Hello, I am wondering if anyone has any personal preferance towards sensors for cliff detection. I am starting a new robot that needs this. Any suggestions?
Something that makes contact with the ground and detects when it is no longer making contact with the ground would work. It could also be out of sight. The only downside is if the sensor didnt report back fast enough to stop the motors it could go off the stairs.
The mini-sumo bot in JunkBots, BugBots, and Bots on Wheels has a kind of "drop switch" to detect the edge of the sumo ring. The switch is normally open, but when the bot reaches the edge of the table the feeler drops and closes the switch causing the bot to back and turn. Looks to me like you could make it out of a paper clip, some insulation and a bit of metal coat-hanger.
Thanks for all the great suggestions, But I am really looking for something that can be hidden away completely. So, I have a question: Could I put a sensor in the head to detect cliffs? I'm thinking no becuase it will be searching for objects and wont have much time to stare down.
Thanks, I will probably use something like that in the front of the head with a slight downward slant. Would that be enough? I could also program the head to move up and down every now and then....
Using a sensor to detect distance to the floor would also have a delay built in to it. Since it has to send a pulse and receive a pulse, then calulcate the distance and stop the motors, your bot may go down the stairs. Not to mention mounting it at an angle to the floor would give false readings.
I don't know what other sensors you'll uses but from my own experiments Frits's LDR sensor is good for at least 50mm-75mm(2-3 inches), more if high intensity LEDs are used and my IR sensors can work on at least 75mm(3 inches) depending on the LED, power level, duty cycle and sesitivity of the IR sensor. You can change the forward angle to suit how far ahead you want to detect a cliff. The down side to these two sensors is that floor colour could affect the results to some degree. Using micro switches or some other sensor that applies direct pressure to the ground may give you more precise readings.
Simply measure from the center of the table to the edge, subtract the length of your robot and tie the string to the back. Scheesh, you techie guys and your sensors!! --K.I.S.S.
@ Wed, 2008-12-17 00:47
Something that makes contact
Something that makes contact with the ground and detects when it is no longer making contact with the ground would work. It could also be out of sight. The only downside is if the sensor didnt report back fast enough to stop the motors it could go off the stairs.
@ Wed, 2008-12-17 11:13
The mini-sumo bot in
The mini-sumo bot in JunkBots, BugBots, and Bots on Wheels has a kind of "drop switch" to detect the edge of the sumo ring. The switch is normally open, but when the bot reaches the edge of the table the feeler drops and closes the switch causing the bot to back and turn. Looks to me like you could make it out of a paper clip, some insulation and a bit of metal coat-hanger.
Mike
@ Thu, 2008-12-18 03:08
sumo bot
parallax's sumo robot are using the QTI IR sensors
can be used to detect cliffs (but sensible to floor color), really small and easy to hide under any robot
I use it for cliff detection and "wheel encoding"
@ Wed, 2008-12-17 01:57
Ya, my robot will be fairly
@ Tue, 2008-12-16 23:57
Thanks for all the great
@ Wed, 2008-12-17 00:41
Depending how high above the
@ Wed, 2008-12-17 01:56
Thanks, I will probably use
@ Wed, 2008-12-17 16:02
Using a sensor to detect
@ Wed, 2008-12-17 14:58
I don't know what other
@ Tue, 2008-12-16 22:40
I would use string