Sariel.pl

Simple Bluetooth-controlled chassis for a smartphone acting as a live feed camera. Features two motors with independent analog steering, and a third one controlling camera elevation.  

Datasheet:

Completion date: 20/10/2012
Power: electric (NXT brick)
Language: ROBOTC
Bricks: 1
Motors: 3 x NXT motor
Sensors: none

I always liked the idea of controlling MOCs from the front of a computer. A while ago I tried this with PF-controlled MOCs and wireless camera, but the PF range was very limited, and the quality of camera transmission was very low. Having found an Android app called IP Webcam, I decided to give it another try, this time with a Bluetooth link for remote control and a Wi-Fi link for video feed.

The whole chassis was extremely simple, with just a handful of parts built around the NXT unit. Two motors with a single wheel each were providing propulsion – I found wheels to run smoother than treads – and another motor was controlling camera’s elevation. The first two motors had analog control enabled from a control pad, while the third was operated by buttons. I have created a simple smartphone holder with rubber connectors, that should fit most of typical smartphones.

The model was fun to drive around, and the video quality was very good. There was a noticeable delay in the video feed though, which made steering a little awkward, and the Bluetooth range was not so impressive – I could hardly drive to another room, just a single wall between the model and the computer was troublesome.

Control program:

#include "JoystickDriver.c"

task main()
{
  bMotorReflected[motorA] = false;
  bMotorReflected[motorB] = true;
  while(true)
  {
    getJoystickSettings(joystick);
    motor[motorA] = 0;
    motor[motorB] = 0;
    motor[motorA] = joystick.joy1_y1 / 1.28;
    motor[motorB] = joystick.joy1_x2 / 1.28;
    nxtDisplayCenteredTextLine(0, "BATTERY: %3.1fV", nImmediateBatteryLevel / (float) 1000);
    nxtDisplayTextLine(2, "B: %d", motor[motorA]);
    nxtDisplayTextLine(3, "C: %d", motor[motorB]);

    if(joy1Btn(5) == 1)
      motor[motorC] = -5;
    else if(joy1Btn(7) == 1)
      motor[motorC] = 5;
    else
      motor[motorC] = 0;
  }
}
									

Photos:

Video: