1. PowerBot Group #2: Tarik Ait 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 Part NumberSST58D3830RS-540 ManufacturerShinano KenshiTamiya TypeStepperDC Brushed Step Angle (°)1.8N/A No Load RPMN/A16,800 Voltage (V)2.14.5-12 Current (A/Phase)3.01 (no load) Resistance (Ω/Phase)0.7N/A Inductance (mH/Phase)1.3N/A Holding/Stall Torque (kg-cm)7.32.84 Rotor Inertia (g-cm 3 )290N/A Weight (kg)0.710.153 Dimension (L)54 mm50 mm

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. Application Layer MCU – Serial 802.11 – Socket iOS – Serial 802.11 – Socket Application Layer Embedded SoftwareiOS Software

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

25. iOS Application 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. SPECIFICATIONSNi-CdNi-MHLi-ionLi-Po Energy Density (W·hr/kg)40–6070-90100-160130-200 Capacity (Amp-hr)12.42.82.6 Internal Resistance (mΩ)100-200200-300100-200200-300 Nominal Voltage (V)1.2 3.63.7 Discharge RateFlat Recharge Life500-700 cycles600-1000>600>1000 DisposalMust be recycledRecyclable Charge/Discharge Efficiency 70-90 %66 %80-90 %99.80 % Cost ($/Whr)22.752.52.8-5 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 MonocrystallinePolycrystallineThin film Power10 W Open Circuit voltage21.521.424.2 Short Circuit Current0.640.680.84 Maximum Power Voltage17.516.817.3 Maximum Power Current0.570.60.64 Efficiency15 %12.5 %6.3 % Cost/W10-118.5-9.510

35. Solar Power Selection Details Solar Panel TypeMonocrystalline ManufacturerINSTAPARK Efficiency15 % Power10 W Maximum Voltage Power17.5 Maximum Current Power0.57 A Open Circuit Voltage21.95 V Cost$39.95

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 Ambient LightPhotoresistorMSP430 Longitude Orientation

38. Dual Axis Control System Ambient Light PhotoresistorMSP430 Latitude Orientation Longitude Orientation

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

41. Budget PartCostQuantityTotal Cost RC Car Chassis $501 Motors Solar Panel$401 Inductive Charger $401 Battery$1052$210 Dev Board$501 PICKit 3$501 Sonar Sensors $3010$300 Circuit Components Total~$550

42. Distribution of Labor TarikLukeMarcelJerald Solar Panel80%5%10%5% MCU Software25% Robot Construction10%5%80%5% Wireless Design5%70%5%20% Navigation/AI5%20%5%70%

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?