By:    Yusuf  Juan  &  Jeffer    

 

Leonardo da Vinci (1452-1519), Florentine artist, one of the great masters of the High Renaissance, celebrated as a painter, sculptor, architect, engineer, and scientist. His profound love of knowledge and research was the keynote of both his artistic and scientific endeavors. His innovations in the field of painting influenced the course of Italian art for more than a century after his death, and his scientific studies—particularly in the fields of anatomy, optics, and hydraulics—anticipated many of the developments of modern science. Microsoft  ®  Encarta  ®  2007.  ©  1993-­‐2006  Microsoft  Corporation.  All  rights  reserved.  

 

� Bridges  have  always  been  important  to  human  societies  as  a  means  to  cross  obstacles  such  as  rivers,  lakes,  or  abysses.  Stable  and  reliable  bridges  have  made  the  transportation  of  people  and  goods  possible,  establishing  long-­‐range  economical  connection  on  a  large  scale.  In  particular,  in  medieval  ages,  with  roads  and  rivers  providing  the  major  means  of  inland  transportation,  bridges  were  crucial.  

� Bridges  were  also  important  for  military  reasons.  They  could  form  a  bottleneck  that  hampered  enemy  troops  laden  with  heavy  artillery.  Bridges  were  of  paramount  importance  in  military  strategies  because  they  formed  a  point  of  defense  against  advancing  enemies,  as  well  as  represented  primary  targets  for  hose  very  adversaries.  

� Leonardo  drew  the  revolting  bridge  in  Milan  in  the  1580s,  and  the  drawing  is  today  contained  in  the  Codex  Atlanticus.  In  his  letter  t  Duke  Ludovico,  he  talks  of  “plans  for  very  light  yet  stable  bridge.”  

�  Figure  1-­‐1,  Leonardo’s  drawing  of  the  Revolting  bridge  

� In  his  design  of  the  revolting  bridge,  Leonardo  relies  on  an  antique  pretext  but  solves  the  problem  of  defending  the  structure  against  the  peril  of  enemies  in  a  fancy  way:  with  hostile  troops  advancing,  the  bridge  could  swing  around  a  pylon,  separating  it  from  the  shore.  The  enemy  could  then  no  longer  cross  the  river.  Simple,  but  completely  efficient.    

� Generally  speaking,  building  a  bridge  with  LEGO  is  not  the  most  complex  thing  in  the  world,  with  Leonardo’s  revolting  bridge,  however,  the  fulcrum  it  swings  around  poses  a  particular  challenge.  The  fulcrum  is  the  only  point  from  which  the  whole  structure  is  suspended.  This  means  everything  must  be  in  balance  and  stable  while  allowing  for  movement.  

� For  the  implementation  of  the  fulcrum  with  LEGO,  we  use  a  turntable  that  is  fixed  at  base  plate.  This  provides  both  the  required  stability  and  flexibility  needed  (Figure  1-­‐2).  

�  Figure  1-­‐3  shows  the  complete  revolting  bridge  robot.  Note  that  we  have  added  an  ultrasonic  sensor  to  Leonardo’s  original  design  on  the  far-­‐side  base  of  the  bride.  It  is  used  to  automatically  swing  the  bridge  when  the  sensor  spots  approaching  enemies  –  a  contraption  Leonardo  certainly  would  have  liked.  

Not  surprisingly,  the  general  flow  of  the  program  for  the  bridge  is  not  very  complex  (Figure  2-­‐1):  

� Wait  for  enemies  to  approach  the  structure  � Once  the  ultrasonic  sensor  has  detected  enemy  tanks,  moves  the  bridge  to  the  side  by  running  the  two  motors,  

� Wait  until  the  sensor  does  not  detect  anything  anymore.  

� Reset  the  bridge  to  its  original  state  

�  LEGO  MINDSTORMS  NXT  Software  �  Again,  we  start  with  a  loop  block  that  turns  forever  (Figure  2-­‐2)  

�  Now  we  wait  the  ultrasonic  sensor  detects  an  approaching  object.  Therefore,  we  insert  a  loop  block  again,  this  time  appropriately  configure  by  the  ultrasonic  sensor  (Figure  2-­‐3).  

�  Once  an  object  is  detected,  switch  the  bridge  away  by  running  the  two  motors  that  operate  the  winches.  For  synchronizing  these  two  motors,  use  a  Move  block  that  is  configured  to  run  them  in  opposite  directions  (Figure  2-­‐4).  

�  Now  that  the  bridge  is  switching  away,  wait  for  the  ultrasonic  sensor  to  detect  that  there  is  no  object,  which  means  that  the  possible  enemies  have  retreated.  As  before,  use  a  loop  block  configured  by  the  ultrasonic  sensor;  this  time,  the  stop  criterion  is  vice  versa  (Figure  2-­‐5).  

�  Once  no  object  can  be  detected  any  longer,  the  bridge  is  switched  back  by  an  appropriated  configured  Move  Block  (Figure  2-­‐6).  

�  And  we’re  done.  Figure  2-­‐7  shows  the  complete  NXT-­‐G  program.  

�  In  this  Leonardo  da  Vinci’s  revolting  bridge  project,  we  were  acquainted  with  another  type  of  NXT  sensor:  the  ultrasonic  sensor.  We  know  what  to  use  if  for,  how  to  use  it,  and  how  to  access  it  programmatically  in  NXT-­‐G  programming  language.  

�   Furthermore  and  most  importantly,  we  know  about  how  to  use  a  turntable  which  provides  both  the  required  stability  and  flexibility  needed  for  the  fulcrum  which  is  the  only  point  from  which  the  whole  structure  is  suspended.  We  also  learn  about  how  to  synchronizing  motors  and  have  seen  how  to  use  strings  to  transfer  motor  control  to  remote  hardware  components.  

� We  would  like  to  thank  Mr.  Haoken,  our  Science  Teacher  and  robotics  trainer,  for  his  guidance  in  hardware  and  software  challenges.    A  special  “Thank  You”  to  our  principal  Ms.  Ilbeth  for  her  kind  assistance.    Lastly,  we  would  like  to  thank  our  family  for  supporting  our  project!