25.04.2009Hannover Messe

Irgendwie mochte ich das Modell von dem kleinen Kerl
Robot

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25.04.2009Fellow and Friend

Here is a nice picture from the Fellow and Friend concert in Bonn

dsc01322

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24.04.2009Using zeroc’s Icestorm in Python

CORBA is great, but ICE is great and cool, which makes it awesome :)

But good examples on using the publish/subscribe channel system of Icestorm in python are hard to find. Here is what I did:
config.icebox

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IceBox.ServiceManager.Endpoints=tcp -p 9999
IceBox.Service.IceStorm=IceStormService,32:createIceStorm --Ice.Config=config.icestorm

config.icestorm

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IceStorm.InstanceName=Simple
IceStorm.TopicManager.Proxy=Simple/TopicManager:default -p 10000
IceStorm.TopicManager.Endpoints=tcp -p 10000
IceStorm.Publish.Endpoints=tcp
Freeze.DbEnv.IceStorm.DbHome=db

start icebox with: icebox –Ice.Config=config.icebox

Simple.ice

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module Simple
{
    struct Message {
        string content;
    };
    interface Processor {
        void process (Message m);
    };
};

subscriber.py

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#!/usr/bin/python

# Subscribe to the storm (channel) 'MyTopic'
# and offer an instance of 'ProcessorI' as remote-object.

import sys, Ice, IceStorm
Ice.loadSlice('Simple.ice', ['-I', '/opt/Ice-3.2.1/bin/slice'])# can also be /usr/share/slice
import Simple

# Implementation of the Processor class (defined in the ice file)
class ProcessorImpl (Simple.Processor):
    def process (self, message, curr):
        print message.content

class Subscriber (Ice.Application):
    def run (self, argv):
        self.shutdownOnInterrupt()
        # Get the TopicManager.
        prx = self.communicator().stringToProxy('Simple/TopicManager:tcp -p 10000')
        topicManagerPrx = IceStorm.TopicManagerPrx.checkedCast(prx)
        # Create the remote object
        oa = self.communicator().createObjectAdapterWithEndpoints('SubscriberOA', 'default')
        processorPrx = oa.addWithUUID(ProcessorImpl())
        # Get the topic from the manager.
        try:
            topicPrx = topicManagerPrx.retrieve('MyTopic')
        except IceStorm.NoSuchTopic:
            topicPrx = topicManagerPrx.create('MyTopic')
        # Subscribe the remote object to the storm (channel)
        topicPrx.subscribeAndGetPublisher(None, processorPrx)
        oa.activate()
        self.communicator().waitForShutdown()
        topicPrx.unsubscribe(processorPrx)
        return 0

Subscriber().main(sys.argv)

publisher.py

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#!/usr/bin/python

# Subscribe to the storm (channel) 'MyTopic'
# and call the remote-objects function 'process()'

import sys, Ice, IceStorm
Ice.loadSlice('Simple.ice', ['-I', '/opt/Ice-3.2.1/bin/slice'])# can also be /usr/share/slice
import Simple
from time import sleep
class Publisher (Ice.Application):
    def run (self, argv):
        # Get the TopicManager.
        prx = self.communicator().stringToProxy('Simple/TopicManager:tcp -p 10000')
        topicManagerPrx = IceStorm.TopicManagerPrx.checkedCast(prx)
        # Get the topic from the manager.
        try:
            topicPrx = topicManagerPrx.retrieve('MyTopic')
        except IceStorm.NoSuchTopic:
            topicPrx = topicManagerPrx.create('MyTopic')
        # Proxy of the remote object
        pub = topicPrx.getPublisher()
        processorPrx = Simple.ProcessorPrx.uncheckedCast(pub)
        # Publish some messages on the remote objects function 'process()'.
        m = Simple.Message('Hello')
        processorPrx.process(m)
       
        sleep(2)
        m = Simple.Message('World!')
        processorPrx.process(m)
        return 0

Publisher().main(sys.argv)

You can download the whole stuff here.
To run everything, open three terminals. Launch icebox (icebox –Ice.Config=config.icebox), start the subscriber (python subscriber.py) and finally start the publisher (python publisher.py) as often, as you would like to shout your “Hello World!” over the storm-channels :D

Hope that helps.
Cheers Gecko

Filed under: Code | 1 Comment

21.04.2009Letztens in Bremen

Hier noch ein schönes Bilchen von Tutu’s Tochter Lovissa:

lovissa

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21.04.2009Driving NXT with Python, using Bluetooth

I had quite a hard time, setting up my NXT the way I wanted. The basic Idea is to tele-operate the robot, using its bluetooth connection under Linux.  Since the robot is running under LeJOS I thought it to be best to start off with a bluetooth socket client/server thing in java.

