Robot IR object detection

[sofaman]

Hi,

I have one of these robot kits ( http://cpc.farnell.com/vortex/ksr4/esca ... dp/HK00968) that I bought many moons ago. It has 3 x IR transmitters and 1 x IR receiver. The robot moves forward until an object is in its way and then it will turn to the side and continue.

I have another robot that uses an RPi for all it controls. How easy would it be to have the same type of IR RX/TX work with the pi?

Any ideas??

I'm already using a L293D, MCP3008 and MCP23017 if that’s any help?

Thanks

Sofa

[Tarcas]

If the receiver is digital and works on 3.3v, it's probably trivial. If not, it may take some doing, but with the right design, the Pi can work with just about any sensor I've seen. Post a link to the datasheet of the sensor in question and we can offer advice. With vague info, all we can give back is vague answers.

[BMS Doug]

So the ksr4 (manufacturer Web page)uses 3 sensors arranged in an outward facing trident fashion, to detect when there is a wall in front, slightly to the left or slightly to the right.
This allows the ksr4 to see where the walls are and turn until there isn't a wall in front of it. This could easily be programmed on a pi, simply set a different signal for each transmitter so that the pi knows which one is bouncing off a surface.

A cheap set of IR transmitters and receivers won't cost much but also consider that a set of ultrasound sensors aren't much more.

[sofaman]

Hi,

Thanks for the replies and guidance.Now I know it's possible i'll give it a try and report back.

I have an ultrasonic sensor but its fairly bulky and has a limited field of vision! I have moving objects (cats) and a fairly wide robot. Thats why I thought the IR might be a better way to go?

Sofa

[sofaman]

Hi again..

I've 'borrowed' the 3x 5mm IR LEDs from the ksr4, I had a new receiver in my bits box but I don't know the model.

I've used this guide http://alexba.in/blog/2013/01/06/settin ... spberrypi/ and every thing works ok. Send, receive and turn a normal LED on/off using GPIO

This only allows me to use 1 x LED. Can you point me to guide or an idea as to the best way to create 3x LEDs using different signals.

Thanks

[BMS Doug]

Hi again..

I've 'borrowed' the 3x 5mm IR LEDs from the ksr4, I had a new receiver in my bits box but I don't know the model.

I've used this guide http://alexba.in/blog/2013/01/06/settin ... spberrypi/ and every thing works ok. Send, receive and turn a normal LED on/off using GPIO

This only allows me to use 1 x LED. Can you point me to guide or an idea as to the best way to create 3x LEDs using different signals.

Thanks

Glad to hear that you've been making progress.

Wire up the other 2 LED's to 2 other GPIO ports in the same way as the one that you have working, this will give you the three LED's needed, after this it's just programming.
Because you are looking for reflected IR levels from walls I expect the signal will need to be fairly simple, just on or off. So you'll need to program the Pi to transmit from the front LED, move forward until it gets a return on the receiver, stop. Check left and right (one at a time) and turn until there isn't a return on the receiver. The software part may need a bit of trial and error, once you have the 3 LED's and receiver working you can figure out what to do with the signals you are getting.

[sofaman]

Thanks BMS Doug,

I'm not with my Pi at the moment but the idea sounds great but I not sure if can add multiple GPIO_OUT_PIN in /etc/modules without it throwing up an error. I'll have a look tommorow and let you know.

Sofa

[BMS Doug]

Thanks BMS Doug,

I'm not with my Pi at the moment but the idea sounds great but I not sure if can add multiple GPIO_OUT_PIN in /etc/modules without it throwing up an error. I'll have a look tommorow and let you know.

Sofa

LIRC will work ok for testing your LED wiring setup but it's wasn't going to work for your escape robot program so at some point you were always going to have to create a program to generate and interpret the IR signals.

Here's a guide to programming in python to monitor for a changing input.