Draughts Sorter

[exartemarte]

A draughts sorter (there's useful!) constructed from fischertechnic parts, with a homebrew reflective IR sensor to detect and identify draughts, controlled by a Picaxe-18X on a Picaxe project board (lurking under the red platform at the left-hand side).



I've been buying fischertechnik bits on eBay, and I fancied building something with a conveyor belt.

There's a video of the thing in action here: http://www.youtube.com/watch?v=kxGT2cTRUIY

'Draughts Sorter
'DJW/exartemarte Jan 2010

'Constants

symbol min_red_level		= 50     'Lower threshhold of IR light reflected from red platform
symbol max_red_level		= 100    'Upper threshhold of IR light reflected from red platform
						   '(Reflected IR light is measured on platform at base of chute)
						   '(Below lower threshhold > black draught)
						   '(Above upper threshhold > white draught)
						   '(Within threshholds > no draught)

symbol black_delay		= 10	   'No of conveyor belt clicks before pushing black draught off belt
symbol white_delay		= 22	   'No of conveyor belt clicks before pushing white draught off belt

'Variables

symbol light_level		= b0	   'For ADC value (reflected light level) read from IR sensor
symbol conveyor_count		= b1	   'For counting conveyor belt clicks while draught is on belt

'I/O Assignments

symbol IR_sensor 			= 0      'Measures reflected IR to identify black/white/no draught
symbol belt_counter		= input1 'Microswitch clicked continuously as belt motor rotates
symbol draught_push_sw		= input2 'Limit switch for motor that pushes drafts onto belt
symbol black_push_sw		= input6 'Limit switch for motor that pushes draughts off belt into black box
symbol white_push_sw		= input7 'Limit switch for motor that pushes draughts off belt into white box
						   'Note: limit switches are off while pushing, on in rest position

symbol IR_led			= 0      'Illuminates draught platform at base of chute
symbol belt_motor			= 1      'Drives conveyor belt
symbol draught_push_motor	= 2      'Pushes draughts from base of chute onto conveyor belt
symbol black_push_motor		= 3      'Pushes draughts from conveyor belt into black draught box
symbol white_push_motor		= 4      'Pushes draughts from conveyor belt into white draught box




init:
	
	gosub initialise						'make sure push motors are zeroed and IR source is on
	
	
wait_for_draught:

	switch off belt_motor					'stop the conveyor while there are no draughts


check_draught_colour:
	
	readadc IR_sensor,light_level				  'get IR level reflected from platform at base of chute
	if light_level < min_red_level then black_draught 'if it's below red then it's a black draught
	if light_level > max_red_level then white_draught 'if it's above red then it's a white draught
	goto wait_for_draught					  'if it's red then there's no draught
	

black_draught:

	switch on belt_motor					'make sure the belt is moving
	gosub push_draught_onto_belt				'push the draught onto the belt
	conveyor_count = 0					'draught is now on belt
	do								'so zero the count
		gosub one_belt_count				'and count conveyor belt pulses
		loop until conveyor_count >= black_delay	'until they get to the required number
	gosub push_black_draught_off_belt			'then push draught off belt into box
	goto check_draught_colour				'all done, so go to check the next draught.

white_draught:

	switch on belt_motor					'make sure the belt is moving
	gosub push_draught_onto_belt				'push the draught onto the belt
	conveyor_count = 0					'draught is now on belt
	do								'so zero the count
		gosub one_belt_count				'and count conveyor belt pulses
		loop until conveyor_count >= white_delay	'until they get to the required number
	gosub push_white_draught_off_belt			'then push draught off belt into box
	goto check_draught_colour				'all done, so go to check the next draught.


one_belt_count:

	do
	loop until belt_counter is on		'wait until belt pulse switch goes on
	pause 10					'debounce
	do
	loop until belt_counter is off	'wait until belt pulse switch goes off again
	pause 10					'debounce
	conveyor_count = conveyor_count + 1	'then increment the count
	return					'and exit.
	

push_draught_onto_belt:

	switch on draught_push_motor		'start pushing the draught off the platform onto the belt
	pause 200					'let the push motor get past the limit switch
	do
	loop until draught_push_sw is on	'wait until the switch goes on again (= push completed)
	switch off draught_push_motor		'then switch off the motor
	return					'and exit.
	

push_black_draught_off_belt:

	switch on black_push_motor		'start the push motor
	pause 400					'wait until the motor gets past the limit switch
	do
	loop until black_push_sw is on	'wait until the push cycle is completed
	switch off black_push_motor		'then switch off the motor
	return					'and exit.


push_white_draught_off_belt:

	switch on white_push_motor		'start the push motor
	pause 400					'wait until the motor gets past the limit switch
	do
	loop until white_push_sw is on	'wait until the push cycle is completed
	switch off white_push_motor		'then switch off the motor
	return					'and exit.


initialise:

	'make sure push motors are zeroed and IR source is on
	do while draught_push_sw is off
		switch on draught_push_motor
		loop
	switch off draught_push_motor
	do while black_push_sw is off
		switch on black_push_motor
		loop
	switch off black_push_motor
	do while white_push_sw is off
		switch on white_push_motor
		loop
	switch off white_push_motor
	switch on IR_led
	return

[Andrew Cowan]

Vary neat and hypnotic!

Next step will be to get it multitasking - adding them to the belt continuously, and taking them off when they get to the right place. Maybe more than one PICAXE?

I love your 'pushing' mechanism!

Andrew

[eclectic]

What an excellent project.
And, an excellent website.

My congratulations.

e

[hippy]

Superb viewing. Excellent project.

[MPep]

I love it. Great project. Well done.

[falkon]

absolutely brilliant..... weldone

[danielsaul]

Really good project. Probably still quicker to sort that number by hand though, haha.
Get multitasking sorted and make the number it can manage more and it'll be even better!
Well done

[exartemarte]

Thanks.

As it happens, I'm just documenting this for my fledgling website and thinking about version 2. I don't envisage any hardware changes, so it won't handle any more draughts (getting draughts sorted was never really a serious requirement!), but the sensing will be improved, I hope - less susceptible to ambient light - and it should be able to deal with more than one draught on the belt at a time (that's the tricky bit).

Watch this space!