PowerBot Group #2: Tarik Ait El Fkih Luke Cremerius Marcel Michael Jerald Slatko

1. PowerBot Group #2: TarikAit El Fkih Luke Cremerius Marcel Michael Jerald Slatko Sponsored By: Aeronix, Inc.

2. Project Description • Autonomous robot purposed to provide supplemental power to mobile devices (laptops, mobile phones, etc.). • Uses onboard navigation algorithms to navigate to user’s location. • Incorporates an iOS application to provide robot statistics and manual control.

3. Project Motivation • Battery life longevity in mobile devices is a constant issue. • Wanted to create a charging solution that could charge the device without inconveniencing the user. • The device would be simple to use, allowing for easy adoption into a users everyday routine.

4. Objectives • PowerBot should be able to navigate autonomously to a user’s location. • PowerBot should be able to be remotely controlled by the user through the use of an onboard camera and the provided iOS application. • PowerBot will contain a battery used to charge external devices through the use of inductive and USB interfaces.

5. Specifications • Will be at most 36” long • Max speed of 5 mph • Battery life of minimum 24 hours • Ability to provide charge to mobile devices 100% of the time.

6. Switching Voltage Regulators • Needed to regulate power to the different systems in PowerBot. • Highly efficient when compared to linear voltage regulators; 14-40% vs. 85-90%.

7. Inductive Charging • 9 V switching regulator: LT1424-9 • Used to step down voltage for charging mat. • SO-8 package. • Charging mat offers a degree of flexibility due to lack of wires. • Inductive cases are needed unless implemented (Qi) by manufacturer.

8. USB Charging • 5 V switching regulator: DE-SW050 • Used to step down voltage for USB charging. • Pin-compatible with 78XX family (TO-220 package) of linear voltage regulators. • USB, although wired, is, well, universal.

9. Microcontroller Supply • 3 V switching regulator: DE-SW033 • Used to step down voltage for the microcontrollers. • Pin-compatible with 78XX family (TO-220 package) of linear voltage regulators.

10. Motors • Stepper Motor: • To be used to rotate (Θ-axis) the solar panel. • Brushed DC Motor: • To be used to drive the rear wheels.

11. Motor Specifications

12. Motor Controllers • MSP430F123 will be used to control the solar panel [stepper] motor. • Contains hardware UART for serial communications.

13. Motor Controllers • MSP430F2616 will be used to control the DC brushed motor. • Its features: • Interfaces with UART. • 16 MHz with 4 kB of RAM and 92 kB of flash memory. • 48 GPIOs. • ADC resolution of 12 bits with 8 channels.

14. R/C Car Chassis • Somewhat standard over-the-counter licensed R/C car. • Large wheels allow for maneuverability.

15. Chassis Modifications • Swap out the drive motor to (DC Brushed). • Remove the [red] plastic body frame and create a foundation for PowerBot.

16. Obstacle Avoidance • Obstacles will be detected using ultrasonic ranging sensors • As PowerBot moves, the ultrasonic sensors rapidly take readings to gather range data in real time. • The obstacle avoidance algorithm will maneuver PowerBot in response to the presence of obstacles. • Three modes of operation: • Active Adjustment (AA) • Reverse-Reset (RR) • Off • Obstacle avoidance is OFF by default. It must be enabled by the iPhone user

17. Modes of Operation Active Adjustment (AA) • Primary mode of operation • Front two ultrasonic sensors are active • A range reading within the AA minimum distance causes PowerBot to steer either left or right to avoid it. • PowerBot will attempt to re-align

18. Ultrasonic Sensors LV-MaxSonar® – EZ0™ • Operates at 2.5 V – 5.5 V • Avg. current draw: 2 mA • Min. Distance: 6 in. • Obstacles closer than 6 in. give reading of 6 in. • Max. Distance: 254 in. (21 ft.) • 1 inch Resolution • Range readings can be taken at about 20 Hz, every 50 ms. • Output modes include: • Analog • Pulse Width • UART (not quite RS-232) Image Credit: www.maxbotix.com