Server:

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// compile with: nxjc BTReceive.java
// uploade with: sudo /home/gecko/Programme/lejos_nxj/bin/nxj -r BTReceive

import lejos.nxt.*;
import lejos.nxt.comm.*;
import lejos.nxt.socket.*;
import java.io.*;

public class BTReceive {
    public static void main(String [] args) throws Exception {
        String connected = "Connected";
        String waiting = "Waiting...";
        String closing = "Closing...";

        while (true) {
            LCD.drawString(waiting,0,0);
            NXTConnection connection = Bluetooth.waitForConnection();
            LCD.clear();
            LCD.drawString(connected,0,0);

            DataInputStream dis = connection.openDataInputStream();
            DataOutputStream dos = connection.openDataOutputStream();

            String s = dis.readLine();
            LCD.drawString(s,0,4);
            dos.writeChars(s);
            dos.flush();
            Thread.sleep(5000);

            dis.close();
            dos.close();

            LCD.clear();
            LCD.drawString(closing,0,0);

            connection.close();
        }
    }
}

Client:

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import lejos.pc.comm.*;
import java.io.*;

public class BTSend {

    private static char END_CHAR = '\n';

    public static void main(String[] args)  throws Exception {
        NXTComm nxtComm = NXTCommFactory.createNXTComm(NXTCommFactory.BLUETOOTH);

        // find the nearest NXT
        NXTInfo[] nxtInfo = nxtComm.search("NXT", NXTCommFactory.BLUETOOTH);
        if (nxtInfo.length == 0) {
            System.out.println("No NXT Found");
            System.exit(1);
        }

        System.out.println("Adr: " + nxtInfo[0].btDeviceAddress);
        System.out.println("Connecting to " + nxtInfo[0].btResourceString);

        boolean opened = nxtComm.open(nxtInfo[0]);

        if (!opened) {
            System.out.println("Failed to open " + nxtInfo[0].name);
            System.exit(1);

        }

        System.out.println("Connected to " + nxtInfo[0].btResourceString);

        InputStream is = nxtComm.getInputStream();
        OutputStream os = nxtComm.getOutputStream();

        DataOutputStream dos = new DataOutputStream(os);
        DataInputStream dis = new DataInputStream(is);

        try {
            System.out.println("Sending data");
            dos.writeChars("Hello from PC" + END_CHAR);
            dos.flush();
            System.out.println("Sending done");
        } catch (IOException ioe) {
            System.out.println("IO Exception writing bytes");
            System.out.println(" ::" + ioe.toString());
        } catch (Exception e) {
            System.out.println(" ::" + e.toString());
        }

        StringBuffer strb = new StringBuffer();

        try {
            char c = dis.readChar();
            while(c != END_CHAR) {
                strb.append(c);
                c = dis.readChar();
            }
        } catch (IOException ioe) {
            System.out.println("IO Exception writing received bytes");
            System.out.println(" ::" + ioe.toString());
        } catch (Exception e) {
            System.out.println(" ::" + e.toString());
        }

        System.out.println("Received data: " + strb.toString());

        try {
            dis.close();
            nxtComm.close();
        } catch (IOException ioe) {
            System.out.println("IOException closing connection");
        }
    }
}

That worked pretty well… But once I tried to use the server from within Python … nothing!

To cut a long Path short, if you are using NXT Python, you don’t need a server running on the NXT. All you need to do is to connect to the brick, hand the connection to the sensor/actuator you want to use and start coding, like you’re working on the robot itself… Maybe that is obvious to some people, but to me it wasn’t. So if there is someone else like me out there, desperately in love with python, trying to run the NXT… here’s how my stuff worked. Hope that helps.

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#!/usr/bin/env python

import nxt.bluesock
from nxt.sensor import *
from nxt.motor import *
#import nxt.locator

# enable bluetooth connection
socket = nxt.bluesock.BlueSock("00:16:53:07:1D:00")
#socket = nxt.locator.find_one_brick()
if socket:
    brick = socket.connect()
    print "connected"
else:
    print "couldn't get bluetooth connection"
    exit(0)

# initialize robot
# BUMPERS
touch_left = TouchSensor(brick, PORT_2)
touch_right = TouchSensor(brick, PORT_1)
# MOTORS
m_left = Motor(brick, PORT_B)
m_right = Motor(brick, PORT_A)
# ULTRA SONIC
ultra_left = UltrasonicSensor(brick, PORT_4)
ultra_right = UltrasonicSensor(brick, PORT_3)

# set motor speed
def set_speed(motor, speed, caps=70):
# limit motor output to caps (default = 70)
if(speed >= caps):
    speed = caps
elif(speed <= -caps):
    speed = -caps
    # set speed
    motor.power = speed
    motor.mode = MODE_MOTOR_ON
    motor.run_state = RUN_STATE_RUNNING
    motor.set_output_state()

# get touch sensor state
# returns true or false
def get_touch(touch_sensor):
    return touch_sensor.get_sample()

# get sonar sensor values (0-255)

def getSonarInfo(sonar):
    return sonar.get_single_shot_measurement()

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21.04.2009Hello world!

Hello World!
Hello Gecko!

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