The 3D positioning and gesture tracking technology incorporated in all of today's sensors, such as the Kinect Sensor or Leap Motion Controller, as well as the camera/sensor included in the VR bundles of Oculus Rift or HTC Vive, is based on IR.
The challenge that this project addresses is to develop a sensor device, alternative to the 3D IR camera/sensor, which -
- costs merely 6.4%, ($7.6, i.e, counterfeit Arduino Uno + geared motor) compared to 2 x Oculus Sensor (2 x $59 as stated in https://www.oculus.com/accessories/), and also much less than other IR cameras/sensors.
- has completely open source hardware (an Arduino project), software and tracking algorithms, as opposed to the hardware and tracking algorithms of those IR cameras/sensors.
- is precise up to 1 mm, along all 3 dimensions, as opposed to a resolution of around 1 cm provided by today's IR camera/sensors.
- can be reconstructed from scratch in a mere 10 minutes, and has very simple schematics and build design.
- as opposed to IR cameras/sensors is able to see beyond opaque obstruction, and whose tracking precision is not compromised owing to white or shiny surfaces.
Brief Explanation of Tracking Algorithm
- Water potentiometer gives the voltage at tip of the stylus.
- Voltage gives a plane containing the tip of the stylus.
- Geared DC motor rotates the sensor to give 3 different voltages for 3 different angular positions, for the same fixed stylus tip.
- 3 different voltages implies 3 non-parallel plane equations.
- 3 non-parallel planes intersect at a unique point.
- x, y, z coordinates of that point is the stylus tip's location.
Detailed Explanation of Tracking Algorithm
(This is not a video of the final prototype. It just demonstrates the water potentiometer technique used in this project and practically verifies the below differential equations.)
The basic idea behind this sensor is the use of a parallelopiped water container as a water potentiometer device. It is similar to a 3-pin slide pot used in electronic circuits, with the 2 aluminium electrodes equivalent to the 2 end pins of a slide pot, and the stylus equivalent to the middle pin (voltage output) of a slide potentiometer. Since water is an electrolyte, its composition, hence, conductivity does not remain uniform on passing current through it. Thus, to retain uniform composition, electrolysis must be minimized. In order to minimize electrolysis, the following adaptations have been made -
- The microcontroller C++ code constantly keeps swapping over the polarity...