4 4
2m d a sin
4
3
4
4
2
4
2m 4 d 3 a 4 sin 4 3 4
m 3 d 2 a 3 m 4 d 2 d 3 sin 3 22 m 4 d 2 a 4 sin 3 4 22
m d a sin 2
4
3
4
4
4
m 3 a 3 m 4 d 3 g cos 2 3 m 4 a 4 g cos 2 3 4
T3 A 2 J B 3 C 4 2F 2 4 2F 3 4 D E 22 F 24 G 3 G 4
d L L
T4
dt 4 4
L
m 4 a 24 J 4 2 3 4 m 4 d 2 a 4 2 cos 3 4 m 4 d 3 a 4 2 3 cos 4
4
Notes_09_02
d L
dt 4
m 4 a 24 J 4 2 3 4
m 4 d 2 a 4 2 cos 3 4 m 4 d 2 a 4 2
m d a cos m d a
4
3
4
2
3
13 of 17
4
4
3
4
4
4 sin 3 4
2 3 sin 4
3
L
m 4 d 2 a 4 2 2 3 4 sin 3 4 m 4 d 3 a 4 2 3 2 3 4 sin 4
4
m 4 a 4 g cos 2 3 4
T4 m 4 a 24 J 4 2 3 4
m 4 d 2 a 4 2 cos 3 4 m 4 d 2 a 4 2
m d a cos m d a
4 sin 3 4
4 3 4
2
3
4
4 3 4 4
2 3 sin 4
m 4 d 2 a 4 2 2 3 4 sin 3 4 m 4 d 3 a 4 2 3 2 3 4 sin 4
m 4 a 4 g cos 2 3 4
3
T4 m 4 a 24 J 4 m 4 d 2 a 4 cos 3 4 m 4 d 3 a 4 cos 4 2
m a 2 J m d a cos
m a
4
4
4
4
2
4
4
J 4 4
3
4
4
3
2m 4 d 3 a 4 sin 4 2 3
m 4 d 3 a 4 sin 4 m 4 d 2 a 4 sin 3 4 22
m d a sin 2
4
3
4
4
3
m 4 a 4 g cos 2 3 4
T4 B 2 C 3 J C 4 2F 2 3 E F 22 F 32 G 4
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
J C m 4 a 24 J 4
J B J C m 3 a 32 m 4 d 32 J 3 2m 4 d 3 a 4 cos 4
J A J B m 2 a 22 m 3 d 22 m 4 d 22 J 2 2m 3 d 2 a 3 m 4 d 2 d 3 cos 3 2m 4 d 2 a 4 cos 3 4
A J B m 3 d 2 a 3 m 4 d 2 d 3 cos 3 m 4 d 2 a 4 cos3 4
B J C m 4 d 3 a 4 cos 4 m 4 d 2 a 4 cos3 4
C J C m 4 d 3 a 4 cos 4
D m 3 d 2 a 3 m 4 d 2 d 3 sin 3
E m 4 d 2 a 4 sin 3 4
Notes_09_02
14 of 17
F m 4 d 3 a 4 sin 4
G 4 m 4 a 4 g cos 2 3 4
G 3 m 3 a 3 m 4 d 3 g cos 2 3
G 2 m 2 a 2 m 3 d 2 m 4 d 2 g cos 2
T2 J A 2 A 3 B 4 2D E 2 3 2E F 2 4 2E F 3 4
D E 2 E F 2 G G G
3
4
2
3
4
T3 A 2 J B 3 C 4 2F 2 4 2F 3 4 D E 22 F 24 G 3 G 4
T4 B 2 C 3 J C 4 2F 2 3 E F 22 F 32 G 4
B 2 2D E 2E F 2E F 2 3
J B C 3
0
2F
2F 2 4
3 4
C J C 4
2F
0
0
D E E F 22 G 2 G 3 G 4
0
D E
0
F 32 G 3 G 4
E F
24
F
0
G4
T2 J A
T3 A
T B
4
2 J A
3 A
B
4
A
A
JB
C
T2 2D E 2E F 2E F 2 3
T
0
2F
2F 2 4
1 3
B
T
2
F
0
0
3 4
4
C
22 G 2 G 3 G 4
0
D
E
E
F
J C
D E
0
F 32 G 3 G 4
