1. Capability Enhancements for Autonomous Mobile Wireless Sensor Platforms 05506 Advisor: Dr. S. Jay Yang – CE Team Members Andrew Mullen – CE Edgar Martin – ME Khoa Nguyen – CEDarnelle Haye - ME Stephen Ortiz – CE Adam Haun - EE Sponsor

2. Presentation Overview Project Goal –Design Objectives Objectives –Task Groups Formed to Accomplish Objectives Senior Design I Timeline Chassis Design Process –Concepts and Prototypes Electrical Design Process –Component Selection Communication Implementation Senior Design II Timeline Questions?

3. Project Goal Develop a set of four mobile wireless sensor platforms with the ability to autonomously communicate and make decisions, independent of a base station, to create formations

4. Design Objectives Phase I –Design a cost effective and energy efficient chassis. –Determine an appropriate sensor configuration to facilitate identification of objects and locomotion. –Implement robust assembly code allowing the robots to move freely through their environment Phase II –Integrate wireless communication allowing the robots to exchange information rapidly and effectively using the Mica2dot RF Transceivers. –Construct an additional Three Mobile Sensor Platforms –Develop and Code algorithms implementing formations

5. Task Groups Darnelle Haye & Edgar Martin (MEs) –Develop Chassis Design –Fabrication and Assembly of Chassis Stephen Ortiz & Khoa Nguyen (CEs) –Communication Interface –Wireless Software Development Adam Haun (EE) & Andy Mullen (CE) –Circuit-board Layout and Design –Sensor Integration –Robot Intelligence Assembly Code

6. Senior Design I Timeline First Quarter –Week 3: First Team Meetings, Performed Concept Development and began Feasibility Analysis –Week 4: Basic chassis fabricated, performed weight test –Week 5: Completed Feasibility Analysis, Began Implementation –Week 6: Second chassis, autonomous movement –Week 7: Improved Movement Commands to allow a more robust and modular Interface –Week 8: Integrated Sonar Sensor –Week 9: Began Planning for Demonstration –Week 10: Debug, perform demonstration

7. Chassis Design Concepts Use a Pre-Built robotics kit or Custom Design –There are many kits to help novices design robots Method Of Locomotion –Different Drive Systems (Differential, Synchro, Skid- Steer, Car-Type) Pivot Point Options –Castor Wheel or Ball Bearing Materials Selection

8. Feasibility Analysis Results Three Tier Design Chose to use 2 Stepper Motors –Utilizing Differential Drive Ball Bearings –More effective than a Castor Material - Acrylite FF Sheets –Lightweight, rigid, and weather-resistant thermoplastic. –Dimensionally stable, resistant to breakage, and can be easily sawed, machined, heat-formed and cemented

9. Initial Concepts -Does Not Rotate around Center of Mass -Inefficient Use of Space -Awkward -Not Enough Space for Components -Overly Heavy

10. Initial Prototypes -Circular shape saves weight -Makes Design more efficient -Space for Sensors -Location For Battery Pack -Used for weight test -Measured Maximum Load -Prototype Unacceptable For actual use

11. Current Chassis Design Ball Bearing Integrated Slight resize of platform levels

12. Mechanical Future Plans Integrate a more efficient ball bearing which is better suited for the mobile platform’s design Attach the compass chip to the chassis –Due to magnetic interference from the motors the compass chip must be at least 6 inches from a motor –Magnetic shielding may allow the compass sensor to be located closer to the rest of the electronics Examine the platform for ways to reduce weight

13. Electronics & Sensor Concepts PIC Microcontroller Selection Motor Controller Selection Distance Sensors –Infrared Sensors –Ultrasonic Sensors –Which is more effective? Compass Sensor –Is one available which meets our needs and budget? Power Supply –Rechargeable battery? Size? Weight? Power? –Universal Power Supply or Multiple Power Supplies

