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  • Google I/O 2010 - Making smart & scalable Wave robots

    Google I/O 2010 - Making smart & scalable Wave robots Google I/O 2010 - Making smart & scalable Wave robots Wave 201 David Byttow, Marcel Prasetya A smart robot must be able to store persistent data. Wave robots can store data in wave structures, like wavelets, datadocs, and annotations, instead of traditional datastores. A scalable robot must perform operations with minimal bandwidth. Wave robots can optimize by selecting the appropriate amount of context, the optimal events, and narrow filters for events. In this talk, we'll share best practices on data storage and scaling. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 9 0 ratings Time: 58:25 More in Science & Technology

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  • Evidence for automatic browsing - Log file analysis

    - by Nilani Algiriyage
    I'm analyzing web server logs both in Apache and IIS log formats. I want to find the evidence for automatic browsing, like web robots, spiders, bots, etc. I used python robot-detection 0.2.8 for detecting robots in my log files, but I know there may be other robots (automatic programs) which have traversed through the web site but robot-detection can not identify. So I want to ask: Are there any specific clues that can be found in log files that human users do not leave but automated software would? Do they follow a specific navigation pattern? I saw some requests for favicon.ico - does this implicate that it is a automatic browsing?. I found this article and this question with some valuable points.

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  • Can the following Domain Entity contain logic for creating/deleting other entities?

    - by user702769
    a) As far as I understand it, in most cases Domain Model DM doesn't contain code for creating/deleting domain entities, but instead it is the job of layers ( ie service layer or UI layer ) on top of DM to create/delete domain entities? b) Domain entities are modelled after real world entities. Assuming particular real world entity being abstracted does have the functionality of creating/deleting other real world entities, then I assume the domain entity abstracting this real world entity could also contain logic for creating/deleting other entities? class RobotDestroyerCreator { ... void heavyThinking() { ... if(...) unitOfWork.registerDelete(robot); ... if(...) { var robotNew = new Robot(...); unitOfWork.registerNew(robotNew); { ... } } Thank you

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  • Need help with fixing Genetic Algorithm that's not evolving correctly