19. PIC32 Microcontroller • PIC32 family of microcontrollers was chosen to drive PowerBots navigation and Wi-Fi communication functions. • The PIC32 features an 80 MHz clock with onboard 512 kB of flash and 128 kB of RAM. • Model Number: PIC32MX695F512H

20. Wi-Fi Communication • Used as the primary mode of communication between PowerBot and the iOS application. • 802.11 Wi-Fi used as a physical layer with TCP sockets used for higher level communication. Embedded Software iOS Software Application Layer Application Layer MCU –Serial iOS– Serial 802.11 – Socket 802.11 – Socket

21. Wi-Fi Module: MRF24WB0MA • The MRF24WB0MA microchip provides a complete Wi-Fi solution for onboard communication with PowerBot. • The Microchip TCP/IP stack works with the MRF24WB0MA and allows for easier implementation of sockets and the passing of data via TCP.

22. PIC32 Wi-Fi Circuit Board • Microchip Wi-Fi Comm Development Board was used for prototyping. • Custom circuit board was based off of this design. • Combines PIC32 MCU with the MRF24WB0MA Wi-Fi module. • Additionally gives access to 4 UART ports, as well as 6 GPIO pins used for ultrasonic sensor data acquisition and motor commands PIC32 Wi-Fi Circuit Board

23. PIC32 Wi-Fi Board Layout

24. Software Layout iOS Application PowerBot Motor Control Obstacle Avoidance Algorithm Power Management Sonar Sensors Stepper Motor Solar Panel Charging Ports

25. iOSApplication • Written in Objective-C using Xcode 4.4. • Provides users access to: • Manual mode • Obstacle Avoidance • Ultrasonic sensor status

26. Manual Control • Gives the user manual controls to drive PowerBot. • Sensor icons blink when currently taking distance readings. • Status of Wi-Fi connection shown above robot controls.

27. System Status • Shows the user the current sensor status of PowerBot. • Displays the onboard sensor distance readings • Shows the number of readings received from each sensor • I/O Data button allows viewing all incoming TCP data

28. System Settings • Allows the user to open a socket connection to PowerBot once the user has joined the ad-hoc network PowerBot broadcasts. • Toggle button for turning obstacle avoidance on or off.

29. Power

30. Battery Requirements • 24 V battery • At least 2 Ah • Deep cycle for increased usage time • Low internal resistance • Flat discharge rate • Lightweight

31. Battery Choice

32. Lithium Polymer Battery • Polymer Li-Ion Battery • 18650 cell type • 14.8 V (working) • 16.8 V (peak) • 2.2 Ah • 32.56 Wh • Reasons for choosing: • High energy density (Wh/kg) • High energy/dollar (Wh/$)

33. Alternative Power Source • Power outlet: • “Unlimited” power • Quick charging of the battery • Solar panel: • Environmental Impact • Financial Benefits • Energy Independence

34. Solar Panels Specifications

35. Solar Power Selection Details

36. Output Efficiency • Increasing the output efficiency of the panel: • Increase panel size • Implement tracking system • Single axis • Dual axis

37. Single Axis Control System

38. Dual Axis Control System

39. Compare and Contrast • Dual axis control system would require more maintenance. • There’s an extra cost involved in utilizing an extra motor or actuator. • Increased complexity. • 6% extra efficiency compared to a single axis control system; not worth it.

40. Solar Panel Implementation • Free rotation of theta ( angle. • Phi ( is fixed in single axis system. • Optimal angle of phi (is 15°.

41. Budget

42. Distribution of Labor

43. Concerns • Ability to accurately depict a global map and link it to PowerBot’s local map. • Ability to correctly implement EERUF. • Ability for PowerBot to become unstuck in a trap situation.

44. Questions?