14. Feasibility Analysis Results PIC-18F4320 Microcontroller MC3479P & UC3770 Motor Controllers –Both will be tested, MC3479 has a simpler interface, UC3770 may be more effective Front and Rear Ultrasonic Sensors –Devantech R93-SRF04 Ranger Integrate Compass Sensor –Devantech R117-COMPASS 9.6 Volt NiMh 1600 mAhr batteries –An LM317T is used to provide the 5V necessary to run the PIC, controller logic, and sensors. –3.3V may be added in the future to power wireless motes

15. Microcontroller Capability We used a PIC18F4320 to control the system. The PIC provides sufficient I/O ports to control the motors and interface with any of the sensors the team examined. –Nearly 40 Input/Output Bits –4 Independent Timers –Internal USART support An internal clock speed of 8MHz gives the team plenty of extra processing power.

16. Initial Motor Controller(MC3479P) Pros: Low current, compact Cons: Weak, high heat

17. Current Motor Controller(UC3770AN) Pros: High power, low heat Cons: Requires two chips per motor and more complicated programming.

18. Sonar Sensor Relatively narrow Beam Pattern Linear Output Highly Accurate Range – 3 to 300 cm

19. Compass Sensor Adds Global Direction to Sensor Platforms Simplifies Algorithms Senses to within 0.1 Degrees

20. Assembly Considerations For the prototype, the main concern was the ability to easily change the circuit. A breadboard fills this need. However, the breadboard is unsuitable for the final robot because of its fragility and complexity. For the final robot, we will order a printed circuit board. This will be more compact and allow for more secure mounting.

21. Communication Goals Integrate the Mica2dot RF Transceiver with the main microcontroller. –Establish capabilities of Mica2Dot Wireless Motes. –Research Mica2 mote applications and proceed with execution on Mica2Dot motes. –Determine how the motes are processing messages (Packet Information) –Learn how to code NC programs to implement desired functionality on the Mica2Dot Motes –Establish Communication between Motes, by means of a base station controlled by PC to other motes Develop an interface through which communication can be effectively established.

22. Mica2Dot Wireless Mote Quarter-Sized (25mm), Wireless Platform for Smart Sensors Designed Specifically for Deeply Embedded Wireless Sensor Networks Battery-Powered Lightweight

23. Mica2Dot Interface The Mica2Dot has 18 solderless expansion pins –6 Analog Inputs –6 Digital I/O Channels –UART (Universal Asynchronous Receive Transmit) interface. UART transmission will be used for direct communication from the Mica2Dot to the PIC chip.

24. Transmission Packet Information Destination address (2 bytes) Active Message handler ID (1 byte) Group ID (1 byte) Message length (1 byte) Payload (up to 29 bytes): –Source Mote ID (2 bytes) –Sample Counter (2 bytes) –Transmission Information Readings (up to 25 bytes)

25. Mica2Dot Code Written in NC (Network Channel) code. The code used to identify both switched and non-switched channel services. NC coding is module C based code. A module header file is needed to define the wiring used by the module as well as determine the module’s interface. The TinyOS operating system is Task Driven

26. Current Communication Progress Radio Communication –Set up wireless communication and packet sending demonstrated by the red LED on a mote. One mote blinks an LED and sends packets to all other motes instructing them to blink their LED. Injecting and broadcasting packets sent by a Base Station –Injected packets from a PC into the sensor network by means of Led_on and Led_off commands. Base Station mote broadcasts messages to receiving motes. RS-232 Cable

27. Communication Future Plans Establish communication allowing a variable number of motes to send, process, and receive information without interference. Eliminate base station control to allow each sensor platform to remain autonomous Write code to visually log the information sent by the Mica2Dot motes on a computer terminal.

28. System Integration Challenges Difficult to Debug if Errors Occur –All Code done in assembly –No effective debugging tool because of sensor input Mica2Dot Motes –TinyOS installation and configuration is complex –UART Transmission difficult to test –CE computer virus Sonar Sensors –Can’t display distance easily –Difficult to manipulate received data

29. Senior Design II Timeline

30. Questions or Suggestions?

31. Extras

32. Motor Comparison

33. Mica2Dot Pinout

34. Microcontroller Pinout