    - by EnderMB
    I am working on a maze solving application that uses a Genetic Algorithm to evolve a set of genes (within Individuals) to evolve a Population of Individuals that power an Agent through a maze. The majority of the code used appears to be working fine but when the code runs it's not selecting the best Individual's to be in the new Population correctly. When I run the application it outputs the following: Total Fitness: 380.0 - Best Fitness: 11.0 Total Fitness: 406.0 - Best Fitness: 15.0 Total Fitness: 344.0 - Best Fitness: 12.0 Total Fitness: 373.0 - Best Fitness: 11.0 Total Fitness: 415.0 - Best Fitness: 12.0 Total Fitness: 359.0 - Best Fitness: 11.0 Total Fitness: 436.0 - Best Fitness: 13.0 Total Fitness: 390.0 - Best Fitness: 12.0 Total Fitness: 379.0 - Best Fitness: 15.0 Total Fitness: 370.0 - Best Fitness: 11.0 Total Fitness: 361.0 - Best Fitness: 11.0 Total Fitness: 413.0 - Best Fitness: 16.0 As you can clearly see the fitnesses are not improving and neither are the best fitnesses. The main code responsible for this problem is here, and I believe the problem to be within the main method, most likely where the selection methods are called: package GeneticAlgorithm; import GeneticAlgorithm.Individual.Action; import Robot.Robot.Direction; import Maze.Maze; import Robot.Robot; import java.util.ArrayList; import java.util.Random; public class RunGA { protected static ArrayList tmp1, tmp2 = new ArrayList(); // Implementation of Elitism protected static int ELITISM_K = 5; // Population size protected static int POPULATION_SIZE = 50 + ELITISM_K; // Max number of Iterations protected static int MAX_ITERATIONS = 200; // Probability of Mutation protected static double MUTATION_PROB = 0.05; // Probability of Crossover protected static double CROSSOVER_PROB = 0.7; // Instantiate Random object private static Random rand = new Random(); // Instantiate Population of Individuals private Individual[] startPopulation; // Total Fitness of Population private double totalFitness; Robot robot = new Robot(); Maze maze; public void setElitism(int result) { ELITISM_K = result; } public void setPopSize(int result) { POPULATION_SIZE = result + ELITISM_K; } public void setMaxIt(int result) { MAX_ITERATIONS = result; } public void setMutProb(double result) { MUTATION_PROB = result; } public void setCrossoverProb(double result) { CROSSOVER_PROB = result; } /** * Constructor for Population */ public RunGA(Maze maze) { // Create a population of population plus elitism startPopulation = new Individual[POPULATION_SIZE]; // For every individual in population fill with x genes from 0 to 1 for (int i = 0; i < POPULATION_SIZE; i++) { startPopulation[i] = new Individual(); startPopulation[i].randGenes(); } // Evaluate the current population's fitness this.evaluate(maze, startPopulation); } /** * Set Population * @param newPop */ public void setPopulation(Individual[] newPop) { System.arraycopy(newPop, 0, this.startPopulation, 0, POPULATION_SIZE); } /** * Get Population * @return */ public Individual[] getPopulation() { return this.startPopulation; } /** * Evaluate fitness * @return */ public double evaluate(Maze maze, Individual[] newPop) { this.totalFitness = 0.0; ArrayList<Double> fitnesses = new ArrayList<Double>(); for (int i = 0; i < POPULATION_SIZE; i++) { maze = new Maze(8, 8); maze.fillMaze(); fitnesses.add(startPopulation[i].evaluate(maze, newPop)); //this.totalFitness += startPopulation[i].evaluate(maze, newPop); } //totalFitness = (Math.round(totalFitness / POPULATION_SIZE)); StringBuilder sb = new StringBuilder(); for(Double tmp : fitnesses) { sb.append(tmp + ", "); totalFitness += tmp; } // Progress of each Individual //System.out.println(sb.toString()); return this.totalFitness; } /** * Roulette Wheel Selection * @return */ public Individual rouletteWheelSelection() { // Calculate sum of all chromosome fitnesses in population - sum S. double randNum = rand.nextDouble() * this.totalFitness; int i; for (i = 0; i < POPULATION_SIZE && randNum > 0; ++i) { randNum -= startPopulation[i].getFitnessValue(); } return startPopulation[i-1]; } /** * Tournament Selection * @return */ public Individual tournamentSelection() { double randNum = rand.nextDouble() * this.totalFitness; // Get random number of population (add 1 to stop nullpointerexception) int k = rand.nextInt(POPULATION_SIZE) + 1; int i; for (i = 1; i < POPULATION_SIZE && i < k && randNum > 0; ++i) { randNum -= startPopulation[i].getFitnessValue(); } return startPopulation[i-1]; } /** * Finds the best individual * @return */ public Individual findBestIndividual() { int idxMax = 0; double currentMax = 0.0; double currentMin = 1.0; double currentVal; for (int idx = 0; idx < POPULATION_SIZE; ++idx) { currentVal = startPopulation[idx].getFitnessValue(); if (currentMax < currentMin) { currentMax = currentMin = currentVal; idxMax = idx; } if (currentVal > currentMax) { currentMax = currentVal; idxMax = idx; } } // Double check to see if this has the right one //System.out.println(startPopulation[idxMax].getFitnessValue()); // Maximisation return startPopulation[idxMax]; } /** * One Point Crossover * @param firstPerson * @param secondPerson * @return */ public static Individual[] onePointCrossover(Individual firstPerson, Individual secondPerson) { Individual[] newPerson = new Individual[2]; newPerson[0] = new Individual(); newPerson[1] = new Individual(); int size = Individual.SIZE; int randPoint = rand.nextInt(size); int i; for (i = 0; i < randPoint; ++i) { newPerson[0].setGene(i, firstPerson.getGene(i)); newPerson[1].setGene(i, secondPerson.getGene(i)); } for (; i < Individual.SIZE; ++i) { newPerson[0].setGene(i, secondPerson.getGene(i)); newPerson[1].setGene(i, firstPerson.getGene(i)); } return newPerson; } /** * Uniform Crossover * @param firstPerson * @param secondPerson * @return */ public static Individual[] uniformCrossover(Individual firstPerson, Individual secondPerson) { Individual[] newPerson = new Individual[2]; newPerson[0] = new Individual(); newPerson[1] = new Individual(); for(int i = 0; i < Individual.SIZE; ++i) { double r = rand.nextDouble(); if (r > 0.5) { newPerson[0].setGene(i, firstPerson.getGene(i)); newPerson[1].setGene(i, secondPerson.getGene(i)); } else { newPerson[0].setGene(i, secondPerson.getGene(i)); newPerson[1].setGene(i, firstPerson.getGene(i)); } } return newPerson; } public double getTotalFitness() { return totalFitness; } public static void main(String[] args) { // Initialise Environment Maze maze = new Maze(8, 8); maze.fillMaze(); // Instantiate Population //Population pop = new Population(); RunGA pop = new RunGA(maze); // Instantiate Individuals for Population Individual[] newPop = new Individual[POPULATION_SIZE]; // Instantiate two individuals to use for selection Individual[] people = new Individual[2]; Action action = null; Direction direction = null; String result = ""; /*result += "Total Fitness: " + pop.getTotalFitness() + " - Best Fitness: " + pop.findBestIndividual().getFitnessValue();*/ // Print Current Population System.out.println("Total Fitness: " + pop.getTotalFitness() + " - Best Fitness: " + pop.findBestIndividual().getFitnessValue()); // Instantiate counter for selection int count; for (int i = 0; i < MAX_ITERATIONS; i++) { count = 0; // Elitism for (int j = 0; j < ELITISM_K; ++j) { // This one has the best fitness newPop[count] = pop.findBestIndividual(); count++; } // Build New Population (Population size = Steps (28)) while (count < POPULATION_SIZE) { // Roulette Wheel Selection people[0] = pop.rouletteWheelSelection(); people[1] = pop.rouletteWheelSelection(); // Tournament Selection //people[0] = pop.tournamentSelection(); //people[1] = pop.tournamentSelection(); // Crossover if (rand.nextDouble() < CROSSOVER_PROB) { // One Point Crossover //people = onePointCrossover(people[0], people[1]); // Uniform Crossover people = uniformCrossover(people[0], people[1]); } // Mutation if (rand.nextDouble() < MUTATION_PROB) { people[0].mutate(); } if (rand.nextDouble() < MUTATION_PROB) { people[1].mutate(); } // Add to New Population newPop[count] = people[0]; newPop[count+1] = people[1]; count += 2; } // Make new population the current population pop.setPopulation(newPop); // Re-evaluate the current population //pop.evaluate(); pop.evaluate(maze, newPop); // Print results to screen System.out.println("Total Fitness: " + pop.totalFitness + " - Best Fitness: " + pop.findBestIndividual().getFitnessValue()); //result += "\nTotal Fitness: " + pop.totalFitness + " - Best Fitness: " + pop.findBestIndividual().getFitnessValue(); } // Best Individual Individual bestIndiv = pop.findBestIndividual(); //return result; } } I have uploaded the full project to RapidShare if you require the extra files, although if needed I can add the code to them here. This problem has been depressing me for days now and if you guys can help me I will forever be in your debt.

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  • getting a pyserial not loaded error

    - by skinnyTOD
    I'm getting a "pyserial not loaded" error with the python script fragment below (running OSX 10.7.4). I'm trying to run a python app called Myro for controlling the Parallax Scribbler2 robot - figured it would be a fun way to learn a bit of Python - but I'm not getting out of the gate here. I've searched out all the Myro help docs but like a lot in-progress open source programs, they are a moving target and conflicting, out of date, or not very specific about OSX. I have MacPorts installed and installed py27-serial without error. MacPorts lists the python versions I have installed, along with the active version: Available versions for python: none python24 python25 python25-apple python26 python26-apple python27 python27-apple (active) python32 Perhaps stuff is getting installed in the wrong places or my PATH is wrong (I don't much know what I am doing in Terminal and have probably screwed something up). Trying to find out about my sys.path - here's what I get: import sys sys.path ['', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python27.zip', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/PyObjC', '/Library/Python/2.7/site-packages'] Is that a mess? Can I fix it? Anyway, thanks for reading this far. Here's the python bit that is throwing the error. The error occurs on 'try import serial'. # Global variable robot, to set SerialPort() robot = None pythonVer = "?" rbString = None ptString = None statusText = None # Now, let's import things import urllib import tempfile import os, sys, time try: import serial except: print("WARNING: pyserial not loaded: can't upgrade!") sys.exit() try: input = raw_input # Python 2.x except: pass # Python 3 and better, input is defined try: from tkinter import * pythonver = "3" except: try: from Tkinter import * pythonver = "2" except: pythonver = "?"

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  • Glassfish war lifecycle question

    - by Robot
    What is the proper way to redeploy a new version of a running app in glassfish? I have a WAR running, and I've made changes. I thought doing an undeploy + deploy might be the right thing, but glassfish (v3) often crashes when I undeploy. What' the proper way to redeploy a running app in glassfish?

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  • Why does my MPMoviePlayerController disappear when I press play?

    - by Digital Robot
    I have a MPMoviePlayerController in a view, something like myMovie = [[MPMoviePlayerController alloc] initWithContentURL:URLfilme]; if (myMovie) { [myMovie setRepeatMode:MPMovieRepeatModeNone]; [myMovie setShouldAutoplay: NO]; [myMovie setScalingMode:MPMovieScalingModeAspectFit]; myMovie.view.frame = vFilme.bounds; [vFilme addSubview:[myMovie view]]; } The movie appears fine, I can scrub it, but when I press play, boooom, it vanishes. I have tried to retain myMovie but nothing changed. I have tried to play a video fullscreen and even using MPMoviePlayerViewController and is still disappears once I tap on play. Even the video player sample by Apple is not working. Is this a bug or what? EDIT Things are getting more interesting. If instead of playing the video manually by tapping on the play button I insert two timers, one to play the video and another one to pause it after 3 seconds, what I see is this: when the play is fired the video disappears and when the pause is fired the video reappears but when it does it has no controls. It is totally frozen, but the app continues to run normally. It is not anything related to video encoding, because I have tried with different videos, including one shot on the iPhone 4 and another shot on 3GS.

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  • iPhone - making the crash information more specific

    - by Digital Robot
    I have an app that is crashing at some point. Even with NSZombieEnabled turned on, the only thing I see is this message on the console: : * -[CFRunLoopTimer release]: message sent to deallocated instance 0x4cb34e0 but as the app is crashed, there's no way to know what object is this and the thread overview is not helping that much. #0 0x34a80466 in objc_msgSend #1 0x357e53c8 in CFRelease #2 0x357f3976 in __CFTypeCollectionRelease #3 0x3580c0b6 in __CFSetReleaseValue #4 0x357e6a5c in __CFBasicHashDrain #5 0x357e6900 in __CFSetDeallocate #6 0x357e54b6 in _CFRelease #7 0x357e53dc in CFRelease #8 0x3580c098 in -[__NSCFSet release] #9 0x3570f3be in -[_NSFaultingMutableSet dealloc] #10 0x3570f260 in -[_NSFaultingMutableSet release] #11 0x35702480 in -[NSManagedObject(_NSInternalMethods) _clearRawPropertiesWithHint:] #12 0x357022a8 in -[NSFaultHandler turnObject:intoFaultWithContext:] #13 0x35703dc0 in -[NSManagedObject dealloc] #14 0x356eab34 in -[_PFManagedObjectReferenceQueue _processReferenceQueue:] #15 0x357127d6 in _performRunLoopAction #16 0x3580ac58 in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ #17 0x3580aacc in __CFRunLoopDoObservers #18 0x358020ca in __CFRunLoopRun #19 0x35801c86 in CFRunLoopRunSpecific #20 0x35801b8e in CFRunLoopRunInMode #21 0x320c84aa in GSEventRunModal #22 0x320c8556 in GSEventRun #23 0x341dc328 in -[UIApplication _run] #24 0x341d9e92 in UIApplicationMain #25 0x00002e02 in main at main.m:14 it appears to be something related to core data, but knowing that doesn't help that much, because the app is all core data based and it crashes when I am not doing anything related to core data. is there a way to make the debugger more specific? thanks

