小朋友學ROS機器人——使用Scratch2和ROS進行機器人圖形化編程學習

01-28

張博士為志願服務者，熱心困境兒童教育，為小朋友講授機器人課程

（上海久牽志願者服務社、2017中國困境兒童關注日）

使用Scratch2和ROS進行機器人編程學習（適用於中小學機器人編程Scratch和ROS）

Scratch是一款由麻省理工學院(MIT)設計開發的少兒編程工具，Python是近年來非常流行的機器人和人工智慧編程語言，ROS是機器人操作系統。

參考JdeRobot的一篇詳細介紹，就可以實現上述的功能，需要安裝Scratch2、ROS Kinetic、Gazebo 7、JdeRobot、Python2.7等。

通過將Scratch2圖形化編程語言轉為Python，然後通過ROS消息機制控制Gazebo或實際機器人。

（上海久牽志願者服務社、2017中國困境兒童關注日）

~~信息化智能化時代下平等受教育的權利~~

1 先看如下一個簡單的示例

1.1 新建hiros.bz2，如下：

1.2 通過下面命令將其轉為Python：

[python] view plain copy print?

$ python scratch2python.py hiros.sb2
Stringify:
when @greenFlag clicked
repeat 10
say Hello,ROS Kinetic!
end
[WARN] Block <when @greenFlag clicked> not included yet
-------------------
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import time
import config
import sys
import comm
import os
import yaml
from drone import Drone
from robot import Robot
def execute(robot):
try:
for i in range(10):
print(Hello,ROS Kinetic!)
except KeyboardInterrupt:
raise
if __name__ == __main__:
if len(sys.argv) == 2:
path = os.getcwd()
open_path = path[:path.rfind(src)] + cfg/
filename = sys.argv[1]
else:
sys.exit("ERROR: Example:python my_generated_script.py cfgfile.yml")
# loading the ICE and ROS parameters
cfg = config.load(open_path + filename)
stream = open(open_path + filename, "r")
yml_file = yaml.load(stream)
for section in yml_file:
if section == drone:
#starting comm
jdrc = comm.init(cfg,drone)
# creating the object
robot = Drone(jdrc)
break
elif section == robot:
#starting comm
jdrc = comm.init(cfg,robot)
# creating the object
robot = Robot(jdrc)
break
# executing the scratch program
execute(robot)
-------------------

2 控制機器人示例

是不是比較有趣，在不需購買任何設備的情況下，就可以用Scratch2進行ROS機器人編程。小學用Scratch2學習簡單編程，中學用Python學習簡單編程，大學用Python和C++學習複雜機器人編程，無縫銜接。

3 scratch2python.py

[python] view plain copy print?

