ROBOT with IR Triangulation Method Type Sensor or Sonar?

[MAPUAN_ME]

good day everyone....
I am a filipino(are there anyone from Philippines here?)
Just new to this FORUM....Found about it while searching for microcontrollers and stuffs about robotics..

I am currently on the designing phase of my robot....

My Plan is to use it as a mixer of RICE being dried under the sun...
(A fork type wood attachment shall be place under or at the back part of it...)

its task are to run at straight directions and make U TURNS afterwards....
I have made it with 3 wheels... One in front and two at rear.....

My preliminary plans are to put a SERVO motor in front and a DC Motor at the Rear... Servo motor fro the steering and the DC motor for RUN/STOP of the robot...

During the U TURNS, i am thinking which sensor to use...
the SHARP IR Rangefinder or the SONAR Type sensor...
because the design of the robot is to make U TURNS once it senses any blockage like walls, vehicles parked etc....

which do you think shall be better to use?

thanks...

[paulstreats]

If its for use outdoors in the sun then a sonar is your best choice. The sharp i/r can suffer bad reading with lots of sunlight

[Rebelgium]

using a servo to turn the third wheel isn't a good idea. This will cause your robot to drive straight and just skid the real wheel when you want it to turn.
you should use two wheels in differential drive, and the third wheel as a caster.