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  • iphone - why is this flip animation using layers not working?

    - by Digital Robot
    I would like to make an animation that goes like this: imagine a picture sitting on a shelve. It drops from the shelve and as it falls it rotates along the horizontal axis and translates along the vertical axis. I would like to do this with perspective and the back side should be the image reversed, like the picture is a kind of slide. I have done this: CALayer* layer = myImageView.layer; layer.doubleSided = YES; CAKeyframeAnimation* animationTransform = [CAKeyframeAnimation animationWithKeyPath:@"transform"]; CATransform3D startTransform = CATransform3DIdentity; CATransform3D endTransform = CATransform3DTranslate (layer.transform, 0.0f, 200.0f, 0.0f); endTransform = CATransform3DRotate (endTransform, degreesToRadian(350.0f), 1.0f, 0.0f, 0.0f); endTransform.m34 = 1.0 / -500; NSArray *values = [NSArray arrayWithObjects: [NSValue valueWithCATransform3D:startTransform], [NSValue valueWithCATransform3D:endTransform], nil]; [animationTransform setValues:values]; NSArray *tempos = [NSArray arrayWithObjects: [NSNumber numberWithFloat:0.0f], [NSNumber numberWithFloat:0.7f], nil]; [animationTransform setKeyTimes:tempos]; NSArray *timing = [NSArray arrayWithObjects: [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut], nil]; [animationTransform setTimingFunctions:timing]; animationTransform.fillMode = kCAFillModeRemoved; animationTransform.removedOnCompletion = YES; animationTransform.repeatCount = 1; animationTransform.duration = 3.7f; animationTransform.cumulative = YES; the result of this has nothing to do with anything. The result is: the image translates down an inch on the screen and then up half inch. Then it disappears and appears at its starting position again. What am I missing? thanks

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  • iPhone - extending a class delegate

    - by Digital Robot
    OK, I know how to create a class extension, using something like that: on .h @interface UIButton (myExtensionName) // my extended methods @end and then on .m @implementation UIButton (myExtensionName) // my implementations @end But how do I declare the extended delegates I may create? If this was a normal class I would do @protocol myExtensionName <NSObject> // my delegate declarations @end but how do I do that on a class extension? thanks

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  • iPhone - sorting the results of a core data entity

    - by Digital Robot
    I have a core data entity that represents the attributes of a product, as number, price, etc. The product number is a NSString property and follows the form X.y where X is a number variable of digits and Y is one digit. For example. 132.2, 99.4, etc. I am querying the database to obtain the list of product numbers in order: The code is like this: + (NSArray*)todosOsItens:(NSString *)pName inManagedObjectContext:(NSManagedObjectContext *)context { Product *aProduct = [Product productWithName:pName inManagedObjectContext:context]; NSArray *all = nil; NSFetchRequest *request = [[NSFetchRequest alloc] init]; request.entity = [NSEntityDescription entityForName:@"Attributes" inManagedObjectContext:context]; request.predicate = [NSPredicate predicateWithFormat: @"(belongsTo == %@)", aProduct]; [request setResultType:NSDictionaryResultType]; [request setReturnsDistinctResults:YES]; [request setPropertiesToFetch:[NSArray arrayWithObject:item]]; NSSortDescriptor *sortByItem = [NSSortDescriptor sortDescriptorWithKey:@"ProductNumber" ascending:YES]; NSArray *sortDescriptors = [NSArray arrayWithObject:sortByItem]; [request setSortDescriptors:sortDescriptors]; NSError *error = nil; all = [[context executeFetchRequest:request error:&error] mutableCopy]; [request release]; return all; } but this query is not returning the sorted results. The results are coming on their natural order on the database. How do I do that? thanks.

