Community Question

V1.1.2 available on page 3

Taking on board some of the comments made recently regarding autonomous roaming, plus a few improvements I wanted to make I have updated the Ping Roam script (which if I knew it would be so popular I would have made more of an effort the first time around).

I've done some quick testing with it however my testbot runs on 4 modified servos with wheels on which isn't the best method of driving it so it may still have some bugs in... that's where you come in :) Let me know if there are any bugs, anything that doesn't work quite like it should, any further improvements you want...

I did have a bug in the escape routine, which I think I have now solved. Where it has a loop in the routine to continue turning until the sensor reading is above the setpoint I think that was throwing off the return at the end of the routine, not returning to where it came from but returning to when it was told to loop. Solved with additional labels and it seems to be working now...

Changes
# Boxed In check added
# Escape from Boxed In added
# Avoidance of left/right/left/right loops
# Automatic calculation of sweep servo center position
# Tidied up code
# More comments added
# Almost completely made with labels and gotos

And, here is the code

Code:


# Ping Object Avoidance
# Using Ultra Sonic Ping Sensor on servo for avoidance
# Version 1.1.0


# Configuration Settings

# Adjust values below for port configuration
$pingport = D0 # Change for Ping Port
$echoport = D1 # Change for Echo Port
$sweepservo = D2 # Change for sweep servo port

# Adjust values below for movement control
$reverseturn = 1 # Reverse before turn? 0 = no, 1 = yes
$maxdistance = 30 # Change for maximum distance from object before avoiding in units
$boxedindistance = 20 # Change for maximum distance for boxed in detection
$turnamount = 500 # Change for how long to turn for in ms
$reverseamount = 500 # Change for how long to reverse for in ms (if applicable)
$movementspeed = 255 # Change for movement speed
$slowturn = 127 # Change for slow turn speed

# Adjust values below for sweep configuration
$sweepmin = 10 # Change for min limit
$sweepmax = 90 # Change for max limit
$sweepservodelay = 500 # Change for delay between sweep servo movements and readings

# Testing Options
$testmode = 0 # Change to 1 if testing without PING sensor



# Do not adjust these values
$sweepcenter = $sweepmin+$sweepmax
$sweepcenter = $sweepcenter/2
$sweepcenter = Round($sweepcenter,0)
$sweepprevious = $sweepmax # Do not change
$sweepcurrent = $sweepcenter # Do not change
$SweepErrorFlag = 0 # Do not change
$BoxedInErrorFlag = 0 # Do not change
$BoxedInRun = 0 # Do not change
$SweepCenterRun = 0 # Do not change
$EscapeRun = 0 # Do not change
$ScriptErrorFlag = 0 # Do not change
$isboxedin = 0 # Do not change
$penultimatemove = "none"
$lastmove = "none"



# ------- The Script --------

# Set the start point for any loops
:begin

# Center the sweep servo
Servo($sweepservo, $sweepcenter)

# Start moving forwards
FORWARD()

# Start the detection
Goto(detect) # This line is redundant



# Detection code

# Set a label for loops and gotos
:detect

# Use random numbers if in test mode
IF ($testmode=0)
$currentdistance = GetPing($pingport, $echoport)
ELSE
$currentdistance = GetRandom(0,255)
ENDIF

# Check the current distance against the max allowed distance
IF ($currentdistance <= $maxdistance)
# If the current distance is below the max distance start avoiding
GOTO(avoid)

# Set label for avoid return to avoid return errors
:avoidreturn
ENDIF

# Run the sweeping servo code
GOTO(sweep)

# Wait
SLEEP ($sweepservodelay)

# Loop back to the start of detection
GOTO(detect)



# Avoidance code

# Set a label for loops and gotos
:avoid

# First check if boxed in
Goto(boxedin)

# If the robot is boxed in run the escape code
IF ($isboxedin = 1)
Goto(escape)

# Avoid return error after escape loop by setting a label for a goto
:escapereturn
ENDIF

# Check to see if to reverse before turning
IF ($reverseturn = 1)
# If the option of reverse before turning is set reverse
Reverse($movementspeed,$reverseamount)
ENDIF

# Check the servo position

# Check if it's to the left
IF ($sweepcurrent = $sweepmin)
# If the servo is in the lowst position (left) move right
Goto(moveright)
# Continue moving forwards
FORWARD()

# Else check if it's to the right
ELSEIF ($sweepcurrent = $sweepmax)
# If the servo is in the highest position (right) move left
Goto(moveleft)
# Continue moving forwards
FORWARD()

# Else assume it's in the middle
ELSE
# If the servo is in the center position check which side is closest to the object and move the other way

