Android remote control app. Send up to three values over wifi using udp protocol

Introduction

Send up to three values over wifi using UDP protocol.

And choose from three methods of input:

• 
  Touch
  
• 
  Slide
  
• 
  And even Tilt!
  

Android API 2.1 and above, open-source, and completely free

For more details on its features, see the next video in the series.

[made by Jonathan Abbott at CINVESTAV]

Features

We’re going to talk about:

• 
  The connections
  
• 
  The controls
  
• 
  The vibrations
  
• 
  The available languages
  
• 
  And advanced features such as artificial inertia
  

The Connections

Hapti uses UDP protocol. UDP protocol (as opposed to TCP protocol) doesn’t check that information arrived. But UDP protocol is fast and simple, and that’s why it is used here.

The Controls

The Three Types of Input

Touch

Slide

Tilt

• 
  The first option is ‘tilt lock’, which means that the position will only move if you are the touching the screen
  
• 
  The second option is whether you want position or velocity. With position, the position is just a linear scale from angle to position. With velocity, the velocity is proportional to how much you tilt the phone.
  

Other Control Options

Note that the min and max values stay fixed; reversing just flips the output within the limits.

Vibrations

The app is integrated with Immersion MOTIV™ Haptic Effects so that you can have your phone vibrate based upon touching the screen or actual input such as forces.

Touch Feedback

Force Feedback

Languages

Esté aplicación de control remoto de Androide incluye ambos español e inglés.

If other languages are desired, see the developer reference video.

Advanced Features

Appearance

Artificial Inertia

The first most basic option is maximum speed.

The other option is a spring-mass-damper system. The app will automatically calculate the damping ratio ζ, the undamped natural frequency ω, and even what settings are needed to make it critically damped. Critically damped has the fastest spring-mass-damper response without overshoot.

You can optionally show the inertial position shown as a darkened image if desired.

Delays

The Socket Timeout option limits the amount of time the app will wait to receive input before restarting. Half a second is good. Large values may prevent the application from ending correctly.

Miscellaneous

• 
  The reset option – view the option to start the position as the position ended from the previous time or from the start position in preferences. This may be useful if you accidently leave the application and want to resume from the same place.
  
• 
  Vibration duration – lets you determine how long to vibrate due to “force” feedback or until another packet is received.
  

Other information

In experimentation, we found that we were sending nearly 400 packets/s when we specified a 2.5 ms delay. However, the rate limiting factor was the rate at which new positions of touching the screen could be recorded. The actual rate of new information was about 90 Hz. Your phone may vary, and if you use artificial inertia, you should see new information more frequently.

If you want more options, you should watch the next video made for beginning developers.

[Made by Jonathan Abbott at CINVESTAV]

Hapti Android Remote Control App – Developer Details

This free open-source Android Remote Control App was designed to be customizable for other developers. It’s well commented, hopefully simply enough, and already pre-built with most options that you would desire.

I will quickly cover

• 
  A few additional things you might like to add
  
• 
  The basics of how this application works
  
• 
  How to get started coding with this application
  

A Few Additional Things You Might Like

Additional Languages

It would be easy to add additional languages in addition to English and Spanish. Simply copy the res-values folder and rename it values-xx (where xx corresponds to whichever language. Search online for “android localization list.”) Then change the text.

Different Bitmaps (Pictures)

Don’t like the color orange? Want other shapes? You can easy change this in the res/drawable. Remember the 3:4:6:8 scaling ratio and use PNG types to keep transparency.

Note: the ‘margins’ of the screen are currently set so the bitmaps will never go off the screen. So make the object boundaries clear.

Precise Time Waiting

Currently the delay is set up at an “additional” delay after each packet sent. It might be better to have an “on-the-go” delay that gives a precise time each packet is sent. This was previously avoided for simplicity and less calculation.

Warning Messages

There is currently only descriptive dialog text for EditText preferences. (Note: ListPreferences do not support dialogs). Having warning messages would be helpful.

Numerical Screen Output

Showing the position will slow down the screen refresh rate, but might be helpful for precision tasks. Furthermore, showing the confirmation of sending, receiving, and loading preferences would be nice.

Ping Test

This would be great to put in the connections options.

Change Structure

Some of the classes could have been moved outside of the main class. Originally avoided this because there are many global variables that get used frequently. It was easier to start with everything together. In Eclipse, press control, shift, / (divide) to collapse all and it is not so bad to read.

The Basics of How the Application Works

There are basically two parts: the main application and then all the preferences. This section here also describes some of the rational for the design.

The Main Application

The main application is one large java class with a number of threads and a few methods (some as methods within classes).

The layout is as follows:

• 
  Imports
  
• 
  public class RemoteControlApplication extends Activity implements OnTouchListener{
  
  • 
    Lots to Initialize as global variables
    
  • 
    onCreate – loads most preferences
    
  • 
    onResume – starts threads
    
  • 
    onPause – stops threads
    
  • 
    onTouch – get position of pointers and do slide
    
  • 
    InertiaAndTilt – combined inertial effects and tilt
    
  • 
    MySurfaceView – draw to the screen
    
  • 
    SendUDPData - send
    
  • 
    ReceiveUDPData – receive and vibrate
    
  • 
    Method: getLocalIpAddress() – used at beginning
    
  • 
    Class+Methods: Screen2Coor – used frequently, transformation
    
  • 
    Class+Methods: Coor2Screen – used frequently, transformation
    
  • 
    Method: MakeByteBuffer() – used frequently, generate the bytes to send
    

One convention I used was that capital XYZ mean screen position and lower-case xyz mean real position. All screen positions are converted to real position, which is then retransformed back to screen position.

The Preferences

I used PreferenceActivity for the preferences for compatibility. The newer PreferenceFragment handles multiple preferences screens better, but may not have reverse compatibility. For this reason, I had to do some work in the java classes. One such example is listing all the keys of preferences for updated summaries. It’s a little tedious, but seemed to be the best method.

I could have used android:dependency to enable/ disable different preferences, but in order to maintain consistency with also referencing ListPreferences, this is all in java.

How to get started coding with this application

If you are new to programming in java for android, I would personally recommend thenewboston.org Android series. The first three tutorials will describe how to get all the necessary free software you need to begin programming. I went through about 70 of the 200 tutorials and then used online references (stackoverflow.com, developer.android.com, and others) for most specific questions. If you are just modifying small parts of this application, online references may be sufficient.

Directory: jabbott
jabbott -> Mit address Jonathan E. Abbott

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