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vrep:socket-com-with-robot
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vrep:socket-com-with-robot [2020/03/17 17:04] admin |
vrep:socket-com-with-robot [2020/06/09 16:39] (current) admin |
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| - | Th socket communication allows for an external program to control the robot inside V-REP. The external program is a Python script. We will use for the socket a server/client communication. The server is written in Lua inside a threaded script in V-REP. The client is written in Python, It will : | + | Back to [[vrep:main|V-REP Main Page]] |
| + | |||
| + | The socket communication allows for an external program to control the robot inside V-REP. The external program is a Python script. We will use for the socket a server/client communication. The server is written in Lua inside a threaded script in V-REP. The client is written in Python, It will : | ||
| * connect to the server | * connect to the server | ||
| * send commands to the robot | * send commands to the robot | ||
| Line 7: | Line 9: | ||
| On the server side of the socket, we use a [[https://www.coppeliarobotics.com/helpFiles/en/childScripts.htm|threaded script]] in Lua as we want to listen to the client's commands synchronously with the V-REP simulation loop. | On the server side of the socket, we use a [[https://www.coppeliarobotics.com/helpFiles/en/childScripts.htm|threaded script]] in Lua as we want to listen to the client's commands synchronously with the V-REP simulation loop. | ||
| - | We will use a [[https://www.ensta-bretagne.fr/zerr/filerepo/vrep/myLittleBot.ttt|simple 3 wheels robot]] and we load it in V-REP. | + | We will use a [[https://www.ensta-bretagne.fr/zerr/filerepo/vrep/myLittleBotNoScript.ttt|simple 3 wheels robot]] and we load it in V-REP. You can rename it **myLittleBot.ttt**. |
| {{:vrep:mylittlebot_view.png?300|}} | {{:vrep:mylittlebot_view.png?300|}} | ||
| Line 29: | Line 31: | ||
| Then you will have to create a file called **simple_robot_control.lua** in the directory where your scene file (here **myLittleBot.ttt**) is stored. | Then you will have to create a file called **simple_robot_control.lua** in the directory where your scene file (here **myLittleBot.ttt**) is stored. | ||
| - | The Lua code looks like this : | + | The [[https://www.ensta-bretagne.fr/zerr/filerepo/vrep/simple_robot_control.lua|Lua code]] looks like this : |
| <code lua> | <code lua> | ||
| - | function hex(s) | + | -- load pack library |
| - | s=string.gsub(s,"(.)",function (x) return string.format("%02X",string.byte(x)) end) | + | -- must have been added previoulsy in V-REP folder |
| - | return s | + | -- if not done yet, see tutorial ... |
| - | end | + | require ("pack") |
| - | + | ||
| - | require ("pack") | + | |
| bpack=string.pack | bpack=string.pack | ||
| bunpack=string.unpack | bunpack=string.unpack | ||
| + | -- define socket | ||
| portNb = 33211 | portNb = 33211 | ||
| serverOn = false | serverOn = false | ||
| - | connexionTimeout = 0.01 | + | connexionTimeout = 0.001 -- set 1 ms time out |
| - | cntTimeout = 0 | + | |
| socket=require("socket") | socket=require("socket") | ||
| srv = nil | srv = nil | ||
| Line 74: | Line 74: | ||
| -- if server is running, accept command and send back status | -- if server is running, accept command and send back status | ||
| if serverOn then | if serverOn then | ||
| + | -- to prevent lock on accept, a timeout is set | ||
| srv:settimeout(connexionTimeout) | srv:settimeout(connexionTimeout) | ||
| clt1 = srv:accept() | clt1 = srv:accept() | ||
| - | if clt1 == nil then | + | if clt1 ~= nil then |
| - | cntTimeout = cntTimeout + 1 | + | -- to prevent lock, a timeout is set |