# Move and check the left side
Servo($sweepservo,$sweepmin)
# Use random numbers if in test mode
IF ($testmode=0)
$pingmin = GetPing($pingport, $echoport)
ELSE
$pingmin = GetRandom(0,255)
ENDIF

# Wait
Sleep(400)

# Move and check the right side
Servo($sweepservo,$sweepmax)
# Use random numbers if in test mode
IF ($testmode=0)
$pingmax = GetPing($pingport, $echoport)
ELSE
$pingmax = GetRandom(0,255)
ENDIF

# Wait
Sleep(400)

# Move and check the center
Servo($sweepservo,$sweepcenter)
IF ($pingmin > $pingmax)
Goto(moveright)
FORWARD()
ELSE
Goto(moveleft)
FORWARD()
ENDIF
ENDIF

# Return to the main code
Goto(avoidreturn)



# The sweep code

# Set a label for loops and gotos
:sweep

# Move in the correct direction and store previous position

# Check what the current position is
# Check if left
IF ($sweepcurrent = $sweepmin)

# Save the current position as the previous
$sweepprevious = $sweepcurrent

# Move to the next position
Servo($sweepservo, $sweepcenter)

# Save the current position
$sweepcurrent = GetServo($sweepservo)

# Else check if its center and where it was before
# If it is center and was left before
ELSEIF ($sweepcurrent = $sweepcenter and $sweepprevious = $sweepmin)

# Save the current position as the previous
$sweepprevious = $sweepcurrent

# Move to the next position
Servo($sweepservo, $sweepmax)

# Save the current position
$sweepcurrent = GetServo($sweepservo)

# If it is center and was right before
ELSEIF ($sweepcurrent = $sweepcenter and $sweepprevious = $sweepmax)

# Save the current position as the previous
$sweepprevious = $sweepcurrent

# Move to the next position
Servo($sweepservo, $sweepmin)

# Save the current position
$sweepcurrent = GetServo($sweepservo)

# Else check if right
ELSEIF ($sweepcurrent = $sweepmax)

# Save the current position as the previous
$sweepprevious = $sweepcurrent

# Move to the next position
Servo($sweepservo, $sweepcenter)

# Save the current position
$sweepcurrent = GetServo($sweepservo)

# Else something has gone wrong
ELSE
# Set an error flag for debugging purposes
$SweepErrorFlag = 1
ENDIF

# Return back to the main script
Return()



# The sweep center code

# Set a label for loops and gotos
:sweepcenter

# Set a flag so we know it has run for debugging purposes
$SweepCenterRun = 1

# Move the servo to the left position
Servo($sweepservo,$sweepmin)

# Use random numbers if in test mode
IF ($testmode=0)
$pingmin = GetPing($pingport, $echoport)
ELSE
$pingmin = GetRandom(0,255)
ENDIF

# Wait
Sleep(200)

# Move the servo to the right
Servo($sweepservo,$sweepmax)

# Use random numbers if in test mode
IF ($testmode=0)
$pingmax = GetPing($pingport, $echoport)
ELSE
$pingmax = GetRandom(0,255)
ENDIF

# Wait
Sleep(200)

# Move the servo back to the center
Servo($sweepservo,$sweepcenter)

# Check which side has the closest object
# If the object to the left is further away than the object to the right
IF ($pingmin > $pingmax)

# Move to the right
RIGHT($movementspeed,$turnamount)

# Move forwards again
FORWARD()

# Else if the object to the right is further away than the object to the left
ELSEIF ($pingmin < $pingmax)

# Move to the left
LEFT($movementspeed,$turnamount)

# Move forwards again
FORWARD()

# Else they are both the same
ELSE

# So move left - this can be customised
LEFT($movementspeed,$turnamount)

# And move forwards again
FORWARD()
ENDIF

# Retyrn to the main code
Return()



# The boxed in code

# Set a label for loops and gotos
:boxedin

# Set a flag so we know it has run for debugging
$BoxedInRun = 1

# Get distance to the side
# Move the servo to the left
Servo($sweepservo,$sweepmin)

# Use random numbers if in test mode
IF ($testmode=0)
$side1scan = GetPing($pingport,$echoport)
ELSE
$side1scan = GetRandom(0,255)
ENDIF

# Get distance to the other side
# Move the servo to the right
Servo($sweepservo,$sweepmax)

# Use random numbers if in test mode
IF ($testmode=0)
$side2scan = GetPing($pingport,$echoport)
ELSE
$side2scan = GetRandom(0,255)
ENDIF

