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  • iphone moving direction using accelerometer

    - by Ruchir Shah
    Hi, I want some help on UIAccelerometer class. I want to find some way to find out or distinguish when I wave iphone device from right-to-left and the left-to-right. I am getting x,y,z values as well as interval value. I am also getting velocity and distance calculated from normal physics rule. Distance = (prevDist + sqrt(pow((prevx - acceleration.x), 2) + pow((prevy - acceleration.y), 2) + pow((prevz - acceleration.z), 2))) Velocity = (Distance * timeintercal) { here distance means newdistance-prevdistance and timeinterval for that distance } When I am moving iphone device right-to-left then left-to-right I am getting total distance traveld in both direction and velocity at regular intervals. Can you help me how I can find out that I am moving iphone device left-to-right or right-to-left? Help would be appreciated. Thanks.

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  • IPhone sdk stop the accelerometer from working when something happens.

    - by Harry
    Hi, I am using the accelerometer to move a few UIImageViews around the screen, at the moment the accelerometer only works when a NSTimer is at 0, this is fine. I would also like to make the accelerometer stop again when a different function happens. here is my code at the moment: -(BOOL) accelerometerWorks { return time == 0; } -(void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration{ if(![self accelerometerWorks]) return; valueX = acceleration.x*25.5; int newX = (int)(ball.center.x +valueX); if (newX 320-BALL_RADIUS) newX = 320-BALL_RADIUS; if (newX < 0+BALL_RADIUS) newX = 0+BALL_RADIUS; int XA = (int)(balloonbit1.center.x +valueX); if (XA 320-BALL_RADIUS) XA = 320-BALL_RADIUS; if (XA < 0+BALL_RADIUS) XA = 0+BALL_RADIUS; int XB = (int)(balloonbit2.center.x +valueX); if (XB 320-BALL_RADIUS) XB = 320-BALL_RADIUS; if (XB < 0+BALL_RADIUS) XB = 0+BALL_RADIUS; int XI = (int)(balloonbit3.center.x +valueX); if (XI 320-BALL_RADIUS) XI = 320-BALL_RADIUS; if (XI < 0+BALL_RADIUS) XI = 0+BALL_RADIUS; int XJ = (int)(balloonbit4.center.x +valueX); if (XJ 320-BALL_RADIUS) XJ = 320-BALL_RADIUS; if (XJ < 0+BALL_RADIUS) XJ = 0+BALL_RADIUS; int XE = (int)(balloonbit5.center.x +valueX); if (XE 320-BALL_RADIUS) XE = 320-BALL_RADIUS; if (XE < 0+BALL_RADIUS) XE = 0+BALL_RADIUS; int XF = (int)(balloonbit6.center.x +valueX); if (XF 320-BALL_RADIUS) XF = 320-BALL_RADIUS; if (XF < 0+BALL_RADIUS) XF = 0+BALL_RADIUS; int XH = (int)(balloonbit8.center.x +valueX); if (XH 320-BALL_RADIUS) XH = 320-BALL_RADIUS; if (XH < 0+BALL_RADIUS) XH = 0+BALL_RADIUS; ball.center = CGPointMake (newX, 429); balloonbit1.center = CGPointMake (XA, 429); balloonbit2.center = CGPointMake (XB, 426); balloonbit3.center = CGPointMake (XI, 410); balloonbit4.center = CGPointMake (XJ, 415); balloonbit5.center = CGPointMake (XE, 409); balloonbit6.center = CGPointMake (XF, 427); balloonbit8.center = CGPointMake (XH, 417); } This all works fine, i would now like to stop the accelerometer from working, using the same accelerometerWorks method or a new method, accelerometerWontWork. This is the code that when it is called i would like the accelerometer to stop. (it is very long so i wont put all of it there, but its all the same throughout): -(void) checkCollision{ if (CGRectIntersectsRect(pinend.frame, balloonbit1.frame)){ if (balloonbit1.frame.origin.y pinend.frame.origin.y){ [maintimer invalidate]; levelfailed.center = CGPointMake (160, 235); } } if (CGRectIntersectsRect(pinend.frame, balloonbit2.frame)){ if (balloonbit2.frame.origin.y pinend.frame.origin.y){ [maintimer invalidate]; levelfailed.center = CGPointMake (160, 235); } } if (CGRectIntersectsRect(pinend.frame, balloonbit3.frame)){ if (balloonbit3.frame.origin.y pinend.frame.origin.y){ [maintimer invalidate]; levelfailed.center = CGPointMake (160, 235); } } } I understand that i may have to turn this into a BOOL. Thats fine. If i haven't explained it well please say and i will re write it. Thanks! Harry.

