Pictures and videos
Here are som pictures and videos of the robot:
The case
In order to validate if the idea about cross-cutting transitions (or global transitions) is better in terms of lower complexity in the state machine two master students where given the assignment to program a robot in ThingML. The robot is Arduino controlled, it have a mortor shield, two dc motors, three bumper sensors, three range sensors, a sound module, two speakers and a lot of LEDs.
The robot is suposed to go forward and adjust the speed depending on the range to the object in front. If it senses things from the sides it shall divert and go in an oposite direction. If the robot crash it should back up a little, find a new direction and make some sound to signal that it is not happy with crashing. The LEDs can be used as the students want.
The solutions
The students where given a precode with all the sensors and things implemented and what they had to do was to define the states, the actions in the states and the transitions. By combining these three elements the behaviour of the robot can be defined.
In the first part of the case study the two master students wrote their own implementation of the robot. The first students program had eigth states and 28 transitions, the source can be seen here:
Student 1 first program
import "Devices/RangeSensor2.thingml"
import "Devices/MotorShieldDFduino.thingml"
import "Devices/LightResitorArray.thingml"
import "Devices/somo-14d.thingml"
import "Devices/Bumper.thingml"
import "../../../core/timer.thingml"
import "Devices/LightChain.thingml"
thing BigRobot includes RangeMsgs, MotorShieldMsgs, TimerMsgs, LightArrayMsgs, SoundMsgs, BumperMsgs, LightChainMsgs {
required port Sounds{
sends r2d2
//sends chrash
//sends happy
//sends cranky
//sends set_sound //set sound with 1 2 3 or 4
//sends play_set_sound
sends stop_sound
}
required port Bumper {
receives bump
}
required port LightIn{
receives forward_dir
receives left_dir
receives right_dir
receives dont_know_dir
}
required port Motor {
sends forward_fast
//sends forward_medium
sends forward_slow
sends stop
//sends backwards_fast
sends backward_slow
sends right
sends left
//sends set_motors_speed
}
required port Timer{
sends timer_start
receives timer_timeout
}
required port Robot {
sends get_range
receives range
}
required port Light{
sends start_green
sends start_blue
sends stop_green
sends stop_blue
sends blink
//sends fade_blue
//sends fade_green
sends start_crazy
sends stop_crazy
}
property range : UInt16 = 0
statechart BigRobotImpl init idle {
state idle {
on entry do
Timer!timer_start(500)
Motor!stop()
Light!stop_crazy()
Sounds!stop_sound()
end
transition -> run
event Timer?timer_timeout
}
state run{
transition -> forward
event LightIn?forward_dir
transition-> stop
event LightIn?dont_know_dir
transition -> crashed
event Bumper?bump
transition -> left
event LightIn?left_dir
transition -> right
event LightIn?right_dir
}
state forward {
on entry do
if(range > 75) do
Motor!forward_fast()
Light!stop_green()
Light!stop_blue()
end
if(range > 25 and range < 75) do
Motor!forward_slow()
Light!stop_blue()
Light!start_green()
end
end
on exit do
Light!stop_green()
Light!stop_blue()
end
transition-> stop
event LightIn?forward_sir
guard range < 25
transition -> forward
event LightIn?forward_dir
transition-> stop
event LightIn?dont_know_dir
transition -> crashed
event Bumper?bump
transition -> left
event LightIn?left_dir
transition -> right
event LightIn?right_dir
}
state stop {
on entry do
Light!start_crazy()
Sounds!r2d2 ()
if(range < 15) do
Motor!stop()
end
end
on exit do
Light!stop_crazy()
end
transition -> forward
event LightIn?forward_dir
transition-> stop
event LightIn?dont_know_dir
transition -> crashed
event Bumper?bump
transition -> left
event LightIn?left_dir
transition -> right
event LightIn?right_dir
}
state left {
on entry do
Motor!left()
end
transition -> forward
event LightIn?forward_dir
