# THE UNIVERSITY OF TEXAS PAN-AMERICAN

Mechanics

Oct 31, 2013 (4 years and 6 months ago)

104 views

THE UNIVERSITY OF TEXAS PAN
-
AMERICAN

COLLEGE OF ENGINEERING AND COMPUTER SCIENCE

DEPARTMENT OF MECHANICAL ENGINEERING

MECE 3380

KINEMATICS AND DYNAMICS OF MACHINES

FALL 2012

FOLDING TRIMARAN

PROJECT

FIRST & SECOND PART

PREPARED FOR:

R. A. FREEMAN

BY:

LUIS F. MARTINEZ

DUE DATE
:

O
CTOBER

4
th
, 2012

Problem Statement:

To design a human
-

powered folding trimaran using Kinematics and Dynamics of Machines.

Procedure Outline:

The two solutions presented were obtained by using Co
-
Planar Motion Synthesis
and Angular
Coordination
with the aid of two different software packages, Working Model 2D and
.

The arrival to the solutions is as follows:

I.

For Co
-
Planar Motion
Synthesis:

a)

The path of motion had to be set, first and last positions had to specifically be established before
attempting a solution in order for the motion to start and finish at the desired locations.

b)

The second or middle path position could be defined
as desired to be able to efficiently move the
arm by not allowing it to cause too much disturbance to the boat.

c)

For the first solution, coordinates for the motor were specified on the boat for the first link. The
pin connection for the second link was spec
ified along the arm.

d)

The pin for the first link on the boat and pin for the second link along the arm were the specified
coordinates for the second solution.

e)

Thus by u
sing Co
-
Planar Motion Synthesis, the coordinates for the rest of the pins, link lengths
w
ere obtained.

II.

For Angular Coordination:

a)

Using the solutions for Co
-
Planar Motion Synthesis,
the maximum and minimum angles of the

and

.

b)

Finding the maximum and minimum angles, allowed for an easier solution for the

position of the
crank, so it would not interfere with the spawn angle of the rocker.

c)

Significant attention had to be paid to the location of the crank, even when knowing the
maximum and minimum rocker angles, because placing the crank too close to any of
the pins
would create an abnormality making the links of the crank to be of length 0.

d)

Thus by using

Angular Coordination, the position of the crank and the link lengths were obtained.

Figure 1.
CMS
Solution 1 in Position 1
.

Figure 2. CMS Solution

1 in Position 2.

Figure 3. CMS Solution 1 in Position 3.

Figure 4. CMS Solution 2 in Position 1.

Figure 5. CMS Solution 2 in Position 2.

Figure 6.CMS Solution 2 in Position 3.

The FPS selection and the pre
-
specified design parameter selections

wer
e chosen in order for the system
to do what it was required by the folding trimaran. Also, during the value selection, close attention was
given for the solution to be allocated around an optimal area in order for the system to have the less
interference w
ith the user and the boat.

Figure 7. Angular Coordination Solution 1 in Position 1.

Figure 8. Angular Coordination Solution 1 in Position 2.

Figure 9. Angular Coordination Solution 1 in Position 3.

Figure 10. Angular Coordination Solution 2 in
Position 1.

Figure 11. Angular Coordination Solution 2 in Position 2.

Figure 12. Angular Coordination Solution 2 in Position 3.

The Angular Coordination of the solution was created, as stated before, from building first a Co
-
Planar
Motion Synthesis system as adding to that a crank to one of the links. The addition of the crank not only
improves a smoother motion, but it also allows

for a continuous displacement of the folding trimaran,
thus a non
-
stop movement between all its predetermined positions.

Table 1 CMS Specified Parameters

Solution
Number

1

(m)

1

(m)

1

(deg)

u
A

(m)

v
A

(m)

u
B

(m)

v
B

(m)

1

-
6

1.7

35

3.216

1.213

3.8

1.4

2

-
6

1.7

35

3.6

1.25

3.966

1.47

Table 2 CMS Determined Parameters

Solution
Number

U
Oa
=X
B

(m)

V
Oa
=Y
B

(m)

U
Ob
=X
F

(m)

V
Ob
=Y
F

(m)

L
2
=O
A
A

(m)

L
3
=AB

(m)

L
4
=O
B
B

(m)

1

-
3.3001

3.1989

-
2.7883

3.9324

1.5406

0.6132

1.4179

2

-
2.8464

3.5326

-
2.4998

4.001

1.5581

0.3982

1.5463

Table 3 Angular Coordination Specified Parameters

Solution
Number

U
Oa

(m)

V
Oa

(m)

U
Oc

(m)

V
Oc

(m)

L
2
= O
C
C

(m)

2

(deg)

4

(deg)

OaA0

(deg)

OaA1

(deg)

1

-
3.3001

3.1989

-
2.8

3.5

0.25

0

0

164.472

83.156

2

-
2.8464

3.5326

-
3

3

0.2

0

0

175.834

94.579

Table 4 Angular Coordination Determined Parameters

Solution
Number

L
3
=CD

(m)

L
4
=O
A
D

(m)

OcC0

(deg)

OcC1

(deg)

1

0.7258

0.4776

232.1066

313.4226

2

0.9123

0.5764

20.6711

101.9261

Motion Characteristics
:

The motion characteristic
s

for the solutions presented fall into two categories. The first one is “path”
generation mechanism, for the CMS portion only. The folding trimaran

could be defined as a point that
follows the desired path, on other words, guidance. It can be observed as the folding trimaran follows the
predetermined positions.

For the Angular Coordination, we can observe a “function” generation mechanism, because i
t does not
create a path, but it incorporates the existing path into an infinite displacement, this is defined as the
control of the existing motion (position and orientation).