使用Scratch2和ROS进行机器人图形化编程学习

使用Scratch2和ROS进行机器人编程学习（适用于中小学机器人编程Scratch和ROS）

Scratch是一款由麻省理工学院(MIT)设计开发的少儿编程工具，Python是近年来非常流行的机器人和人工智能编程语言，ROS是机器人操作系统。

参考JdeRobot的一篇详细介绍，就可以实现上述的功能，需要安装Scratch2、ROS Kinetic、Gazebo 7、JdeRobot、Python2.7等。

通过将Scratch2图形化编程语言转为Python，然后通过ROS消息机制控制Gazebo或实际机器人。

（上海久牵志愿者服务社、2017中国困境儿童关注日）

~~信息化智能化时代下平等受教育的权利~~

1 先看如下一个简单的示例

1.1 新建hiros.bz2，如下：

1.2 通过下面命令将其转为Python：

$ python scratch2python.py hiros.sb2Stringify:when @greenFlag clickedrepeat 10    say 'Hello,ROS Kinetic!'end[WARN] Block <when @greenFlag clicked> not included yet-------------------#!/usr/bin/env python# -*- coding: utf-8 -*-import timeimport configimport sysimport commimport osimport yamlfrom drone import Dronefrom robot import Robotdef execute(robot):    try:                for i in range(10):            print('Hello,ROS Kinetic!')            except KeyboardInterrupt:        raiseif __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 控制机器人示例

是不是比较有趣，在不需购买任何设备的情况下，就可以用Scratch2进行ROS机器人编程。小学用Scratch2学习简单编程，中学用Python学习简单编程，大学用Python和C++学习复杂机器人编程，无缝衔接。

3 scratch2python.py

#!/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__ = "[e-mail]"__status__ = "Development"import kurtimport osimport sysfrom difflib import SequenceMatcherfrom parse import parse, compilefrom termcolor import cprintGENERAL = [    ['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 Falsedef 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, translationif __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 python\n\# -*- coding: utf-8 -*-\n\n\import time\n\import config\n\import sys\n\import comm\n\import os\n\import yaml\n\n\from drone import Drone\n\from robot import Robot\n\n\def execute(robot):\n\\ttry:\n\\t%s\except KeyboardInterrupt:\n\\t\traise\n\n\if __name__ == '__main__':\n\\tif len(sys.argv) == 2:\n\\t\tpath = os.getcwd()\n\\t\topen_path = path[:path.rfind('src')] + 'cfg/'\n\\t\tfilename = sys.argv[1]\n\n\\telse:\n\\t\tsys.exit(\"ERROR: Example:python my_generated_script.py cfgfile.yml\")\n\n\\t# loading the ICE and ROS parameters\n\\tcfg = config.load(open_path + filename)\n\\tstream = open(open_path + filename, \"r\")\n\\tyml_file = yaml.load(stream)\n\n\\tfor section in yml_file:\n\\t\tif section == 'drone':\n\\t\t\t#starting comm\n\\t\t\tjdrc = comm.init(cfg,'drone')\n\n\\t\t\t# creating the object\n\\t\t\trobot = Drone(jdrc)\n\n\\t\t\tbreak\n\\t\telif section == 'robot':\n\\t\t\t#starting comm\n\\t\t\tjdrc = comm.init(cfg,'robot')\n\n\\t\t\t# creating the object\n\\t\t\trobot = Robot(jdrc)\n\n\\t\t\tbreak\n\\t# executing the scratch program\n\\texecute(robot)\n\n\"        # 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:\n\tpython scratch2python.py hello_world.sb2")

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