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  • Java GUI amd FPGA

    - by murat
    Hi, I study on a robot simulator that written on Java environment.But sonar scan simulations and computational burden of some driven algorithms on robot drop my simulator's performance. So i have decided to use fpga module and put the computational burden on it.I have spartan 3a development kit for this implemenatation. Does anyone has any document or application sample that related with communication of java program on PC with fpga code. thanks.

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  • Class Problem (c++ and prolog)

    - by Joshua Green
    I am using the C++ interface to Prolog (the classes and methods of SWI-cpp.h). For working out a simple backtracking that john likes mary and emma and sara: likes(john, mary). likes(john, emma). likes(john, ashley). I can just do: { PlFrame fr; PlTermv av(2); av[0] = PlCompound("john"); PlQuery q("likes", av); while (q.next_solution()) { cout << (char*)av[1] << endl; } } This works in a separate code, so the syntax is correct. But I am also trying to get this simple backtracking to work within a class: class UserTaskProlog { public: UserTaskProlog(ArRobot* r); ~UserTaskProlog(); protected: int cycles; char* argv[1]; ArRobot* robot; void logTask(); }; This class works fine, with my cycles variable incrementing every robot cycle. However, when I run my main code, I get an Unhandled Exception error message: UserTaskProlog::UserTaskProlog(ArRobot* r) : robotTaskFunc(this, &UserTaskProlog::logTask) { cycles = 0; PlEngine e(argv[0]); PlCall("consult('myFile.pl')"); robot->addSensorInterpTask("UserTaskProlog", 50, &robotTaskFunc); } UserTaskProlog::~UserTaskProlog() { robot->remSensorInterpTask(&robotTaskFunc); // Do I need a destructor here for pl? } void UserTaskProlog::logTask() { cycles++; cout << cycles; { PlFrame fr; PlTermv av(2); av[0] = PlCompound("john"); PlQuery q("likes", av); while (q.next_solution()) { cout << (char*)av[1] << endl; } } } I have my opening and closing brackets for PlFrame. I have my frame, my query, etc... The exact same code that backtracks and prints out mary and emma and sara. What am I missing here that I get an error message? Here is what I think the code should do: I expect mary and emma and sara to be printed out once, every time cycles increments. However, it opens SWI-cpp.h file automatically and points to class PlFrame. What is it trying to tell me? I don't see anything wrong with my PlFrame class declaration. Thanks,

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  • Class Self-Reference

    - by Free Bullets
    I have the following code. The angle function needs some information from the class it was called from. What's the best way to do this? class MyScannedRobotEvent extends robocode.ScannedRobotEvent { public int angle(robocode.Robot myRobot) { return (int) Math.toRadians((myRobot.getHeading() + getBearing()) % 360); } } public class MyRobot extends robocode.Robot { int a = angle(**WHATDOIPUTHERE?**) }

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  • Find location using only distance and range?

    - by pinnacler
    Triangulation works by checking your angle to three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and it's to my right at 90 degrees." Repeat 2 more times for different targets and angles. Trilateration works by checking your distance from three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and I'm 100 meters away from that." Repeat 2 more times for different targets and ranges. But both of those methods rely on knowing WHAT you're looking at. Say you're in a forest and you can't differentiate between trees, but you know where key trees are. These trees have been hand picked as "landmarks." You have a robot moving through that forest slowly. Do you know of any ways to determine location based solely off of angle and range, exploiting geometry between landmarks? Note, you will see other trees as well, so you won't know which trees are key trees. Ignore the fact that a target may be occluded. Our pre-algorithm takes care of that. 1) If this exists, what's it called? I can't find anything. 2) What do you think the odds are of having two identical location 'hits?' I imagine it's fairly rare. 3) If there are two identical location 'hits,' how can I determine my exact location after I move the robot next. (I assume the chances of having 2 occurrences of EXACT angles in a row, after I reposition the robot, would be statistically impossible, barring a forest growing in rows like corn). Would I just calculate the position again and hope for the best? Or would I somehow incorporate my previous position estimate into my next guess? If this exists, I'd like to read about it, and if not, develop it as a side project. I just don't have time to reinvent the wheel right now, nor have the time to implement this from scratch. So if it doesn't exist, I'll have to figure out another way to localize the robot since that's not the aim of this research, if it does, lets hope it's semi-easy.

