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page 720

allowing looser tolerances of parts involved, and allowing motions not normally considered. To help overcome the resolution problem there are a couple of tricks. When modelling in

three dimensions the surfaces may be multifaceted, and hard to calculate quickly. This aspect of calculation may be sped up by using simple approximating surfaces not near the start or stop point, where low resolution is acceptable. It is also possible to use gross motionapproximations when travelling through this space. Finally, if the path planner uses collision avoidance, errors in accuracy will be insignifigant, because the avoidance of objects may be greater than the resolution..

40.7 COMPARISONS

Now that the various methods and techniques have been introduced it is possible to discuss them in a general sense. A chart format has been chosen to present some of the known information. The information may be spotty in some cases where researches have not provided complete data. Also, because a chart is a rigid structure to present information of this sort, a small section is included with comments. This table should only be used as an overview, it is not complete, and it is very general.

page 721

Figure 7.1a A Comparative Chart of Path Planning Methods

 

 

 

 

Machine

 

Rotation

 

 

 

 

 

Solution

 

 

 

 

 

Method

 

Space

 

& Time

 

 

Setup

 

Optimize

 

Type

 

Comments Multilink

 

 

 

 

 

 

 

 

Cartesian

 

2D

 

PL/1

 

not

 

conv

 

Distan

 

searc

 

Goo

 

Not

 

Configuration

 

& 3D

 

on

 

inherent

 

ex

 

ce

 

h of

 

d for 2D

 

imple

 

Space

 

 

 

IBM370/

 

 

 

polygon

 

 

 

obstacle

 

mobile

 

mente

 

(Lozano-

 

 

 

16 time

 

 

 

s

 

 

 

corners

 

robots

 

d

 

Perez, 1979)

 

 

 

unknown

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2D

 

 

 

inher

 

 

 

Distan

 

Searc

 

Only

 

 

 

Generalized

 

 

 

not

 

ent

 

Conv

 

ces and

 

h of

 

good for

 

no

 

Cones

 

 

 

given

 

 

 

ex

 

avoidanc

 

midpoin

 

2D

 

 

 

(Brooks,

 

 

 

 

 

 

 

Polygon

 

e

 

ts

 

mobility

 

 

 

1983)

 

 

 

 

 

 

 

s

 

 

 

between

 

.

 

 

 

 

 

2D

 

 

 

 

 

 

 

 

 

obstacle

 

 

 

 

 

 

 

 

 

 

 

inher

 

 

 

 

 

s

 

 

 

yes.

 

 

 

 

 

2 to 5

 

ent

 

 

 

time

 

 

 

good

 

 

 

Joint

 

 

 

minute

 

 

 

Conv

 

 

 

Searc

 

for

 

 

 

Configuration

 

 

 

setup, 15

 

 

 

ex

 

 

 

h of

 

planar

 

 

 

Space

 

 

 

second

 

 

 

Polygon

 

 

 

joint

 

motion.

 

 

 

(Red, et.al.,

 

3D

 

solution

 

 

 

s and

 

 

 

Configu

 

 

 

 

 

1985)

 

 

 

on VAX

 

 

 

robot.

 

 

 

ration

 

 

 

No

 

 

 

 

 

11/780

 

not

 

 

 

avoida

 

Space

 

 

 

 

 

 

 

 

 

 

 

inherent

 

 

 

nce

 

 

 

Exce

 

 

 

 

 

3D

 

VAX

 

 

 

 

 

 

 

 

 

llent for

 

 

 

Spatial

 

 

 

11/750 1

 

 

 

Work

 

 

 

Searc

 

3D

 

yes

 

Planning Vision

 

 

 

to 20

 

 

 

cell

 

 

 

h of

 

mobile

 

 

 

Based

 

 

 

seconds

 

inher

 

views

 

veloci

 

Oct-

 

robot

 

 

 

(Wong, et al,

 

2D

 

 

 

ent

 

 

 

ties,

 

Trees

 

 

 

 

 

1986)

 

 

 

minut

 

 

 

 

 

avoidanc

 

 

 

off-

 

yes,

 

 

 

 

 

es on

 

 

 

unkn

 

e and

 

 

 

line

 

but

 

Velocity

 

 

 

microVA

 

 

 

own

 

joint

 

Opti

 

program

 

link

 

Optimization

 

 

 

X

 

inher

 

 

 

limits

 

mize

 

package

 

collisi

 

(Dubowsky

 

2.5

 

 

 

ent

 

 

 

time

 

path

 

availabl

 

ons

 

et al, 1986)

 

D

 

 

 

 

 

 

 

 

 

splines

 

e

 

ignore

 

 

 

 

 

minut

 

 

 

conv

 

 

 

 

 

mid-

 

d

 

 

 

 

 

e on

 

 

 

ex

 

 

 

 

 

research

 

 

 

Time

 

 

 

VAX 11/

 

 

 

polygon

 

 

 

Opti

 

results

 

yes

 

Collision

 

 

 

750

 

verti

 

s and

 

avoida

 

mize

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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