Final Year Project: Design and Build an Air Mouse for people with lower mobility

1. Final Year Project:Design and Build an Air Mouse for people with lower mobility Electronic and Computer Engineering Colin Grogan 06656404

2. Components • The Toothpick takes readings from an accelerometer and sends the results to the PC • PC will then control cursor based on received information

3. Overview of System

4. Design • Must fit on a glove • Tilting of hand causes cursor movement • Large zone where no cursor movement • Larger tilt causes faster movement of cursor • Buttons should be easy to press • Made from copper contacts. Removes need to “click” the buttons

5. Design Goals • Pass: • Design and build a working air mouse • Average • Design software for PC that receives information from air-mouse and move the mouse around the screen in real time • Good • Design a working gesture recognition algorithm for the mouse • Design a application on the PC so that users can define their own gestures for later use • Very Good • Get both systems working effectively together • Exceptional • Get the system into a case and fitting onto a glove

6. Design Goals review • Air-Mouse is not completely working • Pass • PC successfully controls cursor based on information received from Air-Mouse • Average • Gesture recognition algorithm effectively picks up user made gestures. • Can easily define new gestures and associated commands • Good • Cannot launch Gesture Recognition easily from device, must use shortcut • Device not yet in a case or mounted onto glove.

7. Planning

8. Design Decisions and why • Toothpick microcontroller used for the device. • Toothpick has a good amount of ports(for accelerometer and buttons) • Built in support for Bluetooth protocol. • Coded in C • Using a C++ application on PC to control the cursor • C++ is compiled to machine code and therefore will run quickly • Microsoft libraries to control cursor and serial port

9. Technology • Bluetooth • Bluetooth technology is easily accessible on modern PCs • High speed protocol, battery life suffers as a result • Alternative? Zigbee • Zigbee is suited to low data rate, low power applications • Not as easily accessible to PC users as Bluetooth

10. Hardware • Block Diagram: • Divided into functional blocks • Accelerometer – Changes output based on movement of hands • Voltage Dividers – Changes the reference voltage for the ADC

11. Software • 3 programs needed: • Cursor Control • Connects to device • Controls cursor based on data received • Automatically disconnects when data is not received consecutively • Gesture Recognition • Detects shape made by cursor • Shapes made of movements in 4 directions, Up, Down, Left Right • Executes command associated with shape. Shapes stored in gestures.dat • Device program • Receives control data from PC • Sends requested information

12. Gesture RecognitionAlgorithm • Simple algorithm, can quickly define new gestures for use. • Algorithm: • Store initial position into memory • Check if the user moves past a boundary(say 50 or 100 pixels – can easily change) • Concatenate direction of movement onto String. Will be either U, D, L, R • Save new “initial” position into memory • Repeat until user specifies

13. Mouse Control program • Windows.h made it very easy to controlthe cursor on screen. • Small example:ReadFile(hSerial,inBuff,3,&dwBytesRead,NULL); • This will read from the serial port “hSerial”,save the data into “inBuff”, which an array of size “3” and save the number of bytes actually read into “dwBytesRead” • The “NULL” argument is for special options that weren’t needed

14. Final Device

15. Problems • The device does not work as expected. • The Toothpick wont read information from the ADC • This is a result of rebuilding the circuit, original circuit worked fine. • Accelerometer can only give unique values over 180° • Means mouse cannot be used in any position and thus is not entirely suitable for project • Possible fix would be to use an accelerometer based on different technology • Or use 3 accelerometers all cantered on different angles

16. Questions?