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  • Find location using only distance and bearing?

    - by pinnacler
    Triangulation works by checking your angle to three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and it's to my right at 90 degrees." Repeat 2 more times for different targets and angles. Trilateration works by checking your distance from three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and I'm 100 meters away from that." Repeat 2 more times for different targets and ranges. But both of those methods rely on knowing WHAT you're looking at. Say you're in a forest and you can't differentiate between trees, but you know where key trees are. These trees have been hand picked as "landmarks." You have a robot moving through that forest slowly. Do you know of any ways to determine location based solely off of angle and range, exploiting geometry between landmarks? Note, you will see other trees as well, so you won't know which trees are key trees. Ignore the fact that a target may be occluded. Our pre-algorithm takes care of that. 1) If this exists, what's it called? I can't find anything. 2) What do you think the odds are of having two identical location 'hits?' I imagine it's fairly rare. 3) If there are two identical location 'hits,' how can I determine my exact location after I move the robot next. (I assume the chances of having 2 occurrences of EXACT angles in a row, after I reposition the robot, would be statistically impossible, barring a forest growing in rows like corn). Would I just calculate the position again and hope for the best? Or would I somehow incorporate my previous position estimate into my next guess? If this exists, I'd like to read about it, and if not, develop it as a side project. I just don't have time to reinvent the wheel right now, nor have the time to implement this from scratch. So if it doesn't exist, I'll have to figure out another way to localize the robot since that's not the aim of this research, if it does, lets hope it's semi-easy.

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  • How do I avoid multiple key up/down/press events when holding a key?

    - by Rammay
    I'm creating a web front end to control a small robot. Ajax calls will be made on a keydown, to start the robot, and keyup to stop it. My problem is that when a key is held down the keyup, keydown, and keypress events seem to cycle continually. Does anybody know of a way to only have keydown fire when the key is first pressed and keyup to fire when it has been released?

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  • android - How to draw only the sprite from an image on the canvas

    - by user1320494
    this is the first time for me here, so I hope I'm doing this right :) My question is the following: how do I draw the sprite from an image on the canvas, so that I don't get the entire (squared) image to show, but only the parts of the image I want (= the sprite). For example, I have an image of a robot on a white background and I only want to see the robot, and not the white background. I hope someone here can help me with this problem, because it's giving me headaches of not knowing how to do it :P

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  • How do I make an object a property of a model in Ruby on Rails?

    - by iTake
    I have this in my schema: create_table "robots_matches", :force => true do |t| t.integer "robot_id" t.integer "match_id" and I think I want to be able to load a robot and match from within my robots_match model so I can do something like this: robots_match.find(:id).get_robot().Name My attempt in the robots_matches model was this: def get_robot Robot.find(this.id) end I am super new to rails, so feel free to correct my architectural decision here.

