Obstacle !

[watzmann]

Hi All ,

i have a 4 wheeled robot with Ultrasonic sensor 4 stocks .

my problem is :

suppose that all the 4 sensors for some reason couldn't detect an sepecific obstacle in front of it ..... so my robot will crash with this obstacle although the ultrasonic sensor cannot detect it .

how to solve this problem ..... i thought of using SPDT switches with the ultrasonic sensors.

do you have a better idea ?

 

[Nigel Goodwin]

You could use 'whiskers', like a cat, that operate small switches - it's a common solution on simple robots.

However, if your ultrasonics are that bad, perhaps you should try and get them working properly?.

 

[watzmann]

no they are not so bad , but it's just a case which may happen .....may be because of a very thin rod ...... any upnromal obstacle.

i don't know what is whisler's is , but i'll search on google about it .

 

[watzmann]

yes i got what you mean , but how to build them , i think they need a very sensitve switches

 

[ericgibbs]

yes i got what you mean , but how to build them , i think they need a very sensitve switches

'Whiskers' are springy wires, bit like the wire use in guitars or piano's.

You can make a simple switch, by bending a piece of wire in a loop, use a screwdriver as a former and wrap the wire round in a loop, say 4mm diameter.

Then get a straight piece of wire and pass it thru the loop, [not touching]

The straight piece is one side of your switch and the loop the other.

When the straight piece of wire hits an obstruction it bends/deflects and touches the loop, closing the 'switch'

Bend the straight piece of wire into a curve to suit your robot.

The problem with guitar/piano wire its hard to solder, you may have to use a mechanical screw connection.

 

[Krumlink]

Just have a SPDT Microswitch as an interrupt for the Ultrasonics. Easy.