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

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

Overview of System

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

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

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.

Planning

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

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

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

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

Gesture Recognition Algorithm 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

Mouse Control program Windows.h made it very easy to control the 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

Final Device

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

Questions?