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Topic: Need suggestions for a project (Read 1 time) previous topic - next topic

shiftazz

Hello, so I have to make an obstacle avoiding car for my robotics class. I'm thinking about using a servo and an ultrasonic sensor to detect obstacles. However, there is one problem. I need to use at least 3 sensors (of any kind) in this project and I can not think of anything where I could use more sensors. Do you have any suggestions?

Grumpy_Mike

You can use more than one distance sensor to get a better view of the obstacles. You can use IR distance sensor in addition to the ultrasonic one for better reliability. Also how about a micro switch whisker for detecting the width of an opening.

shiftazz

A question about the ultrasonic sensor. Is it true that it can miss thin objects ( such as chair's leg )? If that's the case, then I might get the IR sensor to avoid such problem.

Now, about the whiskers. Wouldn't they be kind of useless when using two distance sensors?

Grumpy_Mike

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Now, about the whiskers. Wouldn't they be kind of useless when using two distance sensors?
No. Not done much robotics have you. They can detect when a gap is not big enough even though a distance sensor might see right through the gap. The can also detect when you try an turn and you are too close to an object.

shiftazz

In this case, I'll definitely get whiskers and won't have to worry about missing parts. Pretty sure no one in my group is going to use them too, so I'll have something original. Thank you very much for your help.  ;)

shiftazz

One more problem, couldn't find any place to buy whiskers for arduino from. So I found this DIY guide. But I don't understand the leaf-spring switch part. What is it used for and could I replace it with anything else?

gpsmikey

A leaf spring is basically just a microswitch with an arm that sticks out (often with a roller or something on the end) that will trip the switch when it is pressed.  As far as "seeing" things with ultrasonics. while you can get a good reflection off a flat surface, if it is something with a pointed edge with the edge facing you, you probably will not get a good reflection (and you can bet they will have things in the test course that tend to confuse student robots  :)   )
mikey
-- you can't have too many gadgets or too much disk space !
old engineering saying: 1+1 = 3 for sufficiently large values of 1 or small values of 3

shiftazz

Can I use anything else instead of leaf spring to get the whiskers working?

INTP

Give the robot some leds that are light sensitive. Headlights that turn on when dark. Ldr is a simple "sensor"

Grumpy_Mike

One more problem, couldn't find any place to buy whiskers for arduino from.
There is nothing specific about the Arduino any whiskers switch will work with an Arduino.

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So I found this DIY guide. But I don't understand the leaf-spring switch part. What is it used for and could I replace it with anything else?
It is simpley a switch, you wire it up like you would any other push button. That is wire the switch between an Arduino input and ground and enable the internal pull up resistor.

SMM2

Could you also possibly use something like this:here

Or would this not work?
"Success is not built on success. It's built on failure. It's built on frustration. Sometimes its built on catastrophe."

Grumpy_Mike

Yes that would work but you need an analogue input and pull up resistor.

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