| - | else | + | --clt1:settimeout(connexionTimeout) |
| - | -- to prevent locks, a timeout is set | + | |
| - | clt1:settimeout(connexionTimeout) | + | |
| -- get the data (command) from the client | -- get the data (command) from the client | ||
| dataIn = clt1:receive(nCharMessage) | dataIn = clt1:receive(nCharMessage) | ||
| Line 121: | Line 120: | ||
| </code> | </code> | ||
| - | The socket transfers binary data, so we need to pack the data before sending them and unpack them at the reception. For Lua we use the [[http://webserver2.tecgraf.puc-rio.br/~lhf/ftp/lua/|lpack libary]. You can either download the code and recompile **the pack.so** shared library or get it [[https://www.ensta-bretagne.fr/zerr/filerepo/vrep/pack.so|already compiled here]] if you work on x86_64 linux computer. The file **pack.so** should be added in the main V-REP directory. | + | The socket transfers binary data, so we need to pack the data before sending them and unpack them at the reception. For Lua we use the [[http://webserver2.tecgraf.puc-rio.br/~lhf/ftp/lua/|lpack library]]. You can either download the code and recompile the **pack.so** shared library or get it [[https://www.ensta-bretagne.fr/zerr/filerepo/vrep/pack.so|already compiled here]] if you work on x86_64 linux computer. The file **pack.so** should be added in the main V-REP directory. |
| + | |||
| + | //Todo : provide a .dll for windows// | ||
| The socket is between processes on the same computer so the IP address is **localhost** or **127.0.0.1**. The communication port is set to **33211**. The port number is arbitrary, if this port is already used, we will get an error message. To get a list of used port, you can use **lsof**. Here we print only the ports used by V-REP: | The socket is between processes on the same computer so the IP address is **localhost** or **127.0.0.1**. The communication port is set to **33211**. The port number is arbitrary, if this port is already used, we will get an error message. To get a list of used port, you can use **lsof**. Here we print only the ports used by V-REP: | ||
| Line 165: | Line 166: | ||
| </code> | </code> | ||
| - | The Python3 client code is as follows: | + | The [[https://www.ensta-bretagne.fr/zerr/filerepo/vrep/simple_robot_control.py|Python3 client code]] is as follows: |
| <code python> | <code python> | ||
| import socket | import socket | ||
| Line 191: | Line 192: | ||
| def interrupt_handler(signal, frame): | def interrupt_handler(signal, frame): | ||
| print ('You pressed CTRL-C, end of communication with V-REP robot') | print ('You pressed CTRL-C, end of communication with V-REP robot') | ||
| + | time.sleep(0.5) | ||
| try: | try: | ||
| sock.close() | sock.close() | ||
| Line 200: | Line 202: | ||
| signal.signal(signal.SIGINT, interrupt_handler) | signal.signal(signal.SIGINT, interrupt_handler) | ||
| - | # client connection every 50 ms | + | # client connects to server every 50 ms |
| loop_duration = 0.050 | loop_duration = 0.050 | ||
| while True: | while True: | ||
| Line 242: | Line 244: | ||
| (tsock,vrx[2],vrx[3]*180.0/math.pi,vrx[4]*180.0/math.pi)) | (tsock,vrx[2],vrx[3]*180.0/math.pi,vrx[4]*180.0/math.pi)) | ||
| else: | else: | ||
| - | print ("tsock",tsoc,"ms, bad data !!") | + | print ("tsock",tsock,"ms, bad data !!") |
| tsleep = loop_duration - (time.time()-t0) | tsleep = loop_duration - (time.time()-t0) | ||
| if tsleep>0: | if tsleep>0: | ||
| - | time.sleep (tsleep) | + | time.sleep (tsleep) |
| - | + | ||
| </code> | </code> | ||
| + | Go to [[vrep:socket-com-with-robot|top]] | ||
vrep/socket-com-with-robot.1584461094.txt.gz · Last modified: 2020/03/17 17:04 by admin
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