transition-> stop
event LightIn?dont_know_dir
transition -> crashed
event Bumper?bump
transition -> left
event LightIn?left_dir
transition -> right
event LightIn?right_dir
}
state right {
on entry do
Motor!right()
end
transition -> forward
event LightIn?forward_dir
transition-> stop
event LightIn?dont_know_dir
transition -> crashed
event Bumper?bump
transition -> left
event LightIn?left_dir
transition -> right
event LightIn?right_dir
}
state crashed {
property time : UInt16 = 0
on entry do
time = 400
Timer!timer_start(time)
Light!start_crazy()
Motor!backward_slow()
end
internal event Timer?timer_timeout
guard time == 400
action do
time = 500
Timer!timer_start(time)
Motor!right()
end
transition -> run
event Timer?timer_timeout
guard time == 500
action do
Motor!stop()
Light!stop_crazy()
end
}
region Measure init MeasureDistance {
state MeasureDistance{
on entry do
Robot!get_range()
end
internal event m : Robot?range
action do
range = m.cm
Robot!get_range()
end
}
}
}
}
Student 2's program contained 9 states and 23 transitions and the source code looks like this:
Student 2's first program
import "Devices/RangeSensor2.thingml"
import "Devices/MotorShieldDFduino.thingml"
import "Devices/LightResitorArray.thingml"
import "Devices/somo-14d.thingml"
import "Devices/Bumper.thingml"
import "../../../core/timer.thingml"
import "Devices/LightChain.thingml"
thing BigRobot includes RangeMsgs, MotorShieldMsgs, TimerMsgs, LightArrayMsgs, SoundMsgs, BumperMsgs, LightChainMsgs {
required port Sounds{
//sends r2d2
sends chrash
sends happy
sends cranky
sends set_sound //set sound with 1 2 3 or 4
sends play_set_sound
sends stop_sound
}
required port Bumper {
receives bump
}
required port LightIn{
receives forward_dir
receives left_dir
receives right_dir
receives dont_know_dir
}
required port Motor {
sends forward_fast
sends forward_medium
sends forward_slow
sends stop
sends backwards_fast
sends backward_slow
sends right
sends left
// sends set_motors_speed
}
required port Timer{
sends timer_start
receives timer_timeout
}
required port Robot {
sends get_range
receives range
}
required port Light{
sends start_green
sends start_blue
sends stop_green
sends stop_blue
sends blink
sends fade_blue
sends fade_green
sends start_crazy
sends stop_crazy
}
property range : UInt16 = 0
property rand : UInt16 = 0
statechart BigRobotImpl init Stop {
state Start{
on entry do
Antenna!start () //er dette riktig?
Light!stop_crazy ()
Light!stop_blue ()
Light!start_green ()
Sounds!happy ()
end
transition -> Drivefast
event LightIn?forward_dir
guard range > 30
transition -> Driveslow
event LightIn?forward_dir
guard range < 30
transition -> Turnleft
event LightIn?left_dir
transition -> Turnright
event LightIn?right_dir
transition -> Stop
event LightIn?dont_know_dir
}
state Stop {
on entry do
Motor!stop ()
Timer!timer_start (1000)
Light!stop_green ()
Light!stop_blue ()
Light!stop_crazy ()
Sounds!cranky ()
end
transition -> Start
event Timer?timer_timeout
}
state Drivefast {
on entry
Motor!forward_fast ()
Light!stop_blue ()
Light!stop_crazy ()
Light!start_green ()
end
transition -> Driveslow
event LightIn?forward_dir
guard range < 30
transition -> Drivefast
event LightIn?forward_dir
transition -> Turnleft
event LightIn?left_dir
transition -> Turnright
event LightIn?right_dir
transition -> Stop
event LightIn?dont_know_dir
transition -> Chrash
event Bumper?bump
}
state Driveslow {
on entry do
Motor!forward_slow ()
Light!stop_blue ()
Light!stop_crazy ()
Light!start_green ()
end
transition -> Drivefast
event LightIn?forward_dir
guard range > 30
transition -> Backwards
event LightIn?forward_dir
guard range < 20
transition -> Driveslow
event LightIn?forward_dir
guard range < 30
transition -> Turnleft
event LightIn?left_dir
transition -> Turnright
event LightIn?right_dir
transition -> Stop
event LightIn?dont_know_diR
transition -> Chrash
event Bumper?bump
}
state Chrash {
on entry do