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  • Algorithm for optimal control on space ship using accelerometer input data

    - by mm24
    Does someone have a good algorithm for controlling a space ship in a vertical shooter game using acceleration data? I have done a simple algorithm, but works very badly. I save an initial acceleration value (used to calibrate the movement according to the user's initial position) and I do subtract it from the current acceleration so I get a "calibrated" value. The problem is that basing the movement solely on relative acceleration has an effect of loss of sensitivity: certain movements are independent from the initial position. Would anyone be able to share a a better solution? I am wondering if I should use/integrate also inputs from gyroscope hardware. Here is my sample of code for a Cocos2d iOS game: - (void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { if (calibrationLayer.visible){ [self evaluateCalibration:acceleration]; initialAccelleration=acceleration; return; } if([self evaluatePause]){ return; } ShooterScene * shooterScene = (ShooterScene *) [self parent]; ShipEntity *playerSprite = [shooterScene playerShip]; float accellerationtSensitivity = 0.5f; UIAccelerationValue xAccelleration = acceleration.x - initialAccelleration.x; UIAccelerationValue yAccelleration = acceleration.y - initialAccelleration.y; if(xAccelleration > 0.05 || xAccelleration < -0.05) { [playerSprite setPosition:CGPointMake(playerSprite.position.x + xAccelleration * 80, playerSprite.position.y + yAccelleration * 80)]; } else if(yAccelleration > 0.05 || yAccelleration < -0.05) { [playerSprite setPosition:CGPointMake(playerSprite.position.x + xAccelleration * 80, playerSprite.position.y + yAccelleration * 80)]; } }

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  • How to detect iPhone movement in space using accelerometer ?

    - by super_tomtom
    Hi ! I am trying to make an application that would detect what kind of shape you made with your iPhone using accelerometer. As an example, if you draw a circle with your hand holding the iPhone, the app would be able to redraw it on the screen. This could also work with squares, or even more complicated shapes. The only example of application I've seen doing such a thing is AirPaint (http://vimeo.com/2276713), but it doesn't seems to be able to do it in real time. My first try is to apply a low-pass filter on the X and Y parameters from the accelerometer, and to make a pointer move toward these values, proportionally to the size of the screen. But this is clearly not enought, I have a very low accuracy, and if I shake the device it also makes the pointer move... Any ideas about that ? Do you think accelerometer data is enought to do it ? Or should I consider using other data, such as the compass ? Thanks in advance !

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  • Using iphone accelerometer AND UIEventSubtypeMotionShake event simultaneousluy.

    - by lukya
    Hi, I am using accelerometer to move/change things on the screen in my app. I also need to detect UIEventSubtypeMotionShake in the view controller for some other animations. As my app is a simple view based app, there is just one view controller which acts as UIAccelerometerDelegate AND FirstResponder (for detecting the shake event). After the first Shake gesture is detected, I don’t need accelerometer inputs through [accelerometer didAccelerate] method so I set the accelerometer delegate to nil. -(void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event { if (motion == UIEventSubtypeMotionShake) { NSLog(@"shake"); [[UIAccelerometer sharedAccelerometer] setDelegate:nil]; //my shake handling code } } The problem is that the first shake motion is not being detected correctly. I have to shake 2 3 or more times to trigger the UIEventSubtypeMotionShake event, while the subsequent shakes, after the accelerometer delegate is made nil, are being detected perfectly. This must be happening because UIEventSubtypeMotionShake in turn depends on the accelerometer didAccelerate events which are being overridden by my code. But I need to use both the events. Are there any apps or code samples which use both accelerometer and UIEventSubtypeMotionShake simultaneously? Thanks Swapnil

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  • How can I unit test an Android Activity that acts on Accelerometer?

    - by Corey Sunwold
    I am starting with an Activity based off of this ShakeActivity and I want to write some unit tests for it. I have written some small unit tests for Android activities before but I'm not sure where to start here. I want to feed the accelerometer some different values and test how the activity responds to it. For now I'm keeping it simple and just updating a private int counter variable and a TextView when a "shake" event happens. So my question largely boils down to this: How can I send fake data to the accelerometer from a unit test?

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  • iPhone accelerometer:didAccelerate: seems to not get called while I am running a loop

    - by AJ
    An accelerometer related question. (Sorry the formatting may not look right, its the first time I am using this site). I got the accelerometer working as expected using the standard code UIAccelerometer *accel = [UIAccelerometer sharedAccelerometer]; accel.delegate = self; accel.updateInterval = 0.1; //I also tried other update values I use NSLog to log every time the accelerometer:didAccelerate: method in my class is called. The function gets called as expected and everything works fine till here. However, when I run a loop, the above method doesn't seem to get called. Something like this float firstAccelValue = globalAccel; //this is the x-accel value (stored in a global by the above method) float nextAccelValue = firstAccelValue; while (nextAccelValue == firstAccelValue){ //do something nextAccelValue = globalAccel; // note globalAccel is updated by the accelerometer method } The above loop never exits, expectedly since the accelerometer:didAccelerate: method is not getting called, and hence globalAccel never changes value. If I use a fixed condition to break the while loop, I can see that after the loop ends, the method calls work fine again. Am I missing something obvious here? Or does the accelerometer method not fire when certain processing is being done? Any help would be greatly appreciated! Thanks!

