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Author Topic: HummBot  (Read 2393 times)

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Offline MegaTopic starter

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HummBot
« on: December 13, 2007, 12:17:03 PM »
Since I don't want to disturb Robonoob's thread, I started a new thread on the the HummBot discussion.
For more info on the HummBot, see http://megabotblog.blogspot.com.

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You may want to add another servo for scanning the Sharp sensors, because the car like steering is hard to maneuver out of corners, so you want to find bad spots before you get into them. And is also good for pathfinding.
Yes, I plan to do this. I would like to have a servo controled sharp inside the body of the HummBot. I'm slighly worried that the window frames of the body will interfere with the IR signals, so I'll have to position the servo/sensor carefully.

Next to that I will also need (sharp) sensors in the bumper of the HummBot to detect low objects.

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Take a look at Admin's wavefront algorithm to do it. You are on the right track.
Excellent! I will definitely experiment with this algorithm.

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Ohh, I almost forgot, you need encoders for pathfinding.
Yes, I have been thinking about this. But I have not figured out yet what would be the best way to add an encoder to by HummBot chassis:


There is no space near the wheels. One option might be to attach the encoder wheel to the drive shaft that attached the front wheels to the DC motor...
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Offline Ro-Bot-X

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Re: HummBot
« Reply #1 on: December 13, 2007, 12:37:00 PM »
Try to add one encoder directly to the back of the motor, if the shaft is coming out enough so you can superglue a disc made out of photo paper. Make a half of the disc black and install 2 Hamamatsu IR sensors so when one of them is in the middle of the white half of the disc, the other is exactly over the line between the white and black. This will give you a quadrature encoder, with many ticks per wheel rotation, so you will have a great resolution.

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Offline MegaTopic starter

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Re: HummBot
« Reply #2 on: December 13, 2007, 01:14:50 PM »
It will not be easy, since the remaining space around the shaft is limited, but it is definitely worth the try!
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Offline MegaTopic starter

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Re: HummBot
« Reply #3 on: December 15, 2007, 01:34:11 AM »
Where can I buy the IR sensor for my encoder?


Or would it be better to make this myself?
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Offline Ro-Bot-X

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Re: HummBot
« Reply #5 on: December 15, 2007, 08:27:39 AM »
I recomend using Hamamatsu photoreflector sensor, since it is small and has internal Shmidt trigger.
http://www.acroname.com/robotics/parts/R64-P5587.html
There is a schematic there too. Use 2 of these sensors mounted at 90 degrees for a quadrature encoder. Connect the output pin to the Interrupt pin 0 of the Arduino board and the second output pin to another digital pin. Check out this link for how to use them:
http://www.arduino.cc/playground/Main/RotaryEncoders
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Offline MegaTopic starter

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Re: HummBot
« Reply #6 on: December 15, 2007, 08:30:28 AM »
Thanks for the info. What is (the benefit of) an 'internal Shmidt trigger' ?
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Offline Admin

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Re: HummBot
« Reply #7 on: December 15, 2007, 10:42:28 AM »
Browse digikey and mouser for slot encoders (like in that pic of my encoder you posted). Those allow for the highest resolution.

 


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