#!/usr/bin/env python
# -*- coding: utf-8 -*-
__author__ = "Raul Perula-Martinez"
__copyright__ = "JdeRobot project"
__credits__ = ["Raul Perula-Martinez"]
__license__ = "GPL v3"
__version__ = "0.0.0"
__maintainer__ = "Raul Perula-Martinez"
__email__ = "raules@gmail.com"
__status__ = "Development"
import kurt
import os
import sys
from difflib import SequenceMatcher
from parse import parse, compile
from termcolor import cprint
GENERAL = [
[end, ],
[forever, while True:],
[if {} then, if %s:],
[else, else:],
[repeat {}, for i in range(%s):],
[say {}, print(%s)],
[set {} to {}, %s = %s],
[wait {} secs, time.sleep(%s)],
]
ROBOTICS = [
[move robot {}, robot.move("%s")],
[move drone {}, robot.move("%s")],
[move robot {} speed {}, robot.move("%s", %s)],
[stop robot-drone, robot.stop()],
[turn robot-drone {}, robot.turn("%s")],
[turn robot {} speed {}, robot.turn("%s", %s)],
[take off drone, robot.take_off()],
[land drone, robot.land()],
[frontal laser distance, robot.get_laser_distance()],
]
def is_conditional(sentence):
"""
Returns if a sentence is conditional or not.
@param sentence: The sentence to check.
@return: True if it has a conditional, False otherwise.
"""
if "if" in sentence:
return True
return False
def similar(a, b):
"""
Returns the ratio value comparing two sentences.
@param a: First sentence.
@param b: Second sentence.
@return: The ratio of the similarity.
"""
return SequenceMatcher(None, a, b).ratio()
def sentence_mapping(sentence, threshold=None):
"""
Maps a sentence and returns the original and the mapped.
@param sentence: The sentence to map.
@return: The original sentence and the mapped sentence.
"""
found = False
options = []
original = None
translation = None
# first look for general blocks
for elem in GENERAL:
if elem[0][:3] == sentence.replace( , )[:3]:
options.append(elem)
found = True
# then look for robotics blocks
for elem in ROBOTICS:
if elem[0][:3] == sentence.replace( , ).replace((, )[:3]:
options.append(elem)
found = True
if found:
# select the option that better fits
l = [(m[0], m[1], similar(sentence, m[0])) for m in options]
original, translation, score = max(l, key=lambda item: item[2])
if threshold and score < threshold:
return None, None
# extract arguments
p = compile(original)
args = p.parse(sentence.replace( , ))
if args:
args_aux = list(args)
# look for more blocks
for idx in range(len(args_aux)):
new_ori, new_trans = sentence_mapping(args_aux[idx]) #sentence_mapping(args_aux[idx],0.8) --old
if new_trans != None:
args_aux[idx] = args_aux[idx].replace(new_ori, new_trans) #replace(args_aux[idx], new_trans)
translation = translation % tuple(args_aux)
return original, translation
if __name__ == "__main__":
# get current working directory
path = os.getcwd()
open_path = path[:path.rfind(scripts)] + data/
save_path = path[:path.rfind(scripts)] + src/scratch2jderobot/
if len(sys.argv) == 2:
# template creation
template = "
#!/usr/bin/env pythonn
# -*- coding: utf-8 -*-nn
import timen
import confign
import sysn
import commn
import osn
import yamlnn
from drone import Dronen
from robot import Robotnn
def execute(robot):n
ttry:n
t%s
except KeyboardInterrupt:n
ttraisenn
if __name__ == __main__:n
tif len(sys.argv) == 2:n
ttpath = os.getcwd()n
ttopen_path = path[:path.rfind(src)] + cfg/n
ttfilename = sys.argv[1]nn
telse:n
ttsys.exit("ERROR: Example:python my_generated_script.py cfgfile.yml")nn
t# loading the ICE and ROS parametersn
tcfg = config.load(open_path + filename)n
tstream = open(open_path + filename, "r")n
tyml_file = yaml.load(stream)nn
tfor section in yml_file:n
ttif section == drone:n
ttt#starting commn
tttjdrc = comm.init(cfg,drone)nn
ttt# creating the objectn
tttrobot = Drone(jdrc)nn
tttbreakn
ttelif section == robot:n
ttt#starting commn
tttjdrc = comm.init(cfg,robot)nn
ttt# creating the objectn
tttrobot = Robot(jdrc)nn
tttbreakn
t# executing the scratch programn
texecute(robot)nn
"
# load the scratch project
p = kurt.Project.load(open_path + sys.argv[1])
# show the blocks included
for scriptable in p.sprites + [p.stage]:
for script in scriptable.scripts:
# exclude definition scripts
if "define" not in script.blocks[0].stringify():
s = script
print("Stringify:")
sentences = []
for b in s.blocks:
print(b.stringify())
sentences += b.stringify().split(n)
tab_seq = "t"
python_program = ""
for s in sentences:
# count number of tabs
num_tabs = s.replace( , tab_seq).count(tab_seq)
python_program += tab_seq * (num_tabs + 1)
# pre-processing if there is a condition (operators and types)
if is_conditional(s):
s = s.replace("", "").replace("=", "==")
# mapping
original, translation = sentence_mapping(s)
# set the code
if translation != None:
python_program += translation
else:
cprint("[WARN] Block <%s> not included yet" % s, yellow)
python_program += "n" + tab_seq
# join the template with the code and replace the tabs
file_text = template % python_program
file_text = file_text.replace(tab_seq, * 4)
print("n-------------------")
cprint(file_text, green)
print("-------------------n")
# save the code in a python file with the same name as sb2 file
file_name = sys.argv[1].replace(.sb2,.py)
f = open(save_path + file_name, "w")
f.write(file_text)
f.close()
else:
print(
"ERROR: Number of parameters incorrect. Example:ntpython scratch2python.py hello_world.sb2")