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  • Accelerometer stops delivering samples when the screen is off on Droid/Nexus One even with a WakeLoc

    - by William
    I have some code that extends a service and records onSensorChanged(SensorEvent event) accelerometer sensor readings on Android. I would like to be able to record these sensor readings even when the device is off (I'm careful with battery life and it's made obvious when it's running). While the screen is on the logging works fine on a 2.0.1 Motorola Droid and a 2.1 Nexus One. However, when the phone goes to sleep (by pushing the power button) the screen turns off and the onSensorChanged events stop being delivered (verified by using a Log.e message every N times onSensorChanged gets called). The service acquires a wakeLock to ensure that it keeps running in the background; but, it doesn't seem to have any effect. I've tried all the various PowerManager. wake locks but none of them seem to matter. _WakeLock = _PowerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "My Tag"); _WakeLock.acquire(); There have been conflicting reports about whether or not you can actually get data from the sensors while the screen is off... anyone have any experience with this on a more modern version of Android (Eclair) and hardware? This seems to indicate that it was working in Cupcake: http://groups.google.com/group/android-developers/msg/a616773b12c2d9e5 Thanks! PS: The exact same code works as intended in 1.5 on a G1. The logging continues when the screen turns off, when the application is in the background, etc.

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  • android accelerometer accuracy is extremely poor

    - by user564594
    Wrote a simple program that prints out accelerometer output. mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); mSensorManager.registerListener(this,mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_FASTEST); It turns out that: The accelerometer output is always set to "lowest" as determined by: public void onAccuracyChanged(Sensor sensor, int accuracy) { if (collectingData){ accelPrecision.setText("accelerometer accuracy: " + accuracy); } } The actual accelerometer readings are very inaccurate - about 2%-5% fluctuations even when it's resting on the table as far as I can tell it's the same problem on Nexus S, Nexus One and G1 Any idea how it could be made mode accurate / what sets a

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  • Laptop authentication/logon via accelometer tilt, flip, and twist

    - by wonsungi
    Looking for another application/technology: A number of years ago, I read about a novel way to authenticate and log on to a laptop. The user simply had to hold the laptop in the air and execute a simple series of tilts and flips to the laptop. By logging accelerometer data, this creates a unique signature for the user. Even if an attacker watched and repeated the exact same motions, the attacker could not replicate the user's movements closely enough. I am looking for information about this technology again, but I can't find anything. It may have been an actual feature on a laptop, or it may have just been a research project. I think I read about it in a magazine like Wired. Does anyone have more information about authentication via unique accelerometer signatures? Here are the closest articles I have been able to find: Knock-based commands for your Linux laptop Shake Well Before Use: Authentication Based on Accelerometer Data[PDF] Inferring Identity using Accelerometers in Television Remote Controls User Evaluation of Lightweight User Authentication with a Single Tri-Axis Accelerometer Identifying Users of Portable Devices from Gait Pattern with Accelerometers[PDF] 3D Signature Biometrics Using Curvature Moments[PDF] MoViSign: A novel authentication mechanism using mobile virtual signatures

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  • Cocos2d shake/accelerometer issue.

    - by Ryan Poolos
    So I a little backstory. I wanted to implement a particle effect and sound effect that both last about 3 sec or so when the user shakes their iDevice. But first issue arrived when the build in UIEvent for shakes refused to work. So I took the advice of a few Cocos veterans to just use some script to get "violent" accelerometer inputs as shakes. Worked great until now. The problem is that if you keep shaking it just stacks the particle and sounds over and over. Now this wouldn't be that big of a deal except it happens even if you are careful to try and not do so. So what I am hoping to do is disable the accelerometer when the particle effect/sound effect start and then reenable it as soon as they finish. Now I don't know if I should do this by schedule, NStimer, or some other function. I am open to ALL suggestions. here is my current "shake" code. - (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { const float violence = 1; static BOOL beenhere; BOOL shake = FALSE; if (beenhere) return; beenhere = TRUE; if (acceleration.x > violence * 1.5 || acceleration.x < (-1.5* violence)) shake = TRUE; if (acceleration.y > violence * 2 || acceleration.y < (-2 * violence)) shake = TRUE; if (acceleration.z > violence * 3 || acceleration.z < (-3 * violence)) shake = TRUE; if (shake) { id particleSystem = [CCParticleSystemQuad particleWithFile:@"particle.plist"]; [self addChild: particleSystem]; // Super simple Audio playback for sound effects! [[SimpleAudioEngine sharedEngine] playEffect:@"Sound.mp3"]; shake = FALSE; } beenhere = FALSE; }

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  • Preventing sleep in Titanium for iPhone

    - by Morten J
    I'm trying to read the accelerometer for a longer period of time (between one and two hours). However, when the iPhone goes to sleep and locks, the reading of the accelerometer readout is paused. My setInterval timer seems to be running fine though. I can also play sounds. I see two solutions a) Find a way to read the accelerometer while locked b) Find a way to prevent the lock I'm using Titanium with JavaScript.

