Help with a project: black dots detector robot

[keytoe]

Hello all,

I am currently doing my final year project where I need to develop a robot that could detect back dots on a floor in a predefined area & able to avoid them. This is actually a prototype of a mine detecting robot which the black dots represent buried land mines. I have made some brainstorming & research about ideas for this project but not much info gained (maybe due to lack of researching skills). By the way, I have also came up with some ideas which would narrow down the details of the project.

I decided to use a micromouse-like robot as the body where I don't need to worry so much about the hardware parts (wheels,motor). It will be powered by batteries (6V or 9V) depends on space & power consumption. I am thinking of using IR sensor to detect the black dots & proximity sensors (IR or ultrasonic) to detect the edge of the area (wall).

The project is a microcontroller based & I think to use PIC 16F887A with programming in C language. The idea is to make the robot able to scan for black dots in the predefined area row-by-row starting from 1 of the area's corners. When a dot is spotted, the robot will avoid it & able to find a way to continue scanning the same row without entering the unscanned area (at the same time avoiding more detected dots).

Apart from that, robot should also be able to send the info to a PC through a medium (serial connection/maybe wireless) in order to map the location of dots (relative to the area) on the screen by using a software. I still haven't any idea of suitable software for this feature.

That's a brief description about my project & I hope that would be enough to give an overall picture. These are only my initial ideas based on the project objectives. How do you think about it & is it feasible? Any ideas or comments about implementing the features & my current preferences are most welcomed & appreciated.

Thank you.

 

[ronv]

To me the hardest part will be the map. Knowing where he is at all the time may be tough. Encoders on the wheels?

 

[damkia]

To maintain a bit of reality into the system you would be better off using some mapping software and enhanced GPS rather than encoders. The realtime stated use of this project will result in traversing across dirt and slippage in the dirt will render any wheel-based mapping encoder near to useless. There are considerable distances involved in the rotation of small wheels so cumulative errors would definitely be an issue.

Any further info on the detection of the mines in a physical sense (ie using a sweeping arm from the robot)? This will pretty much dictate which way to approach the detection of your dark spots, Simple focused IR detector should be all that's necessary to pick up the temperature difference in a proof of concept test. Perhaps go for FLIR camera, which in itself may be a diagnostic tool to measure the temp diff in the earth surrounding the mainly metallic (warmer?) mine in real life.

 

[FreeRideSkier]

I have just finished a line following robot which follows a Black line using a webcam. This could easily be reprogrammed to avoid Black instead.

I used FlowStone DSP to program it, there is a webcam module and a colour detect module!

Let me know if you need any help?

 

[keytoe]

Thanks all for your opinions.
Is it possible to use IR LEDs to detect the black dots instead of using camera?Bcause I'm trying to avoid the complexity in image processing techniques due to time constraint & limited budget.
As for the navigation,how about using the compass module?I'm not familiar with this one but just came across it while making some research.Please let me know if anybody think it is worth included in the robot navigation system.
For the edge (wall) detection,which sensor is better/easier to be used?(IR ranger or ultrasonic)

Thanks.

 

[cr0sh]

How big are the "dots"? You could (in theory) create a very low-res "eye" using a bunch of phototransistors in a matrix (say 8x8, or 64 phototransistors), and row/column scan them (very similar to row/column scanning an LED array). Focus an image on the array using a lens. You might even be able to figure out a way to do greyscale measurements in a fashion (you'd need some tweaks to the circuit). Your "dots", depending on their size, would show up as crude circles in the array.

Another possibility (which would probably be simpler and cheaper to implement) would be to use the camera device from an optical mouse; you would have to come up with your own optics system again, and used in this way (raw image dumping), such devices are pretty slow (1-3 frames per second) - but they might work ok for your application. Plenty of articles out there on how to use such devices with microcontrollers and such.

If you aren't going to use GPS, and are going for strict dead-reckoning using wheel encoders (note that such a system is very, very inaccurate), adding a compass module can only help. I would seriously rethink about adding GPS, though.

Finally - for wall/edge detection, I would use a combination of sensors, but at minimum, IR or Ultrasonic + physical feeler switches. IR is ok for wall/edge surfaces that will reflect IR light; should the edge/wall be a flat black color, it will probably fail. Ultrasonics are good when the surface to be detected is a fairly solid surface capable of reflecting an ultrasonic signal; hard and flat surfaces work best - a fluffy pillow (or an ornate or rought wall surface) less so...