Please be sure to read the Plugins page to get a general sense of
if the Python module is a good fit for your project.
The Python module provides a way to create custom
Phython scripts that can be used to process image statistics and map then
toward servo/motor values. This module is intented to be used as a way to quickly perform custom
operations without needing to implement a Plugin or use the API which typically require external
The interface allows two methods for specifying your code. One technique requires that you specify a text file as the
source of the program. You can use your favorite text editor to edit/create
this file. The file should be a regular text file containing Python
commands/functions/operators. The program interface displays the current file
being used, available system or user variables (and their values) and any messages
the program produces.
The alternate way is to include the Python text within the provided text box (see below). Using this technique
allows you to include the Python code within the .robo program and not require another user to save
the code and reference a text file as needed by the above file based technique. Using the text
box provides a quick way to enter in text but is NOT meant as a replacement for a full featured
text editor as its editing features are very basic.
Note that in any Python script you MUST "import rr" before you can use any of the embedded Python <-> RoboRealm
RoboRealm Specific Functions
- Print("text") - sends text to the Python module message output area in the dialog interface used for debugging. Note that lack of "rr." as this
function is global.
- rr.VariableExists("variable_name") - returns true or false depending on if the specified variable exists in RoboRealm. Several of the variable
return functions below will return a valid value regardless of if the variable exists or not. You can use this function
to determine if the value returned from one of these functions is a valid value.
- rr.GetVariable("variable_name") - returns an integer value of the specified variable
- rr.GetStrVariable("variable_name") - returns the string value of the specified variable
- rr.GetArrayVariable("array_variable_name") - returns the array associated with the specified variable
- rr.SetArrayVariable "array_variable_name", array_variable - sets an array associated with the specified variable name; for example
points = [100,100,150,200]
- rr.SetVariable("variable_name", variable_value) - sets the variable value to the specified variable
- rr.SetTimedVariable("variable_name", variable_value, timeout) - sets the variable value to the specified variable after
the timeout (milliseconds) has passed. This allows you to specify when in time a variable's value should be
changed. Note that each call to SetTimedVarible will reset the timer so be sure to only call it once to
allow the time to lapse and set the specified value. This function is useful when you would normally use the Sleep function which
is not recommended within the pipeline since Sleep will stop all processing. By setting a variable to a value in the future you can
emulate a Sleep function by allowing something to happen for a period of time, but then switching it off after the time has lapsed. So
instead of using
you should use
rr.SetTimedVariable("motor", 0, 1000);
- rr.AddTimedVariable("variable_name", variable_value, timeout) - similar to SetTimedVariable, this function will instead
add the timing parameter to a queue instead of overwriting the timing information. For example:
rr.SetTimedVariable("motor", 100, 1000);
rr.SetTimedVariable("motor", 200, 1500);
rr.SetTimedVariable("motor", 300, 2000);
will result in the motor variable being set to 300 in 2 seconds (2000 ms). What happens is that the first two calls to
SetTimedVariable are OVERWRITTEN by the third. Instead, if you use
rr.AddTimedVariable("motor", 100, 1000);
rr.AddTimedVariable("motor", 200, 1500);
rr.AddTimedVariable("motor", 300, 2000);
the motor variable will be set to 100 in 1 second, 200 in 1.5 seconds and finally 300 in 2 seconds. The AddTimedVariable will add
each call into a list that is executed in sequence based on the specified time.
- rr.GetPixels() - returns an array of RGB values of the current image
- rr.SetPixels(pixel_data_array) - sets the current image to the specified pixel RGB data
- rr.SetParameter("module_name", index, "param_name", "param_value") - changes the specified parameter in the specified module to the specified value. This is useful when
a GUI dialog does not have a variable selection as part of the dropdown. Avoid using this function unless necessary as it is slow to update the
- rr.GetParameter("module_name", index, "param_name") - returns the specified parameter in the specified module. This is useful when
a GUI dialog does not expose a value within a variable.
- rr.GetStrParameter("module_name", index, "param_name") - the string version of the above routine.
