7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 1/12

DIGITAL ENCODING

TRANSDUCERS

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 2/12

CHARACTERISTICS  Give output in Digital format

  Converts Linear or Rotary Motion into digital

format

  Known as digital Encoders ,linear digitisers  Shaft encoders or shaft digitisers

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 3/12

CLASSIFICATION  achometer ransducer

Single !utput Signal

Motion is only in one direction

"sed only for Measurement of Speed  #ncremental ransducer

hree !utput Signal

hird Signal provided for $ero reference

Loss of power can cause information loss  %&solute ransducer

Limited to measurement of single revolution

Loss of power does not cause information loss

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 4/12

CONSTRUCTION CONTACTING

TYPE  'rushes are placed

as sliding contact

  Sliding contacts

which come in

contact with

conducting area are

completed

  Sliding contact which

come in contact with

insulating area are

not completed

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 5/12

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 6/12

ADVANTAGES  #t is relatively ine(pensive

  %ny degree of desired accuracy

  )uite ade*uate for slow moving systems

  +ear of contactors and maintenance

  %m&iguity of LS' digit

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 7/12

MOIRE FRING METHOD  !ptical method of

amplifying

displacement and

uses two identicalgratings

  Gratings consist of

num&er of slits on

an opa*ue screen  he slits are

transparent

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 8/12

WORKING  Moving the grating

perpendicular to

reference grating

would move the

fringes  Movement of

fringes ,um&er of

fringes passing a point

can &e calculated  %ccuracy of -./010023

over large scale

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 9/12

SHAFT ENCODERS  Measurement of

angular position

  Disc is divided into

concentric circles  %lternate segment

of opa*ue or

transparent

  %ccuracy depends

of num&er of

trac4s

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 10/12

CONSTRUCTIONSector Contact 1 Contact 2 Contact An!"e

0 off off off 05 to 675

2 off off ! 675 to 805

9 off ! ! 805 to2:75

: off ! off  2:75 to2;05

6 ! ! off  2;05 to9975

7 ! ! ! 9975 to9<05

= ! off !9<05 to:275

< ! off off  :275 to:=05

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 11/12

INCREMENTAL  >rovides pulse

each time the

shaft rotates

7/24/2019 Lecture10 (1)

http://slidepdf.com/reader/full/lecture10-1 12/12

A#SOLUTE