E F
24
F
0
G4
Notes_09_02
15 of 17
Validated with harmonic drivers using Haug's inverse dynamics and then calculate torques per
above
-14
1.5
Planar three link manipulator
x 10
T2
T3
T4
Validate torque equations [N.m]
1
0.5
0
-0.5
-1
-1.5
0
0.2
0.4
0.6
0.8
1
1.2
Time [sec]
1.4
1.6
1.8
2
Notes_09_02
16 of 17
Linear State Space Model for Two Link Manipulator
y 1 2
y
{y } 2 3
y 3 2
y 4 3
y1 2
y
{y} 2 3
y 3 2
y 4 3
{y } f ({y})
{y } [A LINEAR ]{y}
linearize about nominal values of y
1
2
2
J A C T2
D 3 2D 2 3
G 2 G 3
2
3
C J B T3
D 2
G 3
J A J B m 2 a 22 m 3 d 22 J 2 2m 3 d 2 a 3 cos 3
J B m 3 a 32 J 3
C J B m 3 d 2 a 3 cos 3
D m 3 d 2 a 3 sin 3
G 2 m 2 a 2 m 3 d 2 g cos 2
G 3 m 3 a 3 g cos ( 2 3 )
J B C G
1
2
2
3
J A J B C C J A H
2
G T2 D 3 2D 2 3 G 2 G 3
2
H T3 D 2 G 3
T2 m 3 d 2 a 3 sin 3 32 2m 3 d 2 a 3 sin 3 2 3 m 2 a 2 m 3 d 2 g cos 2 m 3 a 3 g cos ( 2 3 )
T3 m 3 d 2 a 3 sin 3 22 m 3 a 3 g cos ( 2 3 )
2 2CC / 3 J B J A / 3 J B C G
C J H 3
2 2
3
JAJB C
A
1
2
JAJB C
0
C /
3
C / 3 G
3
J A / 3 H
J B C G / 2
1
2
J A J B C C J A H / 2
G / 3
H / 3
G / 2
H /
2
2
G / 3 3
0 2
3
Notes_09_02
17 of 17
G / 2 m 2 a 2 m 3 d 2 g sin 2 m 3 a 3 g sin( 2 3 )
G / 3 m 3 d 2 a 3 cos 3 32 2m 3 d 2 a 3 cos 3 2 3 m 3 a 3 g sin( 2 3 )
G / 2D
2
3
G / 3 2D 2 3
H / 2 m 3 a 3 g sin( 2 3 )
H / 3 m 3 d 2 a 3 cos 3 22 m 3 a 3 g sin( 2 3 )
H / 2D
2
2
H / 3 0
J A / 3 2D
C / 3 D
2
D
3 J A J B C 2
2
2J B J B C
2
J A J B 2J B C C
G
3
2 2 J A J B J A C C H
J A J B 2J B C C 2
J B C G / 2
1
2
J A J B C C J A H / 2
P23
D
2
P33 J A J B C 2
2
3
1
2
3 J A J B C 2
2J B J B C
2
J A J B 2J B C C
2
G / 3
H / 3
2
G / 3 3
0 2
3
G / 2
H / 2
G
22J A J B J A C C H
J B C G / 2
C J
A H / 2
A LINEAR
J B C G / 2
1
2
J A J B C C J A H / 2
J A J B 2J B C C 2
2
0 0 1 0
0 0 0 1
G / 3 G / 2
H / H /
3
G / 3 0 P23
0 0 P33
2
0 0 1 0
0 0 0 1
G / 3 G / 2
H / H /
3
2
G / 3 0 P23
0 0 P33
2
3
0 0 2
0 0 3
0 0
0 0
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