theory of computation (fall 2014): line following automaton for junun mark iii robot

Theory of Computation

Line Following Automaton for

Junun Mark III Robot

Vladimir Kulyukin

http://www.vkedco.blogspot.com/

Outline

● Hardware & Software Details of Junun Mark III Robot● A Line Following Automaton for Mark III Junun Robot

Hardware & Software Details of Junun Mark III Robot

Follow Line Start to End

Line Following Problem

Follow Line & Avoid Obstacles

Line Following Problem

Junun Mark III Robot

This robot has the 16f84a chip. The chip runs programs written in 16f84a Assembler.

16f84a Assembler Sample Code

Spot1 equ H'30'Spot2 equ H'31'

movlw D'5'movwf Spot1movlw D'2'addwf Spot1,Wmovwf Spot2movlw D'3'subwf Spot2,Wmovwf Spot1clrwclrf Spot1clrf Spot2nopend

What Does This Program Do?

16f84a Assembler Execution

Spot1 Spot2 W

movlw D'5'

BEFORE:

AFTER:

Spot1 Spot2

5

W

16f84a Assembler Execution

5

Spot1 Spot2 W

movwf Spot1

BEFORE:

AFTER: 5

Spot1 Spot2

5

W

16f84a Assembler Execution

5 5

Spot1 Spot2 W

movlw D’2’

BEFORE:

AFTER: 5

Spot1 Spot2

2

W

16f84a Assembler Execution

5 2

Spot1 Spot2 W

addwf Spot1,W

BEFORE:

AFTER: 5

Spot1 Spot2

7

W

Example: 16f84a Assembler

5 7

Spot1 Spot2 W

movwf Spot2

BEFORE:

AFTER: 5

Spot1

7

Spot2

7

W

Example: 16f84a Assembler

5 7 7

Spot1 Spot2 W

movlw D’3’

BEFORE:

AFTER: 5

Spot1

7

Spot2

3

W

Example: 16f84a Assembler

5 7 3

Spot1 Spot2 W

subwf Spot2,W

BEFORE:

AFTER: 5

Spot1

7

Spot2

4

W

Example: 16f84a Assembler

5 7 4

Spot1 Spot2 W

movwf Spot1

BEFORE:

AFTER: 4

Spot1

7

Spot2

4

W

Example: 16f84a Assembler

4 7 4

Spot1 Spot2 W

clrw

BEFORE:

AFTER: 4

Spot1

7

Spot2

0

W

Example: 16f84a Assembler

4 7 0

Spot1 Spot2 W

clrf Spot1

BEFORE:

AFTER: 0

Spot1

7

Spot2

0

W

Example: 16f84a Assembler

0 7 0

Spot1 Spot2 W

clrf Spot2

BEFORE:

AFTER: 0

Spot1

0

Spot2

0

W

16f84a Assembler

● We could program Junun Mark III robots directly in 16f84a Assembler● The two well known problems of Assemblers are:

– Hard to debug– Hard to maintain

● That is why software developers seek higher level alternatives that can be compiled into the target assembly

● JAL is one higher level alternative for 16f84a Assembler

JAL Sample Code: Fibonaccifunction fib(byte in n) return byte is var byte fib_rslt = 0 if ( n == 0 | n == 1 ) then fib_rslt = 1 return fib_rslt else var byte temp = 0 var byte prev = 0 var byte curr = 1 var byte count = n while ( count != 0 ) loop temp = curr curr = prev + curr prev = temp count = count - 1 end loop

return currend ifend function

16f84a Assembler JAL

Spot1 equ H'30'Spot2 equ H'31'

movlw D'5'movwf Spot1movlw D'2'addwf Spot1,Wmovwf Spot2movlw D'3'subwf Spot2,Wmovwf Spot1clrwclrf Spot1clrf Spot2nopend

function fib(byte in n) return byte is var byte fib_rslt = 0 if ( n == 0 | n == 1 ) then fib_rslt = 1 return fib_rslt else var byte temp = 0 var byte prev = 0 var byte curr = 1 var byte count = n while ( count != 0 ) loop temp = curr curr = prev + curr prev = temp count = count - 1 end loop return currend ifend function

Line Following

How can we make Mark III follow

a black line on the floor?

Line Following

Left Sensor

Middle Sensor

Right Sensor

Left Sensor returns black_on_left when it detects blackness.Middle Sensor returns black_on_center when it detects blackness.Right Sensor returns black_on_right when it detects blackness.

Line Following

if ( black_on_center ) move_forward;

We assume that the robotstarts with the middle sensoraligned with the line. So, ifthe middle sensor detectsblackness, the robot movesforward.

LEFT CENTER RIGHT

Line Following

if ( black_on_left ) turn_left;

If the left sensor detectsblackness, the robot turnsleft to align the middlesensor with the line.

LEFT CENTER RIGHT

Line Following

if ( black_on_right ) turn_right; If the right sensor detects

blackness, the robot turnsright to align the middlesensor with the line.

LEFT CENTER RIGHT

An FA for Line Following

read_sensors

turn_left

black_on_left

move_completed

turn_right

black_on_rightmove_completed

move_forward

black_on_center/no_black

move_completed

Line Following in JAL

JAL Code: Required INCLUDEs

include 16f877_20include jlibinclude markiii

JAL Code: FOLLOW_LINEprocedure follow_line is

forever loop -- left line sensor f877_adc_8(0, 7, adc8bitL) -- center line sensor f877_adc_8(0 ,6 , adc8bitC) -- right line sensor f877_adc_8(0 ,5 , adc8bitR)

take_line_follow_action

end loop

end procedure

JAL Code: TAKE_LINE_FOLLOW_ACTION

procedure take_line_follow_action is if ( adc8bitL > 128 ) then turn_left(25) elsif ( adc8bitC > 128 ) then move_forward(1) elsif ( adc8bitR > 128 ) then turn_right(25) else turn_left(5) end if

end procedure

JAL Code: TURN_LEFT & TURN_RIGHT

procedure turn_left (byte in delay) is left_wheel(4) right_wheel(9) delay_1ms(delay) robot_stopend procedure

procedure turn_right (byte in delay) is left_wheel(9) right_wheel(4) delay_1ms(delay) robot_stopend procedure

JAL Code: TURN_LEFT & TURN_RIGHT

procedure move_forward(byte in delay) is left_wheel(7) right_wheel(7) delay_10ms(delay) robot_stopend procedure

References

● Mark III User Guide● Line Following Competition