# Get distance to the front
# Move the servo to the center
Servo($sweepservo,$sweepcenter)

# Use random numbers if in test mode
IF ($testmode=0)
$centerscan = GetPing($pingport,$echoport)
ELSE
$centerscan = GetRandom(0,255)
ENDIF

# Check if boxed in by compairing the results against a fixed boxed in distance
IF ($side1scan < $boxedindistance and $side2scan < $boxedindistance and $centerscan < $boxedindistance)

# If any are true set the boxed in flag
$isboxedin = 1

ENDIF

# Return to the main script
Return()



# The escape code

# Set a label for loops and gotos
:escape

# Set a flag so we know it has run for debugging
$EscapeRun = 1

# Reset the boxed in flag
$isboxedin = 0

# Center the sweep servo
Servo($sweepservo,$sweepcenter)

# Turn slowly
Left($slowturn)

# Set up a loop
:escapeloop

# Scan until clear
# Use random numbers if in test mode
IF ($testmode=0)
$escapescan = GetPing($pingport,$echoport)
ELSE
$escapescan = GetRandom(0,255)
ENDIF

# If the scan result is below the boxed in distance loop
IF ($escapescan < $BoxedInDistance)

# Go back to the start of the escape loop
Goto(escapeloop)

ENDIF

# Continue forwards
FORWARD()

# Return to the main script
Goto(escapereturn)



# Move Right code

# Set a label for loops and gotos
:moveright

# Check the last 2 moves to avoid left right left right loops
IF ($lastmove = "left" and $penultimatemove = "right")

# If it has been right then left dont move right again but escape from a loop
Goto(escape)

# Reset the last move
$lastmove = "none"

# Else just move right
ELSE
RIGHT($movementspeed,$turnamount)

# Save the penultimate move
$penultimatemove = $lastmove

# Save the last move
$lastmove = "right"

ENDIF

# Go back to the main script
Return()



# Move left code

# Set a label for loops and gotos
:moveleft

# Check the last 2 moves to avoid left right left right loops
IF ($lastmove = "right" and $penultimatemove = "left")

# If it has been left then right dont move left afain but escape from a loop
Goto(escape)

# Reset the last move
$lastmove = "none"

# Else just move left
ELSE
LEFT($movementspeed,$turnamount)

# Save the penultimate move
$penultimatemove = $lastmove

# Save the last move
$lastmove= "left"

ENDIF

# Go back to the main script
Return()

# End of scripts



It's also on the cloud PingAvoidanceV1.1.0

And for ease of copying and pasting (in case the forums decide to add in some emoticons) it's also on pastebin


Any and all feedback is greatly appreciated no matter how trivial. Feel free to make your own improvements and modifications (let me know what they are too - believe it or not I'm still learning too).

vhs896
Commented November 2013
OMG this would be perfect . .....
Cardboard Hacker
Commented November 2013
there is a newer version I believe. 1.1.2 I think. check the ez-cloud.
Rich
Commented November 2013
Yes 1.1.2 is the latest one, which is on page 3, the cloud and PasteBin

An update is also in the works which will use smart avoidance which will use sensor based turning rather than time based turning although I need to build a robot to test this before I'm confident enough that it'll work.


If you wanted to alter it for fixed sensors it is a pretty simple alteration. Basically all that would be needed is for the code to be changed whenever the sweep servo is moved and the GetPing() command run, rather than move the servo just change the GetPing() ports to the relevant sensor.

So, for example if you had 3 sensors on D0 and D1, D2 and D3 and D4 and D5, you can omit the sweep code and just use

Code:

$sensor1 = GetPing(D0,D1)
$sensor2 = GetPing(D2,D3)
$sensor3 = GetPing(D4,D5)



And adjust the If for the collision detection

Code:

IF ($currentdistance <= $maxdistance)


to

Code:

IF ($sensor1 <= $maxdistance OR $sensor2 <= $maxdistance OR $sensor3 <= $maxdistance)



The sweep centre sub routine could be pretty much eliminated too and replaced with an If to check which sensor (out of the left and right) is closest...

Code:

IF($sensor1 < $sensor3)
Left($movementspeed,$turnamount)
Else
Right($movementspeed,$turnamount)
EndIf



Hopefully that makes enough sense (if not I will be posting the whole code at some point but right now I'm struggling with the flu so my brain hurts a lot!)

Robot Doc
Commented November 2013
Get some R & R Rich hope you get to feeling better. A bottle of Vodka got me through the flu one year.
vhs896
Commented November 2013
Yea. I just got over something too. And thanks. I have been reading all your posts and the getting started on scripting. Thanks get better soon.
Question
Avatarby Rich
Published Thursday, April 18, 2013