Preliminary Design Report. Project Name: Finger Pointer

Transcription

1 EEL 4924 Electrical Engineering Design (Senior Design) Preliminary Design Report 27 January 2011 Project Name: Finger Pointer Team Members: Name: Nunn, Christopher Name: Hamilton, Travis Project Abstract: Our project is intended to replace a mouse with a glove that the user will wear. The cursor will track the index finger of the user while clicking will be achieved by pressing buttons connected to the middle and ring finger of the user. These buttons can easily be pressed with the thumb of the user, while still maintaining pointing ability with the index finger. We plan to accomplish our goal by using an infrared led on the index pointer that will be detected by a CMU cam at the monitor. The CMU cam will communicate the tracking information of the index finger to the PIC microcontroller. The microcontroller will convert x and y coordinates from the CMU cam into data packets to be sent to the computer. Then, following USB HID (Human Interface Device) Protocol, the microcontroller will send the data packets to the computer through a USB cable. If the protocol is followed correctly, our project should work on a Windows or Mac computer without the need for additional drivers.

2 Page 2/6 TableofContents ProjectFeaturesandObjectives... 3 ConceptandTechnology... 3 Figure Figure Figure MaterialsandResources... 6 SeparationofWork... 6 GanttChart... 6

3 Page 3/6 Project Features and Objectives The main objective is to create a glove that can control the functions of a standard mouse (scroll capabilities implemented if time allows). Features include: Image tracking of the index finger by the CMU Cam2 Wireless glove realized by battery supply and XBEE USB 2.0 connectivity realized by PIC18F27J53 microcontroller Concept and Technology The hardest decision in our design was determining the best way to track the user s index finger. The technologies considered were infrared range detecting, sonar, and image processing. The problem encountered with infrared range detecting was the narrow signals associated with it; therefore the glove would be very directional. We feared with infrared, the index finger would have to be pointed directly at the sensor to register a distance and therefore we would not be able to receive signals at multiple detectors to triangulate the location of the emitter. Because of the problems with IR, we then switched to the idea of sonar. The block diagram for the sonar signal is shown in Fig. 1. Sonar emits in a wider signal, making it a better solution for our application. We were going to have four receivers to triangulate the position of the emitter. Our major concern with this design was the resolution of our detection. We were unsure if the sensors would be accurate and consistent enough to be a good HID. After hearing bad things about a Nintendo Power Glove (used sonar to implement an HID device), we decided to use image processing. Fig.1: Block Diagram of Sonar System.

4 Page 4/6 Image tracking is a resource intensive process that relies on sophisticated software algorithms. After research and suggestions from peers, we purchased a CMU Cam2. This camera was developed by Carnegie Mellon University and does onboard image processing at up to 50 frames/second with up to a resolution of 160 x 255. We determined that this resolution and frame rate would allow us to implement a well designed HID. The CMU cam will serially communicate to the PIC microcontroller and can send tracking coordinates of the centroid of defined blobs. This blob will be created by applying a visible light filter to the camera and aiming the camera at a gloved hand with an IR LED at the tip of the index finger. The blob will look much like the blob in Fig 2. Fig. 2 Blob Detection The CMU cam will locate the center of this blob and send the X and Y coordinates back to the PIC as a pixel location. This location will be compared to the previous frames blob center location and the difference of the X s and the difference of the Y s will be taken. This comparison is how mouse data is conveyed to the PC. The mouse does not send a set of coordinates every time it updates, but rather it sends the difference from the current frames X and Y and the previous frames X and Y. A typical mouse will update at about 100 hz, but since the camera only operates at 50 frames per second, we will be updating the coordinates at 50 hz. This will cause a small lag in mouse operation, but it should only be noticeable in fast paced activities such as game play. The block diagram for the HID device using the CMU Cam2 is shown in Fig. 3. Once we receive data telling us where the user s index finger is, we need to actually send the data to the PC. The PIC microcontroller we chose has two UART inputs, one for the CMU Cam and one for the XBEE device. Also, the PIC supports USB 2.0 capabilities to communicate with the PC. By sending data packets that follow the HID protocol, we should be able to emulate the mouse without installing any drivers for a Windows PC or Mac. There will be two XBEE devices used to transmit the states of the left and right click buttons on the glove. We purchased the low power with chip antenna model for two reasons. Firstly, we needed the

5 Page 5/6 low power because the glove will be operating off of battery power, and secondly, the on chip antenna is not invasive to the user like the integrated wire antenna is. Fig 3. Block Diagram of the CMU Cam System

6 Page 6/6 Materials and Resources: 1. PIC Microprocessor 2. CMU Cam2 3. XBee RF Module (2) 4. IR LED 5. IR Filter for Camera 6. Glove 7. Battery Separation of Work TASK CHRIS TRAVIS Preliminary Research 60% 40% CMU Cam Interface 70% 30% USB Interface 30% 70% Xbee Interface 50% 50% Prototyping 50% 50% Board Construction 40% 60% Troubleshooting 50% 50% Gantt Chart TroubleshooHng BoardConstrucHon Expected Prototyping XbeeInterfaceProgramming USBInterfaceProgramming CMUCaminterface Programming PreliminaryResearch