Timer!timer_start (500)
Motor!stop ()
Sounds!chrash ()
Light!stop_green ()
Light!stop_blue ()
Light!start_crazy ()
end
transition -> Backwards
event Timer?timer_timeout
}
state Backwards {
on entry do
Timer!timer_start (750)
Motor!backwards_fast ()
Light!stop_crazy ()
Light!stop_green ()
Light!start_blue ()
if (range < 20)
do
Motor!backward_slow ()
Light!fade_blue ()
end
rand = 'random(3);'
if(rand == 1)do
rand = 'random(2);'
if (rand == 0) do
Motor!left ()
end
if(rand == 1) do
Motor!right ()
end
end
end
transition -> Start
event Timer?timer_timeout
}
state Turnleft {
on entry do
Timer!timer_start (750)
Motor!left ()
Light!stop_crazy ()
Light!stop_green ()
Light!start_blue ()
Sounds!set_sound (1)
Sounds!play_set_sound ()
end
transition -> Start
event Timer?timer_timeout
}
state Turnright {
on entry do
Timer!timer_start (750)
Motor!right ()
Light!stop_crazy ()
Light!stop_green ()
Light!start_blue ()
Sounds!set_sound (2)
Sounds!play_set_sound ()
end
transition -> Start
event Timer?timer_timeout
}
region Measure init MeasureDistance {
state MeasureDistance{
on entry do
Robot!get_range()
end
internal event m : Robot?range
action do
range = m.cm
Robot!get_range()
end
}
}
}
}
Global transitions
After writing this code both students where introdused with the consept og global transitions, and they where asked to rewrite their programs in according to the new set of rules. Then both students could remove one state from their program, and they got a lot less transitions. Student 1 ended up with only seven transitions and student 2 ended up with eight transitions. This means that the cyclomatic complexity will be a lot lower for the new programs. Student 1's program can be viewed here:
Student 1's second program
import "Devices/RangeSensor2.thingml"
import "Devices/MotorShieldDFduino.thingml"
import "Devices/LightResitorArray.thingml"
import "Devices/somo-14d.thingml"
import "Devices/Bumper.thingml"
import "../../../core/timer.thingml"
import "Devices/LightChain.thingml"
thing BigRobot includes RangeMsgs, MotorShieldMsgs, TimerMsgs, LightArrayMsgs, SoundMsgs, BumperMsgs, LightChainMsgs {
required port Sounds {
sends r2d2
//sends chrash
//sends happy
//sends cranky
//sends set_sound //set sound with 1 2 3 or 4
//sends play_set_sound
sends stop_sound
}
required port Bumper {
receives bump
}
required port LightIn{
receives forward_dir
receives left_dir
receives right_dir
receives dont_know_dir
}
required port Motor {
sends forward_fast
//sends forward_medium
sends forward_slow
sends stop
//sends backwards_fast
sends backward_slow
sends right
sends left
//sends set_motors_speed
}
required port Timer{
sends timer_start
receives timer_timeout
}
required port Robot {
sends get_range
receives range
}
required port Light {
sends start_green
sends start_blue
sends stop_green
sends stop_blue
sends blink
//sends fade_blue
//sends fade_green
sends start_crazy
sends stop_crazy
}
property range : UInt16 = 0
statechart BigRobotImpl init idle {
transitions LightIn?forward_dir {
(range > 25) -> forward
-> stop
} crashed
transitions LightIn?dont_know_dir {
-> stop
} crashed
transitions LightIn?left_dir {
-> left
} crashed
transitions LightIn?right_dir {
-> right
} crashed
transitions Bumper?bump {
-> crashed
}
state idle {
on entry do
Motor!stop()
Light!stop_crazy()
Sounds!stop_sound()
end
}
state forward {
on entry do
if(range > 75) do
Motor!forward_fast()
Light!stop_green()
Light!stop_blue()
end
if(range > 25 and range < 75) do
Motor!forward_slow()
Light!stop_blue()
Light!start_green()
end
end
on exit do
Light!stop_green()
Light!stop_blue()
end
}
state stop {
on entry do
Light!start_crazy()
Sounds!r2d2 ()
if(range < 15) do
Motor!stop()
end
end
on exit do
Light!stop_crazy()
end
}
state left {
on entry do
Motor!left()
end
}
state right {
on entry do
Motor!right()
end
}
state crashed {
property time : UInt16 = 0
on entry do
time = 400
Timer!timer_start(time)
Light!start_crazy()