- rr.StopProcessing() - stops RoboRealm from continuing to process the images with the remaining modules
- rr.CameraOff() - switches off the image capturing from the current camera
- rr.CameraOn() - switches on the image capturing using the current camera
- rr.PushButton("Module_Name", Module_Index, "Button") - automates pushing a button in one of the
RoboRealm GUI windows. For example:
if rr.GetStrVariable("test") <> "pushed":
rr.PushButton("Read_AVI", 0, "Start")
will cause the Read_AVI module (assuming one exists in the pipeline) to start playback.
rr.PushButton("RoboRealm", 0, "Snap")
will cause RoboRealm to create a snapshot of the current image.
To access variables from your Python file/script use the
MyVar = rr.GetVariable("variable_name")
Or to create a new variable use
Once a new variable is created this variable becomes available
to control functions (such as in the SSC module) that can be used to automatically
control a servo/motor.
You can also get variable arrays using
MyVar = rr.GetArrayVariable("variable_array_name")
or get individual entries in an array using
MyVar = rr.GetVariable("variable_array_name:2")
which would return the second entry in an array.
To change a variable's value in X milliseconds you can use
rr.SetTimedVariable("variable_name", variable_value, timeout_in_milliseconds)
which is very useful for resetting motor values after a period of time.
All regular Python commands and operators are available for
use in the file. See Official Python
Website for complete documentation on how to use Python commands.
For example the following program (assuming you have added the Center Of Gravity module) will map COG to servo motors:
cogx = rr.GetVariable("cog_x")
cogy = rr.GetVariable("cog_y")
if cogx < 140:
left_motor = 60
right_motor = 128
if cogx > 180:
left_motor = 128
right_motor = 60
left_motor = 128
right_motor = 128
Note that the COGX values range from 0 to 320. COGY ranges from 0 to 160. These values are
bounded by the current image size. These values may
change if you crop, shrink, etc. the image dimensions.
You could then use a module like the SSC module to map the "left_motor" and "right_motor" variables to actual servos.
You can also process the image pixels directly using Python. This is useful
for prototyping but not recommended due to performance reasons for actual usage.
The Python module supports two routines to get and set the image pixels. Following
is the example SwapColor module but in Python.
width = rr.GetVariable("IMAGE_WIDTH")
height = rr.GetVariable("IMAGE_HEIGHT")
img = rr.GetPixels()
len = width*height*3
i = 0
t = img[i]
img[i] = img[i+2]
img[i+2] = t
rr.SetPixels(img, width, height)
To write variables or debug statements to a log file you can use
f = open('c:\\temp\\test.txt', 'a')
f.write(rr.GetStrVariable("cog_x") + ':' + rr.GetStrVariable("cog_y") + '\n')
If you need to wait for a specific condition in a loop you will have to setup a trigger variable.
You can't really sleep, wait or loop in the Python module as that would stop all image processing while it is waiting for the
loop or sleep to finish. As the pipeline is essentially
an infinite loop (i.e. grab an image, process it, then grab another, etc) adding a sleep would cease all
execution which is usually not desired.
If you prevent the ending of the loop by putting a while loop in the code it will not allow the system to
capture new images and continue processing.
So instead you can use the SetTimedVariable to cause the variable
to change value after X number of milliseconds. Your script would look something like
which would cause the variable data to oscillate between 2 and 4 with a period of 2000 seconds. Note that usage of step and
setting it to 1 and 3 which are dummy steps where nothing is done.
period = 2000
step = rr.GetVariable("step")
if step == 0 :
rr.SetTimedVariable("step", 2, period)
if step == 2 :
rr.SetTimedVariable("step", 0, period)
On each successful run of the script the SCRIPT_COUNT variable is incremented. Thus you can use this variable to
indicate a first run state where variables can be initialized to default values. Note that the Reload and Run button
will reset this count to 0.
If RoboRealm complains about missing components you may need to
|Python_Program Related Forum Posts||Last post||Posts||Views|
Python 32 bit DLL on Win 7 ia64
Got the missing "phython30" (sic) dll error message, but cannot resolve by installing 32-bit python, not even with python 3.0...
Memory usage increases over time
I've found that running a program in Roborealm over an extended period - 1-2 weeks - will resu...