One ring project.An air mouse universal remote controllerIntroductionOne ring project is started since 8 - 2014. The project aims to help people get more easy to connect and control hi tech things in your house with one device only. Touching the device to connect, and making a gesture to control your device are two simplest steps to bring you to the new era of technology.One day you have a presentation. You will need an air mouse can click, move next and back, play a video or handle a problem in your presentation without moving forward and backward between your computer and your place. Your finger is your pointer, your gestures are your commands. These things give you an option to liberate you from mouse stuffs. Or when you are in a car, you need to answer a call, make a call to your favorite person, play a music, or open a navigation system, all your needs is simple click and make gesture. Your life will be better, more convenient than ever.

Firmware description

In this part, we will discuss about the technology behind the ring: Firmware and its algorithm.The system of the ring can be describe as the picture below:

Touch sensorMCU with RF module inside6 axis accelerometer gyroscope.

6 axis accelerometer and gyroscope sensor

This sensor called MPU 6050 with can provide two types of data: raw data , Calculated data( quaternion , Euler vector) from an inside processor called Digital Motion Processor DMP .In order to control mouse: raw data will be used to navigate the location of the mouse pointer, because of the low latency of reading raw data.In order to record a gesture, data from DMP will be used to analyze because its require quaternion data which is not be affects when you are not wearing the ring 100% in the center.Quaternions and spatial rotation.

When you first click your ring before making a gesture, current quaternion will be recorded to calculate the rotation vector matrix to original vector (1,0,0) a vector point ( can be also (0,1,0); (0,0,1) depend on the position of the sensor).Original vectorCurrent vectorRotation matrix

Next, new vector will be rotated base on the rotation matrix

Rotation matrix

Rotated vector

Current vector

A point in 2d space

Rotated vector

Next, rotated vector will be converted to a point in 2D space.

This point on 2D space will be used to draw an image to record gesture Raw data

Raw data uses only 2 of 3 axes of gyroscope.New vertical position = current position + Gyroscope channel Z raw dataNew horizontal position = current position + Gyroscope channel X raw dataBecause the movement pointer was feedback directly by your eyes (you can see the present position of the pointer) so there is no need to use quaternion data to control the air mouse. Gesture recognitionCurrently, the gesture recognition can record 6 gestures:1) Up2) Down3) Anti-clockwise4) Clockwise5) Next6) BackThe current algorithm is very simple. It detects two dimension of the image (height and wide ) and original point to detect 4 gesture : Up, down, next, back. For clockwise and anti-clockwise detection, we need to add more parameter: the movement vector of the original vector to detect the anti-clockwise and clockwise detectionLimits of this algorithm: Hard to develop more gestures: It was limited by the power of MCU ,as well as lack of parameter to detect the gestures Limited in wide angle gesture: Because the pointer is converted from 3d to 2d space. Which means you will get an error when you finger move too much, outside of the 2d space. You can have a look at the picture below

Height =+

Advances of this algorithm: Simple, easy to use, easy to remember. Low error.