1. Mobile Robot Control using Bluetooth Low Energy
Bachelor Thesis – Till Riemer

2. Contents
Concept and Requirements Project Background Software Design Realization Conclusion and Outview

3. Concept Real-world usage scenarios
Agriculture/cleaning vehicles for limited space environments
Consumer Electronics
SWAT / Rescue operations
Camera control / Fly Cam
Archeology exploration

4. Concept
Requirements
Designed for Hardware available on stock for mass production
Extendability and portability
Peripheral totally remotely controllable
Control interface usable by non IT experts
Focus on power saving and speed in accordance

5. Background Bluetooth Short-distance wireless communication protocol
Currently version 4.0 (introduced LE)
Consists of several layers (profiles):
Physical (2,4Ghz band)
L2CAP
GAP (Piconet/Master/Slave)
ATT(GATT) (Client/Server)
HCI …

6. Background Bluetooth Low Energy Extension to Bluetooth standard
Same frequency band and basic protocols
Reduced amount of adjusted profiles
Energy saving through shorter device discovery and sleep mode

7. Background Parallax Sumobot Atmel AVR Butterfly
Devkit for robots participating in Sumobot contest
BASIC stamp controller, easily extendable
Atmel AVR Butterfly
Embedded board based on Atmega 169V MCU
U(S)ART interface (no HW flow control)
1x 16bit, 2x 8-bit HW timer with PWM support
-> power supply changed to Sumobot 4x1.5V

8. Background Texas Instruments CC2540
Embedded Development kit with BLE stack on single chip (8051 MCU)
Embedded/UART and USB version
Supporting single/dual CPU and Master/Slave mode
Closed-Source OSAL, BLE stack programmable on all layers

9. Background
Apple iPhone 4S

10. Software Design
System Architecture

11. Software Design Butterfly application
Communication with CC2540 over HCI
using the UART interface
Receiving 1-byte movement commands over GATT, interpreting into predefined movement actions
example: Forward 1x -> GATT recv. 0x01 -> setMotorSpeed(50,50);
Servo control using hardware timer (PWM)

12. Software Design

13. Software Design CC2540 application
Based on HostTestRelease sample project by Texas Instruments
Peripheral Mode
Registered functions handle external Bluetooth Messages and HCI commands
GAP on device, GATT transmission to host over HCI

14. Software Design iPhone application Based on TI example application
Model/View/Controller
Delegator
Buttons controling relative direction
3-step speed control

15. Realization iPhone application Movements as predefined distinct values
Multi-tab view
using Navigation Controller
and Swipe Gesture Recognizer objects
Movement buttons sending 1-Byte code over GATT
Several improvements such as status bar, different
Connection interval etc.

16. Realization CC2540 application Minor changes:
UART flow control disabled
GATT forwarding over HCI
Peripheral device configuration

17. Realization Butterfly application
Servos using PWM timer like in Sumobot project
UART:
one-time Oscillator calibration
Interrupt-driven UART driver + Message Queues
HCI interface

18. Conclusion Current state
iPhone application more or less done, further improvements
Connection window to be optimized
GATT transmission over HCI tbd
Future testing

19. Conclusion Possible Improvements Control interface:
3-axis gravity sensor control
Fluent 2D-space movement (-> Diablo)
Speech recognition (Siri?)
Authorization / AES encryption
XML data transmission protocol
Efficience analysis and power saving optimization

20. Thank you for attending!