CSE 466 Blimp Project — Final Report

Capt. Dustin A. Richmond Private Eye Alexander K. Horton Robo Tamer Jim Youngquist

1 Introduction

1.1 Technical Goals

• How to produce a custom SimpliciTI application
• Use the SimpliciTI application to develop an interface for wireless control of the robotic blimp
• Implement a wireless RUN/STOP controller for the blimp
• Control the motors
• Control the IR proximity sensing subsystem
• Develop a PC-side GUI for remote control of your blimp.
• Implement autonomous altitude control using the IR proximity sensor.
• Develop a system to integrate all of the board features

1.2 Intellectual Goals

• Learn how to divide work evenly amongst a group in a way that ensures as little code integration overhead as possible
• Learn how to work with the multichannel timer peripherals on the F5510
• Learn how to control motors using PWM and an H-bridge driver IC
• Learn the theory of IR proximity sensing/ranging
• Learn the inner workings of the various blimp subsystems

2 Hardware:

3 Software and Firmware:

3.1 MSP 430F5510 “Operating System”

Our F5510 serially loops through five modes of operation; sense, transmit, receive, control, and sleep, see Figure 1↓. The microcontroller executes each of these states at 20 Hz. In the sense state, data is collected from the IR sensors. The transmit step sends collected data to the PC, where it may or may not be processed. Upon receive, the 5510 looks for a command from the PC, usually containing motor control data. The control phase actually enacts the command sent by the PC. Finally, at the end, the 5510 goes to sleep to maintain a 20Hz update rate and conserver power. It is possible to have a higher update rate, but in our experience that wasn’t necessary for control and merely consumes more power. A watchdog timer is also used to ensure uninterrupted service in case an error occurs somewhere during the main loop. Unfortunately such errors occured quite frequently due to apparent instability in the F5510 chip. These glitches were most pronounced when running the F5510 at 16MHz and higher, but were reduced to an acceptable operational level at 12Mhz.

Figure 1 F5510 main loop.

3.2 Motor Control:

3.3 Wireless Communication and UART System:

3.3.1 SimpliciTI Modules:

Figure 2 UART protocol.

3.3.2 Blimp Board 1.0 MSP430F5510 and Computer:

3.4 Sensor Control:

3.4.1 IR Sensor

1. multiplex into the LED and set its power to off [LED = 0]
2. set an accumulator to zero [acc = 0]
3. sample the value at the analog input channel [samp = ADC]
4. if the LED was off durring the sample, switch the sign of the sample [if LED : samp = -samp]
5. accumulate the value [acc = acc + samp]
6. toggle the LED pin state [LED = !LED]
7. Goto 3

3.4.2 E-Field Sensor

3.5 Final Application and GUI:

Figure 3 Sensor data.

3.6 Extra Functionality:

3.6.1 PS3 Controller

3.6.2 EField Sensing

4 Results and Analysis:

5 Discussion:

    // This code comes from uart_recieve_n(uint8_t len)
	uint16_t idx = 0;
	while(len--){         
		while(rx_hd == rx_tl);  // ERROR HAPPENS HERE
	    buffer[idx++] = rx_buf[rx_hd];
        rx_hd = (rx_hd + 1) & RX_MASK;
    }

6 Improvements

7 Conclusion:

8 Appendix: