Difference between revisions of "F13: Line Following Robot"

Revision as of 16:40, 2 December 2013

Grading Criteria

Line Following Robot

Abstract

The Line Following Robot detects a black line on a white surface and moves forward following the line. If a black line is not detected, the Line Following Robot moves forward searching for a black line to follow. Once the Line Following Robot detects a black line, it will begin following the black line.

Objectives & Introduction

Show list of your objectives. This section includes the high level details of your project. You can write about the various sensors or peripherals you used to get your project completed.

Objectives

The objectives of the Line Following Robot include:

• Move forward searching for a black line on a white surface.
• Detect a black line on a white surface.
• Generate control commands to follow a detected black line.

Introduction

InIn order to follow a black line on a white surface, the Line Following Robot interfaces the NXP LPC1758 microcontroller on the SJ One Board with a Reflectance Sensor Array and Dual Serial Motor Controller. The LPC1758 microcontroller acquires sensor data from the Reflectance Sensor Array, generates motor commands to steer the Line Following Robot based on the sensor data, and transmits the motor commands via a serial interface to the Dual Serial Motor Controller. Upon receipt of the motor commands, the Dual Serial Motor Controller provides the appropriate PWM control signals to the Brushed DC Motors to steer the Line Following Robot. The process of obtaining sensor data from the Reflectance Sensor Array and transmitting the corresponding motor commands to the Dual Serial Motor Controller repeats at a 20 Hz rate.

The Reflectance Sensor Array contains eight IR LED and phototransistor pairs. A capacitor is connected in series with each of the phototransistors. To obtain a reflectivity reading from the Reflectance Sensor Array, the microcontroller GPIO pins connected to the sensor I/O pins are driven high to charge the capacitors. Once the capacitors have been fully charged, the microcontroller switches its GPIO pins to inputs. With the microcontroller GPIO pins switched to inputs, the capacitors begin discharging through the phototransistors at a rate based on the reflectivity of the surface illuminated by the IR LEDs. After allowing an appropriate amount of time for the capacitors to discharge accordingly, the eight sensor I/O pins of the Reflectance Sensor Array are read by the microcontroller.

A white surface has a high reflectivity and will turn the phototransistor on. When the phototransistor is turned on, the capacitor in series with it will be allowed to discharge through the phototransistor. With the capacitor discharged, a low voltage will be present at the sensor I/O pin and will be converted as a logical zero by the microcontroller. In contrast, a black surface has a low reflectivity and will not turn the phototransistor on. When the phototransistor is off, the capacitor in series with it will not be allowed to discharge through the phototransistor. As a result, a high voltage will be present at the sensor I/O pin and will be converted as a logical high by the microcontroller. Thus, sensors detecting a white surface will return a logical zero and sensors detecting a black surface will return a logical one when the microcontroller reads the Reflectance Sensor Array.

Team Members & Responsibilities

• Kurt Breault II
  • Hardware Design
  • Driver Development
  • Software Design
  • Integration and Test
  • Project Documentation

Schedule

Show a simple table or figures that show your scheduled as planned before you started working on the project. Then in another table column, write down the actual schedule so that readers can see the planned vs. actual goals. The point of the schedule is for readers to assess how to pace themselves if they are doing a similar project.

The proposed schedule lists the tasks to be completed each week. The time frame for each task spans from a Wednesday to the following Tuesday. This time frame format was selected to facilitate project progress discussions with the professor at the end of each weekly lecture held on Tuesday.

Parts List & Cost

The table below summarizes the parts used and the cost for the Line Following Robot project.

Design & Implementation

The design section can go over your hardware and software design. Organize this section using sub-sections that go over your design and implementation.

Hardware Design

Discuss your hardware design here. Show detailed schematics, and the interface here.

Power Routing for the Line Following Robot

Signal Routing for the Line Following Robot

Breadboard Connections for the Line Following Robot

Chassis, Assembled Gearbox with Tires, and Ball Caster

Assembled Chassis with Gearbox, Tires, and Ball Caster

Battery Holder (4-AA with Switch) and Breadboard (170-point)

Assembled Chassis with Battery Holder, Breadboard, Headers, and Jumpers

Assembled Chassis and Brushed DC Motors with Capacitors and Wires

Assembled Chassis with Brushed DC Motors

5V Step-Down Voltage Regulator, Dual Serial Motor Controller, 3.3V Step-Down Voltage Regulator, and Pull-Down Resistor

Assembled Chassis with 5V Step-Down Voltage Regulator, Dual Serial Motor Controller, 3.3V Step-Down Voltage Regulator, and Pull-Down Resistor

Reflectance Sensor Array, Universal Metal Joints, 1.0" 2-56 Standoffs, and Hardware

Assembled Chassis with Reflectance Sensor Array

Upper Chassis, SJ One Board (LPC1758), 1.25" 4-40 Standoffs, 0.75" 4-40 Standoffs, 0.375" 6-32 Standoffs, and Hardware

Assembled Upper Chassis with SJ One Board (LPC1758)

Modified USB Mini-B Cable

Assembled Chassis and Upper Chassis with Modified USB Mini-B Cable)

Line Following Robot

Hardware Interface

In this section, you can describe how your hardware communicates, such as which BUSes used. You can discuss your driver implementation here, such that the Software Design section is isolated to talk about high level workings rather than inner working of your project.

Software Design

Show your software design. For example, if you are designing an MP3 Player, show the tasks that you are using, and what they are doing at a high level. Do not show the details of the code. For example, do not show exact code, but you may show psuedocode and fragments of code. Keep in mind that you are showing DESIGN of your software, not the inner workings of it.

Software Flow Diagram for Reflectance Sensor Array Initialization

Software Flow Diagram for Reflectance Sensor Array Read

Software Flow Diagram for Dual Serial Motor Controller Initialization

Software Flow Diagram for Dual Serial Motor Controller Transmit Byte

Software Flow Diagram for Dual Serial Motor Controller Transmit Command

Software Flow Diagram for Dual Serial Motor Controller Stop Command

Software Flow Diagram for Dual Serial Motor Controller Move Forward Command

Software Flow Diagram for Dual Serial Motor Controller Turn Forward Left Command

Software Flow Diagram for Dual Serial Motor Controller Turn Forward Right Command

Software Flow Diagram for Initialization of SJ One Board General Purpose LEDs

Software Flow Diagram for SJ One Board General Purpose LED Set Control

Software Flow Diagram for Display of Reflectance Sensor Array Data on the SJ One Board General Purpose LEDs

Implementation

This section includes implementation, but again, not the details, just the high level. For example, you can list the steps it takes to communicate over a sensor, or the steps needed to write a page of memory onto SPI Flash. You can include sub-sections for each of your component implementation.

Testing & Technical Challenges

Describe the challenges of your project. What advise would you give yourself or someone else if your project can be started from scratch again? Make a smooth transition to testing section and described what it took to test your project.

Debug of the IR LED Reflectance Sensor Array and Dual Serial Motor Controller Drivers with the SJ One Board (LPC1758)

Include sub-sections that list out a problem and solution, such as:

Wifi Connection Issues

Many wifi connection issues were encountered. To solve this problem, a dedicated task was created to re-connect to wifi if the connection was ever lost.

Conclusion

Conclude your project here. You can recap your testing and problems. You should address the "so what" part here to indicate what you ultimately learnt from this project. How has this project increased your knowledge?

Project Video

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Project Source Code

Send me your zipped source code and I will upload this to SourceForge and link it for you.

References

Acknowledgement

Any acknowledgement that you may wish to provide can be included here.

References Used

List any references used in project.

QTR-8A and QTR-8RC Reflectance Sensor Array User’s Guide

Low-voltage Dual Serial Motor Controller User’s Guide

Pololu Round Robot Chassis RRC01A User’s Guide

Video Tutorial for Crimping PCB Interconnect Cables

Appendix

You can list the references you used.