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  • Embeddable forum software

    - by Rented
    I am in the planning stages of a specific subject matter community web site, and one feature I feel is required is that of member discussions. However, not in a typical forum style. For example, I don't want the members to have to navigate away from their own "user space" in order to discuss a topic. I think it is best described with an analogous example. Lets say the site is for literature buffs, and each member has a set of pages for keeping notes, progress, questions, etc. on books they are studying/reading. So Joe will have one page for Great Expectations, another for Hamlet, a third for I, Robot, and so forth. Likewise, Jane will have a page for Don Quixote, Lord of the Flies, and also I, Robot. Now, wouldn't it be nice if Joe and Jane could discuss I, Robot from within their own respective pages? Now, at first thought, roll your own seems like the way to go. However, once we start getting into issues such as spam blocking, banning, ratings, pruning, archiving, flooding and so on, well "roll your own" doesn't sound too appealing anymore. Also, I have next to zero experience with forum software. So I'm looking for forum software that has an extensive API or is generally very integration-friendly. I would like to be able to create user groups, topics, permissions, etc. programmatically,as well as the obvious user authentication (most seem open in that respect). The site will most probably be built with Java. Tangler seems like a descent option, but it seems less mature than what I'd prefer.

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  • Using Fantom USB Driver from JNI

    - by Starky
    I'm having some difficulty with JNI. I'm using JNI to call some Java methods from a C++ program. This implementation of JNI is working fine. The goal of the Java program is to send commands over USB to a LEGO robot using LEJOS. This works fine when running the Java program by itself but for some reason when I call the methods from C++ the robot cannot be detected. My only lead so far is that there may be some problem using the Fantom USB driver from a JNI call. This is the driver that's used for the USB connection to the robot. I've had a quick look at the code for the driver and it looks like it makes use of JNI too. So I guess I'm asking the following things: What differences could there be between calling code from JNI and executing it through command prompt with the 'java classname args' method which could cause this problem? Could it be that there is some problem with me using JNI in C++ when the driver that's being used uses JNI as well? I won't post any code just now as I don't think it's really relevant but if anyone thinks that they need to see it then I can add it.

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  • A dynamic array of class "landmark", inside another single class "landmarks"

    - by pinnacler
    I'm working on a robot localization simulator and I created a class called "landmark". The end result is going to be a robot that is always centered and always faces the top of the screen. As it turns, the birds eye view map will rotate around the robot. To accomplish this, I'm assuming I can rotate one class and have all elements inside rotate as well. So, the landmark class has properties x,y, label, and radius. This is suppose to simulate a tree location in a forest. To test everything, I need "forest data," and I wrote a script to generate 100 trees in a 100m x 100m area. The script automatically generates values within an acceptable range for x,y, radius. The generated data is stored in an object called tempForest and is 100x3. Ideally, I want to create a class called "landmarks" (plural) that has 100 landmark instances inside. How would I instantiate 100 instances of landmark in one instance of landmarks using that randomly generated data? Ideally, I'd just type treeBeacons = landmarks(); and it would randomly populate 100 (user definable, set in config file) instances with x, y, radius data. I'm not sure how to deal with a dynamic array of class "Landmark", inside another single class "landmarks." Any ideas?

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  • Select all points in a matrix within 30m of another point

    - by pinnacler
    So if you look at my other posts, it's no surprise I'm building a robot that can collect data in a forest, and stick it on a map. We have algorithms that can detect tree centers and trunk diameters and can stick them on a cartesian XY plane. We're planning to use certain 'key' trees as natural landmarks for localizing the robot, using triangulation and trilateration among other methods, but programming this and keeping data straight and efficient is getting difficult using just Matlab. Is there a technique for sub-setting an array or matrix of points? Say I have 1000 trees stored over 1km (1000m), is there a way to say, select only points within 30m radius of my current location and work only with those? I would just use a GIS, but I'm doing this in Matlab and I'm unaware of any GIS plugins for Matlab. I forgot to mention, this code is going online, meaning it's going on a robot for real-time execution. I don't know if, as the map grows to several miles, using a different data structure will help or if calculating every distance to a random point is what a spatial database is going to do anyway. I'm thinking of mirroring two arrays, one sorted by X and the other by Y. Then bubble sorting to determine the 30m range in that. I do the same for both arrays, X and Y, and then have a third cross link table that will select the individual values. But I don't know, what that's called, how to program that and I'm sure someone already has so I don't want to reinvent the wheel. Cartesian Plane GIS

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