Motor!backward_slow()
end
internal event Timer?timer_timeout
guard time == 400
action do
time = 500
Timer!timer_start(time)
Motor!right()
end
transitions -> forward
event Timer?timer_timeout
guard time == 500
action do
Motor!stop()
Light!stop_crazy()
end
}
region Measure init MeasureDistance {
state MeasureDistance{
on entry do
Robot!get_range()
end
internal event m : Robot?range
action do
range = m.cm
Robot!get_range()
end
}
}
}
}
Student 2's improved program can be seen here:
Student 2's second program
import "Devices/RangeSensor2.thingml"
import "Devices/MotorShieldDFduino.thingml"
import "Devices/LightResitorArray.thingml"
import "Devices/somo-14d.thingml"
import "Devices/Bumper.thingml"
import "../../../core/timer.thingml"
import "Devices/LightChain.thingml"
thing BigRobot includes RangeMsgs, MotorShieldMsgs, TimerMsgs, LightArrayMsgs, SoundMsgs, BumperMsgs, LightChainMsgs {
required port Sounds{
//sends r2d2
sends chrash
sends happy
sends cranky
sends set_sound //set sound with 1 2 3 or 4
sends play_set_sound
sends stop_sound
}
required port Bumper {
receives bump
}
required port LightIn{
receives forward_dir
receives left_dir
receives right_dir
receives dont_know_dir
}
required port Motor {
sends forward_fast
sends forward_medium
sends forward_slow
sends stop
sends backwards_fast
sends backward_slow
sends right
sends left
// sends set_motors_speed
}
required port Timer{
sends timer_start
receives timer_timeout
}
required port Robot {
sends get_range
receives range
}
required port Light{
sends start_green
sends start_blue
sends stop_green
sends stop_blue
sends blink
sends fade_blue
sends fade_green
sends start_crazy
sends stop_crazy
}
property range : UInt16 = 0
property rand : UInt16 = 0
statechart BigRobotImpl init Stop {
transitions m : LightIn?forward_dir {
(range > 30) -> Drivefast
(range < 30) -> Driveslow
(range < 20) -> Backwards
} Chrash
transitions m : LightIn?left_dir {
-> Turnleft, Chrash
}
transitions m : LightIn?right_dir {
-> Turnright, Chrash
}
transitions m : LightIn?dont_know_dir {
-> Stop, Chrash
}
transitions m : Bumper?bump {
-> Chrash
}
state Stop {
on entry do
Motor!stop ()
Light!stop_green ()
Light!stop_blue ()
Light!stop_crazy ()
Sounds!cranky ()
end
}
state Drivefast {
on entry do
Motor!forward_fast ()
Light!stop_blue ()
Light!stop_crazy ()
Light!start_green ()
end
}
state Driveslow {
on entry do
Motor!forward_slow ()
Light!stop_blue ()
Light!stop_crazy ()
Light!start_green ()
end
}
state Chrash {
on entry do
Timer!timer_start (500)
Motor!stop ()
Sounds!chrash ()
Light!stop_green ()
Light!stop_blue ()
Light!start_crazy ()
end
transition -> Backwards
event Timer?timer_timeout
}
state Backwards {
on entry do
Motor!backwards_fast ()
Light!stop_crazy ()
Light!stop_green ()
Light!start_blue ()
if (range < 20) do
Motor!backward_slow ()
Light!fade_blue ()
end
rand = 'random(3);'
if(rand == 1) do
rand = 'random(2);'
if (rand == 0) do
Motor!left ()
end
if(rand == 1) do
Motor!right ()
end
end
end
}
state Turnleft {
on entry do
Motor!left ()
Light!stop_crazy ()
Light!stop_green ()
Light!start_blue ()
Sounds!set_sound (1)
Sounds!play_set_sound ()
end
}
state Turnright {
on entry do
Motor!right ()
Light!stop_crazy ()
Light!stop_green ()
Light!start_blue ()
Sounds!set_sound (2)
Sounds!play_set_sound ()
end
}
region Measure init MeasureDistance {
state MeasureDistance{
on entry do
Robot!get_range()
end
internal event m : Robot?range
action do
range = m.cm
Robot!get_range()
end
}
}
}
}
The linecount in the second program dropped with aproximately with 20% for both students. This means that there is less code to write while using global transitions, and therefore the programs can be written faster and is easier to maintian over time.
Source code !!!!
Here is the complete source code to run the program yourself Attach:bigrobotsource.zip
Figure O1 !!
Figure O2 !!
Figure O3 !!
Figure O4 !!
Figure O5 !!
Figure O6 !!
Figure O7 !!
