1. Built-From-Scratch Self-Balancing Inverted-Pendulum Wheelie-Popping Remote-Controlled Vehicle March 14, 2008 Jude Collins Christopher Madsen

2. Preliminary Design Presentation ➲ Technical aspects of the robot ➲ Literature/Patent search ➲ Schedule ➲ Finances

3. Overview ➲ Robot system overview—Chris Microcontroller Inertial measurement unit Bluetooth radio H-Bridge/Motors ➲ Remote control—Jude Microcontroller Bluetooth radio N64 Controller

4. Overview ➲ Literature/product search—Chris “Trajectory Tracking Control for Navigation of Self-contained Mobile Inverse Pendulum” (1994). Segway (2002). David P. Anderson's “nBot” (2003). ➲ Schedule and finances—Jude ➲ Questions

5. Robot system overview

7. Microcontroller ➲ MSP430F1611 ➲ Running 4 MHz ➲ 12 bit A/D with 8 pin- accessible inputs ➲ Two 16 bit timers ➲ 1.8-3.6v

8. Inertial Measurement Unit ➲ IDG-300 Gyroscope ➲ ADXL-330 Accelerometer

9. IDG-300 Gyroscope ➲ Dual-Axis rate gyroscope ➲ Operates by oscillating masses and capacitively measuring vibration caused by Coriolis effect. ➲ Sensitivity: 2 mV/deg/s ➲ Max rate: 500 deg/s ➲ Operating voltage: 3.0-3.3v

10. ADXL-330 Accelerometer ➲ Triple-axis accelerometer ➲ Micro-machined structure suspended over silicon by polysilicon springs. Plates mounted on moving structure and a fixed structure act as a variable capacitor in a filter circuit to measure acceleration. ➲ Sensitivity: ~300mV/g ➲ Max acceleration: ±3.0g ➲ Operating voltage: 2.0-3.6v (sensitivity is ratiometric)‏

11. PID Controller

12. Estimating pendulum orientation ➲ Integrating rate gyros is subject to drift errors. ➲ Accelerometers only work to determine orientation when not accelerating. ➲ Use both estimates to get better estimate of orientation.

13. Bluetooth Radio ➲ Basically a breakout board for NXP's BGB203. ➲ Class 1 so has a 100m range ➲ 100 mW max transmitted power ➲ 3.3 volts ➲ 1 Mbps max UART

14. H-Bridge ➲ LMD-18200 ➲ 3 amps continuous, 6 amps temporary

15. Remote Control

16. The Remote Control ➲ Needed Peripherals Joystick A few buttons ➲ Modify old N64 controller. Exceeds requirements Cheap ($5-$15 on Amazon.com)‏

17. Control Flow

18. The microcontroller ➲ Needed peripherals UART fclk > 1 MHz Low Vcc ➲ ATMEGA8515L Already had the chip. UART 20 MHz 2.7 – 5.5 V Low Cost ($3.06-$5.27 Digikey.com)‏

19. N64 Controller Interface ➲ Bidirectional data line. ➲ PWM - 1:3 Micro sends poll request. Bit-Bang 32 bit response. ➲ Fixed Frequency Poll and Transmit ~20 Hz

20. Data Line PWM

21. Literature/patent search ➲ First appearance of similar two-wheeled inverted pendulum that can navigate in 2 dimensions on a plane: “Trajectory Tracking Control for Navigation of Self-contained Mobile Inverse Pendulum” by Yunsu Ha and Shin'ichi Yuta of Japan in 1994. Position encoders on wheels (2000 step)‏ Sensors to detect obstacles No remote-control

22. Literature/patent search ➲ Segway Most popular inverted-pendulum type product. Patented just about everything imaginable concerning inverted pendulum human transportation. Have several Robotic Mobility Platform (RMP) models

23. Literature/patent search ➲ David P. Anderson's nBot Received NASA's Cool Robot of the Week award and subsequently became well-known in the minds of robotics enthusiasts (2003). Launched a revolution of inverted-pendulum robot building. Homebrew shaft encoders.

24. How are we different? ➲ Back EMF encoders rather than mechanical encoders. ➲ Bluetooth radios enabling hardware-in-the- loop simulation. ➲ Goal to stand up autonomously.

25. Schedule

26. Finances—Robot

27. Finances—Remote Control

28. Finances ➲ Allotted budget: $1000 ➲ Expenditures: ~$500 ➲ Main expenses: 1 IMU -- $110 2 Bluetooth radios -- $120 1 MSP430 on breakout board -- $50 2 Motors and H-Bridges -- $80

29. Questions?

30. Simple inverted pendulum model

31. Simple inverted pendulum with force input

32. H-Bridge Direction Control ➲ Forward ➲ Reverse ➲ Brake ➲ Short Circuit

33. H-Bridge Amplitude Control