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  • How To use Android Accelerometer Detection

    - by Rakesh
    Hello Sir,i want to know how to calculate the accelerometer movement.When i place the mobile horizontally in idle state and similarly when i place the mobile in hands,So there accelerometer value change when it is place horizontally or while it is in hand vertically.How To Identify them,Any Sample Codes will be useful Regards Rakesh Shankar.P

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  • Android Speed based on accelerometer values

    - by fraguas
    Hi. I need to obtain the velocity of an android device, based on the accelerometer values. I made a code that allows me to get the accelerometer values, and then I calculate the velocity, using the formula: v = v0 + at. (vector calculation) My problem is that my velocity only increases and never decreases. I think the problem is that the device never gets an negative acceleration. Can you help me with this?

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  • Using accelerometer to detect iPad lock switch trigger?

    - by DevDevDev
    So for complicated reasons I am managing view rotations myself, and am only implementing UIDeviceOrientationPortrait as the autorotating orientation. Anyway, when one clicks the screen lock on the iPad, the device will rotate to UIDeviceOrientationPortrait, which will cause my code to rotate, which I do not want to happen. For instance of the user is holding the device in "landscape mode", i.e. I have already manually rotated the UI to landscape mode, and he/she clicks the screen lock, it will rotate the UI to portrait mode, even though the user did not move the device at all. So somehow I need a way to differentiate between rotations to portrait mode occuring from the screen lock, and those occuring from device rotation. As such, I would like somehow to use the accelerometer to detect whether or not the device was actually 'rotated' or whether the button was clicked. Thanks!

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  • iPhone, I can send accelerometer data via wifi only 248 lines

    - by newbie
    I have created one application on iPhone. I build an application that gather accelerometer value and pass this value to c# server in realtime via wifi connection. I use NSStream with IP and port number. I was working perfectly, but now I realize that it stops after fetch value only 248 lines. I tried to write this value in text file locally on iPhone. I can obtain more than 260 lines of data. Therefore, I suspect that it has some limitation or other problems on NSStream of wifi connection.

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  • Basic doubt about sensor usage

    - by Al
    Suppose I have a cellphone with accelerometer and magnetometer, and want to determine its absolute (wrt North/East/South/West) 3d position. Imagine the phone is laid vertically, with the screen facing me, the "up" vector pointing to the ceil. Whenever I tilt, the accelerometer allows me to get the "up" vector info change. The problem is that if I tilt the device and put it horizontally (screen now facing ceil, and "up" vector pointing to the opposite of where I am), then the up vector doesn't get updated any more if I rotate the phone horizontally on the table. This is something that clearly is detected by the magnetometer now. So, the question is, when to know where to use acc or mag for each case? Is there a generic way to achieve this?

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  • iPhone "multi-threading" question

    - by MrDatabase
    I have a simple iPhone game consisting of two "threads": the main game loop where all updating and rendering happen 30 times per second (NSTimer)... and the "thread" that calls the accelerometer delegate 100 times per second. I have a variable "xPosition" that's updated in the accelerometer delegate function and used in the game loop. Is there a possibility of the two "threads" trying to use xPosition at the same time (hence causing a crash or some other problem). If so how can I fix this w/ minimal impact to the game's performance? I've been using this set-up for many months of development and incremental testing and I've never run into any problems. Cheers!

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  • Android - How to approach fall detection algorithm

    - by bobby123
    I want to be able to feature a fairly simple fall detection algorithm in my application. At the moment in onSensorChanged(), I am getting the absolute value of the current x,x,z values and subtracting SensorManager.GRAVITY_EARTH (9.8 m/s) from this. The resulting value has to be bigger than a threshold value 10 times in a row to set a flag saying a fall has been detected by the accelerometer, the threshold value is about 8m/s. Also I'm comparing the orientation of the phone as soon as the threshold has been passed and the orienation of it when the threshold is no longer being passed, this sets another flag saying the orientation sensor has detected a fall. When both flags are set, an event occurs to check is user ok, etc etc. My problem is with the threshold, when the phone is held straight up the absolute value of accelerometer is about 9.8 m/s, but when i hold it still at an angle it can be over 15m/s. This is causing other events to trigger the fall detection, and if i increase the threshold to avoid that, it won't detect falls. Can anyone give me some advice here with what possible values i should use or how to even improve my method? Many thanks.

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